I am stumped-Eng Temp issues

[Pikeman]

OK most of the time my Scan Gauage is reading in the 190 range but sometimes in traffic 204. What I have found searching is Normal operating range for our vehicles is 178 to 204. I don't like that I am in the upper end of range but get more concerned whenever I head to the Mountains to go wheeling. I turn OD off and still have the temps rise to the 220-227 range. Transmission doesnt feel like it is slipping and no RPM variance either. Steps I have taken already:
Coolant flush/refill, transmission fluid change. I had the TB water pump and T-stat changed at 189k and currently at 217k. Any suggestions?

My next possible things to do are Radiator, Cap, T-Stat(in case I got a bad one) hoses.
What else should I check for?
How likely is it to be Tranny related and not cooling system even though no signs of slipping?

 

[BTO]

What does the scan gauge say the tranny temp is when you go over 220? Have you done the tranny cooler bypass? That's one way to server the tie between the radiator and the tranny. But I really don't think the tranny has anything to do with it. It could be normal temps and a result of continuous load on the engine. How's the condition of the radiator? A new radiator may help. You may also consider an external oil cooler? Maybe try some slick50? I know that sounds kooky but it worked for me years back when I had a similar situation.

 

[Pikeman]

I have a 98 so no Tranny codes for the SG. Damn 99 and newer guys get all the cool stuff(cup holders, transmission temp codes..LOL). No tranny cooler bypass however that is something I am considering as well as new radiator. I just took a big pay cut a couple months back and no money to do anything.

 

[Qyota]

I'm regularly seeing 204 in normal driving. Wasn't always that way...not sure what changed.

I'm going to try a new radiator (can't hurt, good preventive maintenance) when I do my coolant flush next. Along with new hoses, CTS, cap, and t-stat.

When you're temp climbs into the 220's...can you hear your engine fan running? It should be. Perhaps the fan clutch isn't operating properly.

 

[brian2sun]

I'm wondering 1) how accurate the scangauge engine temp sensor is or does it work off of the stock temp sensor, and 2) does your needle still stay just a little under 1/2? I forget if I asked you that when we were talking about it a few weeks ago. Hopefully you can make the JB run on 10/3 and we can have Driffter bring his handheld temp finder along and compare ours.

 

[Pikeman]

The Scan Guage reads it from the ECM so supposed to be same signal going to dash guage. Dash guage sits just under half a couple minutes after warming up and never goes any higher then middle. had fan clutch tested and it is fine. My radiator guy told me that what I describe sounds like a clogged or blocked coolant passage. Recommended I check T-stat, take radiator to him for inspection and cleaning, also check water pump. He asked me a few questions about temp under different driving conditions and based on that also said it does not sound like a fan clutch.

Brian on the trail it is fine and most driving fine, just under heavy load like the drive to the trail it gets hot. I can't afford it but going to order a Koyo A1998 radiator today. Especially since I am putting on a plate bumper that is going to block more of the air flow to the radiator soon.

 

[brian2sun]

The Scan Guage reads it from the ECM so supposed to be same signal going to dash guage. Dash guage sits just under half a couple minutes after warming up and never goes any higher then middle. had fan clutch tested and it is fine. My radiator guy told me that what I describe sounds like a clogged or blocked coolant passage. Recommended I check T-stat, take radiator to him for inspection and cleaning, also check water pump. He asked me a few questions about temp under different driving conditions and based on that also said it does not sound like a fan clutch.

Brian on the trail it is fine and most driving fine, just under heavy load like the drive to the trail it gets hot. I can't afford it but going to order a Koyo A1998 radiator today. Especially since I am putting on a plate bumper that is going to block more of the air flow to the radiator soon.

Maybe if you go on 10/3 (which I know is iffy right now if you'll be able to get it off) you can see what your temps look like compared one of the other guy's right after driving up the mtn?

 

[Qyota]

Hmmm. If it IS a blocked passage, how would you know where...and how would one fix it?

 

[alp]

had fan clutch tested and it is fine.

How did you test the fan clutch? I also read the water temp on my CG in 204-206 range all the time driving on highway. I flushed the system and replaced the cap without any change. So, how to test the fan clutch? Thanks

 

[BTO]

I also read the water temp on my CG in 204-206 range all the time driving on highway. I flushed the system and replaced the cap without any change.

You may want to get a new thermostat. Maybe one that opens at a lower temp. I put a 180 degree in my old Pontiac. It could be that Toyota wants the temp to be at 205 for a reason. It might throw a code if it does not warm up to that. Still, I'd think 190 should be sufficient.

 

[Pikeman]

Factory T-stat is supposed to open at 185. IF you google test fan clutch it will tell you but IIRC you let it get up to temperature then shut engine off and try to rotate counter clockwise, you should feel resistance after 1st turn. If it spins freely then it is more than likely bad.

