Just had pressure test done

[Avus///M3Girl]

here are our numbers. (my and my boyfriends M3's.)
Both our cars have high mileage- but my mechanic told me to try adding some recovery stuff to my oil, and even trying better oil im not totally sure if i want to deal with this...

here are both our numbers:

'96 m3 w/ 98k:

Cyl:
#1: 175 psi
#2: 120 (went up to 160 when added oil to cyl)
#3: 120 (" 150)
#4: 175
#5: 175
#6: 120 (" 160)

'95 M3 w/ 113k:
Cyl:
#1: 120 psi (didnt go up w/ oil)
#2: 150
#3: 150
#4: 100 (150 w/ oil)
#5: 125 (175 w/ oil)
#6: 175

Now, does anyone know if these are bad? At this point I might just go with the 325ic and not deal with this.. help!

[psk145]

I dont think those numbers are that great. My compression test had 200 psi in 4, and 195 in the other 2. I've also got 108K miles.

I think the key is to look for consistant numbers

[UD///M]

I have an average of about 197 across all cylinders. Max deviation is probably +/- 3.

Avus, your numbers would indicate to me that you may have bad rings and valve seats. The the increase in pressure with the addtion of oil says rings. The oil will not have any effect on leaky valves.

[Jim O.]

Sorry, but the numbers don't look very good. 120 is awfully low, and there's a lot of variance between the high numbers and the low. If I remember correctly, having the compression go up when you add oil to the cylinders means that the rings are leaking - if there's no change, then it's something in the head, like the valves or a head gasket.

This looks like quite a lot of wear for not too many miles - many M3s are around the 100K mark and still running strong. So, it sounds a bit strange, especially since both of your cars are showing that much wear. How trustworthy/competent is your mechanic? Might want to get a second opinion here...

Otherwise, out of curiosity, how did you maintain and use your car? What type of oil, weight, and how often do you change it? Short drives or long?

Jim

[UD///M]

Originally posted by Jim O.

Otherwise, out of curiosity, how did you maintain and use your car? What type of oil, weight, and how often do you change it? Short drives or long?

Jim


Enquiring minds want to know.

[gerry_miranda]

Two M3's with bad compression numbers from the same people...
Its either a bad maintenance practices or the compression tests was done wrong...I'm assuming theyre done by the same place and mechanic...get a second set of test from somewhere else....

[Avus///M3Girl]

Well, the problem is that we just bought both M3's recently. Ive only had mine for 1,000 miles, my boyfriends only had his for 5-6k. I also dont trust the guy who performed the test. But you know they both were supposedly "highway driven cars" but who knows. We even had both checked out by a real bmw mechanic. A strange combination of events.
But, were not going to sell my M3. The plan is basically, Im going to keep the 325ic considering the low mileage. Ive owned it for most of its life. We do maintain our cars ourselves and take all measures to ensure that our cars get good treatment. My b/f is really pissed he didn't save the $50 bucks from the compression test and buy his own damn compression tester for $49 bucks :mad:
So, my b/f is going to have the Avus M3 taken for a true leak down test by an excellent mechanic. Then, if the engine needs rebuilding he will do it (which we doubt) and keep it considering he loves '95 M3's (OBD I, 3.0L, suspension, steering - and his first M3 was a '95). He doesn't trust the numbers the other guys gave us. I have a feeling there both very WRONG (the guy doesn't really work on Bimmers's, we just needed it in a rush).

So now were going to sell the Silver m3. Not because the results were bad, just because it is worth more right now. Plus, I really think the real compression results would be much better.

Anyhow, its for sale..lol.. and it looks like everything will work out.

(if anyone would be interested email me: '96, Arctic Silver, 98k, Dove sport interior, 5-spd, have ALL records from day 1, (the guy b4 us was super anal- I have about $20k worth of records from BMW - (which was why we were so surprised at the results), original window sticker, etc....)I can email you records b/c there all on file...and if it means anything he bought a Toyota MR2??? who knows?....) Thanks guys and even though Im going to have to change my name :( I will still visit - for my b/f of course !!

[BMWguy206]

I would have a cylinder leakdown test performed to get an idea where the leak is coming out. The rings, valves, or gasket etc.

[EuroKRN]

How much does it normally cost to do a compression test? leakdown test? Never had one done before. I'm only at 47K miles so it's not a big deal.

[Avus///M3Girl]

The compression only costed us $40 for both cars - but the guy didnt really do it right.
The leak down will be a few hours labor, about 3 hours I suppose. It all depends on who you go to and the rate they charge.
But at 47k I wouldnt worry :)

[EuroKRN]

Cool, just wondering... every once in a while when you read someone posting about their leak down or compression test, you start feeling a little paranoid about your own car, especially if you've never had it done and you have no idea what your numbers are.. =P

[JT-KGY]

Originally posted by 080///M3
Cool, just wondering... every once in a while when you read someone posting about their leak down or compression test, you start feeling a little paranoid about your own car, especially if you've never had it done and you have no idea what your numbers are.. =P

Agree... and especially I bought my car used...
:(

[RobH]

180 to 185 across all cylinders (95 M3). This is low, and it caused my mind to imagine the engine was soft. I don't know if this is true, and I don't want to worry without cause.

Can someone comment on how the compression actually effects performance? It seems obvious that the higher compression test psi the better, but does anyone have anything more technical? Can I assume that lower compression means more blow-by in the cylinders? Also, how can it be corrected (brought back to spec)? Sorry to be such a mechanical retard, but ask me about SAP or Essbase, and I'm a whiz.

RobH
95 M3

[jvit27]

The possibility of a cool chick is always dispeled by the notion of a "significant other" :mad:

For those of you who know me and have heard me be the little bitch I am and rant about everything this proves yet another one of my theories that girls use their boyfriends as trophies and have to work them into the conversation somehow.

Nothing personal AvusM3girl, Im sure your still cool :D

Good luck with the M3's, sounds like the 95 needs some help to be as good as mine though hehe

[Jon97]

I'd like to know what *stock* pressure is for the 3.2. When I bought my car (a 97 with 56K miles) it was tested to have 172 across all six. Because the nunbers were so uniform, I just assumed that these were up to original spec.

[Phantom]

Originally posted by J Vitolo
The possibility of a cool chick is always dispeled by the notion of a "significant other" :mad:

For those of you who know me and have heard me be the little bitch I am and rant about everything this proves yet another one of my theories that girls use their boyfriends as trophies and have to work them into the conversation somehow.



Hmmm, this is waaay of the topic, but I think the mention of their boyfriends ends up as repellant in this type of environment to deter the deluge of all us guys trying to hit on them. Just a guess.

I'll shut up now.

[EuroKRN]

Originally posted by Phantom
Hmmm, this is waaay of the topic, but I think the mention of their boyfriends ends up as repellant in this type of environment to deter the deluge of all us guys trying to hit on them. Just a guess.

I'll shut up now.

Hmm.. so then what does that say about guys (including me) that mention their wives every so often? :p

[JT-KGY]

How much would a compression test cost??
Possible to DIY (and get a accurate reading)???
What should be the avg for 96+ and 95 M3s??

Thanks,