Leak down test, need your thoughts

[Will]

I obtained a donor motor and was performing leak down test. The results were not promising. I'd like some input/suggestions from what I thought was a weird observation.

I'm noticing when the cylinder is pressurized via the leak down gauge/compressor that air is coming out of the hole at the edge of the exhaust port (red arrow in photo, below); I presume it's the outlet port for the secondary air pump into the exhaust path. Do you think the cylinder is head cracked and leaking air into the passages that end up to be the outlet port(s) for the secondary air pump?

Also, for cylinder 6, I was able to achieve 2% leak down on 2 out of 10 tries, every other time it shows 68% leak down. This included removing the gauge from the cylinder and reinstalling it, and it included rotating the engine over multiple times to get TDC. Air also seems to be leaking from the aforementioned port as well. What's up with that?

It might be that I'm not doing something correctly, please help with some guidance. Thanks.

I've attached a photo from the thread on e46fanatics with the dissected m54 head (https://forum.e46fanatics.com/showthread.php?t=711732) (red arrow in photo, below):

31935

[ZHPizza]

were you putting a bit of oil into the cylinder to help seal the rings?

[slater]

were you putting a bit of oil into the cylinder to help seal the rings?

Good call.


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[Will]

Nope, but will do! Thanks.

[ZHPizza]

Nope, but will do! Thanks.

Should help you get consistent results for sure. I don't know if he did it in this video, but here ya go:

https://www.youtube.com/watch?v=svlwuhK0IIU

[Will]

Well, I re-checked the leak down and here are the results:

Cyl. 1: 66%, air expelling from spark plug holes #2 and #3;
Cyl. 2: 12%, air expelling from spark plug hole #1;
Cyl. 3: 4%; no noticeable air from other plugs (weird considering results of cyl. 1)
Cyl. 4: 6%; no noticeable air from other plugs (weird considering results of cyl. 4)
Cyl. 5: 67%, air expelling from spark plug hole #6;
Cyl. 6: 70%, air expelling from spark plug hole #4.

These values were calculated by subtracting the gauge reading from 100 psi (e.g. in cylinder 1, gauge reading was 34 psi, thus 100 - 34 = 66%).
Smoke was used to visualize the airflow, if any, from spark plug holes in the other cylinders.

Background:
- Engine has 72k miles (mileage is corroborated by carfax of original VIN, car was involved in right sided accident)
- Complete with intake manifold, coils, harness, relays, injectors, flywheel
- leaking front crank seal, and aforementioned poor leak-down results
- I haven't pulled the engine from my car yet, but coolant was sprayed out of some spark plug holes in addition to low compression results for a few cylinders


I contacted the seller, and the options are:
1) refund me 100%, but I pay return shipping (out-of-pocket est. $300-350, I think); or,
2) partial refund and keep the engine and rebuild myself, out-of-pocket for the engine will be approximately $800 thus far.

I'd appreciate any thoughts you may have, either via reply to this thread or via PM. Thank you.

[slater]

Well, I re-checked the leak down and here are the results:

Cyl. 1: 66%, air expelling from spark plug holes #2 and #3;
Cyl. 2: 12%, air expelling from spark plug hole #1;
Cyl. 3: 4%; no noticeable air from other plugs (weird considering results of cyl. 1)
Cyl. 4: 6%; no noticeable air from other plugs (weird considering results of cyl. 4)
Cyl. 5: 67%, air expelling from spark plug hole #6;
Cyl. 6: 70%, air expelling from spark plug hole #4.

These values were calculated by subtracting the gauge reading from 100 psi (e.g. in cylinder 1, gauge reading was 34 psi, thus 100 - 34 = 66%).
Smoke was used to visualize the airflow, if any, from spark plug holes in the other cylinders.

