Dumb Thermostat replacement question

[MTBGUY]

Hello to all- I tried to do a search on this and couldn't find out if anyone has had this happen to them.

Today I flushed my coolant and replaced the thermostat with a factory new one from Cdan, used distilled water and Toyota Red coolant.

After topping it off and driving around for 20-25 minutes with both heaters on, the temperature gauge barely moved at all-pretty much not at all. It crept up just a tiny bit a few minutes after shut down. Temp outside was around freezing, but it usually comes alive and starts working after a mile or two. Gauge worked fine earlier today.

Would air pockets cause this behavior? Or could I have put it in backwards accidentally? I took a phone call and was distracted when replacing the thermostat and wonder if it would even allow me to put it in reversed.

Anyone have any experience with this. I'm hoping its just a bubble and needs to burp.

 

[RavenTai]

if you put the juggle valve in the right spot per the FSM (straight up, 12:00) then it is not a bubble,

was the heat hot? or just warm? that is somewhat an indicator of water temp.

try it without the heat on,

 

[AJP]

I doubt if it would fit backwards and allow the water inlet to go back on the housing....you can see that when you hold your old t'stat up against the housing....springy side towards the block.... but as RavenTai says... the jiggle valve is to sit at the 12:00 position ("within 15 deg. of either side of the prescribed position" IAW the manual) ... what was the temp stamped on the thermostat? mine says 82C for a 97 LX450..fwiw
... and you also refilled the radiator reservoir to the line? Usually they will suck up some more coolant as the system clears itself of air and the reservoir will stabilize at a level that reaches the line when engine is at operating temp

 

[cruiserdan]

How much liquid did you put back in after the flush?

 

[AJP]

and I guess it is important to say that you don't want to be putting cold coolant into a hot block if you find that there is insufficient coolant... some concerns have been identified that this could result in a thermal shock that can damage the block etc...

 

[MTBGUY]

if you put the juggle valve in the right spot per the FSM (straight up, 12:00) then it is not a bubble,

was the heat hot? or just warm? that is somewhat an indicator of water temp.

try it without the heat on,

Yes, I put the jiggle valve at the top 12 o'clock position. Outside air temperature was 30 degrees F, and the heat in the cabin was just warm (not really hot). I will see how much it sucks down the overflow reservoir overnight- I may have just not let it get warm enough.

Don't really remember the exact amount of water and antifreeze it took, but tested with the antifreeze tester (ball type) to a 50/50 mix. The marking on it said 82C, and it had the green paint mark on the end of it. I also think it would not even fit if reversed.

Engine seemed around normal temp- by putting hand near the top of it, didn't seem to be running hot. I think I just may have filled it hastily and not let all of the air out the way I have done with cars in the past.

I'll keep you posted if your ideas work. THANKS!

 

[MTBGUY]

FWIW, I drove it today with the heat off. The needle moved a bit, just took awhile.

The previous owner had replaced the T-stat at one time, and the jiggle valve had been at about the 3 o'clock position- now with the new one its at the 12 o'clock position.

Its always seemed to run rich to me, does anyone think this will help it run better now (with the valve at the proper position)?. I don't really fully understand the purpose of the jiggle valve and how it affects temperature- I always assumed it was kind of a fail-safe of limited relief.

Thanks for the good posts.........

 

[boydmick]

The jiggle valve is there to allow air to pass through the thermostat regardless of open/closed position, helping to purge the system.

Once the air is completely removed from the system, the jiggle valve has very little (if any) effect on the cooling system.

 

[IdahoDoug]

Did you have the rear heater on - get heat there? When you flushed was the dash temp at full hot?

DougM

 

[RavenTai]

FWIW, I drove it today with the heat off. The needle moved a bit, just took awhile.

Hmm something aint right, assuming the system is full, after this many drives if the radiator is full then the system should be full. then either the temperature is low as the gauge is saying or the temp gauge in inaccurate. easiest way to tell if the cluster gauge is reading properly is to hook up a laptop with OBDII software and see what the computers temp sensor (separate from the gauge sensor) is reading. do you or someone you know have access to such a setup?

If that one is also reading low I would say you have either a bad thermostat or somehow the water is getting past the thermostat. maybe something got bent on install?

Its always seemed to run rich to me,
Thanks for the good posts.........

the computer will run the engine rich until the water temp comes up to normal operating temperature.

 

[MTBGUY]

Did you have the rear heater on - get heat there? When you flushed was the dash temp at full hot?

