Went looking for my thermostat... and have some questions (1 Viewer)

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Whitehorse, Yukon
We have been having some overheating challenges - be fine on a run to the store, hit about 3/4 max on the way back; periodically belch coolant. I think I have had two problems:

One problem is that the overflow side tube at the top is an aftermarket fix - one of those plastic jobs that may have interfered with the cap motion - Seemed as though the rad wasn't using the overflow to either dump excess or draw down to refill. Blelch when overheated, run low on fluid and heat up after(?) I have just now trimmed this down so hopefully all good now - I know, should get this brazed on...

One problem could have been that I didn't properly burp the system - but I believe I did... twice... also tested fan clutch and seems just fine.

Here is the interesting bit: I went to flush the coolant and ready for my replacement thermostat (due here Monday) and realized that the PO had removed the thermostat - there was none.

General reviews of removing thermostats are all over the place - fine, takes a long time to heat up; not fine, need the restriction in the system to work properly; save $5 and that can help pay for a new head later - etc...

Anyone run, internationally or accidentally, without a thermostat? We are 15 degrees C/59F here, have not actually overheated, but clearly running hotter than it should,

thanks
 
but the t-stat in, as well as the gasket and o-ring
 
It takes time for thermal transfer. Maybe without the restriction of the thermostat, the coolant moves to fast? Who knows, until you try it with the thermostat.
 
Yes, the coolant can flow too fast to transfer heat properly without a thermostat.

That true? News to me! Digging out my Heat and Mass Transfer textbook... Nerd report to follow.
 
Yup! The theory of "coolant moving too fast is bad" is a myth. One that I believed in at one time, and is still heavily believed in and argued by many.
 
The whole point of a thermostat is to get your engine up to a desirable temperature more quickly than it would otherwise and to sort of keep it there. Without a t-stat, the engine just takes longer (a lot longer) to warm up and depending on the efficiency of the cooling system, may never get to whatever the desired temperature is, or may only do so under a load (not desirable). Here in the tropics, many many cars are run without thermostats--even here it's not a great idea, but it can certainly be done. I have heard of engines that suffer from uneven cooling and such things without a thermostat--that seems like the bigger danger to me.
 
I'm guessing that if the cooling system didn't need a thermostat, Mr Toyota wouldn't have spent the millions of dollars to install one, in every vehicle, that ever came out of a Toyota plant. But hey, what the hell do I know.Maybe Mr. Toyota just liked wasting money.
 
A thermostat is more than an open - close valve. It regulates/controls the coolant flow so that the engine warms up faster.

Rudi
 
I agree! I apologise if I confused anybody into thinking that a thermostat is not needed. My intent was only to point out that you can run an engine without one, especially an older, lower tech engine. Is it a good idea? I'd say no. But the OP's question was "has anybody run without one, either intentionally or accidentally"? In which case the answer is "yes", I have done both, and furthermore have seen a great many other cars running without thermostats. Is it a good idea? I don't think so, but will admit that some people have run many years, many miles without them. Your results may vary considerably.
 
If it's a F motor, they have a bypass system. Without the thermostat or if the upper o-ring gasket is missing, coolant flow will go through the bypass, less going through the radiator. The uncontrolled flow will cause longer warmup time, and reduced cooling capability.
 
If it's a F motor, they have a bypass system. Without the thermostat or if the upper o-ring gasket is missing, coolant flow will go through the bypass, less going through the radiator. The uncontrolled flow will cause longer warmup time, and reduced cooling capability.

True. Is it not the same for the 2F ?
 
I had cooling issues, the gauge never got above 150 with a new thermostat. I installed another new one and received an upper gasket as well. Now the water temp gauge gets to 180 and stays there. Who knew the small gasket on top of the thermostat would make such a difference. BTW When I purchased the 40 the upper gasket was missing so I didn't know one needed to be there.
 
I had cooling issues, the gauge never got above 150 with a new thermostat. I installed another new one and received an upper gasket as well. Now the water temp gauge gets to 180 and stays there. Who knew the small gasket on top of the thermostat would make such a difference. BTW When I purchased the 40 the upper gasket was missing so I didn't know one needed to be there.

All too common, most shops don't know, can't be bothered to check the manual.
 
Bringing this back as the problem has persisted (we were stalled because I was also waiting on a new brake master).

Symptom: Once warm, temperature climbs to 2/3 the gauge. At idle, temperature continues to climb, drops once driving again, but not below 2/3 mark.

Checked:
new thermostat (with gasket);
plenty of resistance in the fan clutch when warm (applied quite a bit of force and fan pushed through);
thoroughly flushed at least 3 times in last 6 months - including heater.
burped by running from cold to warm without cap on (and heater on)
no antifreeze apparent in oil - but due for a full change, so will validate this weekend

I may just take it in to a shop who likely recommend rodding or replacing - anything else I should try first?

Thanks!
 
Did you burp on a wicked-steep hill? Recommended.

... truly. Before you buy a new/used radiator. I had overheating issues in my 89 FJ62. I could've sworn I'd burped the system well enough... nope. My friend has a very steep driveway and I let it idle with its nose in the air, throttle upped a bit, and heaters cranked full steam. In the end I added another liter of coolant at least.
 
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