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/dyesforfluids_application-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.

[Seanz0rz]

more likely the rubber oring on the idle air control valve. mine was seeping through there, replaced it with RTV, no problems since.

[Dice Man]

What coolant are you guys using? My Runner still has the Toy Red the dealer uses, was wondering if I can add Zerex Asian Coolant Orange or should I do a complete flush before adding the new orange?

[DHC6twinotter]

I'm just using the Toyota Red coolant in my 3rd gen.

[MTL_4runner]

What coolant are you guys using? My Runner still has the Toy Red the dealer uses, was wondering if I can add Zerex Asian Coolant Orange or should I do a complete flush before adding the new orange?


Bigtime NO!

Best coolant to use is the Toyota pink available at the dealer. It's very easy to use, has a super long life formula (5-7 years between flushes) and comes premixed so you can't get the concentration wrong (especially after flushing the cooling system). There's a large thread on here about all the different coolants and why the Toyota ones will work best for you.

[TheDurk]

What coolant are you guys using? My Runner still has the Toy Red the dealer uses, was wondering if I can add Zerex Asian Coolant Orange or should I do a complete flush before adding the new orange?


Bigtime NO!

Best coolant to use is the Toyota pink available at the dealer. It's very easy to use, has a super long life formula (5-7 years between flushes) and comes premixed so you can't get the concentration wrong (especially after flushing the cooling system). There's a large thread on here about all the different coolants and why the Toyota ones will work best for you.



Take another look at the Zerex Asian Formula. It's a chemical clone of Toyota Pink. It's a phosphated HOAT (Hybrid Organic Acid Technology) just like Toyota Pink and is also a full strength pre-mix. It's half the price and available at Amazon, NAPA and other places. It's only been available for about a year so many people aren't aware of it. It's the first aftermarket blend made to meet Toyota requirements.(I may be a newbie here but I have 1300+ posts on YT and T4R.org.)

[MTL_4runner]

Take another look at the Zerex Asian Formula. It's a chemical clone of Toyota Pink. It's a phosphated HOAT (Hybrid Organic Acid Technology) just like Toyota Pink and is also a full strength pre-mix. It's half the price and available at Amazon, NAPA and other places. It's only been available for about a year so many people aren't aware of it. It's the first aftermarket blend made to meet Toyota requirements.(I may be a newbie here but I have 1300+ posts on YT and T4R.org.)


I do agree it's alot closer than I've seen for many in the past, but there's no indication it's actually a clone for the Toyota Super Long Life Coolant (the SLL is OAT which contains no silicates unlike HOAT and the Zerex Asian formula does not seem to meet ASTM D4340 while the Toyota SLL coolant does). I don't have data sheets to compare the formulations either, but it seems (logical) that while the Zerex formula tried to satisfy everyone, it actually may not be the best choice for the vehicle. In any case, I can't see it being worth taking a chance when the cost vs change interval is as long as it is with the OEM SLL coolant. That being said you probably wouldn't do any damage, but again just too easy to do it right and forget about it IMHO.

In any case if you are switching coolants I would do a flush first then do a complete refill.

[Dice Man]

I got a price from the Yota dealer and they want $25 a gallon for the Toy Red/Pink. I don't know if that is the concentrated or mixed - maybe the Red is concentrate and the Pink is 50/50?

Our 4Runners have a 9.2 coolant capacity so I have to buy 2 gallons of Toy Red - 4qts=1 gallon or I can just buy the pre mixed and not have to worry about getting the mixture correct. Just dump in the 9.2 quarts of pre mixed blend?

Since I decided to replace the Rad - 170K miles on original Rad, I'm going to do the complete flush, it looks like the Red coolant is dirty so I need to flush it, I guess using the Red would be best. I'm also picking up a new thermostat and gasket for $27 - should I get a new Radiator cap? The new Rad is a Koyo A1998 and I guess it should work with the old cap but to be safe should I replace it?

[MTL_4runner]

Red = Concentrate => Flush every 2-3 years
Pink = Premixed => Flush every 5-6 years

Just get 2 gallons of the pink, flush, refill and be done with it.

You can replace your radiator cap, but it's probably still fine as long as it's holding pressure.