Running a little HOT, thermostat? fan? no leaks

[zzman]

The temp outside is close to 90 and my truck is already running about 210 degrees. Pulling heavy, it will never make it this summer at this rate.

Use to run about 205 last summer in 100 plus temp.

I have no water leaks, radiator never needs water, flushed system with new anti-freeze last year, new fan clutch this past winter.

I found a tread from a while back that mentioned the thermostat quit opening all the way. Is this a common issue?

I just added freon to the a/c (about 2 cans low) before adding freon I could hear the fan cycling on and off while driving down the hiway, I can not hear it now, It did help keep it cooler when cycling.

Any ideas what to check first?

I found a thrmostat at oreilleys w/192 degree, is this the right temp to use?

Do you think the anti-freeze needs changing again?

Any help and comments are welcome,

thanks

 

[AH64ID]

I would start with an OEM (only OEM) 190° thermostat and go from there.

The OEM thermostat cracks at 190° ±3° and isn't full open until 207°, but it takes a decent load to get there. I only see full open a few times a year, but on my old thermostat I would see it often. They wear out quicker than you would think, it's due to the HUGE cooling system not letting the thermostat go full open very often.

 

[S.Morris]

Are you absolutely certain the radiator is clean externally? They can be near plugged and yet look relatively clean. . Only way to be sure and do a good cleaning is to pull the rad out. This would be a good time to check on the t. stat.

 

[zzman]

I guess the one at oreillys is probably the stock one.

I'll try that, never had changed it before I guess it is time.

Thanks

 

[ABennin]

This past winter I had mine out and washed it and couldn't believe how dirty it was. Granted I have the oil catch can. Make sure the fins are intact and straight. I had to replace a radiator awhile back because the fins corroded away from road salt and the truck would get hot. I see you are from TX so this probably isn't the problem. But it is something to check.

 

[rbattelle]

Also be sure the A/C condenser and intercooler are clean! Either of those can block airflow to th e radiator.

I've found that having the A/C shedding heat to the condenser on a hot day will raise my coolant temperature by around 5°.

-Ryan

 

[AH64ID]

Are you absolutely certain the radiator is clean externally? They can be near plugged and yet look relatively clean. . Only way to be sure and do a good cleaning is to pull the rad out. This would be a good time to check on the t. stat.

My dad had a old rad on his '97 burb with a 454 in it. It looked clean, and showed no signs of wear yet his burb would overheat. He put a new radiator in and it was night and day.

I just noticed the 370K in the sig, so it's quite possible.

I guess the one at oreillys is probably the stock one.
I'll try that, never had changed it before I guess it is time.
Thanks

I doubt O'Reilly's sells Cummins parts. I have heard too many horror stories with non-Cummins parts to even bother.

 

[jjdiesel]

Agree with all on the cleaning issue... . hard to tell by looking, especially the backside, but makes a huge difference. Take your time and hose it off really well and see if it makes any difference at all, then you know if your on right track or not.

 

[zzman]

I just checked the back side of radiator (with mirror), it looks clean, water flows thru it with water hose in front on rad.

I'm thinking thermo, will get it changed this weekend then Monday I got a 800 mile trip to try it out (loaded at 31k gross).

 

[zzman]

Changed the thermostat and noticed that the new one could be pushed open with my fingers, the old one wouldn't budge.

The new one also had a larger opening than the old one.

When I started it up and waited for operating temp, the old one would rise to about 200-205 before noticing a decline.

The new one would not quite get to 200 before dropping.

I think this is it.

Great advice again from the TDR.

Thanks all

 

[dkalis]

Dash temperature gauge quit working. Needle would move to first line and stop when key turned to start. Replaced the temp sensor and then the thermostat. Still nothing? Any suggestions?

 

[zzman]

RATs Still running hot

Well it worked good in the driveway.

When I pulled a load at night (about 70 degrees) it seem to be fine, stayed right at 200 degrees.

Then when I pulled a load in 93 degrees it would run what I would guess about 210-215 degrees, then I'd slow down a bit to cool to 200 again.

I remember it did not run this hot last summer even in over 100 degree temps.



