JD 70 Diesel Compression in Cooling system

John Deere D · May 16, 2017

I'm considering purchasing a JD 70 Diesel. My neighbour has owned the tractor for several years, and it's been a great machine. Yesterday when the Tractor was placed into service after sitting for the past five months, COMPRESSION is building in the Cooling system. I have read many postings about the injector tubes and would like to know or get an idea what to expect if I purchase the Tractor. When the Coolant (antifreeze) was drained last night, there was slimy evidence of ENGINE OIL in the Cooling system. There is no evidence of coolant in the Engine crankcase.

This JD 70 D was converted to straight electric start several years ago. I own the service and parts catalogues for the JD 70 Diesel as well as the same manuals for the JD 720/730 Diesels. I've read in the archives, the HEAD from a JD 730 and head gasket is a great update for the JD 70 D? The fuel injectors have different part #'s for the JD 70 and the JD 730 D. Do the JD 70 fuel injectors install and work properly in the JD 730 Head? Any ideas why the Cooling system has ENGINE OIL in the anti freeze?

Thanks for all and any advice:

Bob....

Bob....

Blksmok · May 16, 2017

Sounds like a bad head gasket...common problem. If it has been leaking for a long time expect to see pitting of the head and cylinder bore. The F3511 head is the best head as it does not have injector tube seals and has bigger valves than the original F1958 head. There was also a F3211 head used on some 720 diesels. If the injector tube seals are leaking on your head, it's very difficult to remove the tubes w/o causing damage. Replacements are expensive.

buickanddeere · May 16, 2017

The cylinder block and stud bosses are thinner than the 720/730 block. Over torqueing in an attempt stop seapage can crack the block.
Original 70 diesel heads on a 70 tractor today are uncommon as the factory head would crack. Iirc the very late 70's had the 720 head from the factory.

buickanddeere · May 16, 2017

The cylinder block and stud bosses are thinner than the 720/730 block. Over torqueing in an attempt stop seapage can crack the block.
Original 70 diesel heads on a 70 tractor today are uncommon as the factory head would crack. Iirc the very late 70's had the 720 head from the factory.

John Deere D · May 20, 2017

Thanks for the reply guys:

Head gasket is blown.

An interesting find.

The Head is STAMPED / CASTING # "F3511R" with VALVES that have the "HEAD Diameters" of the original JD 70 Diesel VALVES as per JD 70 D Service manual Specs: Not the larger Intake Valves as per JD 720 service manual Specs:

Bob..

JD 70 Diesel Compression in Cooling system

John Deere D

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