Author Topic: Massive Blow By (Read 6083 times)

dvmotorsports · « **on:** March 05, 2011, 12:26:52 PM »

Not your typical circumstance. I havent comp tested or done a leak down yet. It is on start up. BUT..... Only when parked pointing down hill. My strange, off the wall theory is cylinder rings are allowing blow by on start up because the rings are done. And since there is a massive oil accumulation at the front of the sump when pointed down hill, I think the crank is slinging oil up past the rings. I rarely get it when parked on level ground and never when pointed up hill.

I know that is far fetched, but I think the valve seals would do this not matter how the car was parked.

Thoughts from you folks before I start testing?

fiftytakedowns · « **Reply #1 on:** March 06, 2011, 08:56:55 PM »

Obviously the compression test would be your best bet to at least get it out of your system to know whether or not your rings are toast.

I was getting blow by (I thought) by looking at the crank vent hose to the throttle body. Turns out when these cars sit, the water kind of sticks to the oil and gets thrown into the throttle body. It is typically completely normal, but I was confused about hte random condition. (seems like these engines have lots of random things that go wrong). My guess is that if the engine is operating normally, that it's really no big deal. that being said. I have never heard of the guides going out on the m42 engines. the m10's and m20s are a different story. I think the hill parking could have a bit to do about it as the oil likes to travel around the timing chain.

hope it helps I guess.

DesktopDave · « **Reply #2 on:** March 06, 2011, 09:30:46 PM »

I always have oil leaks. But any new leak needs some investigation. I think oil also tends to accumulate in the intake, maybe condensing from the cam cover breather line?

dvmotorsports · « **Reply #3 on:** March 08, 2011, 03:00:28 AM »

Here is something I noticed recently as well. The fuel in Hawaii is by far the most destructive I've ever seen. I just tore down an M54 with 50k on it. There was so much carbon build up that it had fallen off the valve and scored the block so bad that is cannot be saved. This is not the only time I've head or seen this happen here. However, I've only put 12k on my rebuild in the past three years. Half of which have been on this shitty fuel. I think that is premature to assume this could happen to my motor over that short of time. But who knows. I have over 13:1 compression, so I add xylene as well. I figured that would keep it clean. I'll find out soon.

fiftytakedowns · « **Reply #4 on:** March 09, 2011, 03:26:05 AM »

shit man, you also need to post pics of your set-up including your build and some youtube videos haha. Maybe some seafoam in the gas now and then will help keep the carbon gone. It's no snake fuel, but it does get rid of some carbon.

dvmotorsports · « **Reply #5 on:** March 15, 2011, 01:42:19 AM »

170-175 across the board. So the compression test was good. Time for a leak down test.

I also changed from Bosch P+2 to a standard NKG gapped at 0.030. The Bosch plugs had oil on the threads, but none in the hole that I could tell. However, they were lean as hell. Must be a combination of the motor setup and the ACSchnitzer tune. Time for a Walbro and an adjustable FPR.

On another note, I think my injection timing may be off, or somehow one of the cams spun out of adjustment.

DesktopDave · « **Reply #6 on:** March 15, 2011, 06:07:29 AM »

Might be the very high alcohol content. Not sure about Hawaii, but here all fuel is at least 10% by volume. Excellent cleaner, but very poor mileage.

dvmotorsports · « **Reply #7 on:** March 17, 2011, 10:44:16 PM »

Well we have E10 here. However, the state is pushing legislation to eliminate ethanol from fuel here. I'm hoping they do it soon.

I'm still waiting to do the leak down. I also need to figure out if the smoke is fuel, oil or both. I know how to tell, I just haven't made an attempt to yet.

DesktopDave · « **Reply #8 on:** March 18, 2011, 07:31:11 AM »

I'm still leaning to my "intake filling with condensed water & oil" theory. I can't think of how coolant would enter the system if the car had no other symptoms like overheating, coolant loss, etc.

I'd be tempted to put a catch can on the car's vent hose and see what turned up in there, especially if you're using light synthetic oils like me. I get a lot of oil in my intake hoses from blow-by, even in an unmodified motor.

Here's why...let me detail my theory...when the hot motor & oil cool off, it significantly contracts in volume, pulling in a lot of cool, humid air. That humidity condenses in the warm alu intake manifold over the next few hours. To make it worse, oil vapors usually get sucked into the manifold & burned off by the running motor. When you've turned off the motor, that oil vapor also condenses & collects in the intake. It'll float on the water, collecting at the lowest point. The high plenum and long intake runners would force that mixture into the lowest point...and if the lowest cylinder intake valve was slightly open, it would all collect in the combustion chamber.

Normally, when you car is parked level, all four cylinders get a dose of the oil/water mix & pump it out without much drama. When you're parked on a slope, #1 or #4 gets the whole dose & then it takes a bit longer to pump it out.

Eliminating ethanol would help mileage and older car's FI components. OTOH, we'll pay more. Hard choice either way. I wonder if Hawaii makes much of it on the islands? I'd guess it's mostly corn & pumped out of a boat. Not that it makes much of a difference to your problem...

pdxmotorhead · « **Reply #9 on:** March 18, 2011, 11:27:10 AM »

Eliminating ethanol would lower gas prices as well, the alcohol is 7.00 per gallon in bulk. Its in there for emissions, not efficiency or power..

My Jeep loses 5mpg going to the E10 from straight gas. I get 12 to 15 on E10 and 18 to 21 on std fuel.. My 318 is as bad, drops from 35 hwy to 28 on E10..

Xylene causes oil to thin and stop lubricating if it contaminates the oil.. If your car runs rich it will cause the cylinder walls to wash and lose lubrication. There are additives for the E10 (Stabil for Alch, Uplon from Klotz) that will keep the alcohol from separating from the gasoline and protect the fuel from out gassing the volatile components.

I feel the pain, Oregon has crappy fuel as well because our state does not inspect fuel. So if it can't be sold in CA or WA we get it...

Dave

a930rocket · « **Reply #10 on:** March 18, 2011, 05:05:03 PM »

If it's water, it white and sweet smelling.

If it's oil, it would be blue.

If it's fuel, it would be black and smell rich/like gas.

A compression check will tell you if the motor low on compression, but the leakdown will tell you where it's at:

rings = crankcase
exhaust valve = exhaust pipe
intake valve = intake/air filter

Havoing said that, you need to make sure both are done properly or you'll get incorrect results.

Good luck!

dvmotorsports · « **Reply #11 on:** March 31, 2011, 05:24:42 AM »

After a short hiatus and plug change (as mentioned earlier), the problem has mysteriously gone away. It's been gone for over two weeks and about 300 miles now. Bizarre. I'm half tempted to throw a set of P+2 plugs back in to see if the problem comes back. Too bad I shit canned the old plugs.

I never did do the leakdown test. I probably will after I move off this island shortly. Regardless, I still need to address the lean issue.