Valve Seals
Thread Starter
Intermediate
Joined: Feb 2008
Posts: 33
Likes: 0
From: Houston TX
Valve Seals
Ok Guys one more questions! I have an 86 L98 with the iron heads. I think my valve seals are starting to leak a little (puff of smoke on hot start). If I take it in to have the seals replaced, should I go ahead and replace the rockers and springs. If so recommendations? I dont have experience in internal motor issues. 
Le Mans Master
Joined: Oct 2006
Posts: 6,842
Likes: 285
From: Palmdale CA
If you could provide some more info. How many miles on your 'Vette? Do you get the big blue cloud in the morning on cold start too? Because if it's the valve seals, they'll leak through the night, leaving a puddle of oil on the piston.
Have you pulled the plugs and seen what condition they were in? Often, the suspect plugs will be fouled. From experience, the top of the pistons on the affected cylinders will have a crust of hardened oil on top of them. Also, the oil will clog the cats as well.
You could just replace the seals, but I went ahead and did the heads, as I had head gasket leakage from the heads (seeping oil under the heads). Do you have this as well?
As far as rockers and springs, I reused the originals. Nothing wrong with them, unless you want a performance upgrade or they're defective.
Have you pulled the plugs and seen what condition they were in? Often, the suspect plugs will be fouled. From experience, the top of the pistons on the affected cylinders will have a crust of hardened oil on top of them. Also, the oil will clog the cats as well.
You could just replace the seals, but I went ahead and did the heads, as I had head gasket leakage from the heads (seeping oil under the heads). Do you have this as well?
As far as rockers and springs, I reused the originals. Nothing wrong with them, unless you want a performance upgrade or they're defective.
Thread Starter
Intermediate
Joined: Feb 2008
Posts: 33
Likes: 0
From: Houston TX
If you could provide some more info. How many miles on your 'Vette? Do you get the big blue cloud in the morning on cold start too? Because if it's the valve seals, they'll leak through the night, leaving a puddle of oil on the piston.
Have you pulled the plugs and seen what condition they were in? Often, the suspect plugs will be fouled. From experience, the top of the pistons on the affected cylinders will have a crust of hardened oil on top of them. Also, the oil will clog the cats as well.
You could just replace the seals, but I went ahead and did the heads, as I had head gasket leakage from the heads (seeping oil under the heads). Do you have this as well?
As far as rockers and springs, I reused the originals. Nothing wrong with them, unless you want a performance upgrade or they're defective.
Have you pulled the plugs and seen what condition they were in? Often, the suspect plugs will be fouled. From experience, the top of the pistons on the affected cylinders will have a crust of hardened oil on top of them. Also, the oil will clog the cats as well.
You could just replace the seals, but I went ahead and did the heads, as I had head gasket leakage from the heads (seeping oil under the heads). Do you have this as well?
As far as rockers and springs, I reused the originals. Nothing wrong with them, unless you want a performance upgrade or they're defective.
, However runs strong. On a cold start I get nothing, only when the cars has been driven and parked for a few minutes and then started again. I have yet to check the plugs, but I will be doing a full tune-up soon.
Drifting
Joined: Feb 2003
Posts: 1,614
Likes: 163
From: Davis CA
I did this job on my 88 and it was not too difficult. Just take your time and come get advice as needed.
It's tempting to do more but on your motor -- because of miles -- I would not replace rockers, intake manifold, upgrade heads, etc. Just get a good set of Viton valve seals & O ring seals and do replace the valve springs. An OEM spec set of springs is pretty cheap ($30?). With gaskets and Right Stuff, you should get by for under $100 in total. More for the other parts of your tuneup.
It's tempting to do more but on your motor -- because of miles -- I would not replace rockers, intake manifold, upgrade heads, etc. Just get a good set of Viton valve seals & O ring seals and do replace the valve springs. An OEM spec set of springs is pretty cheap ($30?). With gaskets and Right Stuff, you should get by for under $100 in total. More for the other parts of your tuneup.
Thread Starter
Intermediate
Joined: Feb 2008
Posts: 33
Likes: 0
From: Houston TX
I did this job on my 88 and it was not too difficult. Just take your time and come get advice as needed.
It's tempting to do more but on your motor -- because of miles -- I would not replace rockers, intake manifold, upgrade heads, etc. Just get a good set of Viton valve seals & O ring seals and do replace the valve springs. An OEM spec set of springs is pretty cheap ($30?). With gaskets and Right Stuff, you should get by for under $100 in total. More for the other parts of your tuneup.
