Kadi96915

Ok so I figured out that my stock temp gauge not functioning right on my 94 Toyota pickup 3.0 auto 4x4 so installed an aftermarket mechanical temp gauge and was wondering what's the normal reading on these things with and without thermostats. I'm currently running without a thermostats because it's always hot here. My readings without the thermostats is 150 to 190 and that's without using ac. With ac it goes over 190 but never run it long enough to know where it stops at. Any info would greatly be appreciated. Thanks

Kolton5543

I think the stock stat is a 180 and stock is where it should stay. Running too cold will kill your gas mileage and may even keep it in open loop and possibly set a code. 190 sounds pretty high for no stat. I'd guess there's something up with your cooling system you might want to look into. As long as it functions properly, a stat won't make your truck run hotter in hot weather. Its there to regulate it at a certain temp. Pulling it makes it too cold. I'd recommend you put one back in and check other components to make sure they're working as they should.

Kadi96915

I flushed the system several times and even unclogged a small hose at the back of engine due to it being clogged, I also installed a new radiator due to old one leaking. As for gas mileage I get 18 to 20 without stat. I'm thinking it might be when I tried to patch up old radiator with solder and some of the flakes might be blocking a passage. So I might rip of upper n lower plenum just to see cooling passages.

ksti

18 - 20 miles per gallon without a thermostat......................

Kadi96915

Yes I do get 18 to 20 miles per gal and I measured it with my odometer after gassing it. This is the 3vze motor and I know about how it drinks gas. Before I changed out some parts I use to get 12 to 15 miles a gal but now I get 18 to 20 and that's running on 31s and no ac.

RAD4Runner

Second that.
Check out Philbert's thread (may he RIP), I believe there was discussion about his temps there.

Kolton5543

Yeah you could have a clogged up system. Could be something we though. Could be a bad water pump. I have seen the impeller separate from the shaft before and just not really move any water. Could be a radiator cap not holding enough pressure causing it to boil thus inducing air in the system. Could be a lack of airflow through the radiator either from veing dirty or blocked or have a bad fan clutch. Perhaps there's too much antifreeze. Antifreeze is a terrible heat conductor and requires water in it to do the actual cooling part. 50/50 mix is what most people run. I like more of a 75/25. I like to have more water for the extra cooling capacity as 110+ degrees is nothing out of the ordinary here and it never hits negatives. It could also be a lack of antifreeze. Antifreeze not only keeps it from freezing (like it suggests) but it is also a corrosion prohibitor and it raises the boiling point of the coolant. Read above about boiling coolant. Running straight water isn't bad only in the winter but also in the summer.

Kolton5543

Also, I too have a hard time believing your mpg numbers. Running cold will bring them down. Only a few of us 3.0 owners manage to get those numbers and that's running rip top shape on small tires and the right gears. Most run 15ish. I personally only get about 12 but that's also not running the best on 33s at 25/20 psi with 4.10 gears.

Kadi96915

Forgot to mention that I have 2 extra water pumps that I also though was bad so I have a total of 3 including the new one on the truck. So all my hoses are new so is the water pump and radiator, I also have 2 extra clutch fans. 1 I locked up and the other from a 3.4 not including the 1 on my truck so I do have extra spare parts that I picked up because I thought it was bad. I've tried all clutch fans and temp still same. I'm not mixing nor loading coolant. I've tried Copland that's 50/50 and straight purified water. I've also change engine coolant sensor and temp sensor for gauge and still all the same. So I am thinking that I clogged system with flakes of solder. My next step is to remove upper and lower plenum so I can check coolant passages and clean up better I'm just waiting on gaskets for plenum. Oh and for gas mileage I did calculate it and I do get 18 to a gal.

ksti

Sorry i'm not trying to pick on you, but I still question your mileage.
Your running a 3VZE, 4 wheel drive, automatic transmission with AC.
You have mentioned EGR problems. It just doesn't add up.
As mentioned It's puts you in a rare club of 3VZE owners.

