I have updated the link in my post that I think now should take you to the Cat Classic Parts catalog. If not, you can use the link below to the copy I put in my own Google Drive account;

drive.google.com/open?id=0B5lXds_1wtQCUW9ucXZOVlF6MFk

Here is a picture of the cap I have, it had a faint warning label about fuel on it and does not have a pressure spring or anything;



I'm now in the middle of modifying that "radiator" cap so I can attach a fitting to pressurize the coolant system to check for internal leaks. I drained the motor oil this afternoon and there were green droplets in the oil, on top of it all being gray from that last time I ran it so I'm more sure now that something is wrong;





If I get water in pan after pressurizing the coolant system, are the pre combustion chambers the first place to look or do I pull the inspection plates on the motor first and look for leaking around the bottom of the cylinder sleeves? The radiator looks almost brand new so I wouldn't suspect the oil cooler at this time.

Thanks,
Jordan

Well, I just noticed an interesting "trick". I put all the oil in a 5 gallon bucket and had it sitting on the shop floor. When I picked it up there was a pool of antifreeze under it. Wondering how/why I wiped the bottom of the bucket and cleaned the floor (have a dog in the shop) and moved the bucket to a different spot. Picked it up again later, same thing. I must have some hair line cracks in the bucket I'm using that is allowing the antifreeze to seep out but not the oil. And it's regular, green antifreeze and it even looks clean. So, that confirms that I do have coolant getting in to the engine.

Any recommendations one what I should focus on first as the most likely cause?

Thanks,
Jordan

Are you adding a gasket to seal the cap?

I would take the inspection covers off and see if coolant comes down the inside of the cylinder, (PC chamber, chamber seal problem or head gasket or possibly a pitted through sleeve problem) or comes down the outside, (sleeve o-ring problem).

Could pull the injectors and maybe put a small scope down through the precombustion chamber to look for coolant in the piston well. Might even be able to accomplish the same thing by using a syringe and a tiny straw or even a long cotton swab to check for the presence of coolant.

I feel it is a good idea to have as much information about the problem as possible BEFORE tearing into the engine. Got bitten by that one time to the tune of an inframe overhaul AND a factory reman 855 Cummins before it was all over. It was the oil cooler.

In your case, the oil cooler is air to oil, so no chance it has put coolant in the oil or the other way round.

I will bet on a precombustion chamber or seal problem. I would also lift off the valve cover and take a look under there. Found a leaking freeze plug under there on my 9U that saved me an overhaul or scrapping it or the engine more likely.

Thanks! Your info is very much appreciated. I'll pull the covers and see if I can narrow the search.

I thought the j series machines did not have a pressurized cooling system? Mine does not have the spring mechanism and does not have a place for the spring mechanism to seat on... it also has a little tube that comes up almost to the top to allow excess coolant to drain off. Do I also have the wrong cap? I don't see how the replacement cap pictured in one of the above posts would fit?

1L7583 is the replacement for 4F5889
J models used a 5B1343 or 9B2883 depending on s/n.
The J model caps look the same (like gas caps) but the 5B version is vented, the 9B is not. The 9B goes with the later radiator that has the pressure/vacuum vent on the back side of the upper tank. If the p/v feature is not working go with the vented cap version.

Hi Jordan, thanks for the updated access to the Classic Parts List, all 5,000 pages!! Do you know how to back reference the part number, like the Classic Parts List list will say an "Original Part Number" which was never in the D2 or D4 or RD6 Parts Book, like a number starting with 7T or 9L, is there a easy way to find out what the true original part number was, like 2B3467, or 1A9765, so I can cross check it in my parts number books, or do I have to pay a annual subscription to Cat?
Thanks
Mike

At my CAT Classic Cap yesterday and you are right it looks like a Gas Cap!
Without getting the parts book out to look, you have to remember that a later J series cooling system has a device bolted on the radiator that is the pressure relief (If I remember correctly).
And Yes, it still has the "Assembled in Mexico" sticker on it!
LOL!
No part number on it anywhere.

"Old wrote:

1L7583 is the replacement for 4F5889
J models used a 5B1343 or 9B2883 depending on s/n.
The J model caps look the same (like gas caps) but the 5B version is vented, the 9B is not. The 9B goes with the later radiator that has the pressure/vacuum vent on the back side of the upper tank. If the p/v feature is not working go with the vented cap version.

Thanks! 9B-2883 is a current number and is $10.48 at Caterpillar but the other 5B1343 (or 5B-1343 ) that you and Mike have posted I'm not finding a listing for nor reference to an update number. I'll take that to my local Cat dealer and see if it comes up on their system when I get to that point.

"Mike wrote:

Hi Jordan, thanks for the updated access to the Classic Parts List, all 5,000 pages!! Do you know how to back reference the part number, like the Classic Parts List list will say an "Original Part Number" which was never in the D2 or D4 or RD6 Parts Book, like a number starting with 7T or 9L, is there a easy way to find out what the true original part number was, like 2B3467, or 1A9765, so I can cross check it in my parts number books, or do I have to pay a annual subscription to Cat?
Thanks
Mike

I don't know of an easy way. What I have been doing is google searching the original part number to find a reference to a later number which has been hit and miss. It took me probably an hour or more of researching to find the current number to the new packing ring that is in the shift tower (put that info in another thread).

"drujinin" wrote:

At my CAT Classic Cap yesterday and you are right it looks like a Gas Cap!
Without getting the parts book out to look, you have to remember that a later J series cooling system has a device bolted on the radiator that is the pressure relief (If I remember correctly).
And Yes, it still has the "Assembled in Mexico" sticker on it!
LOL!
No part number on it anywhere.

I don't believe this 1942 D2 has that device bolted to the radiator, there is nothing coming out of the back of the upper tank like on my 1949 D4 7U so as Old Magnet posted mine must use a vented cap. Probably just running a fuel cap with out a gasket would be sufficient which is the way this was. I've since made a gasket for it for my now pressure testing cap.

I went around to all of our other equipment just to see what this fuel cap fit and it fits a International Model M fuel tank and a Chevrolet G506 fuel tank which are all of the same era as this D2. I didn't find any other radiators that fit this cap though so no cross-reference to another make/model for a radiator cap yet.

I don't have the later 5J parts book to check but the 3J change to pressure/vacuum vent occurred at s/n 6175 in 1941 so your unit should have that feature unless it doesn't have the original radiator.