DougM

The way I did the job was to take to local shop and they flushed it (per my instructions) with the rear heat on (they claimed they did it, and I turned all of the switches to that position before leaving Cruiser with them to ensure it). They then refilled it with the distilled water I brought them. All switches were still that way when I picked it up.

Later on, I took it home, drained some of the nice clean water, and did the thermostat change, then refilled with Toyota red. After sitting overnight it did draw down some fluid from the overflow reservoir.

After the second drive today, everything seems to be working (fairly) normal again. The only weird thing is that the needle on temp gauge before would usually be in the middle of the of the gauge, now it only moves up about 30% of the way instead of 50%. (The 50% was with a fairly weak mix- not much antifreeze- so could explain the warmer temp reading before).

It has been pretty cold here lately though (for North Georgia). I haven't driven yet on the highway to get it really warm.

I was pretty careful and don't think I bent any flanges on it when installing it, but did not test it first in boiling water on the kitchen stove to ensure operation at temperature. There is no visible evidence or history of any problems with the headgasket.

I have not yet done the RavenTai mod, but now want to!

 

[RavenTai]

It has been cold here the past two days, on a stock gauge it should hit the middle at about 160-165F, if you are below that then that is pretty cold operating temp, IIRC the computer will not go into closed loop until 170F, my 96 still gets up to temp in a few miles in this weather, with the heat running it does run a tad cooler but not that low.

 

[MTBGUY]

Thanks Raven- now I kind of know what to be looking for since you're in the same area/temperatures.

I may pull it in a day or two and redo it if it doesnt purge any more air and start working better. It seems weird that it was registering higher temps. before I put a brand new one in. I've never had a problem with Toyota parts before, so I'm wondering if there was a big air pocket possibly back near the rear heater or the mechanics that serviced it were morons.

I never have problems like this when I do everything myself! Lesson learned.

 

[AJP]

Curious... did the guage read normally AFTER the flush and BEFORE you changed the thermostat?.. Could the flush have dislodged some rust or scale that is blocking flow...

 

[MTBGUY]

Yes, it did. After the flush (when it had distilled water only) it ran normally in the middle of the range. (I drove it with distilled only for several drives).

After the replacement, it runs cooler on the gauge with the new T-stat.

 

[IdahoDoug]

The mechanics being in the middle of this makes me a bit nervous, but I'd just drive it for a few days being sure the system is kept full as it burps out air pockets.

DougM

 

[IdahoDoug]

PS - Dunno which hoses they used to flush, but be sure the heater hoses were not somehow reversed at the firewall. Seems like a true moron could manage that. Not sure what effect it would have though...

DougM

 

[MTBGUY]

I took the thermostat back out today and think I figured out why it was running cool. Somehow the New gasket got seperated from the new thermostat, and coolant was getting past it. (Luckily it didn't get away.

I need to buy an FSM for future repairs. The gasket is supposed to be wrapped around the flange of the Thermostat (metal in the groove of the rubber) is that correct?

Thanks for all of your inputs!

 

[RavenTai]

I took the thermostat back out today and think I figured out why it was running cool. Somehow the New gasket got seperated from the new thermostat, and coolant was getting past it. (Luckily it didn't get away.

I need to buy an FSM for future repairs. The gasket is supposed to be wrapped around the flange of the Thermostat (metal in the groove of the rubber) is that correct?

Thanks for all of your inputs!

correct the T-stat should sit in a groove in the middle inside of the gasket so that one gasket can seal both sides of the T-stat flange, I was going to ask about that as that is a common mistake but usually the T-stat housing leaks when the gasket is only put on one side of the T-stat. did you also use RTV or something?

 

[MTBGUY]

correct the T-stat should sit in a groove in the middle inside of the gasket so that one gasket can seal both sides of the T-stat flange, I was going to ask about that as that is a common mistake but usually the T-stat housing leaks when the gasket is only put on one side of the T-stat. did you also use RTV or something?

Thanks Raven- I put it (the gasket) on the inside the first time (based on how it came out), thinking that my old one was untouched, but evidentally previous owner had someone replace the first one and put the gasket in wrong. I'm surprised it didn't leak. The vehicle has always run cool/rich- this is probably why - it never fully got up to temp.

When I looked it over carefully it seemed to be designed to wrap around the flange as you described. I assume RTV/silicone is not needed- I didn't use it.

All should be well now!