How Hot Is Too Hot?

I have a 09 4 door TRD 4x4 with 4.0 and auto with 93k on it. This Tacoma has the factory tow package. I am using a scan tool and last week while towing a Bantam 1/4 ton trailer with a Hobie Pro Angler kayak that total weight was probably around 700 pounds up a long grade on highway 89 out of Meyers (Lake Tahoe area) to highway 88 the scan gauge showed the engine temp got to 204 degrees while the dash engine temp gauge never moved from the 1/2 position. I did not have the gas pedal floored but I was going 55 to 60 mph easily up the grade. Ambient temp was 82 degrees that day. Normal temp range shown on the scan gauge is 186 to 193 depending on ambient temp.
How hot is too hot?
What kind of engine temps for those of you that use scan gauges or other OBD monitor devices typically see?
I was following my son in his 02 regular cab Tacoma pre-runner with auto and 2.7 and 173k, he said his scan tool showed 186 degrees the entire way, he was not towing anything.

 

184 is what i have been seeing

 

Guessing you have a 180* stat. 204 isn't bad for what you were doing, but you might need some attention. Was your son towing too?

I typically run 186-190 on the highway at 90* ambient (not towing, but 4 passengers and full of luggage) and will get in the low to mid 190s in city traffic.

Be sure the condenser / radiator fins are clean, nothing jamming up the fins, and your fan is working properly, the radiator cap is good and the system is clean and full.

I'd have more interest in the transmission temperature.

 

220 degrees is where ATF, starts, to break down and loose viscosity. If I remember correctly. Any long term exposure to this and higher temperatures will fry the clutch materials and distort the rubber seals and gaskets. Causing serious problems.

 

My Ultra Gauge reads 181.4 when warmed up. It has reached as a high as 196.8 under heavy load with a transmission cooler.

RJM

 

Sounds like an oil cooler and tranny cooler need to be in your future if this is a common occurrence and you dont have them.

 

if you see 214 and it doesn't drop down to 204 in a few mins...it's too hot sumting wong

 

I was pulling a aluminum boat and trailer approx 500 pounds about a month ago. The ambient temp was in the mid 80's and I noticed on my scan gauge the engine temp reached 200 when going up some long hills. I was thinking it was a bit higher than normal too. Mine is usually around 180-195. Might be time to check or clean the radiator/condenserand tranny fins for any obstructions like Bill suggested.

 

Changed original post to include that my son was not towing anything and that the 09 Tacoma has a factory tow package.

 

Do not directly correlate engine temps to trans temps. in all (most?) cases.

Coolant in the engine is one thing, trans fluid is another. The engine can run very hot (because of a problem) and not directly affect the transmission.

Of course there are exceptions, like the fan failing, so the transcooler part of the radiator is being inadequately cooled.

If you want to know the temp of your transmission, you really need a trans temp sensor. A must have in performance vehicles, and a great idea in towing rigs.

My understanding is that there are outputs for this in the newer trucks (not sure what year) and there are updates that can be done to SCIIs to read it. Although I don't recall anyone posting successfully doing this. Certainly something I'll be exploring. Not because I tow or compete anything anymore, I just like to know what's going on!

 

transmission creates it's own heat which is bled off by ridges on the
transmission body (not a lot) but mostly using the exchanger in the radiator
and if you have an additional tranny cooler in open air, that too.


generic average temps/atf age for generic atf

175 Degrees: 100,000+ miles (Normal is typically 179 to 195 degrees)
200 Degrees: 90,000 miles
225 Degrees: 55,000 miles (Pressure Drops)
250 Degrees: 25,000 miles (Valves Stick)
275 Degrees: 17,000 miles (Varnish Forms)
300 Degrees: 4,000 miles (Seals & Clutches Burn)
325 Degrees: TRANSMISSION FAILURE

 

OK people.... first.

OP are you talking coolant temps or transmission temps.

Engine temps are fine up to 210ish.

 

What rpm were you turning during your climb? Was A/C in use? Might be worth a try next time to drop down to 4th and see if it affects your coolant temperature (water pump will move more water).

 

Original post states engine temp although I am concerned about trans temp as well, just have not figured out how to turn on the trans temp for the scan gauge yet.

 

I'm towing a 25' camper @ 5000#'s, I have a 13'DCSB auto w/tow package, I have a scan gage, this weekend ambient temp here in New England was 85*F, my engine temp ranged from 195*F to 215*F and the Trans temp ranged from 210*F to 230*F, truck has 27K miles and I always tow in 4th. I don't think OP's temp is all that bad, sounds like it's in the ball park for what he was towing.

 

I don't know about engine temp but those transmission temps need to down. A bigger cooler should be in order.

95° weather with stop and go driving my auto trans temp was 175° with no load. I can't amagine if I had a load behind it. Mine also has the tow package. Even though I don't haul heavy loads a bigger cooler will be in my future.

 

I believe that Ultra Gauge can monitor Trans Temps on the Tacoma?

 

I have the Ultra Gauge as well, and on my 2013 Taco it DOES NOT monitor trans temp. I went with the scan gauge and presto, now I have trans temp. I know on the Ultra Gauge web site it states that it does monitor trans temps for the Taco, but it DOESN'T.

 

I'm gonna start watching water temp and trans temp (1 or 2) together and
see how close or far the tranny stays to water temp

 

Depending on which model Ultra Gauge you get it can show trans temps. there's a thread around here somewhere discussing the settings to make it work properly.