Thermostat deletion questions

[BONETTI]

What's the down side of running with no thermostat? I'm in Hawaii and I wouldn't mind it running a little colder than normal..?

[technocj]

I have 170 degree thermostats in both of my vans, and have not noticed any ill effects, one has 225k miles and has had the 170 in it for 10 years or more. Doesn't use any oil. I also installed a previa heater core as a supplemental radiator, similar, but not nearly as pro, as Tim's installation. Might be a bit of overkill here in Western New York, but the van has been making a 1500 mile round trip every spring to NC, I consider it some overheat insurance.

[Burntboot]

The T-stat is there to regulate water flow through the engine.
On start up, the engine requires extra fuel to start and run till its warm, having the stat closed during this time can significantly reduce fuel consumption and warm-up time.
Keeping the engine at the correct temperature allows the engine to operate at its most efficient/least polluting temperature.
Thats why there is a coolant temperature sensor, to tell the ECU what engine temp is so that the ECU can supply the required amount of fuel (based on temp)

It will run without it, but it will run better with it.
This is especially important when trying to solve issues.

If the engine runs too cool, it will run richer, which can cause a lot more problems than just spewing a few extra hydrocarbons
(I am thinking things like shortened Cat life, shortened engine life due to carbon build-up, using more fuel.......)

[technocj]

I knew of the possible negative effects of the lower coolant temp when I decided to try the lower temp thermostat. I closely monitor the operation of the engine, check the plugs, etc., monitor fuel consumption, and nothing has changed over the 15 years I have owned it, the first 5 with the 195 degree thermostat. It is an 85, and I don't haul excess load or drive it in the winter. I have an 86, and I feel that the 2.2, although obviously more gutsy, builds more heat in the engine compartment. If I change thermostats again, I would try to find a 180. I have never insisted on OEM thermostats in any of my vehicles, as I have never had an issue with aftermarket, but I don't disagree with the idea of using OEM. I installed after market fan clutches in both vans, and I don't think either one has engaged the fan, except on initial start. I would think about electric fan next time.

[bushcat]

I'm starting to do some work on my newly purchased Van back in December. I was having an issue with a very low temperature coming from the heater. I thought maybe a clogged heater core but it was also operating at the lower range of the temp gauge so I thought it could also be the thermostat stuck open. I drained the coolant and plan to do a flush. I was replacing the thermostat when I realized there was only the ring of the thermostat installed. I'm wondering why the previous owner had done this. Does it have an overheating issue? Was the thermostat broken? It passed smog with flying colors, it doesn't blow white smoke, I'm hoping he was just too lazy/cheap to install a working one after the old one broke. Whatever it may be, I'm concerned what's going to happen when I start the van up. Any thoughts or ideas? Obviously, I'm going to keep an eye on the operating temperature and make sure the engine doesn't overheat but are there any other precautions I can take. This is my first time doing a coolant flush. I plan to fill it up with distilled water and run it for a week or two then fill it up with 50/50.

[oli larsen]

I must fess up, I ran my van in australia without a thermostat for a wee while. it allows a much higher flow rate and you will see, as you describe lower operating temperatures. Just check your radiator is in ok condition (it has the zigzag fins still in it between the pipes) and there no visible leaking or deposits from it. if all is well then maybe the previous owner was a tight ass and simply didn't want to replace a stuck open thermostat. remember to get a decent replacement with the little pin in it! some of the cheap ones do away with this and it can cause problems. I wouldn't be too worried at this point. If it's not using coolant or oil, it's not bubbling out of the filler cap and it runs fine which it sounds like it does then chuck a new one in. Check the radiator cap seals are in good condition though and its holding pressure! it's a cheap part and is worth doing at the same time in my opinion!!

[Burntboot]

BC - Of what remains, does it look like someone purposely modified it or is it possible it self destructed (rare, but possible)?
It's just nice to know where the rest of the stat is and to decide if you need to go fishing.

