Considering the aforementioned statements, given enough time and use, an Oil Cooler assembly can and will eventually fail.\u00a0 And without proper repairs, it will lead to engine failure and\/or coolant infiltration.\u00a0 Just to quickly explain the Oil Cooler’s purpose, it\u00a0cools oil from the crankcase through a small radiator-type network that is encased in a chamber of\u00a0coolant.\u00a0 It is located on the driver’s side of the block, and has ports for coolant-in, oil-in, coolant-out, and oil-out.\u00a0 Also, it holds the oil-filter head and filter.<\/p>\n
When people talk about the oil cooler, they sometimes forget that the oil cooler setup is a whole assembly.<\/p>\n
![\"\"](\"http:\/\/www.nickpisca.com\/diesel\/wp-content\/uploads\/2018\/03\/20180210_165804sfw.jpg\")
<\/p>\n
The Oil Cooler Assembly Contents:<\/p>\n
- \n
- Front Oil Cooler Header (Red in the image above)<\/li>\n
- Rear Oil Cooler Header (Grey in the image above)<\/li>\n
- Front gasket and rear gasket (on the block)<\/li>\n
- An Oil Cooler (cylindrical in shape)<\/li>\n
- 2 thin and 2 thick oil cooler o-rings<\/li>\n<\/ul>\n
The assembly consists of two “headers” that mate with the engine block with gaskets (Note, the front gasket is different between the truck and van, read more here<\/a>).\u00a0 The\u00a0headers cap\u00a0the Oil Cooler cylinder on each end, and four o-rings prevent the fluids from mixing.\u00a0 On the rear header, there is a port for the installation of the engine’s crankcase oil filter.<\/p>\n
![\"\"](\"http:\/\/www.nickpisca.com\/diesel\/wp-content\/uploads\/2018\/03\/OilCoolerDiagramsfw.jpg\")
<\/p>\nIn order to separate the headers from the cooler, I had to pry them apart.\u00a0 It’s kind of a pain in the ass.\u00a0 The rings get rigid and brittle, and they do not want to let go.\u00a0 International Harvester designed the cooler to have two tabs on each end to aide in the prying process.\u00a0 It is imperative the prying action doesn’t bend the tab over, but that is almost impossible.\u00a0 I just had to do my best in trying to work it at its lowest point so that it doesn’t get too destroyed.<\/p>\n
![\"\"](\"http:\/\/www.nickpisca.com\/diesel\/wp-content\/uploads\/2018\/03\/20180210_142517sfw.jpg\")
<\/p>\nEventually the headers will come off.\u00a0 The duration of prying is usually related to the age of the internal o-rings.\u00a0 The headers will eventually slide off without any effort once the cylinder clears the lip.<\/p>\n
![\"\"](\"http:\/\/www.nickpisca.com\/diesel\/wp-content\/uploads\/2018\/03\/20180210_142300sfw.jpg\")
<\/p>\nOnce apart, the oil cooler is pretty simple to handle and fix.\u00a0 Careful to not damage the o-ring metal surfaces, I slid off the o-rings.\u00a0 Mine were so brittle that the fat o-ring broke in the process.\u00a0 Not a big deal, considering I’m replacing them anyway.\u00a0 There is a lot of buzz about the “best oil cooler o-ring” brand on the typical IDI forums, but I’ve used a bunch.\u00a0 All seem to work the same, so I have no major recommendation, unless one of the manufacturers wants to advertise on my blog.\u00a0 Hint, hint….<\/p>\n
With all the parts separated, I properly cleaned the mating surfaces as best as I could with brake cleaner and other chemicals.\u00a0 I removed the gasket material from the block surface, and from the header surfaces.\u00a0 Also, I wiped down the oil cooler.\u00a0 Also, this is a perfect time to try my DIY Oil Cooler tester<\/a>.<\/p>\n
![](\"https:\/\/cimg5.ibsrv.net\/gimg\/www.ford-trucks.com-vbulletin\/1041x550\/80-20150505_oilcoolerparts4_dcf35f9769aa07362fe3959da7a6b747ed0d9fde.png\")
<\/p>\nIt is not going to put out the pressure that the coolant system (approx 13psi) and the oil system (approx 50psi) will do, but if you let it sit overnight, it will at least inform you if the cooler has a pin-hole leak somewhere.\u00a0 I’ve looked all over Los Angeles for a shop that could test my cooler, and for these old IDI engines, no one would entertain the notion.\u00a0 So, for now, this process is all I got.<\/p>\n
![\"\"](\"http:\/\/www.nickpisca.com\/diesel\/wp-content\/uploads\/2018\/03\/20180210_163030sfw.jpg\")
<\/p>\nWhen installing the new o-rings, coat them liberally with vaseline.\u00a0 This will conduct two purposes:\u00a0 1.) lube the rings to make them easier to slid on the oil cooler cylinder, and 2.) aide in the reinstallation of the header caps.\u00a0 Once the o-rings are seated, I slid on the header caps as far as I could humanly push them.\u00a0 Then using same thickness wooden blocks (see the image above), I aligned the block mating surfaces so they are flush.\u00a0 If these are not flush, it would be very hard to rotate the caps to the proper orientation once the o-rings and headers are pressed into place.<\/p>\n
Here’s the point in the process that is better explained in a short video, shown below:<\/p>\n