I've got a 3.0 litre SCV6 which's suddenly started leaking significantly as much as a gallon of coolant on just a short drive. Over it's life I've replaced the water pump twice and the seals, gaskets, cooler tube and o-rings multiple times as well as the upper/lower front crossover pipes to aluminum.

For this situation, I removed eh water pump and replaced the gaskets, o-rings and cooler tube again. But the leak persisted. So I removed the supercharger, water pump, seals, gaskets, aluminum pipes, o-rings, oil cooler and cooler gasket. Inspected the oil cooler and did not see any signs of leaks. Sealed the coolant hole on the back end and applied pressure to the tube. Did not observe any leaks. Replaced all gaskets, seals, o rings with new again and vacuum filled (as I always do) with about 2 gallons of coolant and ran the engine for about 30 minutes and coolant pooled up at the front of the cooler under the cooler tube. As far as I can tell it's not coming from the top or sides of the tube and with limited visibility, unsure where it could be coming from.

Anyone here have any experience with cooler leaks?

Considering how many times I've successfully replaced the water pump tube, rings and gasket I find it hard to believe that's what's leaking so that only leaves the cooler but before I go tearing everything apart again looking for feedback here.

 

"Sealed the coolant hole on the back end and applied pressure to the tube."

Are you using a coolant system pressure tester? That's what I would do to find the leak. You may have to raise the supercharger up to see underneath, but getting pressure in the system while full of coolant is the best way to find leaks and confirm leaks are fixed after doing any work.

 

No. The oil cooler’s bolted to the crankcase under the supercharger. The only way to remove the oil cooler and see the ins and outs is to remove the supercharger and then the oil cooler. It’s quite large and long. That’s the challenge because if it’s leaking there’s no way to see it. Inspection did not reveal any signs of leakage from the oil cooler and internet searches have only indicated an oil cooler leak’s extremely rare but no specifics as to where a leak could occur.

As mentioned I fitted a new seal on the original oil cooler (I purchased a new oil cooler but it arrived damaged and bent from shipping and since the original appeared to be in good order I proceeded with just the seal).

Here’s what it looks like.

 

I am already very familiar with the oil cooler, and the entire cooling system on these cars after owning 4 with the same engines and doing all my own work.

My point is that you are shooting in the dark until you use a coolant pressure tester to confirm the source of the leak. Not using the right tools is causing you to shoot the parts cannon at the problem without solving the problem.

You can borrow cooling system pressure testers from parts stores for free or buy one from Amazon. Any serious DIY mechanic should have one in their toolkit.

You could try using an inexpensive borescope that plugs into your phone to see under the supercharger during the pressure tests, but you may need to lift up the supercharger and prop it on some small blocks to see better. By lifting it up a little, you can reconnect its coolant hoses for the pressure tests.

 

I would do a pressure test ,but the oil cooler you should put black gasket maker around the holes, also the o rings for the water pump and oil cooler should be from jaguar, if you need help let me no ,ps make sure you put lube on the o,rings, if it gets miss alignment there's your leak, check my video

 

Been working on cars for over 20 years, I have vacuum, airlift and pressure testing. System holds vacuum and pressure for several hours, used stethoscope to listen for air noise. Bubbling can be heard from multiple locations so no help there. My borescope's camera resolution's too low to see anything in those tight dark spaces so perhaps a better newer camera but still a challenge.

If you're familiar with the oil cooler then you know how difficult and nearly impossible it is to see anything underneath it even with the supercharger out of the way.

Coolant appears to either be coming from the underside of the outlet tube where it connects to the oil cooler or the coolant's leaking from the cooler underneath and where the outlet pipe's located but as I mentioned with the cooler removed and pressurised, it did not appear to loose air. And with a new seal between the crankcase and the cooler, can't believe that would be leaking either.

 

Did not add any sealant not used at the factory. I get where it seems like putting gasket maker everywhere there's a seal sounds like it makes things better sealed but if the factory doesn't do it and it doesn't leak, then I say leave it be. I've replaced the outlet tube and o rings multiple times over the years with no subsequent leaks. Last time was a year ago using genuine parts. Since the JLR tubes wear out so fast, this time a went with an aluminum one. Compared to genuine everything matches up. Other members hear have done the same with success. I always use silicone lube on o-rings. O-rings always go on the pipes first, then the tube gets fitted. It's definitely NOT leaking at the water pump end. Certainly a possibility it's leaking at the cooler end underneath where I can't see.

Remember the whole reason for this repair was due to a massive leak. R&R'ing and replacing water pump seals twice now (in addition to everything else) hasn't solved the leak problem so I'm still leaning on the leak's elsewhere.

Hence the reason for the query regarding members' experiences with cooler only leaks.

