I searched the forums and did find posts on overflowing expansion tanks; however, none really answered my specific concerns, so I'm hoping someone can help.


I bought an '03 Disco approx. 3-4 months ago with 118k miles on it. I noticed the water pump had a leak, so I recently replaced it with a new part from British Atlantic. I followed the RAVE instructions and went through the bleeding process 2x, and coolant comes out immediately from the bleed screw when I open it. So, l'm puzzled by what I'm seeing. The truck has been running fine and the temp gauge has stayed right in the middle, as it did prior to replacing the pump. That said, yesterday morning when I checked the coolant level (cold engine) it was low, so I added more to the cold line. Then while driving into work this morning I smelled coolant, so once parked I opened the hood and the expansion tank was completely filled (coolant was obviously leaking from the overflow hose while driving).


I'm really at a loss here. Is there air in the system? Should I bleed the system again? Should I replace the expansion tank cap? I'm running Dexcool since that was in the truck when I bought it, but plan to flush and change to Peak eventually. I suppose I can do that now if that would be recommended.


Thanks for any help.

 

If you bled it properly and are still having a problem, you should check for a blown head gasket. When was the last time the head gasket was repaired? As you may be aware from reading this forum, this is a routine issues with these. Leaking head gasket may result in an over pressured cooling system and cause the waterpump to leak from the weep hole in the front. I had the same symptoms. Truck ran fine. No overheating issues (you should be aware that the temp gauge is not accurate as it is a dummy gage - search here for an ultraguage). Changed out the leaking waterpump and the next one started leaking from the weep hole in a matter of weeks. I finally determined and confirmed that the heads were leaking. Good luck.

 

Just spit balling here because we all hope it isn't a head gasket but have you replaced your expansion tank cap? They are calibrated to release at a certain pressure and I'd yours is blown, any sort of pressure will spew coolant.

 

Thank you for the replies. I did not realize that about the temp gauge, but I am aware of the head gasket issues with the Disco 2s, and have actually been trying to do everything I can to ensure the coolant system was in good shape (like the water pump). That could be the issue, but the exhaust doesn't really show much smoke etc... Ive already done an oil change and there was no water in the oil either. I will try the expansion cap idea first, that's something I was planning on replacing anyway. In the meantime I'll do what I can to determine if the HG is blown. I suppose it could have blown within the last week since I replaced the water pump.

 

UPDATE: So, I replaced the expansion cap and the truck has been driving great. Coolant levels have remained spot on. I bought an infrared thermometer (I realize this won't be as accurate as the Ultraguage, but just wanted to get a reading for now) and the top radiator hose read 174F and the highest reading I could find on various points was 180F. It has been in the 30s here in Cleveland, so I plan to add the Ultraguage before the summer months.

I think I'm fine for now, but I do intend to do the head gasket and valve covers this coming Spring as a preventative measure. Thanks again for the replies.

 

You should add an ultragauge or equivalent asap. It will help you save your engine in the event of a failure in your cooking system. I had a lower thermostat hose come off while driving about 18 months ago, ultragauge got to 230 before I was able to pull over safely. The main temp gauge was still in the middle!

 

Lions and tigers and headgaskets, oh my!

I missed this thread when it was started, but Charlie V was spot on. There are more than a few threads on this forum about the need to replace the reservoir cap because they fail to hold pressure when they get old. I'm glad that was the only problem you apparently had in this case.

Try to always start with the most simple, at least expensive solutions and diagnose, diagnose, diagnose.

 

Wow, that is unreal! And yes, thanks Charlie!

The thermostat also appears to be original, so I plan to replace that and then flush out the Dexcool and add Peak.

 

The sun shines on a dog's a$$ occasionally.

 

Be sure to replace the stock thermo with the soft spring 180* version from the TD5. I'm convinced that high temp thermos and high underhood temps contribute significantly to the head gasket issues with these trucks.