So Many Choices

[B Rod]

So, with this E30 I just bought('90 325i), I'm pretty sure the cyl#4 rings are toast. I'm not positive, but I'm basing this off the fact that it is getting spark, but still not combusting. Plus there was oil on the plug when I pulled it and the injector has way more gunk on it than any of the other five. The motor also has 256k+ miles on it. However, I'm pretty sure the top end was recently overhauled, because everything from the head gasket up is clean as hell.

My first question is, could this simply be an improper HG install or is it more likely the rings given the mileage and symptoms?

My main question for this thread, however, has to do with motor options. Should I:

A)Rebuild my current M20(the bottom end anyway)
B)Find an M20 short block for cheap(and lower miles of course) and put my head on it
OR finally...
C)Should I just wait until I do my S52 swap on the E36 and throw the M50 in there?

Obviously, option C would take the longest to complete as well as cost the most, but would also be the most fun when it's completed. Given that all I can drive right now is the slammed E28 though, I'd kinda like to be able to drive the E30 for the winter since its at stock ride height.

And before anyone says it...YES, I have though about putting the S52 in the E30, but I've already got my heart set on making the E36 my "fast" car.

What does everyone think? THANKS!

[Bimmerteck]

well, I would test leakdown and compression before any of the above options, if those didn't give a solid indicator i'd swap the plug left and injector right and see if the problem doesn't move with one or the other.

[SeanDub]

I'd say rebuild or replace m20 if need be. Just whichever is more cost effcient

[Stephen]

S52 s52!

No but slap the super eta bottom end on it and gain a little torque and your good to go. Dont bother rebuilding the i bottom end. Or just find a different i bottom end

[B Rod]

well, I would test leakdown and compression before any of the above options, if those didn't give a solid indicator i'd swap the plug left and injector right and see if the problem doesn't move with one or the other.

Thanks for the info! I'm going to try and find my compression tester and give that a go tonight.

[Bimmerteck]

No problem, I'm as pro motor swap as it gets, but I would **** to swap only to find it was a simple bad injector.

[B Rod]

So I was able to do a compression check over the weekend. Cyl#1,2,3,5, & 6 all resulted in 145-155PSI. Cyl#4 which I originally thought was not making compression read higher. It read consistently at 175-180PSI.

My only thought is that the injector is, in fact, clogged or bad. Given the age of the motor(256k miles), I'm sure some oil is getting passed the rings. So, my slightly educated guess is, the normal blow-by isn't burning off, which gunk'd up the cylinder and caused the higher compression ratio???

Bimmerteck...help!

[SeanDub]

Thats the only theory that made any sense to me. Help us Erik!

[Stephen]

r3vlimited is a good place for the technical stuff. E30 section of bf.c blows.

also, 256k is standard issue for m20s these days lol

[B Rod]

also, 256k is standard issue for m20s these days lol

Good! haha

[Bimmerteck]

So I was able to do a compression check over the weekend. Cyl#1,2,3,5, & 6 all resulted in 145-155PSI. Cyl#4 which I originally thought was not making compression read higher. It read consistently at 175-180PSI.

My only thought is that the injector is, in fact, clogged or bad. Given the age of the motor(256k miles), I'm sure some oil is getting passed the rings. So, my slightly educated guess is, the normal blow-by isn't burning off, which gunk'd up the cylinder and caused the higher compression ratio???

Bimmerteck...help!

They all have plenty of compression for efficient combustion did you swap the 4-5 injectors and 3-4 plugs? and have you popped the valve cover off to verify the rocker arms are intact and valves are properly adjusted?(particularly on cylinder #4)

[B Rod]

I'm going to work on swapping the injectors today. If that doesn't help anything, checking the valve clearances is next!

[B Rod]

Got the injectors and fuel rail out today for cleaning. Minor problem though. The Cyl#2 injector came out without the plastic tip attached. Sooo...I'm pretty sure that plastic tip is now sitting in the intake manifold or in the head. FML.

So, intake manifold comes off next?

[WhiteStripes]

Damn man, how many cars do you have? Either way, with that many miles on the Injectors, I'd think about getting them bench cleaned/flowed anyway.

I also like Stephen's idea of the eta bottom end...

[B Rod]

Damn man, how many cars do you have? Either way, with that many miles on the Injectors, I'd think about getting them bench cleaned/flowed anyway.

I also like Stephen's idea of the eta bottom end...

That was the plan with the injectors, and I was going to do it yesterday, but thats when I realized that one of the plastic tips was missing. So lame! Anyone have a strategy to get it out without having to take the intake manifold off??

I think the bottom end may be fine too, so I don't really have to worry about that. At least not yet...haha.