People do the strangest things sometimes and I have actually met a few people over the years that do just that, thinking they are making improvements.
It is impressive that it passed emissions, as cold running engines tend to run rich.

I would just toss a fresh OEM stat in it with fresh coolant.
Running plain water is not a good idea, even for just a short time.
Aside from the corrosion inhibitors are the lubricants that keep the water pump happy and 50/50 mix is more efficient from a heat exchanging standpoint.
Definitely use the distilled water to dilute the new coolant, unless you buy premix.
And do take a good look at everything else in the system, while your in there and be prepared to find a few surprises and maybe a head-shaker or two.

One more thing to ask yourself.
If the PO did that to the stat, what else did they "fix"?

The other thing about wannabe engineers, their repairs tend to be layered, as each "improvement" often has unintended consequences, presenting yet another irresistible challenge for their superior intellect.

BB

[bushcat]

Well, I flushed out the distilled water. Backflushed the heater core. Installed a new OEM thermostat with the jiggle valve at 11 o clock. The heater is warmer, still not hot compared to other cars I've owned but warmer. The car does run about half way now and can creep up to 3/4. I'm wondering if anyone has changed the fan clutch as a preventative. Should I do a coolant test before replacing the fan clutch to make sure no head gasket is blown?

[oli larsen]

Well, I flushed out the distilled water. Backflushed the heater core. Installed a new OEM thermostat with the jiggle valve at 11 o clock. The heater is warmer, still not hot compared to other cars I've owned but warmer. The car does run about half way now and can creep up to 3/4. I'm wondering if anyone has changed the fan clutch as a preventative. Should I do a coolant test before replacing the fan clutch to make sure no head gasket is blown?

Its very simple to determine if the viscous coupling is working. Leave the van for a few hours or overnight. Start it up, let it run for a bit then bring the refs up to say 1500-200 rpm. You should here the fan roar. It’s very obvious. It should then cut out after a few minutes and free wheel. I’d its not doing this change it. You should also notice it roaring when it gets hot. Anything much over halfway should bring it on. Mine kicks in after a Hill way before I see the gauge move. They are very good st cooling things didn’t if they are working correctly. If it free wheels when it’s been sat then it’s swginitely had it. Should feel like the fan is in treacle when you try to turn it without the engine running after its sat. If it works then consider getting your coolant checked for hydrocarbons.

[Ace MM]

No reason to modify a thermostat on a normal working system.
I have a rear heater and once I fixed a leak\clog the whole system works better.

[bushcat]

No reason to modify a thermostat on a normal working system.
I have a rear heater and once I fixed a leak\clog the whole system works better.

Where was the leak/clog? Do you have a pic? I didn't check the rear heater system. It's running too hot for my liking with the new thermostat.

[Burntboot]

BC - Because the system is so complex, the issues can be many, there are lots of things to check before jumping to conclusions.
Just work thru the system and correct things as you go.

In no particular order:
Did you bleed the system?
Is the clutch fan working correctly?
Do you have the lower fan shroud shield in place?
What's the condition of the rad? cap? overflow hose? hose of death(s)?
Do the fr and rear heater controls work and do you get heat out of both heaters?
Do you have any leaks/are you using coolant?
Does turning on the heater help reduce engine temperature?

Answering these questions would help a lot.

BB

[bushcat]

Responses in bold. Thanks!

BC - Because the system is so complex, the issues can be many, there are lots of things to check before jumping to conclusions.
Just work thru the system and correct things as you go.

