92-4wd

I have a 1992 Toyota 4wd PU with a 22re. Last winter it was loosing coolant with no visible signs of leakage. I drive 75 miles round trip to work and about every 2 trips (150 miles) it was a half gallon low. I checked the compression and all cylinders were the same (180 psi ). I looked at the oil and the coolant and both looked normal. The radiator is less than 3 years old (it’s metal). I replaced the radiator cap, thermostat and water pump and it was still loosing coolant. When warm weather came it was no longer losing coolant. All summer long the coolant level was fine. Well, winter is here again and it is again loosing coolant. About one half a gallon every 150 miles. I did a little test and drove for about 3 days without turning the heat on (temperature lever on cold) and it did not lose any coolant over those 3 days. Also, when I do move the lever to hot the engine temperature gage runs hotter (almost straight up) than it does if the lever is on cold. When the lever is on cold the temperature gage is just barely above the cold line, maybe one eight of an inch. Another strange thing is that when I flip the lever over to hot after is has been on cold overnight I hear gurgling from under the dash like water and air flowing, sometimes for 5 to 10 seconds. I am stumped, no white smoke after it warms up a little, no coolant smell, no wet carpet.
Does any one know where the coolant might be going?

toyota4x4907

Sounds like its leaking from one of the passages to the heater core. Just because you can't see it, doesn't mean it's not there. Check around the transmission, it could be leaking on to the rear of the engine or transmission and just burning off. Or even that since you are driving, you don't see it actually leaking, because, well...you're driving....
Turn the truck on, leave it idling with the heat on and check around for leaking coolant. Make sure its at operating temperature as well.

abecedarian

being a 92, and since it happens when it is cold out...
... you may be leaking through the IAV/AAV under the throttle body. It's a coolant-heated valve whose sole purpose is to let air bypass the throttle plates when it's cold (to raise the idle speed) and not do so when hot. You might be able to check for the tell-tale signs of water by removing the duct from the throttle body and opening the throttle plate.
... on the other hand it could be a leak to, or within, the heater core and only presents itself when the temp slider is over towards the warm setting.

92-4wd

Thanks for the suggestions.
Saturday I parked the truck on a clean piece of cardboard and let it run with the heat on for about 20 minutes. I did not hear the gurgling sound when I moved the lever to hot. I never saw any leaks. I crawled around under it with a flashlight too. I took the heat shield off of the exhaust manifold so I could see the heater hose routings better, no leaks. I also pulled the carpet up on both sides. I thought the passenger side carpet felt a little damp, but after driving it Sunday and to work today with the carpet pulled back, I have not seen any leaks. I heard a lot of gurgling this morning when I moved the lever to hot.
It definitely runs at a high temperature when I move the lever to hot. If I move it back to cold going down the highway it will drop back to normal in a mile or so. It did loose coolant while driving on Sunday.


Still stumped!

hcole

I was having this same exact problem. Google " 22re thermostat problems" and you will have your answer in the first two links. It seems this is unique to the 22re engine in the 85-95 pickup and 4-runner. You can either buy a 2 stage thermostat or drill a 1/16" or 1/8" hole in the side of the flange around the area of the jiggle valve. This will allow enough coolant around the thermostat when its closed to work properly. This is a design flaw in the cooling system of a 22re. On a cold engine, pressure builds up top of the thermostat because you have the heater valve open in cold weather and it blows out the radiator cap a couple times and then you have a loss of coolant and eventually heating problems. Let us know vhow it turns out.

iamsuperbleeder

fancy font



haha, yeah, like others said, sounds like a slow leak in the heater system with the details you give...

drew303

blows out the radiator cap? Not sure what you mean, when coolant needs to escape the system, caps are designed to allow it to escape... into the overflow jug. And when the system cools it causes a vaccum, sucking coolant back in.

And your right about the T-state, the whole is neccesasry and a lot of t-stats come without the nipple. So drilling ONE hole is ideal. 1/16" works just fine! To many holes or to big a hole and the engine won't heat up (not good).



The gurgling you hear isn't normal. I've heard it before in a few trucks, but never had one that leaked. It's pretty simple. Air is in the heater core. When you turn that slider to HEAT, you're opening up the coolant line into the cab.

I'd check under the intake tho, and I'd look at the connection where the heatercore return line passes behind the motor then down onto a steel line. I've had both our rigs crack at that connection.

in your case it might be a small crack, evaporating before making its joureny down the pipe and to the ground.

drew303

i just stole this pic so you can see the line better



that metal line going along the right side of the block is the return line from the heater core. The rubber hose goes up and over/kinda behind the motor and into the firewall.

I had a leak here for a long time, the coolant would drip down and onto the block and evaporate.

