Very slight overheating, relatively new problem (about one month)

[Steveinfl]

I live in central Florida which can get quite hot in the summer, however I tracked my temp several times driving today.

With ambient temp of ~80F:
With ac on runs consistently at 212, highest reading was 216 momentarily.
With heat on ran consistently at 207 to 208.

It isn't hot enough outside to justify running over 210 even if it is slight. Truck is well caught up on maintenance and the radiator was supposedly flushed at approximately 60K along with replacing a a radiator hose. Everything runs pretty much as it should otherwise. The only variable I can think of is that I topped off the refrigerant recently, I don't think I overfilled it but I was towards the top end of the "green zone" on the attached gauge. Should be within spec +/- 5psi. I believe the thermostat was replaced at 60K as well. I Currently have 80K miles on the vehicle. Should I just pretend I don't see the needle creeping to the right, it is only 6 degrees and about 3 percent?




In Response:

No codes or CEL
I visually inspected the fan and I can't see any dings, or chipped pieces but I haven't gone further than that. I suppose it could always be the good old fan clutch, but I do not have the typical accompanying jet engine sound.

According to my maintenance records the fan clutch was replaced at 37K at the dealership. Thermostat was replaced at 60K.

 

[Cooztwo]

Any codes? Did you inspect the fan?

 

[Blckshdw]

How were you checking these temps? Are you using an OBDII scanner of some sort, or just seeing what the dummy gauge in the cluster is telling you?

 

[Steveinfl]

I have one of those advanced auto parts
99.99 OBD 2 readers. It gives me most of the information I would want, but not trans temp.

 

[Steveinfl]

Oddly enough that gauge starts swinging to the right much faster than it goes left, at least proportionally to temperature differential.

 

[Blckshdw]

I know you said the T-stat has been replaced already, any indication if the temperature sensor was also replaced? Could be a slim possibility that it's gone bad. Mine usually runs about 200 to 205 under normal conditions with no AC. I haven't checked it with the AC on, maybe I'll check mine tonight/tomorrow and see how close it is to yours.

 

[Steveinfl]

I am pretty certain that my coolant temp sensor is stock. I am planning on changing my cpas and upstream o2 sensor soon. I will add a coolant sensor to that list, should have plenty of clearance once I clear the way for the cpas.

 

[The_Roadie]

... I will add a coolant sensor to that list, should have plenty of clearance once I clear the way for the cpas.

The power steering pump needs to be moved for the CPAS swap on the passenger side of the engine. The coolant sensor is near the thermostat on the driver's side, with the alternator in the way.

 

[Cooztwo]

I had to remove the alternator to get the coolant temp sensor out. I have the opposite problem. I have code 125, my engine doesn't get hot enough. Stock sensor was 175, I changed it and the new one was stuck on 99, the next one stops at 168.

 

[Steveinfl]

Cooztwo- that is weird, I'll count myself as lucky it's only half a tick off and somewhat consistently at that.

Roadie- you are right, had a minor brainfart there, I suppose I will do the big 3 at the same time. It was wishful thinking that they were located in the same general area.

As always thanks for the input everyone.
- Today I tested my fan clutch by stopping it once it disengaged from engine start. I was able to stop the blade without a problem, so I think the clutch is in good working order.

 

[MAY03LT]

Mine does the same thing with the AC on. Just a touch over the middle of the dummy gauge. I haven't got the ECT data for the actual temp with the AC on but I did get it with the AC off and it's around 206.

 

[fadyasha]

Mine does the same thing with the AC on. Just a touch over the middle of the dummy gauge. I haven't got the ECT data for the actual temp with the AC on but I did get it with the AC off and it's around 206.

Mine does too, but guess you've all seen my thread lol! It sticks there in hot weather while the ac is on. Haven't had the chance to check it out but will try flushing the radiator

 

[Steveinfl]

It seems like this isn't entirely uncommon. I will keep a watchful eye on the temp gauge, but otherwise won't worry about it too much. Still planning on rad flush + new ect sensor. I figure if i can get another 5 years out of the TB then I will have enough saved to call up duraburb since they are a half hour away, and build a diesel suburban or Tahoe. One of these days…

 

[fadyasha]

It seems like this isn't entirely uncommon. I will keep a watchful eye on the temp gauge, but otherwise won't worry about it too much. Still planning on rad flush + new ect sensor. I figure if i can get another 5 years out of the TB then I will have enough saved to call up duraburb since they are a half hour away, and build a diesel suburban or Tahoe. One of these days…

The other day on a 300 mile road trip with over 40 degrees cellcius my temp was slightly high for 3 hours until temps dropped outside in the evening then went back to normal

 

[CaptainXL]

The other day on a 300 mile road trip with over 40 degrees cellcius my temp was slightly high for 3 hours until temps dropped outside in the evening then went back to normal

You guys have one of these right?

