One cylinder intermittently not firing

[rsallen]

Okay.
Let's put 50 hours on the machine. Why would it now start with sticking guides instead of doing so in the first or second run-in period? There's more play in them now than there ever has been.
I'd buy into a broken or weak valve springs if that engine make had a history of putting garbage materials into their product, but sticking valve guides well after the break-in period.....nah, you're just pulling my chain. Right?

 

[tcartwri]

Okay.
Let's put 50 hours on the machine. Why would it now start with sticking guides instead of doing so in the first or second run-in period? There's more play in them now than there ever has been.
I'd buy into a broken or weak valve springs if that engine make had a history of putting garbage materials into their product, but sticking valve guides well after the break-in period.....nah, you're just pulling my chain. Right?

Mine did it at ~250 hours. The guides are pressed into very cheaply cast aluminum heads, and they come loose.

 

[rsallen]

Then you were also sucking oil like crazy?

 

[MBDiagMan]

The engine has less than fifty hours, but was out of warranty by one week when the problem showed itself. Yes I have swapped coils, but have not run it enough to CONFIRM that the problem stayed in the same cylinder.

On another forum, someone familiar with this engine said that I should do a compression check when cold and again when hot. He thought that the spitting and popping in the exhaust after warm up was due to a valve too tight. I am not certain that this is happening only after warm up, but it might very well be. If he is correct with this hunch, I don't want to run it very much for fear of burning a valve. He also said that the valves are a pain to adjust since it is done with shims.

Remember, this is an intermittent problem.

I want to thank everyone a BUUuunnch for their replies and thoughts. I am about to take a little short vacation with my wife and it will probably be late next week before I get back to this.

 

[tcartwri]

Then you were also sucking oil like crazy?

Nope. Very little oil in the top end of these motors.

 

[buickanddeere]

Failing or weak valve spring is what I suspect he's thinking. Either valve spring or a air, oil or coolant leak.

 

[rsallen]

Hmmm,
So could you salvage the head with some over sized guides? Or was it just scrap and having to renew the head?

 

[clemenda]

Sounds like a bad coil pack