I had to run an errand about 10min from work at lunch time today. My truck (86 4runner with a 22re) seemed to be running great and all the gauges looked normal, but after sitting in the parking lot for 5 minutes I come back out and there's steam coming out of the hood that smells strongly of coolant.

​​​​​​ I put the key in the on position and the temp gauge reads about a quarter of the way up, which is it's usual warm position. Since I was parked in a lot when I should not have beenI and did not want to get towed, I decided to risk the half mile drive to my house. By the time I got home, no steam, or any visible leaks/puddles.

Does anyone have any ideas other than testing my thermostat and temp sender and trying to recreate it in the driveway? We're planning a 300 mile trip up into the mountains this weekend on the runner and I'd like to be confident in it.

Thanks for the help.
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The 1/2 mile drive might not have heated the engine enough to open the thermostat, and your leak may be on the downstream side. Sit it in the driveway and idle it enough to heat it up. Look for steam or any visible water/coolant.

Wear safety glasses and carry an old towel to throw on anything really spraying. 190° water can really hurt you, so be careful.

 

Ten minute drive, five minutes sitting with the engine off, visible steam coming out of the engine compartment..

You should have popped the hood and found the source. It was an emergency they can't just tow you off.

The guage should have read higher than its normal cruise temp due to heat soak. You probably should not trust it (the guage) with out verification the fluid levels are correct, the voltages are correct, and there isn't air in the system.

Coolant tends to leave a distinct discoloration, look for it.

Plan accordingly, change plans..

 

It looks like someone put a coolant flush fitting in the upper heater hose that was leaking on to the exhaust manifold, so it it was a 5min fix.

 

Good u caught it.
Yeah, that plastic Tee is not reliable. My truck came with it so I want to replace that hose with a straight one, then reserve existing hose with Tee only when needed for flushing.

 

I have had this (flush tee) fail twice in the last two years, once due to heat (hose rupture, aged rubber hose) and a second due to freeze (tee cap fail).. Still haven't replaced it with a brass fitting, or replaced the whole hose line, and only replaced the six inches of hose that bulged..

worth noting they do say on the package not.to leave the flush tee on it for regular duty, it's just meant to be in place while flushing..

 

Hmmm, I didn't notice that. Makes sense because I do not trust plastic parts on a critical system- especially a hot one.