Ok finally got some motivation to have a look at this problem. It's not actually that bad to get the cooler off. I took a while to remove most of the water hoses so they could be cleaned but really to get the cooler off I just removed my dual battery tray, top radiator hose, intercooler hose, air temp plug off underside of inlet and the coolant line that must run to cool the EGR pipework. Then you can get at all 5 bolts from underneath the manifold curving back up. Tight yes but easily doable.
So a close up of the cooler mounting face.
Note the hole in the dark "smily mouth" is the water side with the other water in/outlet on the back face which connects to a hose into the block. The other 2 are the oil. You may see what looks like corrosion damage on that face but it is actually almost perfect, it's just the pic for some reason. You will see the water comes in/out that hole then travels along a groove in the oil filter body to the actual hole in the timing cover around that arc. Not sure on the principal of that unless to cool the housing itself.
There is no evidence of the o ring letting go or being compromised nor is there any evidence of a travel path on the mounting face.
Here however is the result of my pressure test.
Hopefully you will see the bubbles coming out the oil hole, noting my air line is plumbed through the water circuit. So it would seem that is the culprit. Actually when I was flushing the oily crap out of it I could see a stream of water shooting out the cooling fins right at the oil hole. This was with the hose on a mild pressure held roughly over the water outlet so I'm fairly confident this is the source of the issue.
The next thing is what to do. It does concern me that this is the second or possibly third cooler this engine has been through but I have no theory to cover it. Obviously if it were o ring related you could be looking into mating face problems but I can only put this down to bad luck of dodgy component.
So to fix -
Buy another cooler and whack it back on and hope all is good from now on. This will still give me the space to run an additional auto cooler up front if I desire.
Make an adaptor plate to bolt up instead of the cooler. This would have 3 hose tail connections coming out of it in the appropriate spots. 1 to allow the water flow to continue as I'm not sure of blanking the water in case it generates a hot spot somewhere but upsetting the flow. The other 2 will run via appropriate hoses to the front of the grill to a suitable oil cooler. There is plently of room to achieve this.
There are a couple of questions though.
Does the engine need the warming function of the coolant for the oil and/or would it run too cool with a dedicated cooler. I was thinking a second power steering cooler as it would look factory but this may be too big. YOu can get oil cooler thermostats but that is adding complexity.
The only other little hurdle I will check as soon as I can ge to the hydraulics place is how tight is the bend on a suitable size 90 degree hose tail for the water line as this is the only spot with some clearance issues as the water spot would now be up inline with the manifold so needs to drop down 90 degrees ASAP. Alternatively I could move to weld on dash fittings that may be easier to connect up.
The blanking/mounting plate I can draw up at work so that part is quite easy, I'm thinking some 15mm ally plate as we have some available.
Thoughts from the learned???
