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I''m looking for forum knowledge and experience with these oil cooler and adapters on my XK. I had a leaking rubber hose on the "oil" hose fitting going into the heat exchanger on the filter adapter, which I have Temporarily repaired by adding additional hose clamps, but need to replace the hoses. The repair manual shows a different configuration, and I assume that design changes occurred for later aj 34 engines and turbo charged engines. I think the way this works is that when the oil is warm, it just circulates thru the filter, then the air to oil heat exchanger, back inside the engine to distribute where it is needed in the engine. However, the two oil lines off the adapter housing are inlet and outlets for oil that go up via hoses to a fitting in the coolant lines, that I assume is an water to oil heat exchanger, that I also surmise is for "cold oil" heating for cold starting conditions. Can anyone confirm or offer an alternative explanation for this? Secondly, can anyone provide a part number for dual hoses? Thirdly, these appear to be about 3/4 or 7/8" hoses, which are not standard size. Anyone found a generic source for these that I can use? If my premise about this circuit is correct, I'm also considering just looping the inlet and outlet hoses at the cooler adapter (avoiding what appears to be major effort to access the upper fittings on the coolant lines). THis would negate "oil Heating" during startup. However, this is a summer car, and I don't run it in cold weather. I note that some of the range rovers such as 2005 LR3 have what appear to be identical oil filter adapter housings . As a side note, I got this Jag last spring with no maintenance history, did suspension, fluids, and about everything else for a 75k mile vehicle, and enjoyed an additional 7k miles last year before winter layup. The oil leak appeared after this spring oil change with 5w30. This is my third jag, I did head job on my 87 xj6 (terrible head to remove with the long wetted head studs) and also did head gasket and valves on my 94 4 litter xjs, which I still use at 174k on the clock. Thanks in advance picture of hoses form 2020 engine rebuild on this forum
similar engine, with two oil hoses connecting to device in coolant hose.
There is an extensive thread on this forum from 2020 about a gentleman that did an extensive engine overhall following engine overheat and valve failure in the uk. Apparently, a private reply identified the part number, as it is not in the thread. This image was part of that thread. It is inverted (180 degrees) from the hose orientation shown on the engine in the second picture. The engine in the second picture is an ebay engine that is identical to my 2007 configuration, that shows the two hoses going up to the coolant line.
I haven’t taken either of those hoses off, but looking at photos of how the smaller hoses connect to the lower radiator hose, I’m pretty sure those hoses carry coolant, not oil. Are you leaking oil or coolant at your hose connection?
Thanks Sean. I'm reluctant to go used, as it's probably just as likely to fail as my current one. It is DEFINATELY leaking oil. If it is supposed to be coolant, It would mean my cooler has failed internally, and I would have oil in the coolant (or coolant in the oil) which isn't the case. Any idea how these work? Other than cold start, it may also serve to maintain oil temp near coolant temp. I probably drove it 50 miles since the oil leak started, but it is parked now. It sure looks like it would be a coolant hose thou. I need to determine which it is supposed to be. If coolant, then I need to replace the oil cooler.
Last edited by bill_jags; Mar 21, 2025 at 03:19 PM.
They're definitely coolant hoses and if the cooler itself is leaking, it is rare and you're safe to replace it with a used one imo. I don't think there's anything magical about them since the filter is directly attached to a pipe. By design it's just a pass through.
Thanks again Sean. I pulled apart the radiator hose at the connection with the cooler lines and indeed it is just plastic for sending coolant down to the oil cooler. I am probably very fortunate I did not drive it much after the leak started, as the hose going to the oil cooler "streamed" oil out around the hose clamp. I assume that the higher pressure oil caused the leak on the hose at the cooler. I will replace the oil cooler and flush the coolant hoses, and replace the coolant to remove what must be trace amounts of oil. Thanks for the thread. I had read that, and I also noticed that ford cooler when googling on ebay. ANy idea if it was successful as a replacement?
Last edited by bill_jags; Mar 21, 2025 at 04:28 PM.
I'm calling out @MudDog here and hopefully he'll chime in and give you some tips. I know h had to modify it slightly. It includes instructions posted by @guy on how to R&R the cooler.
