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E36 (1991 - 1999)
The E36 chassis 3-Series BMW was a huge hit among driving enthusiasts from the first moment the car hit the pavement. The E36 won numerous awards over the years it was produced and is still a favorite of many BMW enthusiasts to this day! -- View the E36 Wiki

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  #1  
Old 06-02-2019, 09:16 AM
Racer_75 Racer_75 is offline
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M52 compression test

Performed a compression test on my old '97 323 earlier and just have a couple of questions.

Firstly, numbers were very low, 75psi highest 58psi lowest. I understand that these are bad, but the engine starts very well, even in the cold, idles nice, no rumbles, no misfires and not much smoke from the exhaust. I only got the cylinder closes to the front of the car and the number went up to 100psi ( the rain came on hard before I got the rest of them) This would lead me to belive the rings were shot.

Secondly, I have pink injectors fitted, which I did with the intention on fitting a turbo. Needless to say, that hasnt happened yet so I think it would better to go back to green injectors. It has an M50 manifold, M50 mid pipe and 328i backbox, tubular headers, ecu remap,ccv delete and catch can fitted and a cai. I've lumped some money into this engine and the last thing i want is to find a new one. But I guess that is looking more and more likely and yes, it is a Nikasil block

Does anyone have any similar expieriences? I'm fine with it being a bit down on power for the amount of miles I do, but I'm curious as to wether or not changing the injectors will make a difference, maybe if there is some fuel wash? Maybe not, but thought it was worth an ask
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  #2  
Old 06-02-2019, 10:16 AM
bluptgm3 bluptgm3 is online now
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Sounds like the cylinders have been getting way more fuel than they require for some time now.
Most likely you have accelerated ring wear.



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Old 06-02-2019, 10:39 AM
Racer_75 Racer_75 is offline
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The car has been sitting up for the last couple of years and I've been working on it when I get the chance. It hasn't covered many miles since the pink injectors were fitted. Literally only starting and moving it round the block a few times.

Do you think this is still enough have caused accelerated wear of the rings?
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Old 06-03-2019, 11:11 AM
john kaminski john kaminski is offline
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Possibly with all the non running and then over fueling you've got "dry" cylinders or maybe stuck rings. You might try squirting a bit of oil in each cylinder and turn it over a few times with plugs still out and then retest compression
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Old 06-03-2019, 01:04 PM
bluptgm3 bluptgm3 is online now
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^+1 based on new info…


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Old 06-03-2019, 03:08 PM
Racer_75 Racer_75 is offline
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Thanks a lot gents. Guess that last piece if info was quite important ***55358;***56692;

Will definitely try that at the weekend and swap back to green injectors! Thanks again
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Old 06-12-2019, 04:11 PM
XTech2003 XTech2003 is offline
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low compression

A friend had this happen recently. I couldn't believe the thing ran. His was a sitting too long in a humid environment. He gave each cylinder some Marvel Mystery Oil and let it sit a few days. It loosened up the rings and now compression is around 170. Good Luck!
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Old 06-12-2019, 09:40 PM
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hornhospital hornhospital is offline
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Same situation with my 633CSi. It had been abandoned, bought at a police auction. Probably hadn't run in years, compression was awful. After treating with penetrating oil the compression came back up to the 155-160 range.
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Old 06-13-2019, 05:25 AM
Racer_75 Racer_75 is offline
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Handy information guys, thanks. Will try that as well.

Was doing some reading into the Tester I bought and I guess its one of the worse ones. In a couple of weeks I'll buy a better one
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