fuel pump rattle
 

I've had a CPE fuel pump for a while now (5-7k - haven't checked my records) and things have been great with it in terms of pressure.

After doing some logs yesterday I noticed a rattle only on throttle tip-in. It goes away quickly and does not make any noise at constant RPM.

I traced it down to the pump. It rattles when engine speed is increased suddenly (tip in) at low pressure (off idle).

Very similar to what was described here:
http://www.mazdaspeedforums.org/foru...17/#post111220

I don't have time to take the pump off tonight to inspect it - but has anyone had their fuel pump rattle on tip-in?

What was the cause? Wear? Cam follower?
What was the solution? Pump replacement?

My noisy pump video:


UPDATE - rattle identified:

OK boys and girls - here is the reason for the infamous CPE pump rattle.

Now, a little background. Remember that this metallic rattle happens as pressure is ramped up and a lot of the guys running CPE pumps for a while have this. Bova with a PG pump also has the problem.

The common denominator here unfortunately is the piston SPRING and button.

Below in Figure 1 shows the CPE pump on the left next to a no-name upgraded pump. There are 3 big differences.

1. The CPE pump uses the STOCK cam follower button. This is great because they don't wear out like aftermarket ones.

2. The CPE pump piston shaft is the same diameter from top to bottom. All other upgraded pumps that I see thicken the shaft only inside the barrell and leave it stock width in the lower section inside the spring. This is shown in Figure 2. The CPE pump shaft is thick from top to bottom.

3. The CPE pump therefore requires to use a LARGER diameter spring. The spring in Figure 1 on the left is different from the STOCK one reused with other internals on the right.

Figure 1
http://www.mazdaspeedforums.org/foru...e-cpe-pump.jpg

Now, the larger diameter spring is held at the top to a larger barrell shown by the red circle (1) in Figure 1. So the spring is well attached to the pump at the top of the pump.

However, here is where the design flaw is. At the bottom the push button is the STOCK one that does not wear out (Figure 1, blue circle (2)). It is of STOCK diameter. That means that the upgraded (larger in diameter) CPE spring does not grab onto this smaller diameter button.

The result is that after X number of miles, the push button becomes easily detached from the spring at the bottom. As the pump is moved by the cam follower, the push button RATTLES against the cam follower and spring when pressure is ramped up since it no longer is firmly attached to the spring. So that means the piston inside the pump is no longer dampened by the spring - in other words the spring is no longer doing its job and the system is underdamped.

This causes the annoying rattle sound and probably extra wear on the cam follower.

Unfortunately because of the thicker piston shaft and thicker barrel and spring attachment at the top, the stock spring CANT be used with a CPE pump - it does not fit at the top.

SOOO ... you are stuck with a rattling pump and perhaps more wear.

If you have an upgraded spring/CPE pump, check your cam follower for extra wear and get back to me (esp guys that ran them for a while). I am not sure what the long term effects are (if any). So it's important to see what the higher mileage cam followers look like.

CPE does not know of this issue when I spoke with Josh a few days ago he had no idea about the problem. Unfortunately the problem comes up after some miles when the smaller diameter push button becomes detached from that larger diameter spring.

Figure 2
http://www.mazdaspeedforums.org/foru...n-cpe-pump.jpg

my PG internals did this too when i had them.It only did it when i bliped the throttle. I think its just because of the increased pressure.i didn't notice any abnormal wear when i took them out.

you're gonna fucking blow

Damn, you're still around - good thing!

They did not do this when I initially put the pump in. Did yours do it from the beginning or as time wore on?

How many miles did you put on the pump with the rattle? Any damage to the cam follower?

Also now that i think about it,it made more noise when it was cold outside and when it was warmer it was a little less noisy.I doubt that has anything to do with it though.

I had them on for a while,i wanna say 20k(ish) miles.It did it a little bit after i installed them.Either i never noticed it or they had to 'break in'. The cam lobe was still shiny and looked normal.

Thanks Grim - something tells me it shouldn't rattle all of a sudden after not doing so for quite a few miles.

my mr lil guy did it from day one. i think its a combo of the pump and noisy ass injectors

My Mrlilguy pump is quite noisy as well, but I always remembered my stock one doing the same thing.. maybe I'm imagining things.

my upgraded pg internals have done it for well over 15k miles and they still run like a champ. Had them installed in nov of 08. I always noticed i had the noise then i diagnosed where it was coming from last summer and well its still here and my fuel pressure still holds great. really noticeable when you are in a drive-thru or somewhere where you can here the noise a little better. i was going to put a video camera under there and record it.