As for temp problems, has it overheated or just running hot?
Seems you would need a large wad of "solder flakes" to clog the system
Have you pressure tested the system, including radiator cap?
Have you checked the fan clutch for proper operation? (very important.)
Running without a thermostat is just a mask for another problem.
If it was a older car without computer technology, I wouldn't be so concerned not running a t-stat.

Kadi96915

It's no problem. My miles are correct and I fixed my egr problem. As for overheating, I never heard it boil over or even boil. With ac it runs over 190 but I never ran it long enough but on long rainy days I've ran it over and hour and it never went past 150 on temp. I haven't tried running it over an hour on hot days due to my mileage drops to 14 or 15 when using ac. Most of the time I don't use ac that's why I say I get 18 to 20. I only gauged it a couple time but that was a couple months ago and that's after I put new parts in. So when running ac I get 14 to 15 but without ac I get 18 to 20 and keep in mind I drive my truck almost like grandma. I don't abuse my truck. Oh and I have 2 radiator caps, a 13lbs and 15lbs and both are new. Also wanted to mention that I mounted the aftermarket temp at the back of engine where other sensors are at.i didn't not mount it on upper radiator hose because I'm still waiting on that part.

Kolton5543

You won't always hear it boil. Essentially some coolant will boil a little in a hot spot in the engine. When it boils it turns into steam that then gets trapped in the cooling system. You get a pocket of steam somewhere important like in a cooling jacket on the head it can over heat the head and blow a gasket or warp/crack. Get it to the pump it doesn't pump water. Moral of the story, use antifreeze and have a good cap. Another problem I've had that can happen. When you loose pressure it will boil a bit and get steam trapped at the thermostat. Since the stat wouldn't actually touch the coolant it wouldnt get hot enough to open until the engine was right on the edge of overheating. That's why I like stats with a jiggle valve on them or a small hole drilled through them. The hole allows trapped air bleed past it and coolant to actually touch the stat.

Kolton5543

Have you actually pressure tested the system as in connect a pump and gauge. Fill it to about 15psi and see if it holds it. 190 is still a perfectly safe temperature and you may not have any problems. I just felt.like 190 seemed hot for no stat even on a hot day. I would just put a new stat in it and keep an eye on it. If it still doesn't get much past 190 leave it there.

RAD4Runner

How sure are you that those extra fan clutch aka liquid coupling are good?
Here's good vs bd fan clutch.
https://www.yotatech.com/forums/f199...l#post52229129

Kadi96915

I'm positive all fans are really good and strong, I'm just kinda like OCD on this temp.

Kolton5543

Well you should just put a stat back in it and roll with it. Just keep an eye on the guage. 190 is fine. While it may not be as bad as running too hot, constantly driving on too cold is bad too. You get excess carbon build up from a rich mixture. If its rich enough it can wash the cylinder walls of oil causing it to wear excessively. Also, oil has a set range of temperatures its designed to perform best at. Too cold could cause the oil to be thinner or thicker again causing excessive wear so your best off just using one. The only time I wouldn't want a stat is for single pass drag cars.

Kadi96915

Ok so I put back the stat on my truck but still have not relocated the aftermarket temp sensor and my temp is at 190 and goes very slightly above but never passes 200. I'm happy with that. Im just curious what's the normal readings on these mechanical temp gauges? Also want to thank who ever gave me some info and helped me out with my problems. Thanks again.

86-turbo

190* is absolutely normal. There is a possibility the gauge is off too. It could be calibrated a little off.
If you had a infra-red pyrometer temp gun that would be the best way to check.

Kadi96915

ok thanks. Ì don't have that temp gun but my friend has 1 and he did check and it reads about 180 on everything he checked soon guessing that it's alittle off on the temp gauge or I just need to relocate the sensor because I have it at the back of the engine where all the other sensors are at. Ì will relocate the sensor where it recommends it's suppose to be. Thanks for the info really appreciate it.

Kolton5543

Looks like there isn't really anything to be concerned about. The rear of the engine probably isn't best place for a sensor. There's not as much coolant flow in the rear and less airflow to air cool it too so its gunna give you some higher reading than what it really is. The best place for it is usually right before the thermostat. If its a good enough place to regulate temp then it must be a good enough place to monitor it. you may have to drill and tap a hole but itd be worth it.