Oil pump/flow/cooler question

fester2au

New member
Guys please forgive me but I own a Jeep Grand Cherokee with the 2.7CDI MB engine and I'm asking here as there seems to be far more knowledge and experience than anywhere else.

Am I correct to assume the oil flow through the cooler is a full flow design rather than a bypass system. I'm talking about the engine oil cooler that is water cooled off the rear of the timing case.

I ask as my engine is on it's 3rd cooler (not in my ownership) and the last one onyl lasted 12 months and about 7,000km's. It was repaired under warranty by a dealer for the previous owner. It would appear the cooling system was serviced correctly so exact reason is unsure however even though Google does not show this as an overly common issue I am aware of a number of Jeeps that are in similar position.

To overcome this I was making up a cover plate with fittings to run an external air cooler cooler out the front of the radiator. However an older gent who was going to face the plate to ensure flat has indicated that my oil lines and cooler may be too small beign only 6-8mm id. The holes to the cooler are 16mm and he indicates that if the oil system is in fact full flow through the cooler this restriction may in fact starve the crank of pressure and flow. He has indicated we may need to run lines with 16mm id at least. The issue with this is the size of the fittings and associated plumbing as there is not a lot of room. Our new plan of attack is to simply run a bypass and remove the cooler completely.

So questions:

Is this part of the system in fact full flow in which case starvation or lack of pressure to crank is a real possibility unless sized correctly.
Do the factory water cooled coolers really cool much or are they more of an oil warmer/temperature stabiliser for your colder European climates where these engines originate. Will removing the cooling medium completely cause temperature issues.

Here in Australia whilst it is a hot climate locally manufactured engines do not generally have oil coolers as a necessity and the main reason I want to do away with the original cooler is I do not want the failure again and associated mess with cleaning the cooling system.

Your knowledge is appreciated.
 

talkinghorse43

Well-known member
Oil cooler is definitely necessary as the oil is relied on to keep the pistons cool. Each piston has a dedicated oil jet pointed at the back of the piston to keep it from overheating. And, each jet has a check valve that opens at 20 psi. I don't know for sure, but I assume the full flow of oil from the pump goes through the cooler before entering the filter. I would keep the OEM oil cooling system and work to find out why it's not reliable. The failure of this system does happen, but has only been reported a couple times on this forum.
 

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