Valve Stem seals ???
Thread Starter
Melting Slicks
Joined: Feb 2003
Posts: 2,330
Likes: 6
From: Long Island NY
Valve Stem seals ???
I doing valve stems seals on a stock 95k L82. When I put air in the cylinder, the air does Not stop. I can hear it hiss inside. I'm at TDC on #1. Shouldn't the air stop after the cylinder is filled...?
Le Mans Master
Joined: Apr 1999
Posts: 6,134
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From: Raleigh North Carolina
If you are absolutely 100% positive you have TDC on the compression stroke, then the hiss is probably blow-bye past the rings. On a cold engine, there will be ring end gap + leakage. Also assuming your valves/seats are not all chewed up & carbon embedded from burning a lot of oil.... i.e.- leaking.
Le Mans Master
Joined: Dec 2003
Posts: 5,727
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From: Fremont CA
I agree either your on the wrong cycle or you have other problems. If the guage is reding 100% leak down and you are correctly on TDC at the compression stroke (neither rocker arm lifting the valves) it's time to tear it down for rings (not likley or replacement of valves, can happen on rare occurances.) The mileage being 95K I would do a complete rebuild (valve job and rings if not overbore with new pistons) as the fixing of rings or valves will only make the other side worse and you won't be happy with the results.
Le Mans Master
Joined: Oct 2002
Posts: 7,098
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From: Las Vegas - Just stop perpetuating myths please.
Ur learning and need a good shop manual.
This is how u diagnose the cyl - with a leakdown tester, compression gauge and a oil squirt gun.
Sorry to much too type here and u need to read for urself how to check for bad rings or vlv seats. But a normal/stock bottom end is good for 350K mi and most old iron heads just need the vlv job at 65K mi.
Not to patronize but if u don't know if both vlvs are closed or not then u should read up as using a trial and error method over the internet will be more than frustrating.
Good luck.
cardo0
Sorry to much too type here and u need to read for urself how to check for bad rings or vlv seats. But a normal/stock bottom end is good for 350K mi and most old iron heads just need the vlv job at 65K mi.
Not to patronize but if u don't know if both vlvs are closed or not then u should read up as using a trial and error method over the internet will be more than frustrating.
Good luck.
cardo0
Race Director
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65K valve job?.I got 119K (no valve job yet)with just a wiff of smoke at start up...thinking of seals......runs strong,still got 40 LBS oil pressure at 2000 RPM....change oil when it turns color,treat engine with Rislone once/year since 9,000 miles...L-82, fingers crossed...
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
Ur car condition may be entirely different.
Originally Posted by rihwoods
65K valve job?.I got 119K (no valve job yet)with just a wiff of smoke at start up...thinking of seals......runs strong,still got 40 LBS oil pressure at 2000 RPM....change oil when it turns color,treat engine with Rislone once/year since 9,000 miles...L-82, fingers crossed...
And if thats a bit much for him i would recommend a shop like a Chevy dealer for a compression & leakdown exam. Vlv job is usually around $1k but sure beats an engine overhaul if not needed. The dealer should have it done in less than a week and may save mvftw alot of headaches and time. Hey we're here to have fun not drag each other through the coals with some hard and dirty work - unless someone does enjoy repairing his own.
cardo0
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Le Mans Master
Joined: Mar 2004
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From: Little Rock AR
Originally Posted by mvftw
I doing valve stems seals on a stock 95k L82. When I put air in the cylinder, the air does Not stop. I can hear it hiss inside. I'm at TDC on #1. Shouldn't the air stop after the cylinder is filled...?
If your engine is currently on #1 TDC "EXHAUST" position, you are actualy on #6 TDC "FIRING" position so check for that too. I would pull the cap off the distributor for a reality check. If the rotor is pointing more to the rear of the car, you are likely at TDC #6 Firing position/#1 TDC EXHAUST position where it would behave like it is leaking. If the rotor is pointing more twards the front, you are probably at #1 TDC firing position and you need to check the condition of the engine before you waste any time on seals.
-Mark.
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From: In Dreams There Is Truth Ohio
I've seen where the compressed air pushes the piston down
Regarding the rope, there is a distinct possibility the rope could get hung up insided the cyl....Years ago someone posted that they could not get the rope out after changing the seal.
