I bought my disco two years ago and have always had intermittent problems with coolant leaks. I replaced the water pump and thermostat, which did seem to help. When the leaking is bad I notice "aerated coolant plumes" aka smoke starts to billow out from under the hood on the driver's side. Eeeks. I notice this when my coolant levels are low.

Today I pressure tested the cooling system for about an hour (did not go above 12 psi) and found two areas of concern. I'm looking for some advice on what could be happening and ideas on how I can further track down the origin of this leak. Also, the heater hoses are dry...

Here's the first area of concern and a smaller leak:

view from beneath front passenger side

Here's the second, much larger area of concern:


view from beneath back driver's side (the leak is dripping heavily onto the exhaust system)

view from beneath back driver's side (this is the area where the leak is originating)

 

I'm pretty sure its the head gaskets......especially the last pic

Although I did have a leak from the heater hoses at the firewall which ran down the starter and right rear of block.....

 

+1 on the head gaskets, and it could also be from where the lower intake manifold meets the block.

 

Good call on the manifold. Since it appears to be coming down both sides of the engine it's either both headgaskets (somewhat unlikely given that it's otherwise running and driving pretty well), or a common failure point like the manifold that could be finding its way to each side.

 

Should we just add "replace head gaskets" as a preventative measure for all new owners? We already recommend replacing coil packs and presumably most people take the intake off to get to that, so why not add intakes to this (especially considering this is a common failure point).

 

Well, cvhyatt, to be clear, I meant common as in relative to both sides, aka, a common point in the middle. I wasn't implying that in addition to HGs, intake gaskets commonly fail. Hell, they may, I just don't have a good base of info there.

 

The leak in the photo could be an intake gasket, or an intake gasket and one or both heads. On a newer Discovery I strongly suggest you DO NOT change head gaskets. Live with the leak. I have written quite a bit about how the blocks are prone to crack between head bolt bores and water jackets and if that happens when you release and re torque the block to change the gasket you will go from repairing an annoying leak to rebuilding the motor with machine work for flanged liners and block welding.

I do suggest starting with the intake gasket, unless you have a fiber optic camera to stick down from on top to verify the leak source. We often to that to be sure

 

Ahh I totally missed that and read more into it than I should have. My mistake.

 

I am on #14, never had an intake gasket coolant leak only. Not saying it is not possible, just never had one. Probably done at least 7 hg jobs. If the truck is not meticulously maintained it is on my to-do list. I have two in the queue at the moment where the owners pre-emptively replaced most of the cooling system before allowing them to fail and overheat - fully documented. That is the only case where I consider not doing hg.

 

We have done these engines for 30+ years, and have done hundreds. I can say with certainty that we fix many intake leaks where the heads don't leak or don't leak excessively. Then again, there are cars where they both leak. Five years ago we still did head gaskets. We have seen too many go bad, shortly after repair, and now that the engines are older, we think the risk in head gaskets alone is not worth it most times. If you are an individual and it's only your time and some gaskets you may want to take the chance. From my perspective managing a large service department I would not.