Coolant loss on a 5VZ

[Crazychopstick]

Just took the Runner out for a 3 hour trip.

Checked all fluids before I left and when I got there I noticed there was a hissing sound and the whole underside of the car was wet with coolant.

Also the reservoir was pretty much almost dry. Took about 3-4 quarts to get the reservoir topped off again.

Both waterpump and thermostat are less than 4 years old and the temperature gauge never rose higher than middle ground. Also there's no smoke or smelly exhaust fumes and the reservoir tank looks clean, oil looks nice and black still. Filled up coolant and there are no leaks, still holding after cool down.

Any idea what happened? I still have to drive 3 hours back home!

[DHC6twinotter]

If you have a hissing sound and lose of coolant, then it sounds like your cooling system isn't staying pressurized. More than likely, you just have a cracked hose somewhere.

I would check all the hoses, especially the lower radiator hose, heater hoses (including rear heater, if you have one), and the coolant line that runs down by the oil filter. You may also want to check if there are any cracks in the bottom of the radiator.

Is there any coolant dripping below the waterpump?

Just my $.02.

[Seanz0rz]

what dan said.

what i would do:
clean the underside REALLY good. make sure everything is dry. drive home, and keep some coolant with you, stop half way and refil; (make sure you dont overheat)

when you get home, follow the coolant forward to its source. since you were driving forward, all the coolant is going to spray to the rear, so the forward edge of that is going to be close to the source.

i would look for cracked hoses (or hard, brittle hoses, you might not see a crack but it could be ruptured) and check the radiator for leaks, especially cracks or pinholes around the connections and supporting points.

[04 Rocko Taco]

I agree with what has been said previously, ESPECIALLY if you don't have a lot of spare time before your drive home, if it is going to be awhile, and you have some down time, just clean it up, refill, and crank it up and let it idle to operating temp, and just let it sit for awhile. come back and check it in a little bit and see if it is leaking. You should be able to locate a source more easily if its not moving. Good luck!!

[MTL_4runner]

This type of scenario is especially dangerous because you don't know when and if the system might let go because you haven't found the source of the leak. These engines don't take kindly to overheating (ask me how I know) so I would probably have taken it to the nearest garage, top off the coolant and had the cooling system pressure tested to either find the leak or ensure that it will hold pressure on the way home. If you find that even after testing the cooling system you're still losing coolant, have the truck's coolant tested for traces of exhaust gasses (which might indicate a head gasket leak).

[Crazychopstick]

Well it's been holding coolant all week fine, no oil mixture, no white smoke or smell, doesn't look like it's getting in the tranny (although I may bypass the stock cooler anyway).

There are a few small drips under the car in the morning but practically dried up when I look for them.

Waterpump and thermostat area look dry, I'll have to double check when I get a chance.

[04 Rocko Taco]

just keep a very close eye on it.

[MTL_4runner]

Well it's been holding coolant all week fine, no oil mixture, no white smoke or smell, doesn't look like it's getting in the tranny (although I may bypass the stock cooler anyway).

There are a few small drips under the car in the morning but practically dried up when I look for them.

Waterpump and thermostat area look dry, I'll have to double check when I get a chance.

Don't just hope the problem went away. I'd suggest using a fluorescent dye you add to the coolant.
Drive the car for a bit and then use a blacklite, you should find your leak pretty quickly (even small ones).


Here you go (be sure to use the water based dye):
http://www.tracerline.com/dyesforflu...-specific.html

They sell it at Summit Racing among other places:
http://www.summitracing.com/parts/TRL-TP-3900-0601/

[04 Rocko Taco]

Very cool product Jamie! Good Posting!!

[Crazychopstick]

A little update. Well not really.

I've been keeping an eye on it since this last post and the coolant level hasn't moved. If it's dripping, it's a seriously slow leak, and it doesn't look external. My guess is it's been dripping through a HG leak or something.