Last night I pulled into the driveway and when I got out I head what sounded like an exhaust pinging (expansion/contraction). By the time I got a flashlight it stopped. I opened the hood to hear the expansion tank cap venting and looked on the pass side rear of the block/bellhousing to see it wet. I assume the leak was dripping onto to pass side cat causing the sound.

My coolant temps are usually 194-197.

Is this a head gasket or block or possibly both.

I am tempted to try to retourqe the head studs (I installed ARP studs when I did the heads in Aug '14) to see if that does anything.

Any other suggested diagnosis or ideas for a path forward?

 

coolant system pressure tester is the only true way to find your problem

 

If you warm up the truck and slowly take off the expansion tank cap.
and you rev it up and fluid flies out - well - pressure.

Another sign is when you are parked for an hour and you come back out to the Discovery and you open the expansion tank slowly and you hear bubbles and pressure..

head gasket time.

 

Got some time to do some diagnosis.

Truck was cool and hooked up the pressure tester. Ran it for a while. Never got over 5 psi. This does not explain why the expansion tank cap vents/relieves pressure.

Below is a photo of the coolant leak. The mirror shows the rear corner of the pass side head.



My game plan:
Retorque head studs, if that doesn't do anything (I don't think it will help). Then I will install a new headgasket on the pass side head.

 

I had a leak in that same spot. It went away... for a little while (few hours) after I filled up with coolant. When I got home I checked the rear head bolts and they were tight (since we don't get torque specs it is hard to know HOW TIGHT) so I gave them another 1/4 turn just because.

Best of luck with that. Sounds like you know just what to do. When the inevitable occurs use copper gasket compound (spray) on both sides of the gasket and you'll get a better seal.

FWIW, I only installed the passenger side gasket, too. I haven't had a problem since on that engine.

 

well that was the reason to use the studs, they can be tightened and reused

 

When I was pulling into the train station parking lot this AM. (Train lot is approx 1 mile from my house) I threw a P1300, P0304 & P0308.. I didn't notice it missing at all. Going to pull plugs and see what they look like. A friend has an inspection cam, will borrow that and look in the cylinders.

 

Indeed. But when I have to redo the head gasket won't I have to remove the lower studs to take my heads off? I've had bad experiences with studs (exhaust) on my rover. I've even broken them with a stud remover. Drilling on the manifold is one thing level of badness... I hope I never have to do that on he head.

 

could be worse, I once broke an easy-out off in a bolt hole, a nightmare to drill

 

Where can I learn some more about this copper gasket compound?