Coolant leak (longish story)

NickF

Original poster
Member
Mar 28, 2012
3
A few months ago I was under the hood and noticed the fan wobbling quite a bit. Made an appointment to bring it to my local mechanic to have the water pump and fan clutch replaced. I had no overheating/cooling issues just the wobbly fan. The fan clutch and water pump go in and everything's fine. A month later I am driving home and overheat. I "assume" it's a bad thermostat (since it's the original and i had ~130k miles). I replace the thermostat and fill up the coolant and everything is fine. Over the next two weeks I noticed a small coolant leak from under my passenger side front wheel well when I parked, but the operating temp was staying normal. Finally, it overheats (obviously due to low coolant from the leak). Too busy to fix it (or look into it) I fill it up and go another 2 weeks. Same thing. Now it's leaking at a greater rate (only can go about 2-3 days) so today I take it all apart. Removed the coolant reservoir and inspected for leaks/cracks. Nothing. Ran the truck to look for leaks from the firewall area and nothing. I know the heater control valves can go bad, but how do you test them? I'm lost here! Thanks in advance.:hissyfit:
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
EXT valves can leak, but I don't have one myself. Just change it or bypass for now. The long wheelbase also means you have LONG lines going from the firewall to the rear heater core that could also leak. Hope there's no pool of coolant in the rear.

No smell of coolant in the cabin?
 

NickF

Original poster
Member
Mar 28, 2012
3
No signs of any coolant leaks or smells in the cabin, just directly under the firewall at the heater control valve. It leaks a lot for no obvious signs of where it's leaking from. Compnine is down, where can I find a diagram because I am going to order the valve but one of the hoses is wet (the only one) and figure it might be best to replace this as well while it's apart. It does have a connector that you can see from the wheel well that I haven't used before though...
 

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