I've found that when I leave my oil pan heater plugged in for any appreciable length of time, I get a pretty decent coolant leak. The coolant drips from the lower rear corner of the RH valve cover seal. I can see the coolant pooled on the top, in the little lip that the edge of the valve cover sits in, but I can't seem to find the source. I don't notice the leak when I'm driving, because the coolant drips right onto the hot exhaust manifold and boils off.
A while back, I had an overheating problem. I saw some coolant in this spot and removed the valve cover, but found no other traces of coolant anywhere. I replaced all the water system components, and I'm not having more overheating problems. The truck seems to run just fine. Also, the oil on the dipstick looks nice and clear.
At this point I'm guessing I'll need to do the upper end gaskets, at least. But I wonder if anyone has experienced a leak like this before? Could the head itself be busted? I'm not quite able to visualize how coolant would be getting up into the valve covers, but not leaking elsewhere.

 

This one is simple...just dont plug in your heater.

 

Go do a coolant pressure test to find the problem.

 

Have you checked the condition of the supply/return hoses to and from the a/c heater core. The connections are obvious as the hoses run the length of the RH valve cover to the bulkhead. When you do that pressure test check those areas too.

just a thought...

 

Thanks, Spike!

Mike - Can you elaborate on the pressure test? Would that help me isolate where the leak is coming from? I'm trying to decide if I should go ahead and pull it in and just go after the gaskets, or if I need to look for another solution. I have no doubts that there is a leak. I've produced some rather large puddles. But I'm not quite sure what direction to head with fixing it just yet.

Cosmo - It's definitely not the hoses. I've looked for any strange way that a hose could leak and get the fluid over there (because that would be the easiest fix!), but I couldn't find any. I've tried to look back around the back side of the head and around the back and inboard side of the valve cover gasket, but I haven't been able to see much. I guess I really need to get it in the garage, but I haven't had a good chance yet. My gut is leaning towards a cracked head.

 

Chuck, send me your number and I'll call you today.

 

Mike: PM sent. Sorry for the delay.

 

Came across this on some auto mechanic blog site. It was about a 2002 DII, but it sounds just like my leak, and it gives me a little ray of hope:

"Customer Problem: I have a 2002 Land Rover Discovery with a 4.0 L engine that only has 46,000 miles on it. It is leaking coolant and I can see it drip off the back of the valve cover at the rear of the passenger side but can not see or locate the source. Solution: Filled and pressure tested coolant system. After getting approval, removed the upper intake manifold to gain visual access and found the lower intake manifold gasket was leaking. Found after ordering the part from my local dealer that this is a common issue with this vehicle. Made the repair and customer is now happy!"

Is this the valley pan gasket I hear mentioned from time to time?

 

Lower intake manifold gasket = valley pan gasket, yes. Hopefully, that is all yours turns out to be!

 

Mike: Thanks for the phone call to help figure this out.

I'll see what I can do about doing the pressure test this weekend. It looks like no matter what comes of it all, I'll be replacing at least some of the motor gaskets in the process. I might as well just get the gasket kit on order at this point, I suppose.

Who is everyone's favorite supplier of head and intake manifold gaskets?
So far it looks like Atlantic British has a pretty comprehensive set.