Soo I blew my head gasket

[e30_325es]

Possibly cracked the head. Dunno, but if I'm tearing the top end down, it's getting built better, stronger. Specs on my engine currently: s50us, schrick cams, forged pistons (supposedly, bought it like this), ~250whp. Last year, I drove it Bavauto ~1000mi round trip. Went through 2.5qts of oil though. No external leaks, gotta be internal. It's always smoked, but I contributed that to lack of cats, could be oil.

So I'm looking for advice on a plan of attack. Top end I'm thinking of a VAC stg 2 head with their cams. Or at least I was until I remembered my oil consumption issues. So basically I'm thinking I need to at least re-ring my pistons. Now I've thought of turboing this engine in the future, but having high comp pistons kinda kills that. So what am I to do with the bottom end? New pistons? Or should I just do a different engine or what?

Anybody have thoughts, opinions?

[ck_taft325is]

Re-ring it and drive with the Schricks. If you're tuning is off by a few baseball fields you could be eating oil heavily but it sounds like possibly valve oil seals?

[Adrian_Visser]

Re-ring it and drive with the Schricks. If you're tuning is off by a few baseball fields you could be eating oil heavily but it sounds like possibly valve oil seals?

Care to explain how the tune would cause oil loss? My engine is eating oil at a rate of about a half a quart a month as well, it kind of sucks when you're burning synthetic, shit's expensive.

I figured I probably needed a top-end rebuild, hopefully not the whole engine.

[Lawson509]

Do a leak down test and a compression test. See if the problem is isolated to one or more cylinders with the compression. After a normal compression test, add a couple mL of oil inside one cylinder at a time and re-do the test. if your compression values jump, then your rings are gone. Then use the leak down test to see if the air is being pushed past the rings and listen for air in the valve cover. Another possibility is that your valve stem seals could be bad. Usually if your head is cracked you would be loosing coolant first. Oil loss is usually seal related.

[ck_taft325is]

Care to explain how the tune would cause oil loss? My engine is eating oil at a rate of about a half a quart a month as well, it kind of sucks when you're burning synthetic, shit's expensive.

I figured I probably needed a top-end rebuild, hopefully not the whole engine.

I mis-typed myself into oblivion with that one. I mean the headgasket failure can be from a bad tune. I.e. burning incredibly Rich and having excessive fuel running thru the engine. Or is that rich? Super tired and a bit sick so I'm on a tad bit of cough syrup while I watch my croupy 17 month old.

I talked with a BMW Race Team mechanic (e36 M3's ect) and he said on the first day of qualifying at PIR they blew two headgaskets in two seperate E36 M3's on fresh rebuilds. Turns out their tuning was running very, very lean and was eating up the HG's.

Do a leak down test and a compression test. See if the problem is isolated to one or more cylinders with the compression. After a normal compression test, add a couple mL of oil inside one cylinder at a time and re-do the test. if your compression values jump, then your rings are gone. Then use the leak down test to see if the air is being pushed past the rings and listen for air in the valve cover. Another possibility is that your valve stem seals could be bad. Usually if your head is cracked you would be loosing coolant first. Oil loss is usually seal related.

Bingo. Valve stem seals are my bet.

[Lawson509]

If it is running super lean, then it is lacking fuel and there is running the risk of detonation. Running rich is too much fuel.

[e30_325es]

I'll have to dig my dyno chart out and check my afr's but I'm pretty sure I was good there.

I was thinking the comp test and leak down too, I'll have to find someone with a smaller air compressor. I think the head is cracked because cyl 2 is full of coolant (actually locked up on me after I parked it). I also know it has been machined before so I'm just gonna trash it.

[ck_taft325is]

If it is running super lean, then it is lacking fuel and there is running the risk of detonation. Running rich is too much fuel.

That's it. Again, backwards typing.

[ck_taft325is]

I'll have to dig my dyno chart out and check my afr's but I'm pretty sure I was good there.

I was thinking the comp test and leak down too, I'll have to find someone with a smaller air compressor. I think the head is cracked because cyl 2 is full of coolant (actually locked up on me after I parked it). I also know it has been machined before so I'm just gonna trash it.

What was the previous machining from? Pictures of head gasket and head when you remove 'em possible?

[e30_325es]

Slight overheating issues. I had it running all last year though with no issues. Absolutely on the pics.

[dirty30]

Check the area where the compression ring seats on head closest to the exhaust valves, particularly on the #3,4 cyl. Heat builds up here and then it cracks.

[ck_taft325is]

Check the area where the compression ring seats on head closest to the exhaust valves, particularly on the #3,4 cyl. Heat builds up here and then it cracks.

I figured this is what happend with mine. Ironically enough, I blew on cylinder #6 on the intake side... go figure.

[samiam3356]

In for the carnage....and the fix

[e30_325es]

Alright, did the leak down test last night.

Cyl 1 is perfect, leak is <20%.
Cyl 2 obviously leaking into coolant.
Cyl 3 slightly leaking into cyl 6 and out exhaust, leak is 100%
Cyl 4 leaking into cyl 2 and exhaust, leak is 100%
Cyl 5 leaking into cyl 1, leak is 100%
Cyl 6 leaking into cyl 2, leak is 100%

They all were probably leaking out the exhaust, but I forgot to check the others.

Any thoughts? I know nothing is leaking into the crank case, which makes me feel very good about the rings, but I'm not sure why cyls are leaking into non-adjacent cylinders.

[shiboujin]

you can rebuild the head or get a new one for cheap or upgrade. Sounds like you had leaky valve seals and blew the HG.

Who did the tune on your car? If you had no tune done, that's why the motor went.