Background:
- Engine has 72k miles (mileage is corroborated by carfax of original VIN, car was involved in right sided accident)
- Complete with intake manifold, coils, harness, relays, injectors, flywheel
- leaking front crank seal, and aforementioned poor leak-down results
- I haven't pulled the engine from my car yet, but coolant was sprayed out of some spark plug holes in addition to low compression results for a few cylinders

bummer. sounds like maybe a bad headgasket....which could be the result of overheating, possibly warped head. the worst part is... you installed it before finding this out. major suckage.




I contacted the seller, and the options are:
1) refund me 100%, but I pay return shipping (out-of-pocket est. $300-350, I think); or,
2) partial refund and keep the engine and rebuild myself, out-of-pocket for the engine will be approximately $800 thus far.

I'd appreciate any thoughts you may have, either via reply to this thread or via PM. Thank you.

how much did you pay for shipping at this point? total cost of engine? what is the partial amount?

if the head is warped, it's going to be a lot more involved than just replacing a headgasket.

i actually have a spare M54 head, come to think of it...

[Will]

bummer. sounds like maybe a bad headgasket....which could be the result of overheating, possibly warped head. the worst part is... you installed it before finding this out. major suckage.




how much did you pay for shipping at this point? total cost of engine? what is the partial amount?

if the head is warped, it's going to be a lot more involved than just replacing a headgasket.

i actually have a spare M54 head, come to think of it...

Hi Peter,

I tested the donor engine out of the car on an engine stand. There's no way I'd go through the headache of removing and replacing an engine before knowing that it's good and after all the gaskets and other maintenance items have been performed. It's nice to be able to replace an oil pan gasket, for example, while I'm standing up and rotating the engine on the stand... sure beats the last time I did one, on my back with the car on jack stands.

It was a $300 gamble on my part which is the approximate price of return shipping and my total out-of-pocket expense for this engine. The seller and I agreed, prior to purchase, that he'd refund me my entire purchase price (which included shipping from him to me) on the condition that he'll accept a return within 60 days if I paid return shipping. I had mentioned that the only reason I'd return it is damage, and/or failed leak-down test. It seemed like a fair deal, so I took the gamble. I was hoping that the 72k mile engine from a 2006 would minimize the heat-damaged head/head gasket, and felt that at worst it'd cost me time and return shipping. It's a shame it didn't work out, it would have been a slam dunk. I was surprised the seller was keeping his word, my pessimism led me to believe he'd just say "tough-luck, sorry."

The original engine in my car is still in the car, I haven't pulled it yet. I'll do that next week. Once pulled, I'll start disassembling it to assess the damage. I'm thinking the head is trashed - this was the motor I was referring to, in my post above, that was spraying coolant from the spark plug holes during compression testing.

My initial guess is at a minimum I'll have to get a cyl. head and do some Timeserts for the block. I'm in the initial phase of planning the engine rebuild from a cost/benefit ratio - I have a habit of scope-creep (a.k.a "While I'm in there..."). I'd like to address the piston-rings (oil control ring) problem if it's not too costly. Research continues.

Any suggestions, advice, sage-wisdom, from experienced members are welcomed and much appreciated. And, I'll PM you about the cylinder head.

[slater]

Hi Peter,

I tested the donor engine out of the car on an engine stand. There's no way I'd go through the headache of removing and replacing an engine before knowing that it's good and after all the gaskets and other maintenance items have been performed. It's nice to be able to replace an oil pan gasket, for example, while I'm standing up and rotating the engine on the stand... sure beats the last time I did one, on my back with the car on jack stands.

ahhh... that makes more sense. OK, i was unclear based on your wording, but that makes good sense now. :)

agreed on the oil pan gasket - i just did mine a few months ago, also on a stand. sooooo much nicer to work on an engine on a stand! :)



It was a $300 gamble on my part which is the approximate price of return shipping and my total out-of-pocket expense for this engine. The seller and I agreed, prior to purchase, that he'd refund me my entire purchase price (which included shipping from him to me) on the condition that he'll accept a return within 60 days if I paid return shipping. I had mentioned that the only reason I'd return it is damage, and/or failed leak-down test. It seemed like a fair deal, so I took the gamble. I was hoping that the 72k mile engine from a 2006 would minimize the heat-damaged head/head gasket, and felt that at worst it'd cost me time and return shipping. It's a shame it didn't work out, it would have been a slam dunk. I was surprised the seller was keeping his word, my pessimism led me to believe he'd just say "tough-luck, sorry."