I'm taking the pump off in a day or 2 to inspect. CPE was very quick to respond to my inquiry and if I there are any issues it will be covered.

Here's a video I took of my "rattle" at tip-in. I took the pump out this weekend and all looked very good - no signs of wear visible to the eye.

Does everyone's "noisy" pump sound like this?

Sounds like the spill valve solenoid cycling to me. The camshaft follower and piston are always in motion the same, so if there was a problem there it would be a constant sound. The only thing that changes on throttle tip-in is the solenoid first energizes to cycle the spill valve open/closed to bring the pressure up. It cycles on and off very quickly and that's likely what you're hearing. The spill valve cycles 3 times per camshaft revolution, but the cam rotates at 1/2 crankshaft speed so the noise count sounds within range. I can't say for sure why you can actually hear yours, but mine is silent...? I did my own pump w/KMD internals and it's been perfect for at least 5k miles. I didn't remove the solenoid section of the pump though, so it is still the OEM assembly. I suppose yours (and others with the noise) could be extra clearance or slight damage/wear in the spill valve solenoid/plunger area...? If the spill valve is closing off to build pressure and yours is still in the "good" pressure range, then the noise issue may be of no consequence. Please let us know what CPE has to say about it.

thats how mine sounds ( i didn't install the internals, got the whole pump from PG), or at least its pretty similar. i'll have to see if i can record it tomorrow so we can compare.

I don't agree with that diagnostic. To me it sounds like the cylinder to bore clearance is too large. Similar to what piston slap sounds like. As pressure is commanded higher on tip in the pressure on the piston inside the pump increases and causes it to rattle against the walls of the bore.

The pump was OEM silent for about 4k - this is a recent development. Pressure holds the same as it did when the pump was new.

My PTP pump is noticeably louder than stock but it makes a constant ticking sound. It's never made a rattle like in your video. Hope this helps. Let us know what CP-E has to say. Did you send them a link to your video?

I hear a little rattle sounds like metal hitting at intervals in that video.

That is no where near normal

well mines been making that noise at tip in for over a year and i haven't experienced anything different so to me its normal. and the only reason its in intervals is because he is either giving it slight gas or moving the steering wheel which will cause slight tip in.

Exactly correct. There is a rise in pressure that causes the noise. There is no damage on the pump what so ever to the naked eye when I pulled it out 2 days ago.

I have sent CPE the video link so I expect they will get back to me tomorrow.

will be interesting to see if they know the problem. but the fact that you are experiencing it on a cp-e pump and i'm experiencing it on a pg pump eliminates some ambiguity as well as the fact that they are still operating normally.

for some reason i have a feeling mine does this but i cant say for sure.

to test it, next time you are in a drive thru line next to the building just turn your steering wheel a bit and listen for the rattle. or while parked stick your head out the window and listen while you turn it a bit.

I dont know, Forzda might be onto something. I believe the pumps internal relief valve is a piston type design, it could be that it is wearing prematurely. I wouldnt throw his idea out quite so quickly.

Do you have a stock spring or the upgraded spring with less windings? Mine did this after some high RPM runs. Maybe the spring became deformed/shortened and it's not pushing the piston to the bottom of the stroke quickly enough.

hmm, i am pretty sure its an upgraded spring. but i'm not sure, since i just ordered a whole pump from PG back in Nov of 08.

CPE says it doesn't sound normal but Josh doesn't know what it is. However, I am not inclined to think it has something anything to do with the internals since they looked good. Either the spring or relief valve. Wish I had a good enough microphone to do a frequency spectrum analysis on the noise.

Bova, post up your sound clip.

alright i'll go see if i can record it with my iphone and upload it to youtube.

ok so i went out and did the video, but it is not as noisey when the car is cold. but i think you can still here it a little bit when i rev, wasn't doing it when i turn the wheel. i can do another video after work this evening once i get home. most of the noise is just the injectors though, so i'll have to make another video after it warms up.

Thanks for the video. Mine is also gets louder after the car has warmed up a little.

Bova's sounds similar to me.

When the spill valve closes to build more pressure, that would put more downward pressure on the piston, right? And possibly exaggerate or cause the tappet noise from a weak / short spring?

