Smokin Exhaust Valve

[TrailB2]

Looking for some early ideas since Im stuck at work and its buggin me. So I just finished up my winter engine rebuild and started her up last night. I primed it up turned the key and it fired right up. I heard a pretty good tap right away from the driver side head (sounded like tapping a bolt against the valve cover). I noticed my mech oil pressure guage was up good around 65 right before I shut her off. I pulled the valve cover just to check if I could notice anything. I had my buddy fire her up again while I checked it out. I noticed that the noise was coming from #5's exhaust valve and exhaust was pushing up out of the valve spring. I'm gonna run a comp test tomorrow but some early ideas would be appreciated. Im hoping the tap was the exhaust and not the top of the piston.

 

[IMenriched]

sounds like you're on the right track.

 

[skippy]

collapsed lifter and bad valve seal,or seal popped off its perch?

 

[TrailB2]

Well I had the rocker assembly off to get a better look before I had a chance to do a comp test. Instead I grabbed an air compressor and pumped some air into the cylinder. I can feel air escaping on the palm of my hand when I push down on the valve spring. Im gonna put a new stem seal in tomorrow. The thing that bothers me is that the cylinder still seems to leak down pretty quick when im not pushing on the valve. My question is if the stem seal is shot or even popped off do you think it could cause that valve to walk out of its seat a bit. The ring feel strong (there new) because the valve spring gets tough to push with a little air in the cylinder. Thanks

 

[skippy]

sound like valve isn't sealing well.did you have the heads done durring the rebuild?valves ground,guides replaced and springs checked?is rocker arm adjustment correct?

 

[TrailB2]

I didn't have the heads redone (of course). My options up north here are limited so I let em sit. I stuck with working on the short block to get the oil pressure back up. Adjustment worked out good, I went 1.75 by 0. The rebuild was going too good, I knew something would throw a jab at me sooner or later.

 

[TrailB2]

Well got a stem seal put on, bolted her back together and ran a comp test. Got real good comp on all cylinders including #5 @185. Started it back up and no luck. Still making noise and instead of exhaust blowing up through the valve its blowing out of one of the valve cover bolt holes. I wont be able to tell until I get the head back off. Theres always something.

 

[skippy]

Well got a stem seal put on, bolted her back together and ran a comp test. Got real good comp on all cylinders including #5 @185. Started it back up and no luck. Still making noise and instead of exhaust blowing up through the valve its blowing out of one of the valve cover bolt holes. I wont be able to tell until I get the head back off. Theres always something.

i feel your pain,that stinks.could be anything,burn valve,bent valve,something between the valve and seat,weak spring.

when i had mine off,i srayed em down with gunk engine brite at the wood pile,let em bake in the sun.after 3 hours i hit good w/spray nozzle on the garden hose.then spayed em down w/wd-40.then sprayed em down w/compressed air.

i got valve grinding compound from napa,my cordless drill,pumped oil in the valve guides one at a time,and put liberal amount of compound on the valve and spun each valve for 2 minutes.did this 3 times each valve,oil guide each time.clean valve up and reassemble w/new seals.

if everything passes visual on that head,i would have the valve springs checked.had 2 pennies.

 

[TrailB2]

Got the head off and all looks good. The smoke from the valve cover bolt hole is ok. After I checked it out the hole is open inside the head exhaust port. Without the valve cover on it would smoke anyways. Replaced valve seals, valves are seating good and when I had them out they were all really clean. The only spot left to get rid of my noise is the lifters. Its hard to believe that I have a bad new lifter but when I bought the new ones, one of them was out of round and wouldn't even fit in the bore. I figure if a new lifter could be out of round then one might not be pumping up right. It really sounds like a single lifter so the fun will be trying to figure out which one. I wonder if I just would have just let it run for a while if it would have worked itself out. She sure ones nice though minus the noise.