LUV24BY

I have to say, this is my first true complaint about a 1st Gen Toyota product!
Not the standard under powered or too small type complaint - however this is a true VALID compaint and I want to voice it and hopefully educate others about this. If it is already a know gripe, well add mine to the stack!

Ok, for the past 2-3 days I have been finding my 1985 4 Runner 22RE that I have has been loosing coolant. There's been No sweet smell, no noticable leaks, no water in the oil and not one puff of smoke when started or when driving. I would at times find I was up to a 1/2 gallon down in the radiator only after 24 hours of having checked it and making sure it was full (or topping off!) Every once and a while I would hear a slight bubbling when at a light stopped, nothing that lasted over a couple minutes. My Temp gauge (SR5 cluster) would run at normal operating temp. I checked all belts, hoses and nothing was obvious! It was really worrying me!

I tracked the problem down to a stuck 'closed' thermostat. What apparently was happening was I would fill the radiator, drive it and while driving the coolant would not circulate and begin getting really hot. It would begin bubbling back into the overflow and out the drain tube. It would not be obvious because it didn't cover the undercarriage. The TEMP when driving (MY FIRST COMPLAINT ABOUT TOYOTA's! ) wouldn't show hot because the sensor is sitting right over the thermostat!! With it stuck closed the coolant above it showed normal temp range, however it didn't indicate trouble of running hot! I would have never known it was an issue if I hadn't done a check of fluids this weekend (and on a regular basis!) I can't believe there isn't a secondary (or better) location within the block or head that sensor would be placed!

Why did Toyota put it directly above the thermostat? I could have had a catastrophic failure! I just want to WARN you to make sure to check your fluids and your thermostat! It only had been 18 months since I changed mine! I love my Yota and she is my baby (ugly or not!) and I just can't believe what could have happened!

Please take heed to this experience and know the gauge will not always tell the entire story! I think it's time to go out and get a Autometer and place a secondary sensor somewhere downflow of the thermostat!

John

navyredneck

When I started mine for the first time I checked to make sure that upper radiator hose got hot (indicating valve is open and circulating coolant).

The warranty on my engine said to specifically make sure that thermostat opened correctly and allowed flow.

LUV24BY

Yeah the hose was hot, however I think it was due to the ambiant engine compartment temp and not due to the coolant circulation. I would check it after taking it for a short drive and then checking the hoses and overflow! I have yet to actually pull the thermostat housing, however all deductive reasoning has led me to this conclusion. I got home too late last night to pull it and had to get into the office this morning. I plan on doing it at lunch. I hope there's not residual damage to the engine!

John

4Crawler

iTrader: (3)

The temp sender for the gauge is on the side of the head, not on top of the t-stat housing. That one is for a hot start feature that the ECU uses.

LUV24BY

Thanks Roger! I didn't know that! I will check the FSM PDF I have and verify that! I thought it was that sensor directly over the T-Stat housing, well - see now I can't complain about a Toyota! LOL

John

Buck01

DOn't thay also have a fail safe T stat available now adays?????????

LUV24BY

Whelp, at lunch I went out, pulled the T-stat and went to BAP Import Parts and picked up myself a new T-stat and radiator cap + 1 gallon of Coolant.

The problem, whether the thermostat or radiator cap, has been resolved. There is definately more pressure with the new Tstat in. There was some pressure with the old one, though as Buck01 pointed out I think that this was only because the bypass was the only thing that was allowing flow through.

4Crawler - I checked the FSM and the coolant section has no mention of the temp sensor location. Where on the head is it located?

Anywhere, especially here in AZ where it is already 93 daily it is critical to have good working parts. I just replaced the Radiator, Tstat and cap about 18 months ago so I was suprised that one or two of those three went bad already!

Thanks for the help and support!

4Crawler

iTrader: (3)

That is because it is not in that section of the FSM, check the Body Electrical section where they talk about gauges and senders. It is in the intake, I think between #2 and #3 intake runners or thereabouts.

