My son and I did a full rebuild on an '86 with 196,000 miles that was bought after the PO ran it low on oil and it threw and rod (thing was still running).
I'm good about cleaning parts but just flushed out and brushed off the rocker arm assembly in my parts washer without disassembling it.
First run was fine and break in was normal along with great oil pressure. Problem starting happening during a long running session where I just had it parked while working on something else. It starting ticking missing like a plug was getting fouled. Turned it off for the day and didn't think about it. Thought it might be bad gas from fuel tank (another story). Next day I wanted to get it inspected and registered since it hadn't been legal since 2009. Couldn't even make it to the shop. Made it half way and sounded so bad I turned around and barely made it home.
Got home and pulled the valve cover and found two intake valves stuck. First I thought it was an issue with the machine shop that rebuilt the head. Then, I found one of the push rod cups was broken and laying in an oil return hole and the pushrod was mushroomed and bent. Pulled the rocker assembly on a whim and decided to clean it instead of taking off the head. I did have a small camera that attaches to your phone to check the cylinders and everything looked fine on the pistons and cylinder walls.
From the pics below you can see all the carbon and debris pumped up to the top and clogged the holes that oil both sides of the rocker and the tube itself. One hole on the valve side feeds oil that runs down the valve spring and around the stem.
Don't know if this happened due to mileage, low oil and it just baked the engine or a combination.
What ended up happening was the tighter tolerance intake valves were the ones that stuck since any oil they had on them were being washed off by the fuel mixture and I'm sure the stems expanded too.
To get the valves unstuck I started with pb blaster and tapped them down and they'd slowly pop back up. Then I used motor oil doing the same, just tapping on the valve until it closed all the way traveled freely at it was tapped.
Also replaced a push rod.
For the tube itself I removed the plugs (pics below) and used a shotgun cleaning brush on a drill to get out the carbon and debris.
Something I noticed while researching the issue was how many guys had problems with sticking valves and unknown ticking and mushrooming pushrods on high mileage rigs. You might check for carbon and debris in the rocker arm assembly.
This might be a good thread to add to the "how to not rebuild and engine" thread...
Pic of mushroomed pushrod.
Some pics of the holes that were clogged up.
Pics of plugs on end of rocker shaft.
Plugs available at any parts store.
I'm good about cleaning parts but just flushed out and brushed off the rocker arm assembly in my parts washer without disassembling it.
First run was fine and break in was normal along with great oil pressure. Problem starting happening during a long running session where I just had it parked while working on something else. It starting ticking missing like a plug was getting fouled. Turned it off for the day and didn't think about it. Thought it might be bad gas from fuel tank (another story). Next day I wanted to get it inspected and registered since it hadn't been legal since 2009. Couldn't even make it to the shop. Made it half way and sounded so bad I turned around and barely made it home.
Got home and pulled the valve cover and found two intake valves stuck. First I thought it was an issue with the machine shop that rebuilt the head. Then, I found one of the push rod cups was broken and laying in an oil return hole and the pushrod was mushroomed and bent. Pulled the rocker assembly on a whim and decided to clean it instead of taking off the head. I did have a small camera that attaches to your phone to check the cylinders and everything looked fine on the pistons and cylinder walls.
From the pics below you can see all the carbon and debris pumped up to the top and clogged the holes that oil both sides of the rocker and the tube itself. One hole on the valve side feeds oil that runs down the valve spring and around the stem.
Don't know if this happened due to mileage, low oil and it just baked the engine or a combination.
What ended up happening was the tighter tolerance intake valves were the ones that stuck since any oil they had on them were being washed off by the fuel mixture and I'm sure the stems expanded too.
To get the valves unstuck I started with pb blaster and tapped them down and they'd slowly pop back up. Then I used motor oil doing the same, just tapping on the valve until it closed all the way traveled freely at it was tapped.
Also replaced a push rod.
For the tube itself I removed the plugs (pics below) and used a shotgun cleaning brush on a drill to get out the carbon and debris.
Something I noticed while researching the issue was how many guys had problems with sticking valves and unknown ticking and mushrooming pushrods on high mileage rigs. You might check for carbon and debris in the rocker arm assembly.
This might be a good thread to add to the "how to not rebuild and engine" thread...
Pic of mushroomed pushrod.
Some pics of the holes that were clogged up.
Pics of plugs on end of rocker shaft.
Plugs available at any parts store.