I know we hear the noise on tip-in, but does it continue as long as the fuel pressure is high?

Does mine sound like yours? I hate having no local speeds in my area!

The rattle only happens at tip-in. If fuel pressure is steady the pump is silent.

I wouldn't know, hahahaha


Plus i only have like 1000 miles on my cp-e pump as of now. When i get up and running i'll definitely to a listen test for you.


Maybe it's only on tip-in because it rattles during the time that the rail is being pressurized. Like once the rail is pressurized, that pressure helps steady the piston. And at idle, maybe the spill valve duty cycle is sufficient to maintain some pressure on the piston. But during tip-in, spill valve is shut, and rail pressure is initially low, so perhaps it allows for a bit of slop.


Not sure. And it could possibly take thousands of miles for wear indications to show up.

Well mine's been on for around 4k miles.

Anyone else with similar experience?

mines been in for 15k miles. and when my motor is warm it sounds more like what lex recorded, which i'll record again tonight after i drive home. but i believe its only at tip in cause i remember trying to diagnose this issue last summer and i was very keen on listening to it.

Yup same as you. So what made you think there's no issue?

i had talked to ken about it and he said as long as the pressure is holding and there were no other issues it shouldn't be a problem and if pressure began to drop he would replace it. but my car has been running awesome so i just put it to the back of my mind much like KR at partial throttle.

here is a better video, its pretty distinct now. i was just turning the steering wheel a bit to get the slight tip in as mentioned before.

^ Sounds exactly like mine does so it's like the same root cause. You mentioned this has not given you any problems and was there from day 1. Hmm. Hasn't given me issues either and I kinda dread sending the pump back.

I'm thinking with experimenting switching the stock spring in there.

Where is everyone else that mentioned this noise??

yeah pretty sure its always been there and i haven't had any problems. fuel pressure holds strong in the 1700-1900 range at WOT.

Does the CPE pump have a different spring? Their web site doesn't state so. PTP either....?

Yes, the pump comes with a higher rate spring than stock according to CPE. It has fewer windings than the stock one.

I am pretty sure this is the spring:

Protege Garage - High RPM High Pressure Fuel Pump Spring - Mazdaspeed 2.3 DISI

I wasn't aware of this in the CPE pumps, I thought it was a separate deal to install. The CDI info says you will likely get increased cam lobe wear form the spring. Do the PTP pumps have it as well?

IMO there just isn't enough clearance in the piston/sleeve junction to allow such a clatter as I heard on the clips. I still say it is related to the solenoid action and the spill valve response under the high pressure. It still could be related to the spring tension causing the noise source reaction...

I'm still trying to find the cutaway drawings I have seen of the HPFP that clearly shows how the spill valve opens/closes to fill the pump cavity and cause it build the high pressure required.

The intriguing thing is that this happened after some high RPM runs. I did not measure the spring on the CPE pump but what if it was slightly deformed?

The cam follower looks new with no marks.

By the end of the weekend I will try the stock spring on the CPE pump and rule that out.

Please post when you do :)

http://www.hitachi.com/ICSFiles/afie...4_04_103_1.pdf

This isn't the one I remember, but it gives some idea of how it works. The pumps on our cars is a are later version and only a bit more complex, but the basic principle is the same. The solenoid action controls the amount of fuel allowed into the pumping chamber, so IT is the key to pump/pressure control...

Could very well be the solenoid. I will eliminate the parts 1 by 1 and this should provide some answers.

UPDATE:

Swapped the solenoid as well as the turret, spring, and small push button inside the pump from the OEM one to the CPE one. These are all the parts at the top of the pump where the solenoid screws in and they control the pressure. FORZDA, this was for you buddy!

The CPE had more miles on the core and the tiny spring inside was a little softer. Nothing to really write home about though. I only got to test briefly this evening after fucking around with it but it appears the noise is still there. Will know more tomorrow after some more miles on it.

If it's not it, I am trying the OEM piston spring I said I would try in the first place. IF that still doesn't fix it, I am putting the stocker back in and sending it CPE. After all, I paid good money for that pump.

EDIT: Swapping out the solenoid and pressure control mechanism did nothing for the noise. It's still there - same as before.

Didn't you just void your cp-e pump warranty by messing with it??

I think you are a little under the influence of how OEM/Mazda warranties work.

If anything, I did some legwork for CPE and am helping the community understand the issue.

