umbrella seals

[superpieboy]

the builder of my 261 inline six used seals under the valve caps when they rebuilt the head, the problem i am having is smoke during start up and excelerating AFTER A STOP.

my old 235 engine had umbrella seals along with the valve cap seals, given they were wore out, but i heard that you could not use both! i need to do something with this fresh engine, i have put a couple thousand miles on it and still smokes at times.

once while i was investigating this smoke issue, i took the valve cover off and watched what was going on while the engine was running, it appears that oil is being slung offthe valve springs as the oil comes down from the valve cap retainer ring area, drops of oil will sling over onto the valve stem leaving me with oil burning thru the combustion chamber. what should i do? change to the umbrella seals, the block was also rebuilt with new rings ect ect.

anyone ever had this issue?

thanks
jeff

[Fred T]

While you can run the two styles of seals, it is not recommended. This setup does not allow enough oil down the valve stem, accelerating valve guide wear.

Usually smoke from valve seals or guides occurs only on cold startup. Smoke on acceleration is usually due to unseated rings. First I would try seating the rings. Find an empty stretch of road, go up and down on the throttle several times. What you are doing is switching the pressure on the rings.

If that doesn't fix your smoking, it gets more involved to diagnose. Found this tech tip on the stovebolt board.

So your engine is smoking and you figure you need to rebuild it or get another engine. This is often not the case.

The first thing you should do is figure out what 'color' the smoke is. This 'smoke color' can tell you a lot about your engine and how to test it.

If the smoke is 'Blue-gray' in color, this is evidence that oil is entering the combustion chamber and burning. Don't confuse this with 'Black smoke', which is a sign of to rich of carburetion. Also, you could have 'White smoke' which is the condensation of steam.

Some older V-8 engines, under deceleration, will show a trace of 'Blue-gray' smoke and not be using oil excessivly. But, a dense cloud of 'Blue-gray' smoke, on any engine, is definite evidence that excess oil is burning in the combustion chambers.

There are eight ways by which oil can reach the combustion chambers from the crankcase. Listed in no particular order-

1. Through a broken or porous diaphragm in the vaccum booster of the fuel pump.

2. Through a defective mechanical, vaccum type crank case ventilator

3. through a ventilating tube connecting valve chamber covers to the air cleaner.

4. Through a leak past the head gasket, seperating an internal oil passage and a cylinder at the top of the block.

5. Through the valve guides.

6. Through a leak past the intake manifold gasket where the manifold covers the tappet chamber.

7. Past the pistons and piston rings.

8. (I don't think you have this, but just incase) Through leakage around the seals of mechanical superchargers or turbochargers.

Being as how you're so lucky, not all of these occur in any one engine.

The test for 1., 2., and 3. would be to disconnect it (only disconnect one at a time to test) and plug off the holes. Then run the engine for a few miles- usually 5-10 miles will be sufficient to allow the oil residue in the engine to burn off.

Number 4.- Checking for oil loss past head gaskets.

In some engines there is a drilled oil gallery in the engine block which extends to the top of the block to carry oil to the rocker arms. If the head gasket doesn't properly seal in this area, oil can escape at the top of the block into a cylinder. Also, oil may escape into the cooling system.If you have continued fouling of a spark plug next to this oil passage that is adjacent to the oil gallery in the block, or have found oil in the engine coolant, then this is a good indication of an internal oil leak.

Number 5.- the best way to check for oil loss the the valve guides is- remove the valve cover(s) and shut off the oil supply to the rocker arm assembly(s). (On a V-8, do one side at a time.)
"NOTE OF CAUTION"
This test must be of sufficient time to burn out any residual oil left in the system. The valve train can be opersted for up to an hour without oil supply. REMEMBER!!!- After the test is completed, be sure to restore the oil supply to the rocker arm assembly.

Number 6. Through a leak past the intake manifold gasket where the manifold covers the tappet chamber.

This is normally for V-8 engines.When a rough idle is present that can't be taken out by normal engine tune-up, then I would suspect a leak past the intake-to-manifold gaskets.

The test is as follows-

Start the engine and let it warm up and idle (although it may idle rough)

Squirt some oil around the edge of the intake manifold where it meets the head.

If the engine idle becomes smooth or there is a noticable change in RPM, the gasket is leaking. (This does not always disclose leaks underneath the manifold.)

Number 7. Past the pistons and piston rings.

If all of the other tests have failed to find your culprit then to check for excessive oil smoke because of oil getting past the rings you will need to check this internally by taking the engine apart.

To figure out the reason or reasons for oil getting past the rings will make an entire different Tech Tip.