In no particular order:
Did you bleed the system?
Yes
Is the clutch fan working correctly?
Not sure, this could be the culprit. I need to investigate more, when driving, I don't hear the roar at high operating temps.
Do you have the lower fan shroud shield in place?
Yes
What's the condition of the rad? cap? overflow hose? hose of death(s)?
I'm not sure how I check the condition of the radiator. I need to look at the hose of death some more. I believe I checked it but I'm not sure I looked at the right one.
Do the fr and rear heater controls work and do you get heat out of both heaters?
Better heat now that I backflushed the heater core. Heat gets weaker as you turn it up. I'm thinking I may need to backflush the rear heater hoses too.
Do you have any leaks/are you using coolant?
Just bought the van back in December, haven't noticed coolant loss but haven't driven it that much either except fo rweekend rides. I noticed the P.O. had extra coolant in the van.
Does turning on the heater help reduce engine temperature?
No it doesn't really, I do that but it doesnt really seem to affect anything. What can that mean?

Answering these questions would help a lot.

BB

[Burntboot]

The in car heater is really just another radiator, if turning the heaters onto high doesn't effect engine temperature (when running warm) then they are either not getting sufficient coolant flow or are unable to effectively transfer heat (internal scale build-up)
Producing heat at first then not can also be an indication of poor transfer but can also be caused by flow issues.
The front heater core is mounted upside down and can be very temperamental when trying to bleed, sometimes elevating the nose can help.

The main radiator can be inspected visually, look at the fins and tubes, if the fins are brittle/missing it can't dissipate heat, if it all looks okay, get the van warm and feel the rad with your hand (note, having AC makes this impossible and feeling the backside is not advisable, especially with the engine running)
If you can't access the front of the rad, grab yourself an infrared heat gun and check the temps across the rad and top to bottom (from the backside of course) what you don't want to find is regions that are significantly different (hot or cold spots) as that would indicate a problem with flow.
Top and bottom rad hoses should both be hot, check all the hoses too. If you find some that are cold, then you can be pretty sure you have air in the system causing havoc.

If the fan doesn't make a lot of noise when the engine temperature is well above 1/2way, thats sufficient justification to replace it, now. (Denso preferred)

The fact the PO carried coolant isn't conclusive evidence on its own, lots of people carry spare fluids but it does mean you should pay close attention until you rule out all issues.

Look at all your hoses, there are many and they usually get overlooked.
Hose of death shouldn't be an issue unless it has gear clamps on the hoses, then you'll want to move that item closer to the top of the needs list.
Spring clamps can be a pita to deal with, but provide much better clamping forces over changing temperature conditions.
The biggest failure of gear clamps is they tend to cut into the hose when overtightened which leads to early failure and never in a good way.

If you got a lot of debris out of the core when you backflushed, this could be an indication that more is needed, sometimes a 24hr vinegar bath can be beneficial.

Gwen did a nice write up hoses ( search for "getting to know your vans hoses") that should help you find all the potential scary bits.

Good luck with the process, its not really as daunting as it seems, just time consuming.
Try to enjoy the journey :)

[llamavan]

Gwen did a nice write up hoses ( search for "getting to know your vans hoses") that should help you find all the potential scary bits.

LINK (http://www.toyotavantech.com/forum/content.php?230-Getting-to-know-all-the-coolant-hoses-of-your-Vanwagon!)

Gwen

[Navphoto]

Hello Tvt. I own two vans but one is giving me fits. I’ve replaced head gasket. Water pump. Hoses. Fan clutch radiator flushed and cleaned and oem thermostat. I bought this OTC flush tool to blow out sediment in block and heater core. Flushed out at least a cup full of sediment. I highly recommend this tool. To flush system I cut a cheap thermostat so there was no restriction and I’d get a good seal.
I tried to insert photos but not sure if they loaded sorry. So I ran van with gutted thermostat and she ran nice and cool but when I installed new oem stat van temp gauge runs a little north of half. I’ve taken temp readings and van coolant stays nice and cool without stat 130 with stat 190- 200.

I’m at my wits end with this van

[Navphoto]

90479048

this is temp with thermostat and without

[trestlehed]

I’ve taken temp readings and van coolant stays nice and cool without stat 130 with stat 190- 200.

