Worn Valve Guide Seals?
Question:
My wife was driving me COMPLETELY fruit with that little puff, every evening for about a month " My truck did it again" Did what? " It smoked again, can you fix it?" Every day for a month, just drove me to fix it. Took me about 4 hours to replace all the seals. How much it peace worth to ya?
– Hide quoted text — Show quoted text -> Dave, I wouldn’t bother. I have 360K on my 89′ Jimmy and it’s been > doing that since 250K. I still add no oil between 4K oil changes. If > you want to do it the seals are $15-18 (just bought a set for my 65′ > L79) at Carquest. You need a compressor for this method and an adapter > to connect your air hose the the plug hole. > Remove all plugs and valve covers, connect the air hose to a cylinder > on TDC and pressurize to about 100PSI. > WARNING….The engine may spin if it’s not exactly TDC as the air > pushes the piston down. > Remove the rockers and push rods. > With a small hammer rap each spring, this helps the break the varnish > that may holds the retainers in place. Use the valve spring compressor > to depress the spring. The air pressure will keep the valve from > dropping. Remove the retainers and take the spring off. > NOW BE CAREFUL If the piston isn’t at TDC and you break the pressure > seal you may drop the valve into the cylinder. Then you have to > remove the head to get it out. > Once the springs are off, oil up the new umbrella seal and slide it > down the valve stem AGAIN be careful not to push down too hard on the > valve. A 100 PSI against the 2" valve is a lot of pressure(200lbs > approx) and usually very safe but as soon as the seal is broken…you > could have a problem, so I’m just saying be careful so you don’t drop > the valve. > Now reassemble the spring, retainers but leave the rocker/pushrods > until all seals are done. > Now without the compressor anymore, set each cylinder to TDC on the > compression stroke so both valves are closed(no lift of the pushrods). > Gently tighten the rockers ot Zero lash, the turn down 3/4 turn more. > Do this on all 7 remaining. Install new cover seals and button her up. > It should start and run with no more valve adjustment needed. > That seems to be alot of work for a little puff of smoke in the > morning but that decision is your’s to make. > I’ve done this a few times without problems but usually when the oil > consumption is very high. >I have a 95 GMC K2500 w/ 350 TBI and about 82k miles. Not every time, but >occasionally I get a blue puff when I start the vehicle after it has been >sitting for just a little while. (Won’t smoke when cold, having sat >overnight, won’t smoke if you let it sit for an hour or two, nor will it >smoke on a hot start after sitting 15-30 minutes. Mostly appears to happen >when it parked with the engine down-hill. >I’m thinking valve guide seals. Comments? How difficult to replace? I’m a >good garage mechanic.
Response:
Dave, I wouldn’t bother. I have 360K on my 89′ Jimmy and it’s been doing that since 250K. I still add no oil between 4K oil changes. If you want to do it the seals are $15-18 (just bought a set for my 65′ L79) at Carquest. You need a compressor for this method and an adapter to connect your air hose the the plug hole. Remove all plugs and valve covers, connect the air hose to a cylinder on TDC and pressurize to about 100PSI. WARNING….The engine may spin if it’s not exactly TDC as the air pushes the piston down. Remove the rockers and push rods. With a small hammer rap each spring, this helps the break the varnish that may holds the retainers in place. Use the valve spring compressor to depress the spring. The air pressure will keep the valve from dropping. Remove the retainers and take the spring off. NOW BE CAREFUL If the piston isn’t at TDC and you break the pressure seal you may drop the valve into the cylinder. Then you have to remove the head to get it out. Once the springs are off, oil up the new umbrella seal and slide it down the valve stem AGAIN be careful not to push down too hard on the valve. A 100 PSI against the 2" valve is a lot of pressure(200lbs approx) and usually very safe but as soon as the seal is broken…you could have a problem, so I’m just saying be careful so you don’t drop the valve. Now reassemble the spring, retainers but leave the rocker/pushrods until all seals are done. Now without the compressor anymore, set each cylinder to TDC on the compression stroke so both valves are closed(no lift of the pushrods). Gently tighten the rockers ot Zero lash, the turn down 3/4 turn more. Do this on all 7 remaining. Install new cover seals and button her up. It should start and run with no more valve adjustment needed. That seems to be alot of work for a little puff of smoke in the morning but that decision is your’s to make. I’ve done this a few times without problems but usually when the oil consumption is very high. – Hide quoted text — Show quoted text – >I have a 95 GMC K2500 w/ 350 TBI and about 82k miles. Not every time, but >occasionally I get a blue puff when I start the vehicle after it has been >sitting for just a little while. (Won’t smoke when cold, having sat >overnight, won’t smoke if you let it sit for an hour or two, nor will it >smoke on a hot start after sitting 15-30 minutes. Mostly appears to happen >when it parked with the engine down-hill. >I’m thinking valve guide seals. Comments? How difficult to replace? I’m a >good garage mechanic.
