Oil in Radiator Coolant on M35A2 after 900 mile trip

[Ifixthings]

Hello All!

New here at SS and have been lurking & learning for a while.

This past Sunday, I just picked up a 68 Deuce in Co and drove it back to the DFW area in TX. The trip took about 2 1/2 days (made it home Tuesday evening) and the average speed was 40 to 45 MPH. The truck averaged 9 MPG. It has a Pyro gauge in it and I keep the EGT at 1100 or below. After about half way through New Mexico, most of the country side was flat and EGT was rarely near 1100. The only issue during the trip was a leak at the transfer case where the speedo connection is made. A new seal is needed. Once the connection was tighten (which slowed the leak...) and gear oil added, the trip continued.

Anyway, the fluids were topped off before initial departure and oil checked at every fuel stop. On the initial fluid check 2 quarts of oil were added to bring to full level and about 1 gallon of a 50/50 mix of AF was added. Each morning before departing on the next leg of the trip, the AF was checked while the Deuce was cold. At no time during the trip did I have to add any AF or engine oil.

A warm up period was always perform before departure from a rest stop and a cool down was always performed whenever a stop was needed.
Well, once we arrived home the truck was not touched for 24 hours (had to catch up on sleep and work...). The next day a walk around was performed and I noticed a small amount of AF on the ground so I thought I would check the radiator while the truck was cool. Upon opening the radiator cap, oil burped out! Today, I used a turkey baster to remove about 3/4 quart of engine oil that was setting on top of the coolant. Then, I drained just the radiator (and got out a few more oz of oil) and add plain water to begin flushing out any remaining oil. I checked the engine oil and it is about 1 qt low...

Right now, I'm thinking it is a cooler leak problem and plan on pulling the cover on that next. There is no issues with smoke at the exhaust, and the engine oil appears to be nice and black after the trip. This is no milkshake under the oil cap.


Sorry for the long post, just wanted to provide as much info as possible.

 

[gimpyrobb]

Welcome to the site. It sounds like you are on the right path. I might have a cooler avail if that turns out to be bad. Do you know if they ran water instead of coolant?

 

[Ifixthings]

When coolant was drained, it was the "red" stuff. I'm putting just water in it now untill it is flushed out.

 

[Ifixthings]

Would that cooler be new or used? About what is the cost? Does it come with the gaskets?

 

[gimpyrobb]

If there wasn't any coolant in the oil, I would suspect the oil cooler. I wouldn't want to waste the coolant either. Post pics when tear into it!

It would be a take off. I bet I could rustle up a gasket. I will have to get back to you on price, I will be out of town till the 23rd.

 

[dabtl]

Check the oil cap on the top of the engine to see if you have some milkshake. If not it probably is the oil cooler. You can check the cooler under pressure, but it probably needs new gaskets and O-rings as opposed to a new cooler.

 

[jeeplvr247]

I would say it is probably the head gasket. I think that is the most common cause of oil in coolant or vice versa

 

[WillWagner]

^^^Only with the old style gaskets. Does the engine have old or new style gaskets? You can tell by looking at the exhaust side of the gasket. Old style have tabs that stick out under the exhaust ports, new style gaskets don't come out all the way to thew edge of the deck, It makes it look like there is no gasket. If they in fact are old style, i'd go that way first.

 

[Ifixthings]

Thanks for the info!

I'll check for the head gasket type sometime today and post back.

The engine data plate states that the engine was manufactured 4-85 and there is a refurb tag on the driver's door dated 8-89?

 

[DieselBob]

When coolant was drained, it was the "red" stuff.

That could be your problem right there. Red would indicate a OAT antifreeze, Organic Acid Technology. This type of coolant can cause some types of rubber to brake down and loose it's ability to maintain a seal. I'm thinking it has caused the weaking of one or both "O" rings that seal the cooler to the mount.

 

[Ifixthings]

That could be your problem right there. Red would indicate a OAT antifreeze, Organic Acid Technology. This type of coolant can cause some types of rubber to brake down and loose it's ability to maintain a seal. I'm thinking it has caused the weaking of one or both "O" rings that seal the cooler to the mount.

Thanks for the info! I printed the photo and will look at the o-ring closely.

Do you know the best way to test the cooler? Since there is not much pressure in the rad to begin with, I was just going to blow it out, add clean water and pressurize it with about 20psi. My thoughts would be the clean water will squirt out somewhere if ther is a leak...

 

[Ifixthings]

That could be your problem right there. Red would indicate a OAT antifreeze, Organic Acid Technology. This type of coolant can cause some types of rubber to brake down and loose it's ability to maintain a seal. I'm thinking it has caused the weaking of one or both "O" rings that seal the cooler to the mount.

Thanks for the info! I printed out the photo too. I'll look at the o-rings closely. Will be replacing them anyway.

What is the best way to test the cooler? I plan on blow it out with air then add some clean water to it and pressurize it to about 20 PSI. Thinking that water will squirt out somewhere if it has a leak...

 

[DieselBob]

You could do it that way. If you have a way to pressure it to 40~50 # and place it in a wash tub of hot water you would be good. They are normally seeing at least that with normal oil pressure. If you have a local machine shop that machines aluminium heads and blocks they can pressure test it in a hot water tank just like blocks and cylinder heads.