On top of this, CPE does not touch the solenoid of the pump. It is simply reused from an OEM core pump. They swap out the internals and spring and test the pump.

FWIW, I have the same issue on my CP-e pump.

my cpe pump makes the same noise, i have my stock pump on now, and that rattle isnt there.

8.5MS3 and vtb101 - how many miles did you have on your pumps? Did it start losing pressure over time?

8.5MS3 - how come you pulled the CPE pump off?

I got the pump used with about 10k on it (i think the serial number is 0056). It doesnt hold 1800psi, at least not for me. just rock steady between 1680 and 1750.

I pulled the pump since my turbo started smoking and stocked out for a dealer visit.



Jake - im gonna stay stock until i can get this bitch to smoke again. so the pump will be sitting in my garage unused in the meantime. if you need one for testing or whatever i can send it your way

glad to see there are others with this issue.

funny thing is i initially thought it was my tensioner or something. every time i get off idle it rattled for a split sec, then goes away (or gets drowned out by engine noise) not sure which.

now that im stock it doesnt do it anymore

I am going to change to the stock piston spring and leave it alone until things get worse. I am really starting to think it's the piston to bore clearance. Once some coating wears off, the pump becomes noisy.

I wonder how much fuel gets by the piston and mixes with the oil with a looser clearance.

At least I got to see how all the parts look inside first hand.

Yeah, everytime you increase pressure quickly it will rattle regardless of RPM but you have to really listen for it.

mine is lound but doesnt make that rattle.... good thread, ill keep an eye on mine.

UPDATE - rattle identified:

OK boys and girls - here is the reason for the infamous CPE pump rattle.

Now, a little background. Remember that this metallic rattle happens as pressure is ramped up and a lot of the guys running CPE pumps for a while have this. Bova with a PG pump also has the problem.

The common denominator here unfortunately is the piston SPRING and button.

Below in Figure 1 shows the CPE pump on the left next to a no-name upgraded pump. There are 3 big differences.

1. The CPE pump uses the STOCK cam follower button. This is great because they don't wear out like aftermarket ones.

2. The CPE pump piston shaft is the same diameter from top to bottom. All other upgraded pumps that I see thicken the shaft only inside the barrell and leave it stock width in the lower section inside the spring. This is shown in Figure 2. The CPE pump shaft is thick from top to bottom.

3. The CPE pump therefore requires to use a LARGER diameter spring. The spring in Figure 1 on the left is different from the STOCK one reused with other internals on the right.

Figure 1
http://www.mazdaspeedforums.org/foru...e-cpe-pump.jpg

Now, the larger diameter spring is held at the top to a larger barrell shown by the red circle (1) in Figure 1. So the spring is well attached to the pump at the top of the pump.

However, here is where the design flaw is. At the bottom the push button is the STOCK one that does not wear out (Figure 1, blue circle (2)). It is of STOCK diameter. That means that the upgraded (larger in diameter) CPE spring does not grab onto this smaller diameter button.

The result is that after X number of miles, the push button becomes easily detached from the spring at the bottom. As the pump is moved by the cam follower, the push button RATTLES against the cam follower and spring when pressure is ramped up since it no longer is firmly attached to the spring. So that means the piston inside the pump is no longer dampened by the spring - in other words the spring is no longer doing its job and the system is underdamped.

This causes the annoying rattle sound and probably extra wear on the cam follower.

Unfortunately because of the thicker piston shaft and thicker barrel and spring attachment at the top, the stock spring CANT be used with a CPE pump - it does not fit at the top.

SOOO ... you are stuck with a rattling pump and perhaps more wear.

If yo have an upgraded spring/CPE pump, check your cam follower for extra wear and get back to me (esp guys that ran them for a while). I am not sure what the long term effects are (if any). So it's important to see what the higher mileage cam followers look like.

CPE does not know of this issue when I spoke with Josh a few days ago he had no idea about the problem. Unfortunately the problem comes up after some miles when the smaller diameter push button becomes detached from that larger diameter spring.

Figure 2
http://www.mazdaspeedforums.org/foru...n-cpe-pump.jpg

Note to self, buy a ptp pump.

interesting...although i dont know that i feel like taking my pump out, lol. i hate messing with stuff when my car is running good.

While your car may be running well, there's clearly an issue. It shouldn't make that noise.

