hey guys, i have a 98 4Runner with a 5vz-fe motor, 5spd standard transmission.
i live in manitoba and the temperatures here drop down to about -45 and that was the case last week.

i went to go start up my truck, and after about 10mins of idling, i noticed there was no hot air coming out whatsoever, only cold air, so i figured i drive around for 5 mins and let it warm up, after about 5-10 mins i noticed the temperature guage start to rise near the red zone, and still there was no hot air!, i went back home and plugged it in for the night and next morning i started her up again to my surprise this time there was hot air coming out and she seemed to run fine with the temp guage not moving from the "normal" zone.

i went to work and once i got out of work the same symptoms re-apperared again. there was no hot air after 10 mins of idling, once i started to drive for about 5 mins the temp guage would near the red zone and there was a "ticking" sound coming from the engine bay. once i got home i noticed that she was leaking radiator fluid, but it wasnt from the radiator itself, it was coming from somwhere under the block.

i was thinking a faulty water pump or a faulty thermostat?

any suggestions on what's wrong?

Thanks!

 

If it's leaking coolant, I would check the water pump and any hoses that carry coolant. One guy just posted this morning that he had coolant leaking from from the host that connects to the throttle body.

You probably have an air pocket in the system and that is why it's over heating and you are not getting hot air sometimes.

EDIT: Also, it's not good to let your truck idle for that long. It wastes gas too.

 

Very cold, temperature gauge high, no heat. Sounds to me like you don't have enough antifreeze in there. The coolant slushes up when it gets cold enough and won't circulate. The engine overheats and you freeze your butt off. If I'm right, you could easily damage the engine driving it like this so plug it in to thaw the coolant, drain the system and refill with a known concentration of antifreeze.

My $0.02.

 

Kinda sounds like your radiator. No heat to the heater core and no water to the engine sounds like something's blocked up possibly?

 

In regards to the temperature issue - I'd be looking at the thermostat or water pump like you assumed. I've had a sticky thermostat before, and it sounds like pretty standard behavior. Frozen coolant (water) is also a good guess. I don't deal with conditions so extreme, so I've never seen coolant freeze - but John4R's logic seems sound to me as well. As for the leak, it could be exacerbated by the above conditions - or the above conditions could be caused by a leak. I would diagnose the easiest things first (coolant level, coolant quality), then move on to the thermostat and water pump.

The fact that it's cropping up now tells me that you have a weak link (sticky thermostat or bad anti-freeze concentration) that is simply rearing it's head in the right conditions. I would venture that the leak is either a small problem that can be corrected later (as long as it's not spewing), or you've got bigger problems that are going to be a lot more difficult and expensive to fix than replacing a $10 thermostat.

If I had an overriding guess - it would be slushy or frozen coolant. By the way, is anything weird coming out of your exhaust? I have a T-100 in my garage that was blowing cold air and was red-lining due to a blown head pouring coolant into cylinder 2. White smoke was the "tell-tale" sign, but it still took a lot of diagnosing to find the crack. Hope this is helpful...

 

Do the easy thing first and check to see that your coolant isn't frozen.

 

-45? F or C? That's D@mn cold!

It sounds like frozen / slushy coolant. The slush is blocking coolant flow through the water pump & heater core. You said you plugged it in overnight & it was fine, but at work, I assume, that it was unplugged? You need to check the freeze plugs on your engine block & make sure they are not popped (which they are designed to do to save your block). If a freeze plug is partially popped, you may be able to reseat it to stop the leak.

Good luck,
Paul.