1988 4Runner 22RE 5pd Manual

When I bought the truck it had no heat. Replaced the t-stat; did not fix problem. Blew out the heater core; heat worked great.

As time went on I noticed every now and again the coolant temp gauge would climb slightly, then level off at half way. After it happened a couple times I looked and noticed the reservoir was dry. I added some coolant to the "LOW" level and it was no longer an issue, I assumed it was lost coolant from blowing out the heater core. Ran like this just fine for about 3 weeks.

Yesterday coolant temp gauge climbed, then leveled off. Heat still worked. Later that day the heat was warm, but not hot. Last night had no heat, and the coolant temp gauge climbed and stayed pinned in the red. Finally got it home, went to Advanced and tested the radiator cap. Rad cap was perpetually leaking so I bought a new one and tested the new one; it held 13-lbs all day. Installed; as expected, same results, still overheats.

I have not drained the oil but from pulling the dip stick I have seen no indication that there is coolant in the oil. Its typical 3000 mile oil color with no scent of coolant nor the typical "displacement" effect/look of water mixing with oil.

There are no visible leaks; all hoses are clamped tightly. The coolant line to the heater core is warm but not hot; the heater core return line is cool. Upper rad hose is hot; lower is luke warm. I'm hoping maybe I have a bummed t-stat; it could possibly a water pump, but I'm sure in the end it will be the most expensive problem a coolant issue can give you. I have read online about the timing chain in these trucks rubbing against something and causing overheating issues, but as I've said, no visible leaks. I'm running out of options here and am getting frustrated. Any help is greatly appreciated.

 

Sounds like a bum thermostat. If top rad hose doesn't get too hot to touch, that's usually a thermostat.

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The upper is hot; it's the lower that's cool. I'm gonna put the tstat anyway after I finish lunch

 

Tstat is not the problem. I will swap out radiators tomorrow, for now I need to flush my coolant system with beer.

 

Oh yeah i DLed the yotatech app. Its pretty sweet.

 

So I pulled my water pump and I saw this gunk built up. For the record when I drained the coolant it came out green. When I pulled the water pump it came out green. But this looks like the coolant is mixing with the oil.

Attachment 90153



Attachment 90155

 

Next step is to pull the timing cover and check the chain guides. The drivers side was plastic from the factory. When they wear or break it can open a hole that will allow coolant and oil to mix. Easy and cheap fix. Engnbldr has a front end kit for under $100 I think.

 

Ill check into that next. Ive read about it but forgot until u reminded me. Thanks ill check it out tomorrow when I have sun light

 

Sorry, it's $150 but you get a new water pump, oil pump, timing chain, guides and cover with all necessary gaskets. http://engnbldr.com/toyota-ala-carte.html It's a fun job!

 

I hate when people tell me its a "fun" or "easy" job.

Thanks for the link tho. Big help.