One thing to consider is that Toyota engineered the van's engine to run optimally/efficiently at a predetermined temp range.
I did the electric cooling fan mod back in 2013? and during that process I believe that TimsRV postulated that 205 degrees was the optimal running temp. I can't remember for sure, so you might want to get others here to weigh in on this.

[JPERL]

An engine running too cool is bad too. An engine that does not warm up enough will produce more emissions because the fuel mixture will be too rich and in turn will get poor gas mileage and possible damage the catalytic converter as unburned fuel mixture from running to rich enters exhaust system. Also the piston and rings don't seal as well because they don't expand completely. 130 degrees is just 10 degrees above what is still considered cold.

They have a cooler 170 degree thermostat and that would be the minimum operating temp you would want . while it is aesthetically pleasing to the eye to see the temp gauge point at the bottom 1/4 its better to have the right equipment installed and have the engine run at the correct temp

[bigtone23]

Subscribing for the info that will follow. My thermostat typically shows a temperature range much like your open/missing thermostat reading.

[Navphoto]

My other van runs just south of half way on the temp gauge. This is my daughters van and I would hate to have to do head gasket again. Previous owner gave me old work orders and it was running hot after the last head gasket job. I thought I figured it out when I was able to flush all the sediment out of block but it’s reading the same temps.

Thanks for helping. I’m at a loss to what to do next.

[originalkwyjibo]

The important thing to consider here is that you are putting a lot of faith in a 30 year old gauge and possibly a 30 year old temperature sending unit. If you really want an accurate temperature reading you'll want to install a good quality aftermarket gauge. And 195-215 is considered normal for most engines.

[trestlehed]

Hello Tvt. I own two vans but one is giving me fits. I’ve replaced head gasket. Water pump. Hoses.
Fan clutch radiator flushed and cleaned and oem thermostat. I’m at a loss to what to do next.

If your van has the original radiator, it might be time to do the high efficiency re-core or get a new one.

After I bought my van, I found that the radiator was is really bad shape. Had a shop send it out for a "re-core" job
which turned out to be done very poorly or not at all (scam). Eventually I had the "Ability Radiator Re-core" high efficiency 3 row
done.

[Papay]

Since the OP was posting from Hawaii, just want to add my own 2 cents from Philippines.

-No heater installed, I use a bypass hose at the water pump
-No choke installed on stock 2bbl carb, not needed here
-No t-stat installed, bought the car this way and have not added it
-Upgraded to 3-row radiator to give extra safety margin
-stock clutch fan

Temps never climb above half, unless I am low on coolant or crawling 2nd gear in the mountains.

[Navphoto]

I’m planning on purchasing a watchdog temp sensor for her van. I’ve tried everything else except recore radiator. I have an extra 4x4 radiator so I need to take it to the local shop and see if they can do it for me. The part that has me bewildered is that it runs nice and cool without thermostat but I’m willing to try anything.

[trestlehed]

Check this thread, post #13. It has a link to a nice digital temp gauge.

This mod is on my wish list.

http://www.toyotavantech.com/forum/showthread.php?2759-Cooling-system-Mods&p=16143#post16143
(http://www.toyotavantech.com/forum/showthread.php?2759-Cooling-system-Mods&p=16143#post16143)

[Ace MM]

I didn't check the rear heater system. It's running too hot for my liking with the new thermostat.
I found a corroded pipe that developed a hole when I hit it. Could of been disastrous.
I don't think it was used much as there was a lot of sediment once I opened it.
Next time I flush, I will drain the rear also.

[Navphoto]

Update. Had radiator recored guy that did it said that he could only do a 3 core so I when with it. Didn’t help so gauge on dash so I took temps at fill neck with a laser temp thermometer and temp are reading great 178 180. I should have bought the watchdog temp sensor first before I did all this work and spent a ton of money. The positive is I have a perfectly good extra radiator in case one of these vans need it.