Ideas for oil loss and misfires?

[frazman]

Hi all.  I've been slowly getting an e30 m42 into running shape but I'm running out of ideas for how to solve the latest symptoms:

-Losing oil (definitely a little out the exhaust after starting the car but not much when running; there is quite a bit coming out of the brand new oil filler cap)

-Inconsistently rough/misfiring when accelerating at speed (replacing fuel filter helped a little but still evident)

The thing that bothers me is that the oil loss wasn't bad at all after I replaced the front profile gasket and oil filter housing gasket.  I don't really see much oil on the front of the engine anymore but I'm still losing ~1qt/100mi.

Other details:
-10w40 dino oil
-Compression is right around 200 for all 4 cylinders; vacuum/leakdown test was good 6 months ago but maybe it's changed?
-Timing components are new (<5000)
-Valve gasket is new
-Plenty of lifter ticking

I'd appreciate any input you have on my current ideas of things to test:
-Blowby (even though test 6 months ago was fine?)
-Worn lifters?
-Blocked CCV (I have the standard mess-under-intake setup with the vac hoses)
-Fuel pump (how do I test this to see if it's failing?)
-Would there be any benefit to running something like Seafoam through the engine?

Thanks for the help
Ben

[DesktopDave]

I'm thinking it's the CCV.  That's a common symptom of a plugged/stuck vac valve in e30s or the PCV system in the e36.  Pressure in the engine is forcing oil past the fill seal.

[frazman]

Thanks for your help!  I really hope it's not valves....

Is there any way to diagnose between CCV and stuck valve?  The valve would surprise me because I had the head at a machine shop less than a year ago for another exhaust valve and I think they checked all the others too.  Would it be worthwhile trying something like Seafoam to unstick the valves, if that is the case?

What are the symptoms of worn lifters?

If I pinch the CCV vac line while the engine is idling then let it go, I get a vacuum response so it seems like the thing isn't totally clogged.  Should I just spray some carb cleaner down there or do I need to use something stronger?

[DesktopDave]

I wasn't talking about the engine's intake or exhaust valves.  BMW's emission systems have various different one-way & purge vacuum valves over the years.  The e30 has a similar setup with a purge valve that's far superior to the later CCV.  I don't have any first-hand experience with it, but for what it's worth here's some related (e46) links for you:

http://www.m42club.com/forums/showthread.php?t=8904 (no solution)
http://forums.bimmerforums.com/forum/showthread.php?t=1163377
http://www.bimmerfest.com/forums/showthread.php?t=417819

Doesn't look like fun, that's for sure.

[frazman]

Hmmm, I thought the e30 version of the m42 just had a hose that ran straight to the intake.  Is the valve under the baffle in the valve cover or is it buried in the mess under the intake?  I could definitely take the baffle off and take a look this afternoon.

I'm also giving Seafoam a try this afternoon to see whether a quick clean will shake something loose...and hopefully nothing I need!

[frazman]

Just checked the baffle and there's no blockage.  I don't have any way to check the flow rate through the CCV hose out of the valve cover but I can definitely blow through it (gross).

However, when I was checking out the CCV, I noticed that one of the pipe clamps on the rubber boot between the throttle body and MAF was loose.  The boot was on when I looked at it, but is there a chance it could open up under throttle and lead to some weird vacuum leak/blowby in the crankcase??

I still have another 20mi or so of driving I'm going to do on the Seafoam so I'll see if the symptoms get any better.

Next step is a leakdown test tomorrow to see if valve blowby could be the answer.  I'm a little skeptical of this since the valves were checked recently and it's intermittent.

[DesktopDave]

Don't know why I thought you had an e36, must be getting threads confused.  You're correct, the e30 has a direct connection from the booster to the intake.  There is a vac valve in the evap control system somewhere to contain fuel vapor.

I'm a bit puzzled, seems like everything is normal.  A loose hose in that rat's nest could cause a bit of trouble.  The hose from the AFM goes through the ICV, IIRC.

[frazman]

So I went out for a drive and couldn't reproduce the misfiring.  I think it must have been the loose hose clamp on the boot from the AFM to the TB opening up under heavy accel/loading.  Not 100% sure yet but I'll see what happens with some more driving.

I'm not sure that this is the cause of the oil filler cap leak and too much pressure in the crankcase.  Only time will tell on that one too:-P