Regarding the rope, there is a distinct possibility the rope could get hung up insided the cyl....Years ago someone posted that they could not get the rope out after changing the seal.
Drifting
Joined: Jan 2001
Posts: 1,347
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From: Slidell La
I have done this job several times with compressed air. Some hissing is normal. If you have the valves closed (and) don't have a burnt valve you should have enough pressure to hold up the valve. You can add a gauge to the line to the cylinder and confirm if it is holding pressure prior to removing the snap lock on the valve spring. Good luck. 99 Nassau Blue
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Originally Posted by cardo0
Ya so? Sounds like mvftw's engine still runs too. But how does that help mvftw diagnose his leakdown readings or even take them. If u want to type a small book on how to go right ahead. But ur stiuation has little to do with what he may find due to prior maintenance/abuse.
And if thats a bit much for him i would recommend a shop like a Chevy dealer for a compression & leakdown exam. Vlv job is usually around $1k but sure beats an engine overhaul if not needed. The dealer should have it done in less than a week and may save mvftw alot of headaches and time. Hey we're here to have fun not drag each other through the coals with some hard and dirty work - unless someone does enjoy repairing his own.
cardo0
And if thats a bit much for him i would recommend a shop like a Chevy dealer for a compression & leakdown exam. Vlv job is usually around $1k but sure beats an engine overhaul if not needed. The dealer should have it done in less than a week and may save mvftw alot of headaches and time. Hey we're here to have fun not drag each other through the coals with some hard and dirty work - unless someone does enjoy repairing his own.
cardo0
Le Mans Master
Joined: Oct 2002
Posts: 7,098
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From: Las Vegas - Just stop perpetuating myths please.
Originally Posted by rihwoods
Meant to post that to you....was curious about the 65K...my bad,I guess....and just for info here,I am interested in his results and plenty here are helping with the leak down.....
That 65k mi is what i remember from the days before unleaded fuel and hardend vlv seats. Can't remember where i've read it but feel confident 'bout it. And a engine will run fine for a long time even with vlvs that don't seal - but it will have reduced pwr. And compression gives u a look at vlv seal - ring seal too. Leak down even better to dianose with. And really, i also have to read up on this before using as correct method won't stay in my head forever.
cardo0
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Originally Posted by cardo0
Ok dude. U kinda found my switch there. This forum use to have a lot of members that just liked to raise hell and leave.
That 65k mi is what i remember from the days before unleaded fuel and hardend vlv seats. Can't remember where i've read it but feel confident 'bout it. And a engine will run fine for a long time even with vlvs that don't seal - but it will have reduced pwr. And compression gives u a look at vlv seal - ring seal too. Leak down even better to dianose with. And really, i also have to read up on this before using as correct method won't stay in my head forever. cardo0
That 65k mi is what i remember from the days before unleaded fuel and hardend vlv seats. Can't remember where i've read it but feel confident 'bout it. And a engine will run fine for a long time even with vlvs that don't seal - but it will have reduced pwr. And compression gives u a look at vlv seal - ring seal too. Leak down even better to dianose with. And really, i also have to read up on this before using as correct method won't stay in my head forever.
cardo0
Le Mans Master
Joined: Oct 2002
Posts: 7,098
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From: Las Vegas - Just stop perpetuating myths please.
Originally Posted by rihwoods
Maybe I'm old school,but I would not do a valve job without including the bottom end. Agree on leak down,however.
Oh Buddy, that's the big misconception everyone has. The bottom end is good for 350k mi and that's from David Vizards "How to Rebuild the sb Chvy". Ok here on pg. 58 of " Building Max Perf sb Chevy" DV says at least 200K mi. for a daily driven sb. I also think i recall Checker Cabs used the sb Chevy in thier taxis because of this economy.
Usualy corrosion is what takes out the bottom end if let to sit too long and testing is recommended for this. But the stock cast pistons seal well, also are nice and quite and great for lo-po daily drivers.
A Plast-a-Gauge brg test is the final judge.
And if u pull the oil pan for a cam change y not? 
cardo0
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Originally Posted by cardo0
Oh Buddy, that's the big misconception everyone has. The bottom end is good for 350k mi and that's from David Vizards "How to Rebuild the sb Chvy". Ok here on pg. 58 of " Building Max Perf sb Chevy" DV says at least 200K mi. for a daily driven sb. I also think i recall Checker Cabs used the sb Chevy in thier taxis because of this economy.
