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I have a 87 corvette with a stock l98 with only 88 thousand miles on it I checked the oil and there was nothing on the dipstick when I start it up it puffs out a little smoke but it doesn’t smoke after that which leads me to believe I need new valve seals it makes good oil pressure and has no audible sounds of knocking where do you think I should start
From: Clifton Park, NY ............Clearwater, FL ... 85 Original Owner
Originally Posted by JaredAwells
I have a 87 corvette with a stock l98 with only 88 thousand miles on it I checked the oil and there was nothing on the dipstick when I start it up it puffs out a little smoke but it doesn’t smoke after that which leads me to believe I need new valve seals it makes good oil pressure and has no audible sounds of knocking where do you think I should start
Sentences please!
No oil on dip stick?
Sure you need valve seals.
Not too bad, do the valve seals they are cheap. Typical of an old car
my 5.3 has burned a quart every 1000 since new, almost 190k on it now hasnt gotten any worse.
Compression test maybe? Wet and dry? That might give a hint of whether you should attack it or just dump it. If it is rings, I'd get the motor rebuilt. If it is in the PC Valve Seals, maybe Viton would be a better choice for the old seals?
Compression test maybe? Wet and dry? That might give a hint of whether you should attack it or just dump it. If it is rings, I'd get the motor rebuilt. If it is in the PC Valve Seals, maybe Viton would be a better choice for the old seals?
That is a good idea I just changed the oil and there was no sparkles, I am relieved that nothing major had been damaged
That is a good idea I just changed the oil and there was no sparkles, I am relieved that nothing major had been damaged
If it is sparkling, it is probably toast or will soon be. If it is not sparkling, only way I can see to know it is OK is to do a used oil analysis. It should tell you what is in the used oil and how much. Too much and the parts are going south.
If it is sparkling, it is probably toast or will soon be. If it is not sparkling, only way I can see to know it is OK is to do a used oil analysis. It should tell you what is in the used oil and how much. Too much and the parts are going south.
Well it never lost any oil pressure and it still runs good. I have some valve seals for it I’m going to put in it when fall break gets here in a few weeks I only drive it about 120 miles a week
Well it never lost any oil pressure and it still runs good. I have some valve seals for it I’m going to put in it when fall break gets here in a few weeks I only drive it about 120 miles a week
And that would impress me more if I didn't have a motor that had to be replaced at under 100K. It was making noise that I couldn't hear but the KS could. The knock count calmed down with thicker oil and Motor Honey or some stupid concoction that thickened it from a 20W50 to who knows what. Cool part is the car sounded "just fine" and the oil pressure was where it should be. Now, going forward it probably would have shown low oil pressure but it was just fine then. Using cheap TFS heads, my car was "just fine" even with a part of the piston missing. Just the outer edge and you could see the ring. Compression was 5 psi lower than the highest.
Bottom line is good oil pressure, ASSUMING the gauge is accurate enough, is only meaning that your oil pump can keep up. Doesn't mean everything is good. If you really suspect bearing wear, test the oil and see if the material is excessive.
And that would impress me more if I didn't have a motor that had to be replaced at under 100K. It was making noise that I couldn't hear but the KS could. The knock count calmed down with thicker oil and Motor Honey or some stupid concoction that thickened it from a 20W50 to who knows what. Cool part is the car sounded "just fine" and the oil pressure was where it should be. Now, going forward it probably would have shown low oil pressure but it was just fine then. Using cheap TFS heads, my car was "just fine" even with a part of the piston missing. Just the outer edge and you could see the ring. Compression was 5 psi lower than the highest.
Bottom line is good oil pressure, ASSUMING the gauge is accurate enough, is only meaning that your oil pump can keep up. Doesn't mean everything is good. If you really suspect bearing wear, test the oil and see if the material is excessive.
I read and then re-read every single post in this thread, how did it go from the OP asking about valve stem seals to you stating that the OP suspects bearing wear?
Replace the valve stem seals and you should be good to go. My 88 has a rebuild with about 11k on it now and it uses a quart every 1000 miles or so.
