91Toyota

My gauge goes up to red sometimes...and I can't really verify that it is actually that hot. Just skip to post #16 for help. (the first 15 were to verify that my truck was overheating and it was)

dcg9381

You could test the ohms on the temp sensor of the EFI unit (front of lower manifold) - there's a scale in the factory service manual that would convert to temperature.

When in doubt, assume it's getting hot.

rdharper

I really like my handheld Laser Infrared Thermometer. Not only can you get an instant readout, you can troubleshoot hotspots, radiator effectiveness, etc.

I bought mine online for $41 bucks. It has endless uses. Check fridge, freezer, bathtub water, cooking temps... just a great little device, and rugged as well.

tj884Rdlx

ha! isn't it funny what you'll check the temperature of when you got one of them laser guns? i've found out the posterior of certain people are colder than others. they're fun with the dog too!

oh, to answer the o.p., anyone got any experience with something like this? as long as its leak proof, easiest way to test it is boil it, right? the guy that reviewed it seems to be diggin' it, at least mr. gasket anyway. (ha, read it)

http://www.jcwhitney.com/webapp/wcs/...&storeId=10101

Brenjen

I was going to suggest the same thing. I bought one when I had my RC nitro truck & it has helped me with a few things from automotive to computers & toys.

91Toyota

I have one that I used with rc nitro engines...but the temp bounces around on everything. So where do I point it and what is too hot?

86tuning

Air pockets in your coolant can cause your gauge to do funnay things. I'd check/replace the rad cap, then pull out the temperature gun. Cheap ones can be had for $40 and will work fine, as long as you're at close range.

Brenjen

As far as where to point it, I'd pick a spot on top near the back of the engine, away from the fan where a coolant passage is running. As far as how hot is too hot for these Toyotas I really haven't got a clue but I'd guess anything over 225 to 230 might be heading into danger territory.

rdharper

Well... first thing is to check accuracy in the range of interest. Boil a couple of inches of water on the stove and measure the surface of the boiling water. It should read close to 212 if at sea level, a bit lower at a higher altitude.

Water has a high thermal capacity, so the outside case of the thermostat will read lower, but not much. If you are in the red, you should see high temps near the intake and of the thermostat.

Also check the intake and output of your radiator. You should see a big drop between them if your radiator is working.

There is more you can do, but that it a good place to start. If your panel meter is close to the red (212), it is not working if you probe the thermostat and see 168 for instance. If the panel gauge is right, you will see too-hot temps in your engine... and probably smell that you are close to boil-over.

The radiator is a pressurized system, so it can go well over 212 without converting to steam... but give it a try, see what you get.

91Toyota

Thanks. So, it should be really hot by the thermostat. I can hold onto the upper radiator hose while running and fully warmed...because it isn't that hot. I will check these things tomorrow. Thanks for the help!

DCYota

The upper hose should be uncomfortable to hold onto after a few seconds...you shouldn't be able to hold onto it indefinitely (unless you've got thicker skin on your palms than most ). Remember, it's supposed to be between 180 and 200 degrees Fahrenheit; or somewhere around there give or take. Imagine trying to stick your hand in water that hot on the stove top. That should be about the same feeling you get when you grab that upper hose and squeeze. Sure, you can grab it, but it's not going to be comfortable for long.

91Toyota

O.K, today I took temps. I used my brothers truck (94 22re) and put the infrared thermometer on his head by the spark plug and the temp was 211 degrees Fahrenheit and I took the temp of mine in the same spot and it was at 250 degrees Fahrenheit. So, I am pretty sure it is over heating. Is it?

Jay351

yes. Sounds that way.

From what I have seen/heard if you have no airpockets in your coolant and your factory temp guage moves a few mm, you are overheating.

In the future, install an aftermarket one so you can actually tell whats going on.

91Toyota

Thanks... I want to know why it is doing it? I did run water only for like 2-3 weeks...so is the water pump is screwed up? What do you think it is?
Thanks!

Jay351

Running water only woulnt ruin a water pump ( correct me if im wrong here) so I doubt thats your problem.

What kind of matanence has been done on the truck?
You flush your rad out? Did you burp it?
What kind of condition is your cooling system in?

wjwerdna

if you use a laser temp gun of some sort, I believe the surfaces of what you are measuring make a huge difference. If it is similar in technology to a thermal imaging camera ($15k+) then it relies on the surface emissivity and is different material to material. Cameras can be calibrated for different materials to be more accurate... With cameras, to get an accurate reading, electrical tape is actually used to take a reading. Carefully cut a piece without stretching it, and stick it to the surface, wait, take reading. The surface emissivity of the tape is actually ideal when testing different surfaces

91Toyota

I wouldn't think it would matter either. The water pump makes a noise when I turn it by hand fast though...it has absolutely no play.

Well, I took my head off assuming my low compression was due to my head but it wasn't. So, I put everything back together using new gaskets. I did not flush it...since I would drain the water every night and fill it back up (about every other night) so I drained it and filled it back up with antifreeze. I did burp it...but coolant got EVERYWHERE when it came out. I am assuming that my cooling system is good. What do you think? I used an rc car ifrared thermometer...it seems to be pretty accurate

91Toyota

bump...just need help fast!

Brenjen

Running water for too long through a water pump will damage it. I can't say how long it takes because it varies, but the antifreeze has a lubricant in it for the WP.

You may have a bad head gasket or the WP may be bad; sometimes they seem ok but aren't functioning correctly. I take it you've run the engine with NO thermostat to check what happens without one? If not you could try that, if the temps return to normal the WP & head gasket are fine & it's a thermostat problem, if it doesn't return to normal it's probably the WP or a head gasket blown....& probably at #3 cylinder.

91Toyota

really? I just replaced my thermostat...actually twice. So, you are saying take the thermostat out and run it...and if it over heats I have bigger problems? Thanks!