I recently purchased a 97 disco that has a coolant loss and overheating issue.In starting to trace the problem I checked everything out and found the coolant fan to be missing one of the blades and another that is cracked.I have since replaced the fan and fan clutch.After replacing the fan I proceeded to top up the cooling system but I found that there is a leak somewhere on the rear of the engine that is running down the transmission area and dripping.Has anyone else had this problem? I was told that the truck had a leaking freeze plug at the rear of the engine but I cannot verify that.

 

Freeze plug would be better news than what I'm about to tell you. I had the very same problem and mine ended up being the valley Pan gasket. The intake manifold pumps coolant through it and it terminates on either side at the back of the block. When the valley pan goes the coolant leaks out the back of the intake manifold/head union and down the back of the bell housing. Mine wasn't leaking much at all until it reached full operating temp/full flow. Then it would bleed like a stuck pig. There's a thread on here from me. Called "need help brainstorming" I think. Should be fairly detailed. Valley pan isn't hard. just go slow.

Idk if thisink will work. I just grabbed it from my mobil phone. Let me know if it doesn't.

http://picasaweb.google.com/m/viewer...09930563184833

 

Yikes. I hope it's just a freeze plug then. That sounds labor-intensive and expensive.

 

Labor intensive yes. Took two weeks to diagnose and a full 8.5 HR day with 2.5 guys to do. But not pricey. Whatever the valley pan kit costs from AB. You may as well get pcv hoses too. Not bad price wise. I believe valley pan kit comes with rocker cover gaskets. While it's drained you may as well do an oil Pam gasket too.

 

Update..I found out that I have a freeze plug missing in action..The freeze plug on the passenger side in front of the starter is gone...I have not run the engine long enough to build heat since I purchased the disco and I was going by what the po told me as far as the overheating concern.....Does anyone know what size freeze plug they use on the 4.0 engine?

 

Let us know your results.

 

I will do a pressure check on the system after I replace the freeze plug and do a compression check and let you know what I found....

 

Hopefully thats it. FWIW when i did my pressure test it didnt turn anything up

 

It seems to me that with a freeze plug completely missing that the coolant leakage would be fairly significant if the coolant is circulating as it should. Does this not suggest another potential problem as well, possibly water pump or a major blockage.

The freeze plug could possibly have been blown out during a previous overpressure/overheat condition prior to your vehicle purchase.

Otherwise what feasable reason is there for the total absence of a freeze plug. Surely it must have been fairly recent I would think.

 

Danny,
You are absolutely correct about the probability of other problems.I found the fan was broken and the fan clutch itself was suspect but I also believe there are other problems which led up to the dispelling of the frost plug.I am going to install a freeze plu and fill the system with water so I can do a pressure test.I am also going to do a compression test as well.There is no mixing of the coolant in the oil,the plugs have carbon on them and do not appear to have been contaminated with coolant.If the system holds pressure and the compression test is good I will begin checking out other areas.The radiator also looks good with no signs of leakage and from what I can see the inside looks clean.Thanks for your help.Mike