75 Smokes on Startup
05-16-2011, 10:06 AM
#1
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75 Smokes on Startup
I have a 75 Vette. If i let it sit for a few hours it is hard to start and smoks a lot, after about a minute it will stop smoking or at least it isn't noticible to me. I assum valve seals but not sure what else could be the problem. I looks like oil burning but i am not sure how white coolant burns as i have never seen coolant burn and i am not even sure if that is a possibility. One other piece of info, if i run the car up to 80ish or more and then let it coast down to 55ish, it will start to smoke as it gets closer to the 60ish mark, then when i get back into the gas, a puff of smoke will come out then all is well again.
If this is the valve seals, is that something i can fix with the engine in the car? Just pull the vavle covers, rocker arms and springs?
Thanks.
If this is the valve seals, is that something i can fix with the engine in the car? Just pull the vavle covers, rocker arms and springs?
Thanks.
05-16-2011, 10:38 AM
#2
Safety Car
Valve seal will most likely be your problem. I would pull the heads and if the money is there ??? a nice set of Alumium heads! If not then a simple valve job for $400 and bolt em up
05-16-2011, 12:05 PM
#4
Race Director
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yes the valve seals can be replaced easily with the engine in the car. I have done it-all you need is a compressor for the valve spring and a way to pump air into the cylinder.
Is not much of a job at all.
Is not much of a job at all.
05-17-2011, 10:25 AM
#5
Burning Brakes
Agree, it's not too big a job. I did this on my '70 many years (35) ago. I broke off the ceramic part of a spark plug and welded on a shop compressor quick disconnect fitting. When working on a cylinder, screw in the modified spark plug and connect an air hose. This will hold the valves up tight as you work on them. Make sure the cylinder is at the top of the compression stroke.
I still have this home made tool decades later. A spring compressor tool is simple and cheap to buy. If you need a pic I can take one but it seems self explanatory.
After you finish the job it would be a good idea to do a cylinder leak down check on the car (not a compression check). This will check valve sealing, ring sealing, intake manifold and head gasket integrity. Based on where the leak down is coming from will tell you what area needs attention. BTW...if you have a leak down test kit you will have a way to attach the air hose to the cylinder and not need to make a tool.
I still have this home made tool decades later. A spring compressor tool is simple and cheap to buy. If you need a pic I can take one but it seems self explanatory.
After you finish the job it would be a good idea to do a cylinder leak down check on the car (not a compression check). This will check valve sealing, ring sealing, intake manifold and head gasket integrity. Based on where the leak down is coming from will tell you what area needs attention. BTW...if you have a leak down test kit you will have a way to attach the air hose to the cylinder and not need to make a tool.
05-17-2011, 11:05 AM
#6
Le Mans Master
Here is one post I did about the job:
http://forums.corvetteforum.com/c3-t...tem-seals.html
OK, here are my directions from an old post:
Here is my method. No air compressor required and I can do 16 seals in 3 hours.
1. You need a small magnet, hammer, wheel grease, spring compressor (I use the cheap bar type), rope, a balancer that is marked every 90 degrees plus wrenches, etc.
2. Remove spark plugs.
3. Rotate balancer (I use the bolt) till you get to the 0 degree TDC mark.
4. Ensure that you are on #1 TDC on firing stroke by pulling the distributor cap. Rotor pointing close to #1? Good. If it is pointing to #6. If not rotate crank 360 degrees and recheck.
5. I feed a little rope into the cylinder through the spark plug hole but it is not required since the piston is at TDC.
6. We are now ready to replace the springs/seals on #1.
7. Remove rocker arms and pushrods. I then do each spring in turn.
8. Tap spring retainer with hammer to help "break" friction.
9. Compress spring and remove the keepers using the magnet.
10. You can now replace the seals and springs.
11. Compress spring and retainer assembly and reinstall the keepers. A little grease on the inside of the keepers will help them stick to the valve stem when doing this.
12. Reinstall pushrods and rockers.
13. Since the piston is at TDC on the firing stroke, both valves are closed and the cam lifters will be on the base circle of the cam. This means that you can relash the valves at this time for that cylinder.
14. Remove rope and rotate crank 90 degrees.
15. Repeat for next cylinder IN FIRING ORDER.
The beauty of this method is that with the piston at TDC, the valve cannot drop down more than 1/2" and will not fall into the cylinder bore. Also, block the oil drainback holes in the heads. I use those thick blue paper towels so I don't get lint in the oil.
1. You need a small magnet, hammer, wheel grease, spring compressor (I use the cheap bar type), rope, a balancer that is marked every 90 degrees plus wrenches, etc.
2. Remove spark plugs.
3. Rotate balancer (I use the bolt) till you get to the 0 degree TDC mark.
4. Ensure that you are on #1 TDC on firing stroke by pulling the distributor cap. Rotor pointing close to #1? Good. If it is pointing to #6. If not rotate crank 360 degrees and recheck.
5. I feed a little rope into the cylinder through the spark plug hole but it is not required since the piston is at TDC.
6. We are now ready to replace the springs/seals on #1.
7. Remove rocker arms and pushrods. I then do each spring in turn.
8. Tap spring retainer with hammer to help "break" friction.
9. Compress spring and remove the keepers using the magnet.
10. You can now replace the seals and springs.
11. Compress spring and retainer assembly and reinstall the keepers. A little grease on the inside of the keepers will help them stick to the valve stem when doing this.
12. Reinstall pushrods and rockers.
13. Since the piston is at TDC on the firing stroke, both valves are closed and the cam lifters will be on the base circle of the cam. This means that you can relash the valves at this time for that cylinder.
14. Remove rope and rotate crank 90 degrees.
15. Repeat for next cylinder IN FIRING ORDER.
The beauty of this method is that with the piston at TDC, the valve cannot drop down more than 1/2" and will not fall into the cylinder bore. Also, block the oil drainback holes in the heads. I use those thick blue paper towels so I don't get lint in the oil.