 

[alp]

Factory T-stat is supposed to open at 185. IF you google test fan clutch it will tell you but IIRC you let it get up to temperature then shut engine off and try to rotate counter clockwise, you should feel resistance after 1st turn. If it spins freely then it is more than likely bad.

Thanks for advice! Will do the test tomorrow.

 

[alp]

So I did the test. First I checked fan rotation before starting the engine.
I couldn't freely rotate the fun more than 1/4 turn. So far so good.
Then I started the engine and run it for about 5 minutes.
Stopped the engine and try to turn the fan counter clockwise. I could spin it
for many turns without ant resistance whatsoever. Same story when I turned it clockwise.
Does it all mean that it is time to change the fan clutch?
Can you guys performe this simple test on your trucks and let us know about results, please?
Thanks a lot!

 

[BTO]

I don't think that is an accurate test. Check it when the engine bay is hot like after driving home from work. There should be much resistance at that time.

 

[TheDurk]

So I did the test. First I checked fan rotation before starting the engine.
I couldn't freely rotate the fun more than 1/4 turn. So far so good.
Then I started the engine and run it for about 5 minutes.
Stopped the engine and try to turn the fan counter clockwise. I could spin it
for many turns without ant resistance whatsoever. Same story when I turned it clockwise.
Does it all mean that it is time to change the fan clutch?
Can you guys performe this simple test on your trucks and let us know about results, please?
Thanks a lot!

That's a pretty useless test, if I understand correctly how these things work. Stationary resistance is meaningless because it is a 'centrifugal' clutch and it has to be spinning for the fluid to reach the places where it causes the clutch to engage. I recently changed mine, and I had the old, bad one sitting next to its replacement in front of me. Both were identical in their resistance to turning (some, but not much). Many swear by the magazine test, but I believe that is somewhat hit or miss. The most dramatic difference on the replacement was the return of the roar of full engagement at start-up of a cold engine. If you don't have that, your clutch is dead.

 

[alp]

I can clearly hear/feel the roar for about a minute when I start the engine.
What bothers me is the 204-206 coolant temp reading on my SG which is higher than 190 deg F territory reported by many people. At the stop and go traffic the temp can climb up to 215 and than drops to 195 cycling back and forth. Obviously the fan is working but perhaps it is not perfect.
I guess I just need to replace a fan clutch but I am still very curious why the "normal" temperature when I drive on highway is too high. Any ideas?
Thanks

 

[COShadow]

My engine used to run at about 177F with the original radiator and old t-stat, new water pump. I changed the radiator, hoses and thermostat and it ran in the 202-204 range. I changed back to the old t-stat, back to 177F. Back to a 2nd new t-stat, back to 202-204.

??

I don't think the 202-204 range is bad. I live in CO. and even on the toughest mtn passes, the engine doesn't go above about 204. (The tranny does though, even routed through radiator AND external cooler).

Maybe I'll change the temp sensor sometime and see what that does.

 

[NickF]

They do sell 170* t-stats, rather than the stock 180* tstats, you might look into those.
Also, a couple bottles of Water Wetter or Purple Ice, might shave a few degrees off and put it back into the 180s-190s.

 

[Drcoffee]

I never really checked my coolant temp until I changed the TB and water pump last weekend. Using an app on my iphone it reads 204.8 mostly. I used a 180* t-stat with jiggler at 6 oclock. I have read so many threads that some are at 190* and others at 205*. So giving it some thought, it makes sense it runs that hot when the t-stat is down low by the inlet and the temp sensor is up high on the back of the intake plenum. I ran the engine with the rad cap off and I can see the fluid moving and the lower hose is warm not hot. The upper is hot. The radiator is newer so its working well to cool the coolant. Im not sure why the t-stat is on the inlet and not the outlet. That certainly will give higher engine temps. Would it be a good idea to go with a 170* t-stat or is this okay for the temp to be this high all the time?

 

[0xfded]

I never really checked my coolant temp until I changed the TB and water pump last weekend. Using an app on my iphone it reads 204.8 mostly. I used a 180* t-stat with jiggler at 6 oclock. I have read so many threads that some are at 190* and others at 205*. So giving it some thought, it makes sense it runs that hot when the t-stat is down low by the inlet and the temp sensor is up high on the back of the intake plenum. I ran the engine with the rad cap off and I can see the fluid moving and the lower hose is warm not hot. The upper is hot. The radiator is newer so its working well to cool the coolant. Im not sure why the t-stat is on the inlet and not the outlet. That certainly will give higher engine temps. Would it be a good idea to go with a 170* t-stat or is this okay for the temp to be this high all the time?

I switched to a 170 degree t-stat (Stant 14077) before throwing on an SC, and it keeps me pretty solidly at 180-182. Before that I was sitting at 189-190. I actually worry that it's running cooler than it should now, but I'll take that over too-hot.

200+ makes me think "t-stat is in at 12:00", but sounds like that's not the case for you. You could try flipping it, or just replacing it with a new one. Not a very expensive part.