Crap...need some help on what is causing this?

[jdean]

So after 4-5 weeks I finally take the Cobra out for a cruise. It seemed to be running real well last time out. Today I drove for about 20 miles down the highway, then exited and took off down a country road with no traffic in sight. I hit the gas moderately hard once and noticed oily fumes, white-ish blue, coming from the engine compartment. Pulled over, then I looked under the hood with it idling, then manually popped the gas a few times and saw a LOT of light colored blow by come out the valve cover vent with a bit of a pulsation to the flow.

Headed back home and noticed when I gave it enough gas to pass a car, the light colored oily smoke came on strong again. Side pipes were clear and no smoke coming out of those. This symptom came on suddenly...any ideas?

I pulled all the plugs to inspect. Below are the pics of the lightest and darkest of the eight plugs. I expected to see at least one black and tarred up, but not the case.

[rustyBob]

Do you have a PCV valve???? it may be plugged up...

[jdean]

I do have one. I will check it out, thanks Bob.

[olddog]

Check the oil and make sure there is no anti-freeze in it.

[209]

I wish my plugs were that lean, well maybe not that lean. Anyone else say lean? Or am I all wet and sooty? 209

[joyridin']

Blow a hole in one of the pistons? I've had this happen a few times. You would really notice a loss of power though.

[Wbulk]

I agree with olddog. Doesn't look like the problem is in the combustion chamber. Possible antifreeze leak into the oil. Dipstick would be milky if it's leaking a lot. Or, let it set over night and loosen the drain plug. The water goes to the bottom.

[jdean]

joyridin,

I thought about either the some rings were trashed or a hole in the piston, but in either of these cases I would think the plugs would not be clean.

209,

In what would be normal conditions, I would expect the plugs to be pretty lean looking as they are, since I have EFI and it is set to run at 14 AFR while idling or cruising.....and I just cruised it home for 20 miles holding really light on the throttle.

I will check the oil today.

[BT SNAKE]

I had that happen once. It turned out to be contaminated gasoline. Drove me nuts until I
figured it out. I ran out of gas and filled up a 5 gallon container that had a little diesel in the bottom. Go fill up the tank with premium and
put in some Heet. That just eliminates the one possibility.

Hersh

[vector1]

you know some is normal, so you are having more then normal? if all your plugs look good then i would say it is normal, til they start getting funky.

that aluminum engine had normal looking plugs but the piston to cylinder clearance was excessive for an aluminum block and i had really lightened the tension on the oil control rings and probably washed the cylinders pretty good when i was messing with the efi. this engine would do the same thing with puffs of smoke out the crankcase, but it still ran good. i would say your dilema runs somewhere in there.

[Hotfingrs]

Without having a really clear picture, I can only offer a few guesses. The heat range of plug looks to be a little to hot, there should only be 2 threads discolored from heat. and it looks like about 4 on those plugs. Initial timing looks about right, but seems like you have to much total timing. Also there should be about a .020 brown ring around the tip on the insulator, if it's not totally around the tip and not there, it also indicates to much timing. The ground strap should change color exactly in the middle of the bend. Towards the threads is to much timing, and towards the tip is not enough. The discoloration at the end of the ground strap also indicates where your initial timing is. Is that melted metal on the top of the electrode in the top plug??

[jdean]

Jack,

I looked at my plugs and could not find one that had something on the end of the electrode like you are referring to from the picture, so I guess whatever it was fell off. I agree with your reading, that there is a bit too much timing. I will back it off a couple of degrees and see what I get next time.

Vector,

I hope it is not washed out rings like you had. But I do not sense any loss of power either like you said. Did you lose any noticeable compression after your oil rings went loose? I have not done a compression check yet, but will in a day or two.

BT,

Come to think of it I did buy gas at a really cheapo place that was convenient just before hitting the road.

[vector1]

Originally Posted by jdean

Vector,

I hope it is not washed out rings like you had. But I do not sense any loss of power either like you said. Did you lose any noticeable compression after your oil rings went loose? I have not done a compression check yet, but will in a day or two.

i really didn't have a loss of power that i could notice, i had plenty. when i did a leakdown the numbers were similiar, 1 or 2 maybe a little lower of which one had the compression ring gaps line up, i was generous with my ring gaps btw. my plugs looked similiar to yours, the bases were black but the porcelein looked good. the only reason i tore my engine down was a gasket that came out and the bearings were shot because of too much clearance. unless it is bad i wouldn't worry about your situation. have you ever seen an engine that had the crankcase vented to atmosphere, they will blow smoke pretty good.

[SSSammy]

Originally Posted by jdean

... then manually popped the gas a few times and saw a LOT of light colored blow by come out the valve cover vent with a bit of a pulsation to the flow.

John, you must have cylinder gases going into the crankcase (and thus up the oil returns to the valve covers and out the breather).

Suspect rings or holed piston ...

Do a compression check asap before unscrewing anything!

Sam

[jdean]

Well I hope it is fixable without tearing into the engine, heck I only have 1,000 miles on it. I hate to think of what might have happened in the event of detonation caused by a bit too much timing, bad fuel and even a brief romp on the pedal.

[jdean]

I finally had the chance to get back to working on this. I did a compression check and 7 cylinders ranged from about 185-195. One only read 110 or so.
I pulled the head on that side and the low cylinder is where I found the head gasket to be blown. It was blown at the top and went directly into the intake valley, so there was no water breach anywhere. Mystery solved.

[rustyBob]

nice to hear it wasnt anything that couldent be fixed without pulling the motor.......
by the way ....your car i awesome looking......love the paint job.......

[madmaxx]

What causes a head gasket to fail as it did? Did you find loose bolts? warped mating surfaces? did the engine ever overheat?

[jdean]

It is a new engine, with about 1,000 miles on it. It could be my mistake for not going back and re-tightening the head bolts to specs after the first few cooling cycles.

[Barry_R]

Good find. Easy fix and no damage. Parts like head gaskets can function as "fuses" in an engine - failing under detonation before expensive items do.