Cyl no3 dead. Butwhy??

[Cyclone101]

Hey guys,

I started up my car again yesterday, as it stood for about 2 weeks without me touching it. It started but ran VERY rough, so pulled the plug leads one by one and it seems cyl 3 is dead as nothing changed without its lead on.

I then tested to see if there was spark in that lead, and there was.

I pulled the plug to see if that might be the problem, it looked good and gave a blue spark.

So now i have no idea why its dead...

BTW, its has a singe solex PDSI40, si it cant be fueling or the other cyl wouldnt run.

Is my logic flawed somewhere?

Does anybody know what can cause this?

Any Help would be appreciated. Thanx

Jacques

[eurotrash]

Swap your plugs and wires around to see if the issue travels. This will reveal the culprit.

Are you running pertronix?

[c.d.iesel]

bad head gasket

cylinder filled with antifreeze after shutoff

and cooled down - fouled plug when you returned

reams of information here on steps to take

and how to diagnose - just read the bunch of threads

in the last few days

[Mike87]

I have run across this very situation. It turned out to be a bad intake gasket at the dead cylinder. I am not saying that this is your answer, but something to look at.

[Cyclone101]

Swap your plugs and wires around to see if the issue travels. This will reveal the culprit.

Are you running pertronix?

Thanx, gona try that now. I guess i can also rotate dizzy to check that side. And no, im running std dizzy with new points, cap, rotor. My rotor was scored, as were the contacts in the cap. Is that indicative of a bad coil?

Regards

Jacques

[Mike Self]

pull all four plugs and do a compression test--wet and dry. If #3 cylinder alone is significantly lower than the other three wet or dry, then the problem is either a head gasket or a bad valve. Pull the valve cover and see if a valve is stuck open--this can happen to an engine that sits, given the right circumstances. If #3's valves move up and down, then one of 'em is burned and leaking.

If a cylinder adjacent to #3 is also low, I'd suspect a blown head gasket.

If #3's compression is significantly lower dry than wet, then I'd suspect a bad or broken ring on #3 piston.

That'll keep you busy for awhile; report what you found.

Cheers

mike

[OriginalOwner]

Install a different spark plug and start the car, see what happens.

I had that problem on my truck, and all the troubleshooting indicated the plug was OK. But the porcelain had just enough of a crack to short while running. A different plug solved the problem.

Afterward, I found the porcelain crack with a magnifying glass.

Cheers,

Carl

[TobyB]

holy crap, really?

Try a different plug wire on the one that's not working.

Bosch, especially, in the last 10 years will do this.

Spark looks OK, but doesn't have the welly to actually do anything.

I would chase ignition a fair way before I got out the compression tester-

but then, I'd get out the compression tester....

and yeah, your cap can do this too...

t

[OriginalOwner]

+1 what tobyB said.

Cheers,

Carl

[rtheriaque]

Recall also that the brake booster pulls vacuum from the cylinder 3 intake runner. A blown booster will allow a massive vacuum leak that will make it appear as though cylinder 3 isn't firing.

[eurotrash]

Recall also that the brake booster pulls vacuum from the cylinder 3 intake runner. A blown booster will allow a massive vacuum leak that will make it appear as though cylinder 3 isn't firing.

Isn't this the #4..?

[rtheriaque]

Is it? For some reason my hazy memory seems to recall this problem/solution for a Cyl. 3 problem. I could be (and probably am) totally wrong.