Response:
I might burn a quart in 5000 miles. If it ain’ too hard to fix, I’d like to fix it, but with a wife and two kids under 4yo, I may have to take your approach!
– Hide quoted text — Show quoted text -> Gents, my 90 K1500 with the 350 has been doing that for 100,000 miles. It > has 187,xxx on it now and still does not use a quart in 3000 miles. It will > beat 16MPG on the road and 14 in town and road. I’ll be darned if I am > going to tear it down for a puff once in a while. Are you old enough to > remember when we built an engine and if it did not use a quart in 1000 we > had it too tight? Hell you puff once in a while too don’t ya? > — > Denny > I have a 95 GMC K2500 w/ 350 TBI and about 82k miles. Not every time, but > occasionally I get a blue puff when I start the vehicle after it has been > sitting for just a little while. (Won’t smoke when cold, having sat > overnight, won’t smoke if you let it sit for an hour or two, nor will it > smoke on a hot start after sitting 15-30 minutes. Mostly appears to > happen > when it parked with the engine down-hill. > I’m thinking valve guide seals. Comments? How difficult to replace? I’m > a > good garage mechanic.
Response:
Who asked you to?
– Hide quoted text — Show quoted text -> Gents, my 90 K1500 with the 350 has been doing that for 100,000 miles. It > has 187,xxx on it now and still does not use a quart in 3000 miles. It will > beat 16MPG on the road and 14 in town and road. I’ll be darned if I am > going to tear it down for a puff once in a while. Are you old enough to > remember when we built an engine and if it did not use a quart in 1000 we > had it too tight? Hell you puff once in a while too don’t ya? > — > Denny > I have a 95 GMC K2500 w/ 350 TBI and about 82k miles. Not every time, but > occasionally I get a blue puff when I start the vehicle after it has been > sitting for just a little while. (Won’t smoke when cold, having sat > overnight, won’t smoke if you let it sit for an hour or two, nor will it > smoke on a hot start after sitting 15-30 minutes. Mostly appears to > happen > when it parked with the engine down-hill. > I’m thinking valve guide seals. Comments? How difficult to replace? I’m > a > good garage mechanic.
Response:
ToIf you Valve guide seals are bad enough to cause symptoms other than a puff of smoke, that will probably be a good tool/test. However, if it’s no more than the usual Chevy dry valve seal problem, it probably won’t tell you much. Sam
– Hide quoted text — Show quoted text -> I had heard the way to diagnose the guides themselves was to hold the > RPM’s at a constant level, let off, then resume. If you get a puff > then of blue, then the guides are worn. > Is that correct? > Tony >THose would be the symptoms of worn valve guide seals. >Sam >> I have a 95 GMC K2500 w/ 350 TBI and about 82k miles. Not every time, but >> occasionally I get a blue puff when I start the vehicle after it has been >> sitting for just a little while. (Won’t smoke when cold, having sat >> overnight, won’t smoke if you let it sit for an hour or two, nor will it >> smoke on a hot start after sitting 15-30 minutes. Mostly appears to >happen >> when it parked with the engine down-hill. >> I’m thinking valve guide seals. Comments? How difficult to replace? I’m >a >> good garage mechanic.
