azgold

1995 Toyota 4runner 3VZE 286,000 miles

A quick preface ......
Had the head gaskets done about 2 years ago, and I have always suspected that they did not install a thermostat. ( Master Engine , Phoenix ) .

Today I decided to find out for sure. Nope ! No thermostat.......
I installed a new Toyota OEM Thermostat and gasket following the FSM.
Drove 5 miles and the thing was overheating and spewing fluid out of the radiator cap. Worst I`ve ever seen the poor truck.
Removed the thermostat to test it per the FSM . Checks out fine. Opens at 180 degrees , and open 8+ MM at 203 degrees.
Since I have to go to work and stuff . Im leaving the T-stat out for now.

Any thoughts ? I`d really appreciate any input.

millball

A little difficult to get a 3vz full of coolant. Easier when thermo is not installed.

Put thermo back in. Remove top rad hose from rad, loosen on engine side and rotate the hose up vertical. Fill slowly til coolant overflows from radiator top barb. Then she's very near full.

RAD4Runner

How good is your fan clutch? https://www.yotatech.com/forums/f199...l#post52229129
How good and clean is your radiator?
Flushed the system? I did the Prestone "heavy-duty flush" as described on the Prestone Flush container... drain rad, rinse well, fill with water and flushing solution, drive for many miles a few days, drain, rinse, re-fill with coolant.
Got shroud? It focuses airflow through the radiator.

azgold

I can certainly try that. After all these years , I never knew or heard about a sequence for re filling coolant. This must pretty critical considering the serious overheating that occurred.
If the thermostat is closed , then how does the coolant get by the t-stat while filling from either direction ?

azgold

Keep in mind , nothing was wrong before I installed the t-stat. (except any symptoms caused by not having a T-stat for a long time.)
Radiator is near new at 2 years old. its very nice btw, from Performance Radiator in Tucson.
Fan shroud is present and near new.
Fan clutch , fan, are all in top working order
Did not do any type of flush. My system appears to be very clean. Also , I only use OEM red Coolant from Toyota.

azgold

Ok guys , I have two more questions on this topic.

1.) Is it possible that the shop I had the head gaskets done two years ago did not install them correctly, and they deliberately left the thermostat out , because they knew it was over heating?

2.) Is it possible that the head gaskets have been installed incorrectly for the past 2 years , and I have not had any issues , being that the t-stat has been gone the entire time as well?

RAD4Runner

Both of the above.
BTW, gage is really reading overheat and not just overflowing, right?
Rad cap tested good?

azgold

Yes, the gauge was maxed out , and you could hear all the boiling , while the cap was releasing coolant & steam.

Well , It sounds like the gaskets were done incorrectly, or, unless I had to much air in the the engine when I drove it after the coolant re fill. I didnt run the heater either , after the refill. Wonder if I should have .

L5wolvesf

Is it possible - yes, Is it probable - I'm not sure. Before going with that guess is there other evidence?

We don't know if the system was sufficiently burped and if you want further evidence test it - I would start with a compression test after a through burping.

azgold

Ok, I will re install the t-stat this weekend, and purge the system of air. I pray that was the problem.

Compression test will likely be the following weekend unless I can get my hands on a test kit for that beforehand.

ksti

Why not do a compression test before you put back the t-stat?
If your near a Autozone they loan out that compression tester.
Or Harbor Freight sells them for about $25.00, good tool to have on hand.

azgold

[QUOTE=ksti;52375238]Why not do a compression test before you put back the t-stat?

Actually, I have to drain the coolant to install a oil cooler hose anyway, so I may just as well put the T-stat back in . Im dying to figure this out .
Thanks for the info on the compression tester.

azgold

Well,
Borrowed a compression tester from Orileys . After much effort I finally got the tester threaded into # 5 . 149 ,148, 147 was the PSI on that one. Then I proceeded to # 3 ..After alot of trial , and all error, I just couldnt get that thing threaded into the #3 cylinder. I dont have all day to mess with this BS. The tester needs to have a straight piece ( not hose ) to do the threading. I gave up. That was a serious PITA . The #5 cylinder was at minimum spec though, so that was not good news.

I installed the thermostat again, and filled the coolant properly, also with the heat lever on and fan off. Ran the engine at 2200 RPM for 7 minutes and it finally began overheating again. I am confident that there was no air in the system.

Back to square one. Its my only truck so the thermostat will have to come back out, so I can drive it.

sphealy

iTrader: (1)

Make sure you turn the heat on and leave the radiator cap off. Start the truck and wait until yiu aee the coolant flowing for several minutes to get the air out. Once it starts to boil out cap it.