Consistently losing valve clearance on one valve
#1
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Consistently losing valve clearance on one valve
I am consistently losing valve clearance on the cylinder 1 intake valve. It started after an offroading adventure up near deep creek hot springs. There was a very cold start heading home because we left after midnight (it was about 30*F), so I'm thinking it is definitely something to do with that cold start- or maybe hitting a bump too hard on the way in. I remember the motor barely being able to turn over and shuddering for a while until it warmed up.
It seemed to be fine on the highway on the way home, but then again this problem is only noticeable at idle / no load. When I started it the next morning, it shuddered violently and slowly dissipated in vibration as it warmed up. I immediately suspected harmonic balancer, but since it seemed temperature related I then decided to check valves and do a leakdown test.
Sure enough, cylinder 1 was down to 90psi compression. I had tested just before the trip with 175 +/- 4psi across all cylinders. After popping the valve cover, I found that intake on cyl 1 was way out of spec- zero clearance. All other valves checked out great.
Since then, I have been having to readjust the valve clearance for that valve every 1000 miles. The shudder always returns after a load is applied to the motor for a little while. After the third adjustment, I realized that for sure the tappet was not the culprit. I had backed it out 2mm farther than all of the other tappets. Recently, it only went 600 miles before needing readjustment, so I decided it was time to stop using it until I had a chance to pull the head.
I also have a leak at the rear main seal along with a small leak coming from the front near the head gasket, so I decided I would pull the whole motor and fix everything all at once rather than just doing the top end. I'll be getting the obvious metal backed timing guides, and maybe dual row timing chain. Still yet to be seen what the problem was, so I might even need a new head (let's hope not).
Engine is out! Anyone that wants to take bets on what I find, feel free. More updates to come.
It seemed to be fine on the highway on the way home, but then again this problem is only noticeable at idle / no load. When I started it the next morning, it shuddered violently and slowly dissipated in vibration as it warmed up. I immediately suspected harmonic balancer, but since it seemed temperature related I then decided to check valves and do a leakdown test.
Sure enough, cylinder 1 was down to 90psi compression. I had tested just before the trip with 175 +/- 4psi across all cylinders. After popping the valve cover, I found that intake on cyl 1 was way out of spec- zero clearance. All other valves checked out great.
Since then, I have been having to readjust the valve clearance for that valve every 1000 miles. The shudder always returns after a load is applied to the motor for a little while. After the third adjustment, I realized that for sure the tappet was not the culprit. I had backed it out 2mm farther than all of the other tappets. Recently, it only went 600 miles before needing readjustment, so I decided it was time to stop using it until I had a chance to pull the head.
I also have a leak at the rear main seal along with a small leak coming from the front near the head gasket, so I decided I would pull the whole motor and fix everything all at once rather than just doing the top end. I'll be getting the obvious metal backed timing guides, and maybe dual row timing chain. Still yet to be seen what the problem was, so I might even need a new head (let's hope not).
Engine is out! Anyone that wants to take bets on what I find, feel free. More updates to come.
#2
Pretty sure you already know the answer
When I set my valves for the first time I found one exhaust at .008 and I hope that was a mistake by whoever set the valves before me. I've put on about 4,000 miles since then and need to check it. Crossing my fingers here
I like it, that'd make some motorhead a nice tatoo
When I set my valves for the first time I found one exhaust at .008 and I hope that was a mistake by whoever set the valves before me. I've put on about 4,000 miles since then and need to check it. Crossing my fingers here
I like it, that'd make some motorhead a nice tatoo
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I like the tattoo in the knee. lol As far as the valve backing off, I have seen some of the adjustment screws and nuts get loose at time. I might would try to replace the two or maybe even try some blue locktite on it.
I dont blame you for pulling the motor when doing multiple repairs. Your back will thank you for that. Working on it in the truck get a little rough. Hope all goes well for you and you get it on the road again soon.
I dont blame you for pulling the motor when doing multiple repairs. Your back will thank you for that. Working on it in the truck get a little rough. Hope all goes well for you and you get it on the road again soon.
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