Great. Not sure if it will be the right one, but I ordered one for ford "New 9C2Z6A642A Engine Oil Cooler 6.2 6.8L For 2008-2018 Ford Models Super Duty". will update if it works. Got the filter assembly (filter, cooler, adapter housing) off the car, and disassembled the cooler from the housing (very tight). Clearly drained coolant out of the hoses, with no sign of oil. Very strange as the hose was streaming oil before I added hose clamps, and the oil slowed and stopped as I squeezed down on the clamps. Prior to this, clearly had oil below the car for the past week. Awaiting parts.
Last edited by bill_jags; Mar 21, 2025 at 09:00 PM.
Oil cooler - RESOLVED. I replaced the Jag leaking oil cooler with a ford "9C2Z6A642A Engine Oil Cooler 6.2 6.8L For 2008-2018 Ford Models Super Duty". It was identical in size and fittings, just needed to use the original Jag center bolt thru the cooler for proper thread. One minor modification was required on the cooler. The cooler's outer aluminum rim is notched for positioning the oil filter adapter, and the ford positioning is different than that for the Jag. However, it is easy to grind/file this ring to properly position the cooler on the adapter. Anyone needing an oil cooler should consider the ford as it is a small fraction of the cost of the Jag cooler. Thanks again for all the advice and previous replies.
Clearly drained coolant out of the hoses, with no sign of oil. Very strange as the hose was streaming oil before I added hose clamps, and the oil slowed and stopped as I squeezed down on the clamps. Prior to this, clearly had oil below the car for the past week.
The oil cooler is probably cracked, and torque you applied to the clamps may have put appropriate pressure on the cooler, closing the crack.
Glad you got it fixed.
The cooler was leaking significant oil from the aluminum coolant outlet. It was due to an internal leak in the cooler that allowed the oil (higher pressure) to flow to the coolant line. The clamps just stopped the oil flow out the coolant hose fitting. Since I didn't run with this very much, my coolant was not foaming, nor badly contaminated. However, I REPLACED the oil cooler with Ford cooler noted in my last post, flushed the coolant and refreshed, and topped off the oil. No leak, issue resolved. The lessons learned is to go after oil leaks PROMPTLY, and secondly there is a very cost effective alternative to the $600 Jag cooler. Although the O rings on the block to adapter looked good (maybe replaced by the PO), I also refreshed these O rings since I was in there anyway.
Thanks for the write-up. I just had the exact same problem on my '08 XK, came out a couple of days ago and found a small puddle of oil. Checked underneath and it was slowly dripping off one of the oil cooler coolant lines. No sign of oil in the coolant or coolant in the oil - still can't get my head around that! I'm ordering the Ford part now, but I was wondering - if you ground off the positioning tabs, how is it kept in place on the bracket? Did you just torque it down until it was metal to metal?
you do not need to grind off all the positioning ring. The adapter is notched (3 I believe) and you only need to file or grind the cooler aluminum ring where the adapter notch positions it. when you have the new cooler and the old cooler off it is obvious where the notches need to be filed. THis still maintains the anti-rotation character of the cooler, it is just rotated from where the ford cooler positions on the adapter ring.
The cooler was leaking significant oil from the aluminum coolant outlet. It was due to an internal leak in the cooler that allowed the oil (higher pressure) to flow to the coolant line. The clamps just stopped the oil flow out the coolant hose fitting. Since I didn't run with this very much, my coolant was not foaming, nor badly contaminated. However, I REPLACED the oil cooler with Ford cooler noted in my last post, flushed the coolant and refreshed, and topped off the oil. No leak, issue resolved. The lessons learned is to go after oil leaks PROMPTLY, and secondly there is a very cost effective alternative to the $600 Jag cooler. Although the O rings on the block to adapter looked good (maybe replaced by the PO), I also refreshed these O rings since I was in there anyway.
Originally Posted by bill_jags
you do not need to grind off all the positioning ring. The adapter is notched (3 I believe) and you only need to file or grind the cooler aluminum ring where the adapter notch positions it. when you have the new cooler and the old cooler off it is obvious where the notches need to be filed. THis still maintains the anti-rotation character of the cooler, it is just rotated from where the ford cooler positions on the adapter ring.
Spoiler
That seemed like the obvious route to me. I found another source for the cooler - apparently Dorman now makes the same Ford cooler for about $46!
Quick Update:
Sort of suspected the oil filter might be the cause of the leak based on its position, and since it was time anyway I went ahead and had the oil changed. Well, the leak stopped, at least for now. Coincidence? Causation? I'll drive it for awhile and see.
2007 xk NA oil cooler