OK, very cool - you're definitely covering your butt here. nice work! i hope the return process goes OK.



The original engine in my car is still in the car, I haven't pulled it yet. I'll do that next week. Once pulled, I'll start disassembling it to assess the damage. I'm thinking the head is trashed - this was the motor I was referring to, in my post above, that was spraying coolant from the spark plug holes during compression testing.

gotcha. curious to see what you find - please post pics if you can!



My initial guess is at a minimum I'll have to get a cyl. head and do some Timeserts for the block. I'm in the initial phase of planning the engine rebuild from a cost/benefit ratio - I have a habit of scope-creep (a.k.a "While I'm in there..."). I'd like to address the piston-rings (oil control ring) problem if it's not too costly. Research continues.

sounds like a good plan. i'm also guilty of "while i'm in there" - it's a double-edged sword, for sure. if you have the means, it's worth it for the time savings. but there is definitely a fine line of going to far. ;)

re: the oil control rings... are you just going to replace them with new OE M54 rings? i'm not aware of an aftermarket solution.

[Sockethead]

Most of the work in rebuilding the engine is going to be the head/cams, setting up the timing, etc. by the time you have all of that off, it's not going to be that much more work to replace the rings and bearings (which myself, I would do because it would bug the shit out of me that I was that far into the engine without doing that) The end result is peace of mind of a completely refreshed motor that runs great and should last a very long time

[Will]

...
curious to see what you find - please post pics if you can!
...
sounds like a good plan. i'm also guilty of "while i'm in there" - it's a double-edged sword, for sure. if you have the means, it's worth it for the time savings. but there is definitely a fine line of going to far. ;)

re: the oil control rings... are you just going to replace them with new OE M54 rings? i'm not aware of an aftermarket solution.

I'll post some photos as I get them, I've always enjoyed perusing the forums and appreciate those who include photos with their posts. I figure I'll start a new project thread when I do.

In regards to the oil control rings, I'm still undecided. But, it seems like new OE rings would be most cost effective for the goal of a refreshed daily-driver that provides peace-of-mind. I've noticed the same thing you've mentioned, options appear limited to new pistons with rings and conrods (e.g. CP or JE and Arrow or Carillo). Seems kind of excessive to replace pistons (~$1000-1100) and rods (~$1100) to fix the oil consumption issues known of the m54. At those prices I'd rather rebuild my s14 to get that thing running.




Most of the work in rebuilding the engine is going to be the head/cams, setting up the timing, etc. by the time you have all of that off, it's not going to be that much more work to replace the rings and bearings (which myself, I would do because it would bug the shit out of me that I was that far into the engine without doing that) The end result is peace of mind of a completely refreshed motor that runs great and should last a very long time


Agreed. Besides the machining work and timing, it appears that the rest would be relatively straight forward "wrenching," and adhering to torque/torque+angle, and clearance parameters. For the top end, I'm thinking at a minimum valve job and new valve seals (in addition to machining), and for the bottom end: rings, rod bearings, rod bolts (if they aren't spec'd to be reused), gaskets/seals at a minimum. I haven't read much about the main bearings being an issue for the M54, I know they're typically not a problem in the s54.

Right now, my plan is first to pull the engine and start disassembly. Then inspection for cracks and measurement of straightness (head and block), as well as continued research for options and solutions (e.g. machining, tolerances, torque specs, parts). Also, I'd like to find a machine shop in southern California (Orange County, specifically, but would venture out to LA County) that has experience with BMW heads/blocks (ideally with the m54).

As always, I'm open to your perspectives as well as any guidance and advice from your experience.