Usualy corrosion is what takes out the bottom end if let to sit too long and testing is recommended for this. But the stock cast pistons seal well, also are nice and quite and great for lo-po daily drivers.
A Plast-a-Gauge brg test is the final judge. And if u pull the oil pan for a cam change y not? cardo0
Usualy corrosion is what takes out the bottom end if let to sit too long and testing is recommended for this. But the stock cast pistons seal well, also are nice and quite and great for lo-po daily drivers.
A Plast-a-Gauge brg test is the final judge.
And if u pull the oil pan for a cam change y not? cardo0
Race Director
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From: FL
If the piston is at TDC, you don't need air. The valve does not have enough room to drop into the cylinder.
Here is what I do:
-Put piston at TDC.
-Feed some rope in anyway.
-Tap keeper lightly wirh hammer.
-Compress spring with bar type compressor. Valve may move but will stop when it hits rope and then the locks will break loose.
- Release tension, remove bar, remove spring.
- If valve moved, pull it back up with fingers. Seal keeps it up while compressing spring on reinstall.
It is that easy. I just rotate the crank 90 degrees between cylinders and do it in firing order.
Oh, and how do I confirm #1 on TDC. Rotate balancer to ZERO timing mark with pointer. Pull dist cap. If the rotor is pointing forward, I am on #1, pointing back #6. If on #6, rotate cranck 360 degrees and recheck.
Remobe locks with pencil magnet.
Here is what I do:
-Put piston at TDC.
-Feed some rope in anyway.
-Tap keeper lightly wirh hammer.
-Compress spring with bar type compressor. Valve may move but will stop when it hits rope and then the locks will break loose.
- Release tension, remove bar, remove spring.
- If valve moved, pull it back up with fingers. Seal keeps it up while compressing spring on reinstall.
It is that easy. I just rotate the crank 90 degrees between cylinders and do it in firing order.
Oh, and how do I confirm #1 on TDC. Rotate balancer to ZERO timing mark with pointer. Pull dist cap. If the rotor is pointing forward, I am on #1, pointing back #6. If on #6, rotate cranck 360 degrees and recheck.
Remobe locks with pencil magnet.
Drifting
Joined: Aug 2004
Posts: 1,327
Likes: 5
From: 2010 C6 Grand Sport Convertible
Originally Posted by SteveG75
If the piston is at TDC, you don't need air. The valve does not have enough room to drop into the cylinder.
Here is what I do:
-Put piston at TDC.
-Feed some rope in anyway.
-Tap keeper lightly wirh hammer.
-Compress spring with bar type compressor. Valve may move but will stop when it hits rope and then the locks will break loose.
- Release tension, remove bar, remove spring.
- If valve moved, pull it back up with fingers. Seal keeps it up while compressing spring on reinstall.
It is that easy. I just rotate the crank 90 degrees between cylinders and do it in firing order.
Oh, and how do I confirm #1 on TDC. Rotate balancer to ZERO timing mark with pointer. Pull dist cap. If the rotor is pointing forward, I am on #1, pointing back #6. If on #6, rotate cranck 360 degrees and recheck.
Remobe locks with pencil magnet.
Here is what I do:
-Put piston at TDC.
-Feed some rope in anyway.
-Tap keeper lightly wirh hammer.
-Compress spring with bar type compressor. Valve may move but will stop when it hits rope and then the locks will break loose.
- Release tension, remove bar, remove spring.
- If valve moved, pull it back up with fingers. Seal keeps it up while compressing spring on reinstall.
It is that easy. I just rotate the crank 90 degrees between cylinders and do it in firing order.
Oh, and how do I confirm #1 on TDC. Rotate balancer to ZERO timing mark with pointer. Pull dist cap. If the rotor is pointing forward, I am on #1, pointing back #6. If on #6, rotate cranck 360 degrees and recheck.
Remobe locks with pencil magnet.
BTW, to those doing the job for the first time, don't be afraid to rap those valve spring retainers firmly with a ball peen to break them loose from the keepers and varnish that has built up over the years. Have patience and Good Luck!
Mike