It's tempting to do more but on your motor -- because of miles -- I would not replace rockers, intake manifold, upgrade heads, etc. Just get a good set of Viton valve seals & O ring seals and do replace the valve springs. An OEM spec set of springs is pretty cheap ($30?). With gaskets and Right Stuff, you should get by for under $100 in total. More for the other parts of your tuneup.
Pro
Joined: Nov 2005
Posts: 602
Likes: 0
From: North Bay Ontario
I did the seals on my '85 this spring when it came out of storage. It was not a difficult job, important things to think about...what steps/procedure do you feel most comfortable with so as to not drop a valve down a cylinder, and what method do you prefer to use to adjust the valves when you put it back together. You're welcome to send me any questions that you might have. Just take your time and it can go very smoothly.
Burning Brakes
Joined: Aug 2004
Posts: 1,174
Likes: 125
From: Dunstable MA
St. Jude Donor '05
Repeating the above; valve seals usually give a cold start cloud. I recently replaced mine (big cold start cloud), but I was advised to check fuel pressure leak-down first (and I did). Have you done that?
Yes, the valve seal replacement killed the cold start cloud completely.
Yes, the valve seal replacement killed the cold start cloud completely.
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Thread Starter
Intermediate
Joined: Feb 2008
Posts: 33
Likes: 0
From: Houston TX
I did the seals on my '85 this spring when it came out of storage. It was not a difficult job, important things to think about...what steps/procedure do you feel most comfortable with so as to not drop a valve down a cylinder, and what method do you prefer to use to adjust the valves when you put it back together. You're welcome to send me any questions that you might have. Just take your time and it can go very smoothly.
Thanks for the good info.
Instructor
Joined: Jan 2008
Posts: 163
Likes: 1
From: Idianapolis Indiana
A word of advice from someone whos been there. The exhaust valves on these engines actually need to eat a little bit of oil to maintain proper lubrication. If the valve seals are too good it will cause premature valve guide wear. I used expensive racing "positve" valve guide seals and every single exhaust valve guide had to be replaced. Just use stock valve seals and you should be fine. As for mods at 190k I would advise against it unless you harbor resent for your current engine. Just start saving for the rebuild so when she starts to let go you don't have to skimp while your in it.
Instructor
Joined: Jan 2008
Posts: 163
Likes: 1
From: Idianapolis Indiana
when it starts fouling plugs and eating too much oil. If it smokes a little its ok. on initial startup after lots of miles there is a little slack in the valve guides due to normal wear and when its all cold with high oil pressure then some gets in the head. Changing the seals will make it run a little cleaner. If it isnt smoking hellaciously there wont be any damage.
Le Mans Master
Joined: Oct 2006
Posts: 6,842
Likes: 285
From: Palmdale CA
Get the Factory Service Manual. To pull the valve cover on the driver side, you have to disconnect the battery, then pull the serpentine belt (easy). The next step is to pull the alternator and air pump, because you have to pull the upper accessory bracket. The valve cover won't come off or go on, until you pull that bracket. You'll see that it extends over the front part of the valve cover by a mere 1/4 to 1/2 inch, but that's enough to make it a no-go.
On the passenger side, the valve cover comes off much easier when you pull the AIR hose that is on the right side, or front of the valve cover. That big rubber hose makes it a royal pain.
Finally, go with the Fel-Pro rubber gaskets, use no goop. Be patient and take your time. The L-98 looks deceptively easy to work on. Don't drop any bolts or sockets! You might not see them again.
On the passenger side, the valve cover comes off much easier when you pull the AIR hose that is on the right side, or front of the valve cover. That big rubber hose makes it a royal pain.
Finally, go with the Fel-Pro rubber gaskets, use no goop. Be patient and take your time. The L-98 looks deceptively easy to work on. Don't drop any bolts or sockets! You might not see them again.
Pro
Joined: Nov 2005
Posts: 602
Likes: 0
From: North Bay Ontario
All good advice in the posts preceding. I used the compressed air into the cylinder method for holding the valves in place when removing the retainers/springs. I took some extra precautionary steps (some might think it was unnecessary but it gave me peace of mind and lots of time to inspect things) - I rotated the engine so that each cylinder had the piston just approaching TDC. I then clamped the crankshaft pulley with vice grips (rubber hoses on the jaws) and turned it backward against the rack and pinion casting. THEN, I put the air into the cylinder, removed the retainers/springs, clamped each valve stem with a mini clamp (rubber surfaced jaws again), turned off the air and released the mini clamps letting the valve slip down and rest on the top of the piston. This gave me all the time I needed to inspect the springs/dampeners, valve guides, install seals, have lunch(!) etc. Be sure to inspect your springs/dampeners carefully - I discovered that I had 2 broken dampeners. Nothing feels better than the pride of a job well done and the little puff of smoke on start-up is gone!