I have very good luck with the Toyota dual-valve t-stats, I have about 9 years on the one in the truck now and it still works just like the day it was installed:
- http://www.4crawler.com/4x4/CheapTri...tml#Thermostat

rdlsz24

Yes the sensor location is on the intake manifold under all the vacuum wires. It's kinda hard to get at without everything being apart.

Rob

LUV24BY

Thanks for the location of the temp sensor. I just didn't have a lot of time @ work to go through the whole 1024 pg PDF. I ran a search and it didn't return any results. Anywho, just a quick quesiton for you Roger - I read your link you posted and you mentioned in there you did run your Runner at some point without the T-Stat. Considering the gasket for these things goes around the exterior of the T-Stat and without it in place did you just place the gasket in without the T-Stat? I considered running mine w/o the T-Stat in however without it I was worried that with the housing tightened down it would 'squeeze' the gasket out of it's channel (without the Stat keeping it from collapsing upon itself) and it get stuck somewhere within the system or engine.

Just curious!

Thanks!
John

4Crawler

iTrader: (3)

Never ran mine w/o a t-stat, there is one for a reason. Engine will run very poorly without it in most cases.

LUV24BY

I must have misread the sentence "On the subject of the overheating thread, an engine can run hotter with no t-stat." as you had actually done it!

I just misunderstood - Sorry!

John

rrmike

Betcha a dollar that your HG is gone. It's cylinder pressure that's pushing water into and out the overflow. It is not hot and that's why the gauge doesn't show it as being so.

Mine was the same way. It wouldn't get hot until it got too low on water. No steam from exhaust, no water in oil or vice-versa.

Quick check. Take the cap off and see if bubbles come up in the rad when it's running. Have someone rev it up some to be sure if you don't see any at first. Mine you could see the bubbles coming up steadily.

rdlsz24

You know what, when I first started reading his first post I was thinking the same thing. When my headgasket was blown, I didn't have any mixing, etc, but was loosing coolant and my heat didn't work very well.

Rob

LUV24BY

HG!?!!?? I think I need to go change my underwear!!

I changed out the Thermostat yesterday and the pressure was dramatically better in the upper rad hose. I topped off the coolant and started it up, initially there were a about 10 bubbles that came up when I was keeping the throttle @ about 2500RPM (EFI I can just reach over and do it by hand without having someone doing it in the driverseat) and it all looked good. I then did the test drive and after it cooled down it checked the Rad level again and the level hadn't dropped. I can use my heater and it blows hotter than a Spring Break free for all!

I hope to God it's not the HG - it runs strong and happy - did you guys notice any performance loss or other noticable factor aside from the coolant disappearing that may have led to your HG conclusion?

Thanks!
John

Oddmar

You can also drill two 1/4" holes in the flat metal part of the thermostat, to keep water flowing over the valve/ plug a little, so it reacts to temperature spikes faster.

foot0069

Here's another answer to the tstat question. Page down till you get to the relevent section. Just put one in my new motor and it seems to work great. No temp fluctuation and the motor warms up really fast.
Jim

http://www.4crawler.com/4x4/CheapTri...tml#Thermostat

TOYZILLA

the air bubbles you seen are prob the cooling system burping "normal" after opening up the cooling route. but then again keep an eye on it for a few days then see if you see bubbles. yours sounds like it was just the thermostat. let us know.

rrmike

No. Ran fine the whole time. Eventually started steaming out of the exhaust when it'd get hot from blowing all the water out.

LUV24BY

Well, I have been keeping an eye on the Radiator level and overflow. I have been noticing there has been a steady decrease in fluid level. Perhaps a 1/2 inch or so every couple days.
I have a 22R long block I was going to sell, it's from a Carb 86 truck. I thnk I may just keep it and slowly build it and replace my engine. This way I know it's done right! I will do a Engbldr Rebuild kit, a beefier Cam, and maybe have it bored a bit over for some more ponies.

I have now accepted the fact I may have a problem with the HG and it's more than likely due to the hack that 'supposedly' rebuilt the engine 2000 miles before I bought the truck.

Hopefully the engine will hold through the summer so I can build up this other one without having my Daily Driver!

John