Prepping for a long trip with high coolant temps.

[gamefreakgc]

That makes sense. Thanks for this -- super insightful I didn't even consider that impact of air near the sensor. Are there any risks when moving heat into the radiator like that? I'm assuming you're suggesting that because that's less of an issue with an aluminum radiator. But are there any other potential risks?

No risks, you want the heat moving into the radiator as then the air moving through the front of the vehicle can cool it off. A hot radiator doesn't harm your engine, a hot cylinder head does. As much energy in the form of heat you can get either out the exhaust or into the passing air via the radiator, the better.

 

[DenverAirport]

So today I noticed that my alternator was whining -- it likely may have been doing so for the last few weeks but in all honesty I didn't really notice it. Is it possible that a failing alternator has somehow led to this increase in coolant temp?

 

[Bad Luck]

I really doubt it if you aren't experiencing any other electrical problems

 

[gamefreakgc]

So today I noticed that my alternator was whining -- it likely may have been doing so for the last few weeks but in all honesty I didn't really notice it. Is it possible that a failing alternator has somehow led to this increase in coolant temp?

No, alternator would only affect that ability to charge the battery. Even if the alternator pulley belt failed it would only affect the alternator and nothing else.

P.S. check your battery.

 

[DenverAirport]

No, alternator would only affect that ability to charge the battery. Even if the alternator pulley belt failed it would only affect the alternator and nothing else.

P.S. check your battery.

My voltage is fluctuating a bit, but not enough for it to be a major concern. Not having any obvious trouble starting or anything -- could be a bearing wearing out. Picked up a Desno one and I plan on putting it in on Saturday.

Back to the temp problem: I brought my car to the dealership to get their opinion and they pointed out to me that you can see the tabs on the passenger side noting that the headgasket was done correctly (the sides are market on the back of the heads, if the job is done incorrectly you don't see the marks.) So I'm somewhat relieved by that.

They also said that I'm totally safe under 220 and that 210 is more than normal for this vehicle. That said, they also pointed out that the timing belt area was generating some noise and that the idler may need to be replaced (they quoted me $775 so I thanked them and left lol) -- wondering if this could be caused by a water pump issue? I had my timing belt and water pump replaced with the engine work so that would surprise me...

 

[Romeo1]

You need to verify your coolant sensor reading first. The parts cannon gets kinda spendy quick, so diagnose properly.

You also need to verify that the pump is actually pumping. I know, it sounds dumb, but it can happen.

 

[DenverAirport]

You need to verify your coolant sensor reading first. The parts cannon gets kinda spendy quick, so diagnose properly.

You also need to verify that the pump is actually pumping. I know, it sounds dumb, but it can happen.

Understood. Is there any way to verify the pump is pumping without taking off the cover / timing belt? Also curious about diagnosing coolant sensor -- I'm assuming I can pull it out and test it in water but are there any better ways of doing so?

 

[alumarine]

I know it's a new thermostat but why not try and test it or put in a new 180.

As a rule bad water pumps either leak or seize.
They don't normally start working poorly.

 

[Bad Luck]

Like alumarine said, when a water pump fails it either seizes (which will probably break your timing belt) or leaks (which should be visible coming from the front of the engine at the bottom of the timing cover. Is the thermostat OEM? I used an aftermarket thermostat for a couple weeks and saw temps around 210 before swapping to an OEM thermostat.

 

[phattyduck]

You say OEM thermostat, but where did you purchase it? It might be a knock-off.

Most of the times I have had consistently high coolant temps is when I have had leaky radiator caps. Make sure it is in good shape and the correct model for your radiator (and OEM if one fits the Champion).

-Charlie

 

[19963.4lsr5]

I’d replace the rad and the fan clutch and see what that gets you if there original yet.


Sent from my iPhone using Tapatalk

 

[gamefreakgc]

Understood. Is there any way to verify the pump is pumping without taking off the cover / timing belt? Also curious about diagnosing coolant sensor -- I'm assuming I can pull it out and test it in water but are there any better ways of doing so?

Yes. When the engine is completely cold, remove the radiator cap. Start up the engine (might be a little bit of a mess if it's filled high). Rev the engine for a little bit, periodically checking the top of the coolant. If the water pump is working, as the thermostat opens you'll start to see coolant flow slowly across the top of radiator from left to right. If the water pump and/or thermostat is not working, it will just look stagnant with no flow.

 

[19963.4lsr5]

As the water heats up and expands it will push out the top if the level is touching the bottom of the cap. Which it should be if your cap is good and your overflow tank and hose are in good shape.


Sent from my iPhone using Tapatalk

 

[Romeo1]

Understood. Is there any way to verify the pump is pumping without taking off the cover / timing belt? Also curious about diagnosing coolant sensor -- I'm assuming I can pull it out and test it in water but are there any better ways of doing so?

After the thermostat has opened you can visually see flow in the radiator. Impellers and shafts can break. That sort of situation is more common in semi‘s, but I have had it happen on a Chevy 350 before.

As far as getting your sensor baseline it’s fairly straightforward, you’ll obviously want to test the coolant temperature at a cold state using whatever you choose for a thermometer or a temperature probe you can use with a DVOM. Even a cooking thermometer can work. Compare yours pro breeding with your scan tool reading. You can even use the ambient air temperature as a baseline if the vehicles been sitting for a while and not in the direct sunlight.

