Hello, I have a 86 f350 with the 460. I have all the smog parts off and all the holes plugged where needed. Every once in a while say every 2 out of 10 times I drive it it smokes on start up and then cleans up as you drive. It is blueish oil so its got to be oil. But you drive for a little bit and it clears up. I have noticed you can hear the pcv valve rattling sometimes, I can pull it off while running, and it is sucking. Should I try a new pcv? Thanks

 

How many miles on the engine? How much have you driven it? If you have driven it enough, does it use any oil and how much?

Usually the PCV valve only causes a problem when chrome aftermarket valve covers are used. The chrome covers do not have the oil separator under the PCV hole like the factory covers, or if they do it's not as good as the factory cover, so it is can let the PCV valve suck oil out of the engine.

Also, the drain back holes in the tops of the heads under the valve covers can get plugged with sludge, and oil can puddle under the valve cover, causing it to use oil through the valve guides.

If it has a lot of miles, and uses some oil, then it's probably just a worn engine. Smoke on start up and after you have decelerated is usually caused be worn valve guides and hard/brittle valve seal umbrellas.

Once you get it good and hot after driving it, let it idle, and with the PCV valve still installed in the other valve cover, pull the pipe off the other valve cover, usually where you put the oil in. If the PCV valve is sucking in the one valve cover, and you still have oil smoke coming out of the oil fill hole, your engine has a lot of wear in the piston rings.

 

TRuck and engine only have 40,*** miles on it. It has done a lot of sitting in its life. It is hard to tell if it burns much up between oil changes because it drips oil from the rear main seal area and front oil pan. I will check the oil fill cap when I drive it next. I drive it at least a couple times a week for about 10-15 miles.

 

Low mileage like that could mean some stuck rings. The valve guides are probably fine, but the valve seals are surely toast.

If you find lots of oil smoke coming out of the oil fill, you might have to pull all the plugs and put some sort of solvent/penetrant into the sparkplug holes and let it sit to try to loosen the rings. You can do a google search on what methods different people have used that has worked. Sometimes just driving it will eventually loosen them up. When you pull the plugs, if certain ones are fouled you will know which ones are stuck.

 

Sounds like a mystery project for the week. Thanks

 

Ok so I stuck a new pcv valve in any who since they are cheap. There was some oil residue on the old one.

Started the truck and let it warm to operating temps, it was smoking pretty out the exhaust a white ish blue smoke. Once it warms up it pretty much cleans up. I do however see some of the same colored smoke coming out of the passenger side exhaust where he manifold bolts to the exhaust, so I am guessing the issue lies on the pass. side of the motor. I will pull the plugs when it cools back off under the hood and see whats up.

Also Franklin2 I pulled the oil fill cap off when it warmed up and nothing coming out of the tube, I can put a piece of paper on it and it sucks it down to hold it to the pipe.

IS it maybe leaking coolant? I will have to watch the radiator levels? THanks

 

Sucking the paper down is a good thing. Very little blow-by, the rings are in good shape and doing their job.

You can pull the plugs and see if any coolant is on them. You can also drive it more and see if it's losing coolant. If not, it may just be condensate in the exhaust system.

 

These are the plugs off the pass. Side


Same plugs off pass. Side. The plugs are left to right, rear to front.

 

When I drove it the other day it smoked some until it warmed up, I gave it the beans a couple times to burn it up,and it quite smoking then, not at idle or while driving. Could it be valave stem seals? I will try to drive more to check coolant levels.

 

Keep driving it, it may straighten itself out. Looks like it was burning oil at some point, and it has subsided some looking at the plugs.

 

Well, not looking to good, The coolant was a little low so I added some. Drove it for the day, only smoked in the morning when cold, good when warmed up and rubs out good it seems. Let it cool overnight and checked the coolant low again. So looks like a leak down test is in order.

For the leak down test, do I pull all the plugs and then start checking or leave them all in except the one I'm testing.

Guess I could do a compression check also. Same thing pull all plugs or just the cylinder I'm testing? Thanks

 

Usually most people pull all the plugs, it's necessary to get the engine turning over at a pretty good clip. Make sure the battery is all charged up. Block throttle open up all the way and the choke plate.

Only smoking on the weekends, at parties? /jk

 

By leakdown test, do you mean the radiator leakdown/pressure test? I do not think a conventional compression test will help you any on a coolant leak. Unless you are going to put compressed air in a cylinder and look for bubbles in the coolant in the radiator?

 

Low identical compression on two adjacent cylinders points to head gasket. Plugs may be very clean, etc.

 

Are you filling the radiator up to the vary top? Drive it for a day and check next morning and it is low?
How low was the level? Really low / cant see it or just a few inches down from the opening?

If just a few inches down that is normal for the cooling system. When it heats up the coolant expands and goes to the over flow tank.
Once it cools if radiator is really low it will pull coolant back in from the over flow.
Dave ----