Unknown Coolant Leak Location

Prior to recently replacing my coolant hoses, I did not have any drips, runs, and/or leaks. Now, after driving and letting the HMMWV sit for several hours, I will see a very small amount of green-colored coolant hanging underneath the fan shroud (enough for 2-3 drops on the garage floor). The coolant will not show up immediately during a post drive inspection but rather after several hours of cool down. I was unable to locate any leaks in the hoses and their connections. I was worried about a radiator leak and thus wiped out the inside of the lower fan shroud without any evidence of coolant. I even thought about it being accumulated spillage from the coolant change but it continues to appear after each drive. Any ideas of where to look would be greatly appreciated.
- HoveringHMMWV

Water pump seal?


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Also, check the underside of the hoses that connect to the expansion tank for wetness.

Leak found in the radiator shroud area? My guess is a soldered tank or tube connection. Doesn't take much to be a PITB to find those kind of leaks.

See it, smell it... can't find it, CAMO

People who do coolant flushes on these old cooling systems always run the risk of
creating radiator leaks...do a cooling system pressure test with a cooling system pressure tester.

Retiredwarhorses said:

People who do coolant flushes on these old cooling systems always run the risk of
creating radiator leaks...do a cooling system pressure test with a cooling system pressure tester.

Click to expand...

It was just a drain to change out old hoses and then refill. Didn't do a true "flush".
The limited leak/seep/weep has me stumped but I now have a few more things to look for.
Thnx,
- HoveringHMMWV

Coolant system pressure tester will be you best bet

I just replaced the fan clutch on my M998. No leaks whatsoever before...... After the fan clutch install I have a unknown Drip that appears to be Dripping down onto the six o'clock position on the bottom of the fan shroud...below the fan clutch shaft. I guess somehow the seal on the shaft got upset..... Cant determine any other source. Inside the fan shroud is dry, as are the hoses.... Hate it....

Completed a radiator pressure test as recommended. Found the top inlet hose wasn't quite tight enough. The insidious seep was running between the radiator and the shroud where it then pooled at the bottom. Test drive to follow this evening. "Thank you" to everyone for the insight.

Update: Successful test drive.

- HoveringHMMWV

Retiredwarhorses said:

Coolant system pressure tester will be you best bet

Click to expand...

Where can someone buy a coolant system pressure tester??

Napa,oreilly etc. Any real parts store.

Some stores also have them in their loaner tools.