Oil anti-freeze intermingling

[Luis A.]

It appears my head gasket may have been compromised on my hard run to the vintage. I can see some oil scum in the anti-freeze tank. My question is how is it possible that the reverse is not happening: to have any antifreeze scum in the oil. There is nothing visible in the dipstick or the oil cap.

 

[thehackmechanic]

Oil in the coolant

Luis, sorry to hear that. I've had cars where the chocolate milkshake of antifreeze mixed with oil showed up in both the coolant tank and the oil pan (on the dipstick), but I've also had cars where it's appeared only in the coolant tank.

But, as we all now know from The Vintage, a blown headgasket isn't a big deal, as it can be replaced in a hotel parking lot in an hour and 52 minutes. Just call Wegweiser and Thongsai.

:^)

--Rob

 

[Mike Goble]

Oil is lighter than coolant, so any coolant that leaks into the oil will settle at the bottom of the pan. If you drive the car regularly, the water component of the coolant mix will be boiled off as the oil gets hot. Does your oil appear milky after you run the engine?

 

[x_atlas0]

Plus the oil is under much more pressure than the coolant when the engine is running.

 

[Luis A.]

Thanks for the replies guys. I think that the car was being driven sufficiently long and hard at full operating temperatures that any antifreeze in the oil might have boiled off.

This coupe has a full restoration coming to it in the next 2-3 years so I'll just do the head gasket at this point. I ordered the parts today and will have next Monday. I'll baseline compression readings and take them again post-gasket replacement.

 

[jmackro]

I'll baseline compression readings and take them again post-gasket replacement.

Go ahead and check the compression before and after the gasket replacement.

But don't be surprised if it reads the same at both times. Often head gaskets will let go between the water & oil, but not between the combustion chamber and the atmosphere.

If you do find one or more low compression readings prior to removing the head, consider having the valve seating checked - while the head is off, it will be easy to re-grind or replace any leaking valves.

 

[sfdon]

Oil in the water is a sign of a cracked block at the head bolt bore holes.
Add some liquid dish WASHER soap to the expansion tank and then flush.
If you get more gray scum then you have a problem.

 

[Luis A.]

Pulled the head and...

There is no obvious oil to water breach...

Before doing anything I removed all the plugs and cranked the engine to look for any coolant being expelled from the bores since the cooling system was pressurized when I last ran the engine and shut it down so some coolant ingress into the bores would have taken place if there were cracks there.

Head gasket looks like it was doing its job, I can't find any visible cracks anywhere on the head nor on the block surface... A cold compression test revealed cyl 1-6 pressures at 164-170-170-161-166-172. Nothing to get excited about.

I think I am now committed to pulling the block as well and having it inspected for cracks in the bolt bores, as Don suggests. Any ideas?

 

[sfdon]

No need to pull the block-clean the surface and inspect for cracks between the bolt bores ant the water jacket. Easy to see after cleaning.

Interesting combo you have- piano top pistons with ancient head. Those heads are prone to cracking. What year is it? Take it to a shop for pressure testing and inspection- my guess would be the head could be the problem.
Don't forget to take the old gasket with you.

 

[61porsche]

A minor leak

would not show much.

Concentrate first on exhaust valve to water jackets. From your photos concentrate on number 1 is my best guess looking at the head and gasket. Then look at the clean area between the exhaust valve and the plug compared with the others.

I agree with Don- clean it up. No need to pull the block.