Amazon.com: Prestone AF1420 Professional Antifreeze / Coolant Tester: Automotive

Lack of cooling could mean there is a restriction in the radiator. Coolant needs to be changed every 5 years or 150K miles. Whichever comes first. Usually the thermostat goes out before 150K so the coolant is changed at that time.

 

[Steveinfl]

I have never tested my anti freeze percentages, that said whenever I add/flush the rad it is with
50 50 and distiller water. That said I would be very surprised if my mixture was off enough to affect the cooling. I am still going to aggressively flush the rad.

On that note, has anyone ever found a way to power flush the system with a garden hose secured to a rad hose, or something of the like. I am thinking that will be a good flush after I drain it. Then refill and see, I will change that coolant out and report any changes/improvements.

 

[CaptainXL]

I have never tested my anti freeze percentages, that said whenever I add/flush the rad it is with
50 50 and distiller water. That said I would be very surprised if my mixture was off enough to affect the cooling. I am still going to aggressively flush the rad.

On that note, has anyone ever found a way to power flush the system with a garden hose secured to a rad hose, or something of the like. I am thinking that will be a good flush after I drain it. Then refill and see, I will change that coolant out and report any changes/improvements.

I would get a Prestone or Gunk flush kit and use the instructions on he box. Its likely you have scale inside the core which a garden hose will not get rid of. The flush kit will dissolve the scale.

http://www.amazon.com/dp/B000BPSVWI/?tag=gmtnation-20

 

[Steveinfl]

I don't know why I didn't think about that, I've done that to the 79 MGB before with good results. The heater core was still toast though. Going to have a lot of coolant to take to the hazardous disposal, but the truck will be happy.

 

[Steveinfl]

**UPDATE

I am in the process of flushing out the radiator, it was pretty funky. Temps dropped to between 200 and 207, right where they should be. I am going to change the fluid with straight distilled water once or twice more to get it really clean. Some one used green coolant in it last time.

- Do I have to remove he thermostat to completely drain the coolant? What about the bolt to drain the heater core referred to in other threads on the same subject? Anyone ever done a "complete drain"?

 

[CaptainXL]

**UPDATE

- Do I have to remove he thermostat to completely drain the coolant?

No, you should have a wing nut type valve at the bottom of the radiator for a 2002. But if you have chunky stuff in there then I would remove the thermostat. Mixing green and pink coolant will cause it to sludge. Your using some type of flush solvent right? I would highly recommend Prestone flush.

 

[Steveinfl]

I'll look better for my drain, couldn't locate it before. Truck was built December 02, so I should have it. Only reason I asked about the thermostat was that it doesn't seem to be emptying all of the coolant when I pull off the bottom hose, I have refilled with water twice and it still has a tinge of green in the water when I drain.

Luckily it hadn't started to gel up, I was just surprised how much dirt sized particles were in the overflow. That could have been scale that the chemical flush broke loose too. I just know that I'm not getting anywhere near 2.7 gallons out. I will leave it disconnected and let it drip for a few hours today and see if I get more.

 

[CaptainXL]

I just know that I'm not getting anywhere near 2.7 gallons out. I will leave it disconnected and let it drip for a few hours today and see if I get more.

You need to drain it while the coolant is hot. Other wise the thermostat blocks off the coolant from draining from the block. Just remove lower radiator hose after warming up engine and let it drain. Your gonna have some scale to get rid of anyway that mearly opening the petcock will not let out.

 

[Steveinfl]

Thank you caption Xl.

That was the missing link I think I an all set. I will log on from a pc later today and mark this solved. Sometimes it's the little things that stump me.

Thanks Again and War Eagle.

 

[fadyasha]

I just purchased the Prestine flush off amazon and now will need to wait a week or two before getting here. Guys think you can do a quick write up on this?

I think I got the plug too since mine is a 2003