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5150 · Posted: Mon Aug 18, 2003 1:38 am Post subject: HELP! I got Problems :(

78 n/a euro 924...

Ok, so I've got one cylinder where the plug is constantly getting fouled with oil, this has come on slowly for a while and now suddenly it's doing it within minutes

At first when this first started I suspected just a dodgy plug or lead causing it to stop sparking so I replaced them... the car would run fine then suddenly lose one cylinder as I was driving.

Yesterday the car was running spot on, absolutely flying along with no loss of power or anything, it still feels to have the same power as it always has had. If i clean the plug it fires up again and runs no probs until it suddenly fouls the plug again...

I've not got a compression tester, going to pick one up/borrow one over the next few days though... if the rings were gone, would the car still run so well upto the point of fouling the plug?

Is this more likely to be the valve stem oil seals? if so how much work is involved in replacing these?

Any other ideas to check?

Can't hack the idea of the car being off the road for ages if it's anything major

Lizard · Posted: Mon Aug 18, 2003 2:21 am Post subject:

it would have to be a pretty major valve stem leak for it to fould a plug, and I doubt that it is your rings that would let that much oil in, I am thinking maybe a blown head gasket would allow it to be blowing oil into the cylinder, but I am not 100% sure on this
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3 928s,

gohim · Joined: 02 Nov 2002 Posts: 4459 Location: Rialto, CA

Sounds more like a fuel related problem to me.

When the cylinder stops firing, have you taken the time to pull the plug out and look at it?

An oil leak in the cylinder from the rings or the stem seal would not cause the plug to fire sometimes, and not fire sometimes. It would fire when new/clean, and gradually stop working.

A headgasket leak could cause a plug to not fire when the engine is cold and the plug a shorted out by leaked coolant. But eventually, after the engine is running on the other cylinders, the non-firing plug would dry out and start firing.

What's causing it to stop firing (causing a short from the center electrode to the side of the plug)? Oil, fuel, coolant?

If it is the same cylinder each time that you are having problems with, I would guess that you have a problem with the related fuel injector, or the fuel distributor. For some reason, either the injector is leaking, dribbling, or not opening, or the fuel distributor is not sending fuel to that dylinder, or sending too much fuel to that particular cylinder.

augidog · Joined: 03 Mar 2003 Posts: 1360 Location: New Jersey

I'm just curious. Which plug?
Did you check your wires?
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1978 924 95 mile daily driver.
Audi TB/POR174M/High Flow Cat/2.25" exhaust
I knew that positive thinking thing wouldn't work.

Joes924Racer · Posted: Mon Aug 18, 2003 3:49 pm Post subject:

if the head was off ited probly get hydro-locked. check the cp with the tester then take the head off or do a leak down and Im thinking its the rings.
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1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo.

Sleykin · Posted: Mon Aug 18, 2003 4:02 pm Post subject:

Unless you broke a ring all the plugs would be about the same if it were rings. Oil fouled and fuel fouled look very much the same. Black and shiney. Dump some injector cleaner in the tank and run that through it and see if there is a change.
When you do your compression tests be sure to run a wet test if you get uneven readings. A bad exhaust valve will cause fuel fouling too. But that would show up on a vacuume guage or you should be able to hear it in the exhaust or do the rag test on the pipe and check em that way.
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Glenn Neff
Medford, OR
87' 924S

5150 · Posted: Mon Aug 18, 2003 4:40 pm Post subject:

Looks like i've a lot to check here

wet shiny plug, it's on cylinder #4 (assuming #4 is the one nearest the cabin, ie the back of the engine)... it's happening within minutes now so the car is unusable until it's fixed... i'll be trying to find a compression tester this week.

If it was the rings, wouldn't I surely be losing power? I've tried alternate plugs and leads so eliminate them, checked the ignition system over to make sure the cap, points etc are all ok. She's often been "spluttery" in the mornings then it clears, ditto after a run and she's stood a while...

Sleykin · Posted: Mon Aug 18, 2003 5:05 pm Post subject:

I'm not too up on the Audi motor but I believe #4 is the one closest to the cabin and also the one most common to blow a gasket.

Bad rings won't show up as a loss of power for a really long time. The plugs fouling and smoky exhaust and increased oil consumption would be noticed first. You would also have considerable blow by which you can check by just opening the oil filler and feel if there is a lot of pressure pulsation or even smoke coming out of there.