I read and then re-read every single post in this thread, how did it go from the OP asking about valve stem seals to you stating that the OP suspects bearing wear?
Replace the valve stem seals and you should be good to go. My 88 has a rebuild with about 11k on it now and it uses a quart every 1000 miles or so.
Jared
Thank you I will change the seals in the next week or so. will raising the piston to TDC be high enough to keep me from dropping a valve into the cylinder?
And that would impress me more if I didn't have a motor that had to be replaced at under 100K. It was making noise that I couldn't hear but the KS could. The knock count calmed down with thicker oil and Motor Honey or some stupid concoction that thickened it from a 20W50 to who knows what. Cool part is the car sounded "just fine" and the oil pressure was where it should be. Now, going forward it probably would have shown low oil pressure but it was just fine then. Using cheap TFS heads, my car was "just fine" even with a part of the piston missing. Just the outer edge and you could see the ring. Compression was 5 psi lower than the highest.
Bottom line is good oil pressure, ASSUMING the gauge is accurate enough, is only meaning that your oil pump can keep up. Doesn't mean everything is good. If you really suspect bearing wear, test the oil and see if the material is excessive.
I’m sorry to hear that you have had such bad luck with your motor but I had the heads off less than 1,500 miles ago and I can assure you all the pistons were there and the only reason I mentioned bearing wear was due to having such low oil and my oil and filter change yesterday had no sparkles in it which is enough for me to believe my motor is healthy
Thank you I will change the seals in the next week or so. will raising the piston to TDC be high enough to keep me from dropping a valve into the cylinder?
Some people like to use compressed air. Others like to stuff rope into the cylinders. I usually raise the piston to TDC. If the valve drops, what happens? It hits the piston and stops. Now you can fumble it back. If it goes past the tip of the valve, you are screwed. The piston at TDC will limit the fall regardless of the valve drop.
Thank you I will change the seals in the next week or so. will raising the piston to TDC be high enough to keep me from dropping a valve into the cylinder?
No it will not. Although the valve certainly wouldn't fall all the way in, it would fall further than you would be able to compress the spring to get the keepers back on.
I use a fitting that you thread into the spark plug hole with 35psi of air pressure to keep the valves seated while the springs are removed
Jared
Last edited by lotsofspareparts; Sep 16, 2019 at 10:06 PM.
I’m sorry to hear that you have had such bad luck with your motor but I had the heads off less than 1,500 miles ago and I can assure you all the pistons were there and the only reason I mentioned bearing wear was due to having such low oil and my oil and filter change yesterday had no sparkles in it which is enough for me to believe my motor is healthy
Nothing to do with bad luck. It couldn't take the abuse of daily WOT runs. I don't believe it was designed for that. During the summer or whenever I get enough traction, I would take the ramps at WOT. So if you make 4 WOT passes a day on the stock motor as a minimum, it stresses stuff more than just driving with a WOT pass here and there. Also, I did autocross a bit for fun so that might add to the stress. I guess my point was that the oil pressure wasn't an indicator of the bearings and rings and it wouldn't be until it lowered the pressure enough that the capacity of the pump was reached.
If the oil level is low and you added it right, it has to go somewhere. That is why I think it is either leaking onto something and blown away or it is being burned.
No it will not. Although the valve certainly wouldn't fall all the way in, it would fall further than you would be able to compress the spring to get the keepers back on.
I use a fitting that you thread into the spark plug hole with 35psi of air pressure to keep the valves seated while the springs are removed
Jared
Sure but can't you pull the valve up and do what you have to do? I did. Also the new valve stem seals often have more drag and hold the valve in place.
Sure but can't you pull the valve up and do what you have to do? I did. Also the new valve stem seals often have more drag and hold the valve in place.
I can see a new intake valve seal possibly holding the valve long enough to get the spring back on, but certainly not the umbrella seal on the exhaust valve.
I prefer purpose built tools, it removes the possibility of making 16 possible mistakes. The fitting is cheap too, less than $10 when I bought mine 15+ years ago.
L98 oil consumption