OP updated with findings.

but like you said there is nothing we can do about it. ok so maybe i'll look at mine if i get a free moment. what is it i do again to get the fuel out of the lines going to it, which fuse gets pulled?

wonder if cp-e is gonna chime in here. ive got their pump with almost 15k miles sitting in a box if they wanna tear into it and check for damage.

Don't worry about pulling fuses it's not required. Just let the car cool off for a few hours.

The only damage you may see (if any) is on the bottom of the push button or on the cam follower. I am discussing this with CPE as we speak.

alright i just gotta find my torx bit i bought for when i did it the first time. probably won't get to it this weekend though. maybe sometime next week.

well i only had it on the car for about 1-2k miles, so i dont think im gonna have any glaring damage, ill take a look at the pump when i get off work tho, see if anything looks worn

Well for sure not a CPE....

Shouldn't there be constant pressure against the button at all times? Even if it's not attached to the spring as it should be?

Is the rattle coming from the button moving from side to side within the spring, rather than bouncing between the spring and tappet?

Yeah, IMO, the button is allowed to "wallow" around and MAY be rattling against the cam follower itself? That would be my guess...

Then stiffer spring may be the cure all, right?

Hmmm, could be, but then you might run into impact/wear issues (oil film strength) with the cam follower and camshaft lobe(s). The spring should already have a higher rate as the piston design appears much heavier than OEM. I remember reading all about the piston design/weight, spring tension, etc. on one of theses forums a while back.... Dang it sucks to get old!

FORZDA, you nailed it.

The spring becoming separated from the retainer (button) does not dampen the motion of the piston and you get the rattling noise. This explains why it first happened after some high RPM runs.

Let me make something clear. I DO NOT KNOW what damage it may cause. It may imapct/wear the follower, it may not. I don't think anyone knows unless they put many miles on the car and pump. This is not a VW and the follower is hardened.

CPEs quality has been the best in the aftermarket for Mazda. I really do applaud them for that and making parts that don't fail like most aftermarket ones do. This is WHY I bought their pump in the first place. This is not a shot at CPE. This is an observation of the pump I have and what others have noticed with the larger diameter and higher rate spring using the stock retainer.

Don't bring competitors in here such as PTP. Fact is that CPE has had less internal failures than anyone else out there.

It would be very good to see what the followers look like from people that have ran a rattling pump for thousands of miles. This might shed some light on the issue. If it's just a noise, I am sure we can all live with that. If impact wear happens then maybe it has to be addressed.

Bova.... i think you need to get to it this weekend :)

It'd be a great example of wear from this type of rattle, even though your pump isn't the exact same setup as Lex's.

This is DAMN TRUE.

My guess is this rattle won't be an issue, especially if bova's been rocking the rattle for thousands & thousands of miles already.

Little bit of noise from upgraded pump is nothing considering that upgraded pump will likely last the life of the car, requires no suspicious break-in period or seizing episodes, and comes with a full lifetime warranty.

IMO cp-e pumps are hands-down the best option.

Can you check the seat pressure of the two pumps, I was thinking about it and it sounds like the CPE spring is too short.

Set side by side, OEM and CPE springs are same length.

Thats not a measure of a spring being too short. Whats the installed seat pressure? That spring is thicker with one less coil.

ok question i was thinking, why does it only occur after the car warms up? i would think that when metal gets hot it expands so if what is said is true wouldn't that tighten the tolerances?

When you first start the car the pressure is held high by the ECU. When pressure is constant you don't get the noise. It only happens when pressure is ramped up quickly.

How would I measure this?

Thats why I think there is a spring measurement that is wrong, it kinda clicked last night when I was thinking about it. The spring is moving on the retainer. I am betting there isnt enough seat pressure, even though the spring is heavier, because the spring isnt long enough to be compressed to such a length to reach a point where the spring actually has more seat pressure to dampen the heavier piston.

A cheap way would be to measure the installed spring length of both springs, then take the springs out of the pumps, put them in a vice with a bathroom scale and tighten them down until you reach the same installed length.

Longer or stiffer spring should help, right?

Or could you use a shim between the button and spring bottom to compress the spring a bit more?

How much of that piston goes into the pump when fully depressed by the cam? Like how deep does the piston go into the pump?

If we have some extra length between the spring installed height and the bind height vs the lift of the cam lobe, a shim would likely fix it.

