[Big Eggy]

Hello all..

now i could post this on a car forum but i cant be bothered joining yet another forum so i thought i'd run this by you guys.

I have a 2001 focus 1.6 zetec that after a long run for the family holiday started to misfire on Cylinder No.3

I change the coil pack and ht leads (this had happened before) but the problem was still there.

the spark plug in no.3 is covered with black sooty crap.. and after being replaced it soon builds up again.

my mechanic says that it's probably a burnt valve.. and when i hold a peice of paper to the exhust it sucks it towards the exhust pipe and then blows and so on.. so i guess his diagnosis is correct.

But this has me wondering maybe the valve is stuck (i assume open) .. do any of you guys no if a stuck open valve will have the same symtoms as a burnt valve?

and if the answer to the above is yes.. can i add deisel to the crank case prior to an oil change to try and free the stuck valve?

i've thought about a new head but my Mech says that the new head will probably cause the bottom end to go plus the cost of the job will be more than what the car is worth.... same goes for a engine swap.

so i guess i'm hoping the symtoms for a stuck valve are the same as a burnt valve and there may be some hope?

[gingerale]

Big, is the motor actually firing #3 spark plug? Pull the coil pack, stick a spark plug in it, then hold the metal (threaded) side of the plug up against a metal part of the engine while a helper cranks it....does it spark? If not, double check the others too. If you're getting spark then next step is a compression check, and idle vacuum test. Can you take a picture of the "black sooty crap"?

[Snagglepuss]

It helps to find out why the valve burned in the first place ..Most often it is the exaust valve caused by extreme temperatures ...Bad thermostat or other cooling issues related to the engine...When i have a burned valve ,i just replace the whole head....

Insure that all your issues related to engine cooling are sorted out.Whilst this may cause the bottom end to eventually go...You'll most likely get alot more use from the engine before this may happen.....

Find someone who would help you replace it yourself .....to save you the excessive charges......

"Todays auto tip" .....Adding 1/2 quart of dextron transmission fluid to a tank of gas ,will help clean the carbon deposits on the inside of your engine .......Ladazzzzz...

[burns1n209]

Originally Posted by gingerale

Big, is the motor actually firing #3 spark plug? Pull the coil pack, stick a spark plug in it, then hold the metal (threaded) side of the plug up against a metal part of the engine while a helper cranks it....does it spark? If not, double check the others too. If you're getting spark then next step is a compression check, and idle vacuum test. Can you take a picture of the "black sooty crap"?

Good place to start. to soot could just be carbon loosineing up because the cylinder is not firing, and building up on the plug. a compression check with tell you if valve is stuck or burnt. you could also do a vacuum test on the cylinder. if it holds a vacuum, the cylinder is good. How many miles does the engine have on it? If it has under 150k u could get away with just a head job, the bottom will hold on for awhiile longer, as long as your not beating it to hell. while you have head off, good time to replace timing chain/belt and water pump, cheap insurance usually 30 bucks, and belts. Youll have a Strong engine you shouldn't have to worry about. A reasonable shop would charge 1000 to 1300 i would quesstmate. rebuild head is 500/600 alone and then parts and labor. fairly simple job.

[burns1n209]

Originally Posted by Big Eggy

Hello all.. my mechanic says that it's probably a burnt valve.. and when i hold a peice of paper to the exhust it sucks it towards the exhust pipe and then blows and so on.. so i guess his diagnosis is correct.

First id find a new mechanic, no upstanding mechanic is gonna say well its probably... and if its not hes still gonna charge you with a new head, and the price of fixing the actual problem.. A good mechanic would say let me put the compression gauge on the cylinder and see what kinda pressure you get. takes 5mins. or atleast check if you got spark to the plug.

[amber666]

i can't help at all, i suck at car stuff. but i just wanted to say how i hate it when cars needs repairing. man do they burn holes in your pockets!

[gingerale]

^^ Exactly, all this burnt valve talk is premature....you must diagnose the problem, unless you want to just throw money at it and hope it magically starts running right, like most people do. Rent a vacuum gauge and compression tester from the auto parts store and I'll tell you how to use them.

BTW I absolutely would NOT recommend pouring any kind of oil into your gas tank, not even ATF, because your fuel injectors were not designed to pump fluid as viscous as oil and it could clog them. If you ever want to clean your injectors, the product to use is Sea Foam, either poured in the tank or sucked through a vacuum hose while the motor is running.

[kongbud]

One question does this car have one of those noisemaker mufflers?

And as a follow up I have to question the mechanic who says replacing the head will cause the bottom end to fail.

[izzybud]

ur gonna find urself throwing money in a whole that doesnt fill up. it keeps getting deeper!

[usda101]

Originally Posted by gingerale

^^ Exactly, all this burnt valve talk is premature....you must diagnose the problem, unless you want to just throw money at it and hope it magically starts running right, like most people do. Rent a vacuum gauge and compression tester from the auto parts store and I'll tell you how to use them.

BTW I absolutely would NOT recommend pouring any kind of oil into your gas tank, not even ATF, because your fuel injectors were not designed to pump fluid as viscous as oil and it could clog them. If you ever want to clean your injectors, the product to use is Sea Foam, either poured in the tank or sucked through a vacuum hose while the motor is running.

What he said .