Is my motor toast?

[Stevo585]

Recently purchased an e92 335i with blown stock turbos to start my build.

I started by pulling the motor, removed the turbos and the rest of the accessories. I saw that at some point this motor may have ate a belt...There was belt debris under the power steering pump, ac compressor and a VTT seal guard was installed (I'm assuming too late).

I planned on doing rod bearings in prep for big boost, so during that process, checked the oil pump and pick up tube for belt debris - All was clean including no abnormal bearing wear for 90k mileage.

Also tried to check the cylinder walls the best I could for scoring or damage - checked out ok.

While doing a walnut blasting (all of the intake ports were coated in oil/ gunk which was expected from the blow turbos drinking oil)
I saw that cylinder 5 exhaust port is full of oil while 1,2,3,4 and 6 are completely dry. When looking into cylinder 5 spark plug hole I see oil.


My question is does that automatically mean I have a bad oil/piston ring?
I'm assuming a compression test would give me an answer? any other ways to test?

Thanks for reading!

 

[wheela]

Sorry to hear about these issues. I don't know much about this so hopefully others will chime in, but I believe leaky valve seals can also be a source of oil in the cylinders. I'm not sure what's more likely - to have oil leaking from bad valve seals, or oil coming up past bad piston rings? Probably depends how the motor has been treated.

A compression test is probably a good idea. If that cylinder has good compression then you can probably assume the oil is from a bad valve seal. Hopefully since the cylinder walls didn't appear scored that means the piston rings aren't the culprit.

Like I said, hopefully other more knowledgeable people will chime in. Hopefully whatever is going on with your motor will end up being on the more simple end of the spectrum.

 

[Stevo585]

I'm hoping that cylinder 5 valves were open when I flipped the motor over to do my rod bearings and oil seeped into the combustion chamber and out the exhaust valves.

Who knows...

I'll start with a compression test when the motor goes back in and if all is well, I'll let it rip.

 

[Torgus]

Any good news?

 

[Stevo585]

I don't have the motor in just yet waiting for some parts, I will update once I do.

Fingers crossed!!