I've loads of experience disassembling this engine, replacing water pumps, pipes, gaskets, hoses and more.

The other day on a long drive I was prompted with a low coolant warning. No temp issue and heat was working. Pulled over, opened the bonnet and saw what looked like a coolant explosion, coolant everywhere.

Trouble shooting has narrowed the leak to the top of the engine. Cleaned and refilled with about a gallon of coolant and ran the engine. Coolant dumped out immediately from the top of the block. I've had water pump leaks, but this was WAY more coolant than a water pump leak. Pipes not leaking and throttle body hose not leaking.

Removed the water pump, replaced the pipe, o-rings and gaskets, reassembled and coolant leak still present.

I'm stumped, there's nothing left to leak so where's the coolant coming from?

 

I would pull the intake, pretty easy on the LR4s. The coolant outlet Y pipe will crack in places you can't see with the intake on. Also that metal box looking this the little pipe for the water pump connects to is the oil cooler. That could be leaking as well

 

Sorry to hear.

 

Aluminum pipes not leaking, water pump serviced and not leaking. Oil cooler removed and shows no signs of leaking however the metal gasket's original. Since there's no where else coolant could come from, and it seemed the leak was coming from the rear of the valley, I reckon coolant must've been coming out from the rear of the gasket. Funny though, no coolant in the oil so not sure how coolant would leak at a high rate from the oil gasket and not fall into the crankcase below.

 

If it's coming from the back of the engine it could be the pipe at the rear that runs from cylinder head to cylinder head. Pressure test it and see where the coolant is flowing

 

I said valley, not engine. No pipes or hoses back there.

Pressure tested oil cooler, no leaks. Fitted new gasket and putting everything back together.

 

Well, put it all back together, new seals/gaskets for everything. Spent a few hours vacuum filling. Not sure where all teh coolant went, used nearly 3 gallons. Even with the vacuum fill, can't get heater to blow hot like it normally does when I refill.

Any way, the big problem....

It's still leaking, at the front now, not the pipes (new o-rings), doesn't appear to be the pump or oil tube (aluminum one fitted).....

 

And you can't see the leak while its running?? Under the reservoir??

 

Reservoir?

All I can see is coolant pooling up around the oil cooler front outlet pipe which connects to the tube. The first, easy repair I tried was removing the pump and replacing the crush gaskets, orings & outlet tube. That didn't work and it didn't look like coolant was leaking from there any way.

It appears to be coming from under the oil cooler, but I just fitted a new gasket, cleaned and polished all mating surfaces. I tested the cooler by plugging the holes and applying air pressure to the inlet pipe and I did not observe any air leaking out and it held low pressure.

There's nothing else it could be unless either the new orings and outlet are leaking on the underside or something amiss with the cooler. I've ordered and new one, $500!! and facing tearing it all down and redoing all. Ugh

 

I must have missed an earlier message. Sorry. :-/. Good luck!