Temperature can be done a couple of different ways. You can get geeky and actually measure the resistance at a specified temperature with a sensor directly. The simplest way it’s going to be to depressurize the cooling system with it hot and then use your probe to verify. The flip Radiator cap so nice for this, you can obviously unscrew the radiator with a rag/towel and a good amount of caution. The cooler is obviously going to be hot, and depending on your coolant mixture and what you have going on depressurizing the radiator can/will change the boiling point.

Lots of ways to skin the cat, just depends on how you want to do it.

Don’t assume anything and do a good job of diagnostics.

Since you’ve had a recent head gasket and cylinder repair, that does bring a few things into the equation. Make sure there is no excessive pressure in the radiator, or any kind of gas coming to the cooling system out of the top of the radiator once it’s full. If you’re getting a white smoke, that is coolant being burned.

You also mentioned that your gauge doesn’t move. Sensor measures resistance and reports to ECM, that information gets pushed to the display.

The thing is is without verifying the data and the flow m. We just don’t know what’s going on, the shop could have had a rag stuffed in there somewhere for all you know. That said, I wouldn’t put 215 in the danger zone. Elevated, but not danger zone assuming you have a radiator and cooling system that can hold pressure and good coolant in it.

 

[Romeo1]

Yep. Recently replaced it with a new OEM and it's in the 6 o'clock position. From what I've read the jiggle valve is actually supposed to be in the 6 not 12 (many complain that 12, common procedure in other vehicles, leads to higher engine temps in this truck and some other Toyotas)

All that jiggle valve does is help to release the air initially. Once the system is purged it really doesn’t do a whole lot. We used to drill tiny holes into the thermostats to help bleed the system is easier back in the day.

It has no function other than to assist in burping air out quicker. I’m not a 5vz expert by any means, but I would really have to question that one hard. Once that thermostat opens and assuming the pump is working, air cannot exist at that point in the system as it is one of the lowest points in the system.

 

[DenverAirport]

I purchased via Partsouq. Was stamped -- everything I've gotten from them has been in stamped OE boxes and seemingly good parts, the exact size of the OE parts I'm pulling out of the vehicle for some pieces. Might be worth pulling it out and testing it though.

 

[DenverAirport]

After the thermostat has opened you can visually see flow in the radiator. Impellers and shafts can break. That sort of situation is more common in semi‘s, but I have had it happen on a Chevy 350 before.

As far as getting your sensor baseline it’s fairly straightforward, you’ll obviously want to test the coolant temperature at a cold state using whatever you choose for a thermometer or a temperature probe you can use with a DVOM. Even a cooking thermometer can work. Compare yours pro breeding with your scan tool reading. You can even use the ambient air temperature as a baseline if the vehicles been sitting for a while and not in the direct sunlight.

Temperature can be done a couple of different ways. You can get geeky and actually measure the resistance at a specified temperature with a sensor directly. The simplest way it’s going to be to depressurize the cooling system with it hot and then use your probe to verify. The flip Radiator cap so nice for this, you can obviously unscrew the radiator with a rag/towel and a good amount of caution. The cooler is obviously going to be hot, and depending on your coolant mixture and what you have going on depressurizing the radiator can/will change the boiling point.

Lots of ways to skin the cat, just depends on how you want to do it.

Don’t assume anything and do a good job of diagnostics.

Since you’ve had a recent head gasket and cylinder repair, that does bring a few things into the equation. Make sure there is no excessive pressure in the radiator, or any kind of gas coming to the cooling system out of the top of the radiator once it’s full. If you’re getting a white smoke, that is coolant being burned.

You also mentioned that your gauge doesn’t move. Sensor measures resistance and reports to ECM, that information gets pushed to the display.

The thing is is without verifying the data and the flow m. We just don’t know what’s going on, the shop could have had a rag stuffed in there somewhere for all you know. That said, I wouldn’t put 215 in the danger zone. Elevated, but not danger zone assuming you have a radiator and cooling system that can hold pressure and good coolant in it.

Thanks for the insight with all of this. I'm going to test temp across the board tomorrow and see where I'm at. I'm definitely not getting white smoke or smelling coolant.

 

[alumarine]

I've had bad OE thermostats a couple of times.
Not Toyota but Toyota doesn't make thermostats anyways.

 

[Bad Luck]

All that jiggle valve does is help to release the air initially. Once the system is purged it really doesn’t do a whole lot. We used to drill tiny holes into the thermostats to help bleed the system is easier back in the day.

It has no function other than to assist in burping air out quicker. I’m not a 5vz expert by any means, but I would really have to question that one hard. Once that thermostat opens and assuming the pump is working, air cannot exist at that point in the system as it is one of the lowest points in the system.

You're not the first to question the jiggle valve affecting operating temps, but multiple people (including myself) have seen coolant temps drop with the same thermostat just by putting the jiggle valve at 6 instead of 12. I dropped 10 degrees according to my UltraGauge. I don't know why it makes a difference but it does.

EDIT: Also, the jiggle valve allows for a small amount of coolant to flow through the thermostat so that coolant can still flow through the engine and allows the hot coolant to reach the thermostat and open the thermostat. Without the slow coolant flow from the jiggle valve opening you would be depending on heat transfer to warm up the coolant by the thermostat enough for the thermostat to open which would likely mean that the coolant in some spots of the engine would be way too hot by the time that happened.

 

[HiLife]

It's even listed in the FSM. Install with jiggle valve downward (6 o'clock).

Yes I know it doesn't make sense on the 5vz. Would be good for engineer in fluid dynamics explain this one.
Lots of members see solid before and after results of moving the valve downward.