I'm not sure what to check now. The water pump is about 2 years old (150k miles) and I changed the fluid last summer.

Can the pump begin to move less and less water??



It almost seems something is in the system slowing the flow.

When I changed the thermastat I drained a gal out and it didn't look rusty or even dirty, just kinda sticky feeling.

No sign of water in oil or oil in water, no leaks and never looses water.



I guess I'll flush and clean system, any thoughts what to use?

I do use Zerex G05 antifreeze.



Thanks for your thoughts

 

[ABennin]

How's the fan clutch? I believe they are computer controlled, just wondering if it is fully engaging. We had grain truck that would run hot and the fan clutch was shot it would not engage.

 

[zzman]

Thank you, but it is working fine, a new one put on a few months back.

I can hear it working with the A/C on and it doesn't seem to help when it is running hot.



I just noticed that the bottom radiator hose is about 1/3 up from the bottom of the radiator. Also noticed that the wire inside the hose stops about 6" from the radiator.

Just wondering why this is?



I'm going to drain fluid tomorrow and try to find a 180 degree thermostat to put in.

Hopefully I will find something in the fluid that will suggest something wrong.



Thanks

 

[B.G. Smith]

That bottom hose could be collapsing when you are at high rpms, wire should go full length. bg

 

[zzman]

Thats kinda what I was thinking BG, but weren't sure if the 5-6" long pc was long enough to collapse.

I flushed the system out pretty good today. Flushed the over-flo tank as well.

Put a 180 degree thermostat in and 4 gal anti-freeze. Drove to town and back (12 mi) empty just the truck. Never moved off the 2 of the 200.

The real test will be next week loaded.

I didn't see anything in the fluid that looked bad to me, but it did foam alot. I kept flushing til it ran clear and no foam.

I may just change the lower hose just for kicks.

Thanks

 

[BIGNASTY]

On my 04. 5 2500 I dont pull the weight that you do consistently but have had WAY TO MUCH WEIGHT on a goose neck trailer and tow it from Ca to MT lots of times in summer heat across desert. I put in a 180 stat on my first coolant system change. The temp NEVER GETS above 200 at anytime. Changed WP on Sons truck (same as mine) because the WP for some reason just as we started to do coolant change started to weep. He said that it recently had just started to creep into the 210 range on a tow trip to MT. Could be an indicator that your pump is going down and out for the count. If I dont have my Espar on my truck wont even get to temp on a 12 mile run unless my foot is in the turbo A BUNCH. I installed a coolant filter on mine when I changed the coolant I changed the filter and upon cutting it open you would be amazed at the crap that the filter had in it and my coolant looked good. Spring in lower hose on mine dint go the length of the hose short by a few inches both ends.

 

[zzman]

Thanks BIGNASTY, I thought about the pump too. It has only gone out once a couple years ago. I never noticed any water leaks it just starting squeeking then about 20 miles later the belt came off and that was it.

I think it cost about 6 hundred and something at a Dodge house in San Antonio.



I wish I knew if it was going out with a little warning



Good info thanks

 

[BIGNASTY]

My Son got his parts thru Geno's to do the job. It cost allot less than if he were to buy the parts at a parts store. He replaced the belt (thats fun in its self) the pump both hoses and the therm o for under a hundred bucks. And what ever you can get your coolant for. He used Zerx GO 5 concentrate we picked that up here in MT for 12 or 13 bucks a gal. He got 5 gal so to have extra for future. The job is really pretty straight forward the belt was fun but there are some posts that helped me figure out how to get it back on and the time estimate of 20 min water pump change is TOTAL B S at least on our year truck. But that part is JMO. Need some questions answered let me know i'm no rocket scientist with tools especially on these computerized rockets but if I can help no problem.



BIG

 

[zzman]

Thanks BIG, I'll check for a seeping pump and I checked Jeno's website, now I know WHAT the water pump looks like.

Your right about that belt, just dumb stuff they make these days. I had to change the ALT out a couple months back and that belt was scary. I tried to keep it in place and slide the ALT out and then back in. I guess it stayed on correctly, all works now.



I think I read here that the weep hole is on top-side of pump, I'll check it out this morning.

Thanks again