 

Check to see if the aluminum replacement hoses are firmly in the holes if they are not seated right, they could leak they have a tendency to be very snug but not down all the way.

 

Doesn't sound like you've done what I recommended. That's ok. Best of luck.

 

For other people that may have this problem, another thought is to remove the supercharger entirely and then just put back the supercharger lid that has the air-to-water coolers so you can pressure test the complete system and still have lots of room to see the oil cooler underneath.

 

If you’re suggesting draining the coolant, disassembling, then reassembling without the super charger then refilling the coolant to pressure test then you’re correct. That’s a lot of wasted coolant. Other problem is it doesn’t leak when pressurised, only with the engine running for more than 30 minutes does it leak. Can’t run the engine without the supercharger or throttle body.

 

You’re correct in that fitment’s not the best with these pipes but the joints are dry. No leaks there.

The leak’s lower down, either from under the cooler or under the cooler pipe.

 

That's a rare one for sure?
The only thing sorta close to that is I have heard of highly boosted CTS-V's that sometimes suffer damage to the same oil cooler brick from the extra SC pressure.
But that seems unlikely here?

Hope you can post back with what you find.
.
.
.

 

Uh, use a large plastic and clean bucket to capture the coolant you are removing to add it back in. But since I save thousands on labor by DIYing, I never penny pinch on supplies, like coolant. Fresh coolant is always a good thing.

So you are saying you have massive leak, but it can only leak while the engine is running, even if the system is under 30 PSI of pressure (the actually rating of the expansion cap), and you think its the oil cooler that is leaking, and the oil cooler is somehow different when the engine is running?

Hmmm.

 

Your’re making assumptions on things I didn’t say.

I’ve been building and repairing cars for over 20 years including a lot of JLRs.

Coolant’s not cheap compared to the costs of everything else in repairs. I NEVER reuse coolant, even if it’s only been used once. In this specific situation I’ve already gone through about 6 gallons. Not that I’m opposed to going through another 4-6 gallons for the test you suggested, there’s no guarantee this’ll provide any answers and so not eager to waste more.

And no I don’t put 30 psi on the system, I’ve gone as high as 20 psi, higher than that I’ve had pressure testers explode. I have found some leaks using pressure testers. Again the system held pressure and vacuum for several hours. Most techs will tell you 15psi should be sufficient, up to 20 to see if it makes a difference but never more.

To be clear, I’ve not driven yet. It’s only been stationary in my shop and as I said it’s only leaking at the moment not significantly. It was gushing before the repairs, literally coolant everywhere top to bottom and all over the ground after a drive.

After R&Ring the coolant pump and seals, it did it again. That’s why I moved to the oil cooler.

There’s only 2 possible sources for the leak, the cooler tube at the cooler or the cooler itself.

New cooler’s $500, had one on hand which was damaged in shipping so I returned it.

Before I go through ordering another cooler and tearing everything apart again I was looking for cooler leak feedback.

A super high quality high resolution micro borescope may be the only way at this point to try to see.

 

If the cap is 30psi, a test is not complete unless it is tested at 30psi.

Maybe a gallon at most needs to be drained out of the radiator drain valve to be able to disconnect the supercharger cooling lines, but probably closer 1/2 gallon would do it. No idea why you would think it would take 4-6 gallons.

In terms of getting feedback on oil cooler failures, I suggest you go to where more DIY people are for these engines, which would be the XF and Range Rover Sport forums. There were more of those vehicles made at a lower price point, and the current owners are more likely to DIY.

 

Like i says put black gasket maker around the 3 holes for the oil cooler ,I've done quite a few jlrs for members here on this forum ,its in my videos ,not one has leaked ,the XJ i did same thing, also check the hose to the throttle body from the the rear heater pipe for damage ,very rare but could happen, just trying to help

 

Appreciate the suggestion. TB hose not leaking. I’ve actually got it detached so if it ever fails, it can be replaced with only removing the TB, I can pull it freely from front or back.

Have you ever seen an oil cooler leak and if so what part of it leaked?

As for pressure testing, I’ve never had a need to go higher than 15 psi to find a leak, but with the leak only appearing when the engine runs for a while, may be an indication I need a pressure tester which can go above 30 psi. The one I’ve been using was only
$300 and doesn’t like going higher than 20 psi at which point it either leaks or pops apart. . Going to try to find a more expensive one.

 

Yes it leaked on the F-type a member has, It filled the valley, the gasket let loose, you could see it when I pulled up the gasket around the holes,so when I do jags I always put the black gasket maker around the holes and torque to 13nm, but I'm not sure what your experiencing unless I'm infront of the car,I hope you find your leak,we here for you

 

So it wasn’t the oil cooler, it was the gasket then? I’ve already fitted a new gasket. The original was quite fatigued but no signs of dried coolant or any traces indicating a leak any where.