Response:
Gents, my 90 K1500 with the 350 has been doing that for 100,000 miles. It has 187,xxx on it now and still does not use a quart in 3000 miles. It will beat 16MPG on the road and 14 in town and road. I’ll be darned if I am going to tear it down for a puff once in a while. Are you old enough to remember when we built an engine and if it did not use a quart in 1000 we had it too tight? Hell you puff once in a while too don’t ya? — Denny
– Hide quoted text — Show quoted text -> I have a 95 GMC K2500 w/ 350 TBI and about 82k miles. Not every time, but > occasionally I get a blue puff when I start the vehicle after it has been > sitting for just a little while. (Won’t smoke when cold, having sat > overnight, won’t smoke if you let it sit for an hour or two, nor will it > smoke on a hot start after sitting 15-30 minutes. Mostly appears to happen > when it parked with the engine down-hill. > I’m thinking valve guide seals. Comments? How difficult to replace? I’m a > good garage mechanic.
Response:
I had heard the way to diagnose the guides themselves was to hold the RPM’s at a constant level, let off, then resume. If you get a puff then of blue, then the guides are worn. Is that correct? Tony – Hide quoted text — Show quoted text – >THose would be the symptoms of worn valve guide seals. >Sam > I have a 95 GMC K2500 w/ 350 TBI and about 82k miles. Not every time, but > occasionally I get a blue puff when I start the vehicle after it has been > sitting for just a little while. (Won’t smoke when cold, having sat > overnight, won’t smoke if you let it sit for an hour or two, nor will it > smoke on a hot start after sitting 15-30 minutes. Mostly appears to >happen > when it parked with the engine down-hill. > I’m thinking valve guide seals. Comments? How difficult to replace? I’m >a > good garage mechanic.
Response:
THose would be the symptoms of worn valve guide seals. Sam
– Hide quoted text — Show quoted text -> I have a 95 GMC K2500 w/ 350 TBI and about 82k miles. Not every time, but > occasionally I get a blue puff when I start the vehicle after it has been > sitting for just a little while. (Won’t smoke when cold, having sat > overnight, won’t smoke if you let it sit for an hour or two, nor will it > smoke on a hot start after sitting 15-30 minutes. Mostly appears to happen > when it parked with the engine down-hill. > I’m thinking valve guide seals. Comments? How difficult to replace? I’m a > good garage mechanic.
Response:
Although my symptoms were not "exactly" the same, my 93 4.3 got valve guide seals under warranty at about 30K miles. I really didn’t pay attention to exactly when it smoked since it was under warranty and didn’t have to be diagnosed/fixed by me. Maybe it is a trend.
I have a 95 GMC K2500 w/ 350 TBI and about 82k miles. Not every time, but occasionally I get a blue puff when I start the vehicle after it has been sitting for just a little while. (Won’t smoke when cold, having sat overnight, won’t smoke if you let it sit for an hour or two, nor will it smoke on a hot start after sitting 15-30 minutes. Mostly appears to happen when it parked with the engine down-hill. I’m thinking valve guide seals. Comments? How difficult to replace? I’m a good garage mechanic.
Response:
I have a 95 GMC K2500 w/ 350 TBI and about 82k miles. Not every time, but occasionally I get a blue puff when I start the vehicle after it has been sitting for just a little while. (Won’t smoke when cold, having sat overnight, won’t smoke if you let it sit for an hour or two, nor will it smoke on a hot start after sitting 15-30 minutes. Mostly appears to happen when it parked with the engine down-hill. I’m thinking valve guide seals. Comments? How difficult to replace? I’m a good garage mechanic.
