The Stovebolt Site Forums The Shop Area Engine Shop motor smokes, good compression, rebuild head

1966 inline six. The motor smoked the plugs were oil fouled. There was good compression. I took the head off and the valve stems were loose in the guides. I bought the vehicle in this conditon. I had the head rebuilt.
The motor still smokes...alot. The plugs have soot on them as I let it idle for an hour but do not have wet oil on them. I noticed drops of oil coming out of the exhaust pipe. I shut the motor off and took the intake exhaust manifolds off. Both the ports on the head and manifold had plenty of oil, enough to wipe onto your fingertip, even the intake. It seems they forgot to put the oil seals on the valve stems. The motor smokes pretty much the same as before I put the rebuilt head on. A few notes.
I did not put a straight edge on the block deck. Could the block be warped?
I did not use any permatex or silocone on the new head gasket.
I torqued the head correctly and have sucessfully done the same job to another six before.
In cleaning the tops of the pistons I noticed it is .60 over.
I have 140 plus compression in each cylinder and the plugs were not wet with oil.
The pvc hose goes back into the intake manifold. I can not imagine blowby can carry this much oil. Is that possible?
I am going to clean out the ports on the head, leave the manifolds off and crank the motor to see if oil is coming down the valve guides. Will I get enough oil pressure for this test by cranking or does the motor need to run?
Any thoughts will be greatly appreciated.

Freds,

Welcome to the Stovebolt forum. Great explanation of your dilemma. I am not an expert, but have a few thoughts.

A malfunctioning PCV setup can allow raw oil vapor to enter the intake manifold. Installing a new valve would be a simple step.

I am wondering if your exhaust system is soaked with oil from your previous problems. I have seen a small amount of oil make a rig smoke for hours.

If your compression is as great as it appears, and your PCV system is working properly, I think I would take a long trip down the road and see if the exhaust would eventually burn itself clean.

My bet is all the valve have quad ring seals, you might not see them. The exhaust guide isn't as critical in regards to oil consumption as a intake.

Take a trip, get the system hot and see what happens. Good luck.

Stuart

you can do a proper wet / dry compression test.

do the dry one first, mark the findings down.
squirt some WD or light machine oil in the plug hole and do the wet compression test.
if the wet has better readings.... your rings are bad as the oil helps seal the ring gap.

Seems to me the oil is coming from the pcv system. Look inside the valve cover. There should be a housing around the area that the pcv valve goes in. Some aftermarket chrome covers don,t have this or it could have broken off at one time. Make shure the valves are adjusted o.k. Loose valves can throw excess oil around. The test you discribe is no good. Try running it with the pcv valve out of the hole & see if the smoke stops.

If you have a exhaust system full of old oil and suet it may take a while to burn it all out. Did this one time replaced a smokey motor with a fresh one, it smoke like the old one till all the old oil burned out.

I'm betting you raised the compression against some bad rings, oil rings in particular, and it's actually burning the oil. If it's burning a lot and smoking heavily, it has to be cylinder related. If it's a puff under decelleration then maybe valve seals, but I doubt it from you description. I had a car that the oil rings were stuck due to carbon build up and a timing belt breaking. The rings got compressed into the piston and it ran fine but burnt a quart of oil in 200 miles. I rerung it and it never burned a drop since.
Scott

I vote for removing the PVC valve from the valve cover and going for a drive. Get it good and hot and drive it prett hard. Valve seals can make it smoke, but they won't oil down a intake, they will oil down the exhaust, but stock 230/250's didn't have seal on the exhaust anyway! Go for a drive and clean out the system befor getting to worked up about it, just leave the PVC out for a bit till you know you got it good and dryed out... Joe

So I assume this applies the same way after installing new valve cover gaskets also? I got most of the oil build up that was there due to the old gasket leaking however she still smokes like a chimney after a good drive. Most of what is still remaining is what ran down and got on to the exhaust.

Oil driping from the tail pipe? Daaaamn! First thought is that the exhaust system is full of oil and untill it all burns out it is gonna smoke. The thing is where or should i say when did the exhaust system fill with oil? With the old head or after the head was replaced? If you dont find any PCV problems and the engine seems to run ok. I would check the oil on the stick and drive this vehicle for 1000 miles then check it again. If it is using oil the level should get low in a 1000 miles.
I have also seen an oil bath air filter cause the same thing because it was over filled.

There are eight ways that I can think of that oil can reach the combutstion chamber from the crankcase. 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.

You can test most of what you need without taking the engine down for an enternal examination.

You can easily check- 1. 2. 3. 4. 5. 6. and 8.

If you would like me to take you through each test please let me know. I will gladly help. Each test will give you a postive out come as to if it is where the problem is.

I just bought a 1970 Truck with an inline 6 (not sure if it is a 250 or 292). It smokes so bad that you can't even drive it. It just pours deep blue smoke, yet it runs strong and sounds great, no rod knock, no overheating, just valve train tapping. I am at a total loss as to why it is smoking so bad!

So your not the only one with a smoking problem, I guess I have the same problem. Perhaps we just need to re-ring our engines?

a 292 has 6'' side valve covers, because of the longer stroke of 1.75'', larger volumn H2O pump, distributor @ #2 cylinder, just behind the spin on oil filter which is just below the #1 cylinder

HuckMubb, you may want to find out 'how' the oil is getting into the crankcase. I wrote a tech tip that you may want to check out- Engine smoking, Tech tip . I hope this can help you and you don't need to rebuild the entire engine.

"loose" rod bearings can cause excessive oil to be thrown on the cylinder walls, more than the rings can control.

Does your truck have an automatic Trans ? A vacuum modulator that is bad will suck the trans oil out of the pan and smoke like a steam train.If It's a stick shift,do what Wrenchbender Ret. suggested.