My 390 is burning oil. The problem is, where is it getting in to get burned. Here are some observations I have acquired to help diagnose my problem:

1--it only burns oil on the right bank.
2--I rev the engine and more smoke comes out as the engine rpms return to idle speed.
3--after revving the engine, it smokes pretty good for a second or two then the smoke lets up.
4--the vacuum reading says a steady 16psi (I also live at 4000 ft)

I'd appreciate your advice!


~Ryan

 

Ryan
Sounds like your rings are shot. Best to get it reringed before it scores the cylinders if it hasn't already as this will entail a costlier repair.

 

Could be worn out valve stem seals/O-rings/umbrellas or whatever you prefer to call them or possibly worn valve guides. Oil could be being sucked down the valve stem into the cylinder. If the compression is good in all the cylinders I would consider the rings and valve seats to be ok.
If that is 16" vaccuum at idle that is fairly good. You might just need new valve seals, of course easier said than done. Unless you have experience doing the seals with the heads still installed on the engine.
Just my opinion, I am sure there could be other reasons for the smoking.

Sparky

 

Id say its the rings.

Anthony DiPietro
79 F150 Ranger

 

Here's a thought... Take ur compression tester, and unscrew the Quick Connect and connect to a Air Supply (homemade and much Cheaper Leakdown Tester) if you add in air then check where the iar is coming from.. (Rings from dipstick Tube) Seals from Oil Fill on Valve Cover..

If its Any Consolation... When I redid the 390 in my truck it needed both.
Just a Suggestion...when you send in the block, if you do, make sure to check the Cam and lifter bores..along with the Crank... Align hone it..


ScottF

 

If it's smoking under a load, its probably the Rings, it it's smokin when you back off, its probably the Valve guides or the Valve stem seals.
You can replace the Seals without too much work. If that does not change the condition, you better plan on pulling it out and doing some deep repairs.

 

Do a compression check to see if the rings are good, but this does sound like valve stem seals. The valve stem seals on FEs are not that good. They are not positive seal type and will leak sooner that most others.

I would remove the valve covers and use a flashlight to see the valve stem seals. I ran my engine without valve covers to check the amount of oil flow to the top, this amount should be very small and should not flood the head so much that it overflows the sides. If the valves are flooded, I'd replace the stem seals and flush the engine. Also, they are supposed to have baffle plates protecting the valve springs from oil splash, some people remove these, you should have them.

Using a on-engine valve spring compressor and compressed air to hold the valves up, you can change these without removing the heads, some shops might do this too. You might try the oil restrictor trick that is very common with FE guys, this restricts oil flow to the head and helps give more oil to the crank where it's needed. Just drop a Holley carb jet down the oil passage below the rocker arms (one on either side).

 

 

Karljay, could you explain the oil trick. Are you talking about the oil hole under the rocker arm bolt? I am having the same problem with my truck also. I just put in a rebuilt engine (27K miles) I bought through the newspaper. I heard it run and it did not smoke. But when I put it in my truck it smokes on the passenger side only. I put new heads on since the heads the engine had were GT and wouldn't work with my exhaust manifolds. When I first fired it up it was leaking oil out of the passenger side valve cover like a faucet. I tightened the bolts and it stopped, but it did seem like alot of oil was coming out. i am going to pull the valve cover off this week and check the valve stems and see how they look. Is there such a thing as to much oil flow to the heads? Thanks for any info.

 

The trick is to insert a restrictor into the oil passage that runs under the rocker arm stands. There is one on each side and the bolt for this stand is longer and is thinner at the shaft. the inner two shaft bolts are different, they are thinner at the shafts and the one that has the oil passage under it, is longer.
Most people use a holley jet because it is the correct size and just drops in, I tried a alum spacer from Home Depot and if fit well. I removed them after looking at the amount of oil that was comming to the heads, it was a very small amount.

Check the rocker arm shafts, a common mistake in building the heads is to install the rocker arm shafts upside down. The oiling holes in the shaft MUST face DOWN! Some have had luck with running the rare, fast return spring baffles used on some 427's, I have these and they drop the oil down the space between the head and the intake manifold, whereas the stock ones just let the oil drop on the head. I also ground the return passage in the head larger (where it shares with the head bolt)

If you have the shafts with 16 holes, you can get the 8 hole version, I got mine from NAPA for about $25 each. Also, most every used shaft and rocker arm setup I've ever seen has been worn heavy, this causes more oil to pass by. I got luck and found an excellent set for $18 at the junk yard that looked new, examine the amount of play the rocker arms have at the bottom of the shaft, most have a lot of wear here.

 

Karljay, I took off the valve cover and started the engine. The oil pumps out like a faucet by #3 and #4 cylinder. A little comes out of the pushrods but a gusher from somewhere in the back and piles up and flow over the side of the lip on the head on to the ground.(Fast)It pours. I pulled the plugs and they are oil fouled on #3 and #4. The head is totally rebuilt with new everything, seals and all. I think the oil is flooding out the back cylinders and causing the smoking. But how?? Any suggestions? Should I restrict that oil hole under the rocker arm bolt? I am not sure what the oil flow pattern is for these engines and how it is suppose to be distributed. Any suggestions from you or anybody else is greatly appreciated how to fix this problem.

 

It sounds like the rocker arm setup is bad. Take off the rocker arm setup from that side and clean it. Inspect the underside of the shaft by sliding each rocker over a bit (you'll have to remove the cotter pin to inspect the outside ones). I think you'll find a worn shaft. Inspect the stands for cracks. Look to see that you have a thick flat washer on top of each bolt. Check the bottoms of the stands for flatness and nics (they have to seal oil)
If you have to break down the whole rocker shaft setup, just replace the shaft with a new one. They tend to bend at the ends because the last rocker has no support after it. The stands are a tight fit and you can damage them trying to get them off. extras are cheap at the junk yards. Also, look into getting a set from the junk yard, just slide the rockers over to see wear on the shaft, and inspect the rocker arm for wear at the tip that touches the valve.

This really sounds like an upside down shaft, or worn rocker arms and shaft.

The oil goes from the head up one of the middle stands, down the shaft and thru a hole for each rocker arm, then out the pushrod side of the rocker arm to the pushrod.

 

Karljay, just wanted to update you. I took the rocker arm assembly off and checked it out. When I was getting ready to put it back on I discovered that the back bolt was missing a washer. I put a new one on and installed the rocker arm and fired it up. No gushing of oil. I must of missed that washer some how and it was not letting the rocker arm assembly sit flush on the head and causing a gap for oil to come out. The truck is not smoking at all and is running great. Thanks for your help.

 

Another satisified FTE customer. You did good KJ.

John
jowilker
Club FTE since 01 01

NC Chapter


66 F100s
In the still cool hours of the night,
you can hear chevys rusting away.

 

Glad to hear it!