View Full Version : Where does the oil cooler leak from??

11-25-08, 10:52 PM
Okay, I know there is tons of threads on this topic and i have read a lot of them trying to figure this one out.. So far i know that the oil cooler is a hugely common coolant leak source and often times is associated with oil in the coolant.. What i am trying to figure out is WHERE the coolant usually leaks from.. i have a really bad coolant leak that is leaking a straight line of coolant after the car has been running for a while. I already tore into the car and have the whole intake assembly off, just replaced the valve cover gaskets and spark plugs because i had oil in the plug wells and i'm planning on doing the thermostat also. Anyways.. (got a bit off track) i was looking at the oil cooler in the engine, and it almost looks like the coolant leak isn't coming from there. Instead i unbolted the crossover thing that crosses over the rear oil cooler line and the 2 upper metal/rubber seals are more or less blown out.. can that be the source of my major coolant leak or do i need to look elsewhere around the oil cooler, too..? if so, where do i look? i don't have a coolant pressure tester for a system like this that doesn't have an "old-school" radiator cap.. i'm just really trying to avoid having to tear the whole engine apart twice to fix one thing... THANK YOU GUYS!!!

frank moran
11-26-08, 11:24 AM
heres the deal, oil cooler leaks that have oil in the coolent is the result of the cooler failing and allowing oil to enter the cooling system, if you notice, the cooler sits in the block emersed in coolent.
The other leak possibility is the cooler is bolted down to the block with RTV sealer, if the rtv beaks down you have an external coolent leak.
The bridge you refer to is also very big possibility for a external coolent leak, you should be able to see traces of a leak from this area. The O rings are relatively fragile, you'll have to do some research to get them w/o the complete bridge. Someone had a part number for them, try the dealer...

11-26-08, 03:22 PM
so to get to the rtv'd part that could be leaking, the oil cooler needs to come out, correct? and if i do take the oil cooler out, im going to need some more copper "gaskets" for the banjo bolts, right?

i found that part number for the o-ring gaskets a while ago through these forums and i already got those so im good on that part. i also got the thermostat replaced now today so thats good, too. =]

frank moran
11-26-08, 04:07 PM
Yes, I would recommend replacing the copper seals on the banjo bolts, they are cheap and available. Suggestion, before you go bending the lines, jump down below and loosen the 2 lines above the oil filter, If I remember it was a 3/4 in. ? not a big job. Lift the cooler out, its quite small, clean the mateing surfaces with brake clean, rub a very thin layer of rtv into the two surfaces, sort of like a thin primer coat. Lay a 1/8 bead of rtv and and assemble.

11-26-08, 10:56 PM
sweet thank you. =] how many coppers will i need? is there any down below by the oil filter

11-27-08, 08:31 AM
The banjo bolts on the cooler need 2 washers each, the coolant bridge bolts require two washers each but they are a different type.
The banjo bolts for the oil cooler will come out okay but if you try to remove the oil cooler plate to reseal it you will want to buy a new oil cooler. The nuts that hold the cooler onto the plate must be removed to get the plate off. When you take the nuts off they will strip the cooler, period. I haven't done one yet where they didn't.
If you go in there just get a new oil cooler.

Be sure to look above the back of the engine, there is a "heater control valve" there that has 3 hoses on it.
They are just as bad (if not worse) for leaking as the coolant at the back of the oil cooler plate.
If you are in there that far, it might be worth your efforts to just replace it now. It will be a lot easier to do with all that stuff off.

Oh and there are no seals on the lower parts of the oil cooler pipes by the filter housing. They are flared fittings.
You might want to take the oil filter housing off the engine to get better access to the pipes.
Get new seals for the oil filter adapter.

12-01-08, 01:43 PM
I would like to further elaborate on this... How does coolant get into the oil fill cap? But not in the main oil?
Making the white peanut butter sludge but not fully contaminating the oil to turn white? I also have a leak from somewhere with the white stuff in the oil being a new one. No air in the coolant tank while running.

12-02-08, 06:59 AM
The stuff on the oil fill cap usually isn't actual coolant, but just condensation.
Usually due to a breakdown of the PCV system.
They have something really funky on Catera so I am not sure how it gets messed up.