The Heater IN line travels from the pass side of the head, down under the intake, around the back of the head (steel pipe) then out the driver side where it hooks into the rubber line that feeds the valve (that you control with your hot/cold slide lever)

Theres a 3rd line that ive had crack, that travels out the pass side of the front cover (behind the water pump) then back then a rubber line then it connects into the bottom of the intake.

drew303

Another nice spot coolant likes to leak is actually the plate on the back of the head. I had a coolant leak here for years (slow) and you can see it usually ie it wont evaporate fast enough not to notice it. You'll see water droplets form on the crossover pipe below it. and bottom of the bellhousing where it finally collects and falls to the ground.

Pretty hard to fix without pulling the head.

hcole

Drew 303, When I said coolant comes out of the cap that is what I meant. The coolant overwhelms the small 1/4" line going to the overflow bottle and spills out over the whole engine. The upper hose swells up and gets hard just before it blows and then the thermostat opens and then all is well. After this event occurs about 3 times you are low on coolant and then you have overheating problems. I also agree that the hole you drill should be no more than 1/8" big. I have stood over the engine and watched this happen.

92-4wd

Thanks for all of the replies.
While I was trying to diagnosis the coolant leak problem the timing chain started slapping, making a lot of noise. I ended up tearing the front of the engine off in order to fix the timing chain. I was able to borrow another vehicle to drive while I was doing the job so I was in no hurry. I decided to bite the bullet and pull the head while I was in there, so I spent about 2 weeks tearing it down and putting it back together. I inspected the throttle body and saw no signs of coolant leakage. When I pulled the head off the only evidence of head gasket leakage I saw was that the rear piston and valves were extremely clean and the other 3 pistons were black with carbon. The head gasket looked fine as well. I took the head and had it cleaned and pressure tested and, $55 later, they told me it was fine. I put on a new head gasket, cam gear, crank gear, timing chain, timing chain guides, tensioner, valve seals, injector o-rings, head blots and all new gaskets. I even pulled the oil pan and got out all of the pieces of the timing chain guides. I put it all back together on 1/31/09. I managed to get it running on 2/01/09 after pulling the distributor out and moving it a tooth two different times. The second time it ran like a charm. I adjusted the timing a little and it was running fine. I have driven it almost 300 miles and no coolant loss so far. The temperature gage seems to be fine as well. All I can say is that it was either the head gasket or one of the many other gaskets that I replaced in the process but I never saw any signs of leakage.
Does anyone know if I should re-torque the head after a certain number of miles???

Oh yeah, I only had two small bolts left over…….I have no idea where they go.

Thanks again!

leftcoastbill

I hope the two small bolts don't go in the holes where the coolant comes out.....

trackhead

hcole,

I think you may have just answered my question I've been researching for the past 36 hours.

My problem: 22RE blows coolant out all over driver side, under reservoir. After 40 or so miles, reservoir is empty, rad is slightly low.

-No exhaust smoke
-Plugs look normal (tan)
-No murky oil, no funk on oil cap, coolant looks normal
-Engine runs strong, no misfire or stumbles
-Pressure tested at 14psi, held pressure for an hour, no leaks visible
-Oil level steady, does not fluctuate
-Engine temp gauge mid level, not overheating
-No bubbling in rad at idle

WHAHAHAJR

trackhead: You need to have your radiator checked to see if there is signs of exhaust gas in it. This was the same thing my 92 did. It was blowing exhaust gas into the radiator pushing the coolant out. I never had oil in my coolant or water in my oil. My test results were the same as yours except it eventually started bubbling in the radiator a few days before the head gasket blew.

It would loose about half a gallon of coolant every month for a year before it blew. I still check my coolant regularly since my rebuild and happy to say it has not been losing anything.

trackhead

Thanks. Hoping to do that this weekend.

Did your temp gauge read normal?

WHAHAHAJR

Yes I would just notice the overflow bottle empty

trackhead

Bummer. God forbid it would be something simple.

trackhead

I'm a 22RE newb, but now I'm noticing weeping fluid from the top of the timing chain cover area.........could this be the HG?

trackhead

I rented a Block Tester from Autozone today and did not have any positive results indicating exhaust gasses in the coolant. (Fluid stayed blue, no yellow discoloration)

WTF?

trackhead

Fixed my problem: Just bought this truck a few days ago, so the previous owner had some things backwards.

The cap on the reservoir tank was essentially reversed, so the air flow going in to it was backwards. I flipped the cap around, reattached the tubing, and it's fine. Prior to that, when heat/fluid/pressure increased in the radiator, the heat would pass to the reservoir and out the vent tube, sucking all the fluid out just like a syphon.

Funny fix. Glad it was so simple.