This afternoon I had about 40 miles on the interstate driving home from my son's baseball tournament. Temp outside was mid-upper 80s. I was running the A/C and was running low 80's mph. The terrain was a little hilly and I was driving "hard". You know, not just cruising along.....Anyways I looked down and my temp gauge was about 70-80% up the scale. It has never been there before. My needle has ALWAYS sat right at the top of the little thermometer symbol in the temp gauge.
I exited the interstate, pulled into a service station, ran water over the radiator and the temp dropped to the normal point. I drove on home w/out running the A/C and the nothing seemed abnormal.
Once home I checked everything out. The level in the radiator overflow tank was same as it ever was. The antifreeze / water ratio was a little off (I had flushed and refilled last fall). I drained a gallon from the radiator and added antifreeze to correct that.
In short, I found nothing wrong. I have driven the truck since with and without A/C. Everything was fine.
So, do you ever see your temp gauge get that high? I'm not overly concerned, more just curious.
Thanks!

 

Deja vu! I had the same thing last friday. It's exactly like you said, I ran the air for the first time this year, and I was in a little traffic sometimes and sometimes runing 75+ . My temp gauge was only about a half inch from the hot side. I kept running, and it finally cooled down. Needless to say I flushed and drained my system on saturday, and changed my thermostat to be on the safe side. I put in a failsafe thermostat, that will fail in the open position,just a little extra insurance. I refilled w/ 50/50 and have had no more problems. I drove 120mi. this morning, cool as a cucumber.

I have no idea what caused this problem,but if it shows up again, you will definitely hear from me.

 

Thanks for the reply. I have driven my truck several times since and seen nothing out of the ordinary.
I think my t'stat is fine. In all honesty, that is probably the first time in 123,000 miles that my truck has run sustained 80-85 mph, with A/C on w/ temps 80-85 degrees outside.
And like I said, I wasn't just cruising along. (I-65 North from Columbiana to I-459, then East toward Trussville)
So, I guess I'll just keep a close watch on it.

Any others ????

 

I think you're fine man. Sounds normal to me. I have only 13000 miles on my truck and when I run in consecutively at the track a few times it runs hot and the coolant and everything is fine. Not realy hot, just a little hotter than normal.

 

Nope, definitely not normal. Mine was only a heartbeat from being overheated and spewing steam. I have put all 111,00 miles on my truck, and I have driven w/air at 100deg.@80mph w/no trouble. Friday it was 80deg. , the traffic was not too heavy, and I never exceeded about 78mph.

Brian , your's may not have been that hot, but mine was near it's boiling point. I was only about three needle widths from the big H at the top of the scale. If you have the time, just replace the thermostat, and you won'st have to worry about it. Takes about 1 1/2 hrs. Someone in this forum said something about his truck leaking coolant and everyone agreed that this was not normal. Maybe a little higher is ok, but not as high as mine was, and it sounds like Brian was very close to this also. It concerned him enough to pull off and hose down his radiator.

With those aluminum heads, you can't take a chance, or you will be pulling them off and replacing or having them milled because they are warped. Better to err on the side of caution and buy a $12 thermostat.

 

Well, it happened again today, only worse. It never got even with the top tic mark on the temp gauge so obviously it never "overheated". But, it sure ain't right.
I was going to start replacement pf t'sat tonight at approx 8 pm, BUT Advance Auto only had a 195 deg. t'sat.
Darn it!
180 deg. is factory, is that correct?
Thanks.

 

Well guess what!! I drove home today, about 80deg outside, and about 70mph, and boom- ran hot again. I noticed that the faster I went, the hotter it ran. I exited I-20 on u.s.78 west and came home through oxford(about 7 mi.) before I had gone 2 miles it was back to normal, and ran normal all the way home.I curious if I may have a high speed slip of the belt that doesn't squeak. If it was airflow, my problem would have gotten worse as I slowed down, not better.

The water pump may be cavitating at high rpm. I hate to throw money at it until I get it right, any more help would be greatly appreciated.

 

This is s t r a n g e....
Both of us at the same time. What's up here?
Mine appears to be either a sticking thermostat, water pump or possibly radiator efficiency (or some other heat transfer problem)
I suspect t'sat because it was a sudden distinct onset. Not gradual like you'd expect if it was radiator or scaling inside the block.
Mine seems directly related to when you'd expect the t'sat to be opening to allow more flow. There is a short lag behind the increased load and then the temp gauge climbs. It recovers fairly slow (much slower than the rise). I HOPE it is the t'sat because work prohibits me from taking the time to do it myself. I sure don't want to pay somebody to replace a good one with a good one.
I'll check back and keep you posted. You please do likewise.

edit to add:
I do not think mine is water pump cavitation. I had thought about that but it just doesn't seem to explain my symptoms as well as a sticking t'sat.
Thanks.

 

sounds like your tstat is sticking. might want to go with 180, compared to the stock which is 195

 

It is in the shop right how to get a new thermostat. I am going back with the factory (195 deg.) t'stat. I believe that is the wisest thing to do.
I gotta believe the engine was designed to run at that temp and keeping it cooler would put it outside its design parameters.
Sort of a case of "if it ain't broke, don't fix it".

 

Thermostat did not fix mine. I drove to work this a.m. , no problem. I even drove up to 80mph for a long time to see if it would effect it, nothing. I know you can get bad thermostat's, but I don't believe with the same problem , at the same time, that I got a bad thermo and am getting the same symptoms. The only difference in the a.m. and the p.m. is the ambient temp. I will probably replace the belt today, in case it's slipping at high rpm. I'll be in touch if I nail it, please do the same.

 

$92 and one new thermostat = no fix.
Now I suspect water pump or radiator.

BUT...could it be head gasket??? Could it be that under high load, there is a leak that is blowing hot exhaust gases into the coolant and heating it up?
My coolant level has never dropped but I just wonder if a leaking gasket could cause what we are seeing?
It seems to me that such could be the case. The coolant would get hot but you wouldn't be losing any coolant if the leak is from the cylinder out, rather from the coolant jacket into the cylinder.

This is very inconvenient for me....

 

If that's the case then your coolant will bubble when you rev it at high rpm. That is a common symptom for a blown headgasket. If the gasket is blown and leaking in, then we would be losing coolant. Either the pump is going bad , or the belt is slipping. The belt is the cheapest, so guess what I will be getting first.

 

It does sound like an in efficient radiator to me. The first thing that I would do is to remove the upper cover and was out between the radiator and a/c condensor. Somehow leaves and things tend to accumulate there. At the higher speeds, the coolant is not in the radiator as long so if there is any blockage, it will show up worse then.
Also never run more than a 50/50 mix of coolant and water. Water dissapates heat alot better than anti-freeze. So if there is too much anti-freeze in the system, it won't cool as good either.
I would start by checking the airflow path of the radiator. If all is good, I would pull the radiator and see if a local shop can flow test it to see if it is internally clogged.
I am hesitant to recommend the cavitating waterpump. What rpm's are being turned at the speeds that this is occurring?

 

2500-2800rpm at highway speeds for me.But if the thermostat is functioning normally, then the water is in the radiator for the same amount of time as always. If it was an airflow problem, then it would get worse when I slow down, not better.This was not a gradual problem, it just happened suddenly. With my mileage,(111,000) I would have seen a gradual problem with a closed radiator. Also this is the second time in 2 yrs. that I have flushed and refilled my radiator and cooling system.Internal cleanliness is not the problem. Pump cavitation will cause bubbles which do not absorb heat. A slipping belt would result in a reduced pumping volume.