Help with misfire code

rjaywhit · Post by **rjaywhit** » 19 Dec 2011, 09:41

Still low compression on #4.

I'm gonna sell it or part it out.

Check the for sale board.

rjaywhit · Post by **rjaywhit** » 04 Jan 2012, 15:27

Did a leak down test this past weekend.

Seems to be a leaking exhaust valve.

Is it possible to have a burnt valve in 15k miles of use?

Any other reasons that an exhaust valve would be leaking?

Post by **erikv11** » 04 Jan 2012, 15:44

So you did a head rebuild or something like that, only 15k back? Burnt valve in 15k is so so unlikely.

Could be a broken valve spring, they are very uncommon but it happened to my car (https://www.matthewsvolvosite.com/forums ... =1&t=40633).

rjaywhit · Post by **rjaywhit** » 30 Jan 2012, 12:57

It's a burnt valve...

Post by **erikv11** » 30 Jan 2012, 14:07

Bummer!

When you say you rebuilt the head, what did you have done? What was the reason?

Did it burn a valve in the same cylinder again?

rjaywhit · Post by **rjaywhit** » 31 Jan 2012, 08:31

Had machine shop inspect and resurface head, replace one exh valve, and inspect and recond all valves.

I believe that the problem was worn dist cap and rotor (should have replaced after rebuild but was cheap) causing misfires that resulted in build up of carbon on exhaust valves. Carbon on one of the exh valves in cyl #4 burned off a piece of the valve resulting in no compression.

If the check engine light had worked I probably could have avoided this issue...

Post by **erikv11** » 31 Jan 2012, 09:09

Sounds like no install of fresh valve stem seals then. Good chance the valve stem seals were bad, leaked oil onto the exhaust valves, then like you say carbon buildup and a hole. Valve stem seals are a weak link in these engines, good idea to replace them when the head is off.

Anyway, bad news about the burnt valve. Are you pulling the head? Or, pushing the car off a cliff?

rjaywhit · Post by **rjaywhit** » 01 Feb 2012, 07:41

Gave the machine shop new valve seals when I had the valve job done.

Pulled the valves out of the head last night and found some interesting things -

1) 3 of the valve spring seats were missing. (this explains the mysterious metal pieces inside the head)

2) A couple of valve seals were torn and several others loose enough to not hold onto the valve stem.

I'm calling the machine shop today and ask if it were possible that the 3 spring seats were inserted upsidedown. This would result in them shattering from the spring pressure at load. Missing valve seat would result in wear to aluminum head and not maintaining the valve spring geometry.

I'm thinking that he owes me a free rebuild and cost of new gasket kit and head bolts.

We will see what kind of business man he is...

Help with misfire code

Re: Help with misfire code