A couple of months ago I noticed what appears to be a thin film of oil floating on top of the coolant reservoir.

I also noticed that the needle on the oil pressure gauge was fluctuating moving rapidly back in forth in idle and usually returning to normal when I gave it gas. When I checked the oil I was running pretty low. Filled it up and ran it for a few more days. The oil when checked from the dipstick appears fine but there is still oil in the overflow. There also seems to be a loss in power.

I stopped driving it as soon as this happened. I was about to start work this weekend and assumed it was a head gasket but I am still unsure.

What could it be?

Thanks,
Mike

 

Possibly a blown head gasket, or possibly a cracked head.

 

Hoping for gaskets. I am going to have the heads inspected and machined along with a valve job (If they aren't cracked). Do you think I could rule out a cracked block? That's my major concern its my first car and my daily driver, need to have it going before school starts up again in late august.

Thanks

 

I would inspect the heads, and gasket condition. If you find a blown gasket, or a cracked head, you have probably found the culprit. If the heads and gaskets are in good condition, then you may need to look further. Did your engine freeze due to lack of antifreeze?

 

How does your transmission fluid look?

 

did the car overheat? if not maybe intake manifold gasket?

 

I think with a blown intake gasket the oil gets contaminated with coolant.

 

Yeah it did over heat just before the problem occured. (the TB hose ruptured due to age). Thats why I think its the head gasket. It didn't red line but did get very hot had to drive for about 5 min before I could pull over.

My engine has never been frozen.

And I just checked the transmission fluid, there is no change in color or anything out of the ordinary.

 

This is a little bit of an odd issue. Coolant psi is higher than the oil psi, so normally the oil gets contaminated. I know that its not unheard of, but still odd nonetheless.

Now I see that you overheated it. That is *usually* headgasket failure. As long as you didn't go past the red, your heads might still be ok.

 

overheated more than likely headgasket

 

Do a carbon test on w/ a sniffer on the antifreeze, if positive it's a headgasket or worse, if not it could be just an intake.....

 

You can check for a blown head gasket by starting the engine cold and seeing if the cooling system pressurizes. With a blown head gasket, the compression goes right into teh cooling system if it blows out into the water jacket. This will also cause the puke bottle to constantly have exhaust bubbling up through it.

Also, what color is the oil? Is is brown, or red like ATF? Another possibility is a blown ATF cooler in the radiator. If its a 350 TPI, it may also have an oil cooler, which can leak oil into the cooling system. Not an uncommon problem as they age and degrade internally.

 

Good point-OIl Cooler, been so long since I had a TPI motor I forgot about that...

 

The oil is the right color.
I did notice that the upper radiator hose is sometimes squished like it has a vacuum or something, that's gotta mean something.

And I do have the oil cooler option. One of the hoses did rupture recently and leaked in the drive way after I shut the car off. But I don't think its the oil cooler because of the loss in power. Could the oil cooler flowing in to the radiator cause a significant loss in power?

I'm going to pull the heads within the week so I'll let you guys know if I find anything.

Thanks,
Mike

 

Did you do a pressure test to your cooling system??

 

No I haven't, I've never done a pressure test before.
do I need one of those kits?

 

Yes you will, or take it to a mechanic. I did a search and found this:http://www.benplace.com/pressure_test.htm

 

Pressure test and Carbon test on Anti-freeze, you have a collapsed hose and need to replace it....

 

I agree, if you overheated it recently it's a head gasket or a cracked head.

I had a friend who had a crack in one of his cylinder heads that, due to the location of the crack, would get gas/oil into the coolant system but wouldnt leak coolant into the engine. He had to bleed the coolant system constantly at the racetrack.

Hopefully its just a gasket and not a head that needs replacement.

 

Think I found the problem!
Took the heads to a machine shop to get a valve job.
The valve guides were worn out and there was a cracked seat!
Get the heads back friday and will be putting everything back together hopefully this is fixed!

Thanks for all the help

 

I didnt know you could fix cracks in iron heads?

 

Ive seen it done in alum. heads, but I dont know if Id trust a welded cast-iron head due to the difficulty with welding cast iron. On top of that, the crack is in a real critical area.

 

I believe the OP said the crack was in the seat...not the head. So no welding would be needed.
The valve seat is replaceable.
IMO...I don't believe this would answer the oil in the coolant issue, since there is no oil or coolant that touches the seat, aside from leaking valve seals.
A slight loss in power could be noticed, not sure how much because I have not experienced that yet. I'd imagine it to feel like a constant murmur of a misfire though.
Perhaps the replacement gaskets will fix that oil issue. Like magic. Did you inspect the old head/intake gaskets upon removal?
Hope you find the problem.

 

Correct the crack is in the seat, just needed to be replaced. I noticed today a spot where the head gasket had come up from the head. So I had a combination of a cracked seat, worn valve guides and seals and a damaged gasket

Will have the car up and running within the week.
I'll give you guys updates as soon as I start driving again
Thanks!

 

It's good that it will all be fixed at the same time.
Good luck.