Look at your exhaust pipe. Is it really black and sooty looking or black and shiney? (Ideal would be a nice light tan or just clean rusty steel) Black and sooty is over rich and shiney is oil fouled or water fouled.

Good Luck
Glenn
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Glenn Neff
Medford, OR
87' 924S

5150 · Posted: Mon Aug 18, 2003 6:12 pm Post subject:

Sooty exhaust, yep...

blow-by wise there's very little, certainly no huge amount of smoke or gas blowing out when you open it up... it's no different in that respect to when I got the car 2 years back...

The head gasket sounds plausible, I was suspecting this earlier in the year when I was having other problems as there was some oily crap in the coolant, the head was re-torqued and seemed okay after that.. though there is a degree of pressure in the cooling system and I have had to top the system up a couple of times lately (though it's been very hot and I wondered about the radiator at that point)....

Mike77 · Joined: 14 Dec 2002 Posts: 103 Location: PA

Smell the plug and make sure it's really oil. Mine was doing that and it was really FUEL fouling, not oil fouling. Maybe that injector is not functioning properly.
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Mike

64 Volvo 1800s

Richard · Joined: 04 Nov 2002 Posts: 617 Location: Pacific N.W.

If it's fuel fouling, maybe the distributor cap and not the wire or the plug.

5150 · Posted: Tue Aug 19, 2003 3:15 am Post subject:

JUst popped out and checked as suggested, clean plug in and it was wet within a few minutes again, definately oil.

Should be getting a compression tester midweek with any luck... see what that tells me and take it from there I guess...

5150 · Posted: Wed Aug 20, 2003 6:56 am Post subject:

Following the advice from my original post here I ran the compression test with a borrowed gauge...

It's pretty dark outside and I was struggling to get the guys guage in (it's on a very long shaft and I managed to get it wedged between engine and body at one point!) anyhow, the results are:

#1 - 11
#2 - 11
#3 - 9
#4 - 9

allowing for me struggling to get my hands in and knocking the damn tester causing it to reset a couple of times! lol.. my haynes manual says 8-11 bar with a wear limit of 6.... so i'm thinking they seem okay (though odd 2 are higher?)...

I havent access to any kit to perform a leak down, so going from here what do you guys think?

cheers all

wdb · Joined: 02 Nov 2002 Posts: 2024

since you said you had some oil in the water and getting some pressure in the cooling system and you recently retorque your head bolts , I'd say you should try retorqueing them again .i dont know if the bolt holes are open to the crank case at the bottom, it might be that when the head bolts were loose you got some fluid in the bottom of the bolt holes and it gave you an false torque reading when the bolts were tightened .maybe you could get a thread tap and clean the head bolt bores to be sure you get an accurate reading, like others have said, thats alot of oil for it to be coming from the valve guides . I would say make sure you check ALL the possibilities before pulling the head to check and replace the gasket , because then your into the " I might as well " have the head done since I have it off , and the bottom end bearings are only $150 , and the clutch disk and pilot bearings are only $100 , since the tranny is down I should replace the shift bushings etc etc etc .

jpab924 · Posted: Wed Aug 20, 2003 2:34 pm Post subject:

Heres my thought. Ok, so you know you are losing a cyl, right? You checked this by pulling the spark plugs and looking at them. If you set them aside, a plug fouling out with fuel will dry out, one wet with oil will not. Coolant can also feel oily!

Black smoke out of the exhaust means you have an overly rich mixture. Blue smoke means you are buring oil.

In my experience. Bad valve seals will burn blue smoke, initially on start up, until the engine warms up, and burns out the oil that leaked into the cyl. while the car sat still. I`ve never run into a worn out or cracked valve guide causing a plug to foul that quick, so I wouldn`t go that route yet. Bad rings will usually show up under a load ie...under acceleration.

A compression check will reveal if you have low compression on any given cyl. I don`t know the conversion from bar to psi. But your numbers look close.

At this point I would reach for leak down tester. With the valves at tdc *closed* pressurize the cyl and look at the gauges for a drop. If you don`t have access to a guage. Use the compression tester hose and hook it up to the compressor. Pull the overflow tanks cap off, and look for bubbles. A severely blown headgasket will make the engine overheat and run rough consistently. A slightly blown headgasket would make the engine run rough until the coolant burned out of the affected cylinder. This is usually indicated by a rough idle when cold and smoothing out when warm.

Start with the basics, and work your way deeper from there. I can`t stress this enough.

Gotta picture of the plug? How did the original plug look? You can tell alot about engine condition by reading the plugs.