m50 low compression repair Q

[kylebes1]

Car:

1995 525i five speed 258k miles

Im getting low compression numbers on 4 cylinders and blue smoke at start up and under power... not to mention lack of power

Would you think I could install new ring on the engine or m54b30 internals, or would you think its the cylinder walls that have worn out?

easy option is lower mileage m50 or m52... just looking to keep my daily driver on the road.

[scottinAZ]

you wont know if a re-ring will help until you tear into the motor.

Best bet for a daily driver is to get a new motor. Time to replace will be about one day.

[greyis89]

Valve seals a posible culprit for blue smoke?

[MaksV]

pretty hard to kill those blocks. Honestly might just be valve seals.

[kylebes1]

pretty hard to kill those blocks. Honestly might just be valve seals.

I always thought it would be nearly imposible to messup these blocks.

Valve seals would not attribute to low compression values, would they?

[!kid]

do a leak down test to pin point the leak. could be valves not sealing, youll pay about
200$ for a good head rebuild. if your on a tight budget just find a known good motor.

Valve seals would not attribute to low compression values, would they?

you are correct, they would not. but a poor sealing valve seat would

[Roysneon]

Basically it seems that to find any real answers you'll have to take the head off.

[BBDirtbiking]

A leak down test will help you know what the real issue is...

If they are leaking from the valves bad, hit the tops with a screw driver and a hammer while under air to make sure nothing is clogging them when doing your test. If they still leak, probably found your issue.

[kylebes1]

Its like going to the dr for a cold. I knew what I should do now I'm kicking myself

[FredK]

You can do a wet comp test, where you put a tablespoon of oil down the problem cylinder. If comp goes up a lot, it's the rings. If it doesn't, it's probably the valves.

[kylebes1]

You can do a wet comp test, where you put a tablespoon of oil down the problem cylinder. If comp goes up a lot, it's the rings. If it doesn't, it's probably the valves.

That sounds great too! Good technique