We'd have to know the cam lift to have an idea about this. It's not simple to measure or even tell how deep the piston moves or how much the spring is compressed when the piston is fully out. Although with some calipers you can get an idea - just have to be able to turn the motor slowly (by hand).

If trying a shim, I would only try it at the top of the pump, not at the retainer at the bottom. The shim can't too thick or the spring will pull off the top as well and you definitely don't want that.

What would have caused the noise to start "all of a sudden." I have a hard time believing the spring deformed or shortened during a run. Only plausible thing is that the bottom retainer slowly wore loose.

I agree with Lex here. If the spring did/doesn't fit VERY snugly to the OD of the retainer raised section, it WILL vibrate in use and cause wear on either the retainer and/or the spring ID itself. I would expect to see the wear if you removed the keeper and spring to inspect them at the retainer end.....


The HPFP is a high-speed precision-clearanced device. There is a plethora of failed attempts to create what we have today. EVERY attempt has met with several failures before any sustained success. A thorough web search provides tons of information on inventions/patents, etc. trying to develop/improve upon the design. Ours is a single piston design, but there are several mutli-piston HPFPs in use as well.....

There is wear on the spring seat at the retainer from the spring not fitting snugly and moving against the retainer. I wish I snapped more pictures.

The question is - where do we go from here?

At first look, I think CPE should produce a retainer with the correct ID to support their larger piston/spring OR use a piston/sleeve combo closer to those used by the "other" kit suppliers with OEM spring. The OEM spring has proven to be just fine in supporting the larger capacity piston. The further we get from the OEM design, the more problems we'll have. IMO, the aftermarket (even at CPE prices) just doesn't have the resources to adequately test/develop this part........

It's true with most aftermarket parts. This is especially difficult to produce due to the tolerances and design. It's a complex part as you mentioned. One thing to make a downpipe and another to make an HPFP.

So you're right, either redo the retainer but it has to be done to OEM spec or it will fail like the competition.

Or reuse the stock spring. That means the top mount and perhaps the piston itself will have to be redesigned like the competition with just the top of the piston being thicker.

Sure, people can opt for one of those from someone else but I've read WAY too many stories of seized pumps.

On top of that - the piston that is only thicker at the end suffers from less lateral support in the bore. This causes more lateral forces on certain parts of it leading to scuffing and ultimately failure. There's a reason the stock piston is the same diameter throughout. The CPE pump is closest - it's just the detail at the retainer.

If the spring is worn at the retainer then ide say we have our answer, I had been thinking that it wasnt worn lol.

I bet they can design a new retainer that uses the OEM button.

I've heard that before.

Thanks for updating the OP. This is good info.

We don't have an upgrade for the spring right now. We have not seen a reason to add the spring due to anyone being able to confirm that the OEM one is not up to the job.

Fewer windings, it must have a larger diameter wire? If I were to build a custom wire spring it would have the same amount of windings, but with a higher tension wire to increase the spring tension.


How does the lateral laoding happen? The piston cup that rides on the cam follower can only move up and down, there is not lateral loading at the push end of the pump, so if the pump is not being pushed laterally how could is all the sudden be getting lateral loads in the pump?

What do you want tested? We are 4 to 6 weeks out on having our own testing staition ready for the pumps. Let me know what you want tested (post in our section) and we will get to it0.

Bova, any progress on checking out the cam follower?

yeah i'm a slacker, i'm still trying to find my e8 torx

Hahahahaha... Keep looking, its around there somewhere.

Lex, does your pump rattle when you are idling and you turn the steering wheel left to right? My PTP pump started making a similar rattle on initial throttle application from a 700 RPM idle or causing the power steering to kick in while idling.

It holds pressure fine, and the problem isn't always reproducible but I have noticed it. This does have me slightly concerned.

Yup, it happens when there is a pressure spike. So turning the steering wheel or tipping in causes it.

I can hear mine in any gear if I coast at low enough RPM and just tap the gas. There's a quick rattle as pressure builds.

mine has done that from day one, mr lil guy pump

So I guess it's an annoyance, but it's still safe to drive around like this right?

more or less yes. i found my e8 torx bit but haven't found the time to take the pump out. maybe tomorrow.

Do it bova! Mine's been rattling since I started this thread. Pressure is fine - rattle is the same.

I hear mine now...in fact I've heard it way before and thought it was the axle...thanks for all the work Lex! (again!)

my pump is definitely high mileage...but pressure is good, for now.