Oil In the Radiator

If I didn't have bad luck I would not have any luck at all! I finished my Jeep earlier this summer and have been using it when I can, put a couple of hundred miles on it. It was a complete overhaul, all new stuff. The block was a crate motor NOS (1976 231 OF), found a set of compatible heads, new front cover, oil pump etc... Well all of a sudden my engine oil is getting into my coolant. The funny thing it's not getting any coolant into my oil. It seems to be moving oil into the coolant under pressure but static the coolant stays put. I can't think of any obvious things that would cause this to happen. No oil cooler in the radiator, the oil gets to the valve train through the push rods. I'm pretty gloom and doom right now.

 

I'm sorry for you--I hope you get some help from someone here.

Good luck,

 

What kinda antifreeze are you using.. I used some of that high dollar pink stuff that had a lubricant in it for the water pump. When I took off the radiator cap it had what looked like water oil mixed, caked around the bottom of the cap. This was in my GMC. I drained it and put in prestone green and have had no more occurances since.

 

The oil is coming from the crankcase, I put a qt in and it comes out the overflow, it's not pretty. I just can't wrap my mind around coolant not getting into the oil. Oil and coolant pass close together in the block and front cover, the oil is fed to the rockers through the push rods so head gasket wouldn't be bad. I just hope it's not the block passages, and how do I find out? I guess it could be the front cover too due to the oil under pressure is in close proximity to the cooling passage. But I keep coming back to the fact the coolant is not draining into the pan when the engine is turned off.:?

 

I'd look into the timing cover area.
Oil pressure is greater than cooling system pressure.
bad timing cover gasket or small crack in the cover where oil is entering the cooling system.
if no overheating is involved, that would be my guess.
you might be able to supply compressed air into an oil galley/pump area and see what happens; may have to remove the cover as well.

 

In a static situation, the water gravity pressure may not be sufficient to overcome the oil standing in a galley. If you pressure the radiator to 17lbs and watch for degeneration you may find the problem. If oil can get in then water can get out. Were looking at a pressure related issue in connection with operation.

 

the water could be below the affected area that's under oil pressure.

 

I know I will be looking for issues relating to running condition. I may be seeing things too simply, if during running the oil pressure is 20 to 50 psi the pressure is higher on the oil side, now with the engine off the pressure is on the coolant side, 14 to 16 psi right after I shut it off and higher due to the radiator tank being higher than oil, when there is a pressure differential liquids should move from high to low. It still doesn't make sense. I sure hope it is the front cover gasket, that's where I will start. My friend works at the Ford garage in town and has dye we will put in the oil and coolant, I will look at what I can with a black light to possibly see casting flaws, the oil galleries will be harder to see. #$%@ I was really enjoying the Jeep for once in four years!

 

Do the standard tests first, check the compression, put about 30 Psi one at a time in the cylinders with the radiator cap off(valves closed) and see if you get any activity. Put about 30 Psi in the radiator and see if you get any activity in oil, exhaust, or intake. Check routing of all external oil and water lines and make sure there is nothing miss routed. If none of this does anything, I guess it has to be an internal passage. Could the heads or there gaskets have water vs oil passage alignment problems?

 

Well I pulled the front cover off and there was no obvious problem with gasket or cover. These odd fire engines pass oil pressure through the block up to the cam galleries, the hole in the front of the block connects to those galleries transiting the cooling jacket in the cast iron. I found where the oil passage makes the first 90 degree turn there is a crack, flaw, or hole in the casting. I put dish soap in the water jacket and blew air into the oil hole and bubbles formed. I guess my block is junk. I don't see a reliable repair, vise figuring how to bypass oil pressure around the casting to the cam galleries (not an option).

 

I have been looking for another block to replace the one I have. But in the mean time I was bench racing (off-roading) in the garage with some friends and looked over at my bad engine sitting in my Jeep. I was at an angle to see a glint in the gallery hole and upon closer examination there is a set screw in the gallery hole. It seems there is a set screw plug plugging a hole between the oil pressure gallery and the cooling jacket. I looked in a couple of my bad old Buick v-6' blocks and in the oil gallery hole and can see where the drill point marked the back of the gallery, but no plug. I don't think GM would of repaired an oil gallery that way, but maybe they did. What do you think?

 

A picture would help.
Lot's of people swear by J B Weld, I know I have several holes in my dirt bike motor that have held for years.

 

Here are a few close ups.

Looking through oil gallery into water jacket. Note there are not many threads tapped in block, maybe 2-3.

Another close up.

A view with the plug installed.

This is a picture of a block with the gallery you would expect.

 

If it's not your plug....

Only one way to get oil in the radiator,
Cracked block.

There is on oil pressure in the head(s).
The only oil above the block deck is pumped up through the lifters/pushrods,
And it runs back down through the same passages.
There are no points where oil and water can mingle in a head gasket failure.

The ONLY way oil can get into the radiator is through a crack in the block that intersects both oil gallery and water core.

Time to check on your warranty for the engine...

 

Any sort of sealer/threadlock on the plug?

 

No, at least not that I found, it is a brass plug. I am leery about putting this engine back in service with that plug in there. At best it is a band-aid fix.

 

Most engines have several plugs in them for oil passages and such. Admitably most of them have more iron for the threads.
Rather than go to the time,effort and expense to replace the block, I would at least try some type of sealer on the plug after cleaning the heck out of the threads.
If this is indeed the leak.

 

It is the leak, no doubt. I could have my Jeep on the road in a couple days :driving: if I just put the plug back and seal it in. The area is quite difficult to ensure complete coverage of a sealant, and even if I do it just may just wash out, unless I use a JB Weld or something similar. I do have a rebuildable block that needs a trip to the machine shop. I will have to make a decision. :toetap: