Cooling Issues

[DaveHess]

I need some help! About a month ago I changed out thermostat, radiator cap, and coolant replacing them all and the coolant with Zerez G-05. I had no issues and the truck ran where it always has on the temp gauge, just below the center mark. Two weeks ago, I began a trip to Colorado out of North Dakota with my TT and I noticed the temp gauge was a tad over the center mark. I decided to just keep an eye on it since the amient was at 90 and higher. By the time we were rolling through Wyoming, the temp gauge was over top the second zero of 200. Again, I decided to just monitor since the owners manual calls this the "normal range". When I got to the campground outside of Denver, I checked the "status" of my coolant and found I was "heavy" to the coolant and light on the water. Meaning I was way over 50/50 mix. I drained it and redid my mixture and got it to 50/50. I thought I had corrected my problem. I also did not get a CEL at any time. A week later we started back to ND and had the same problem. Luckily we caught a cold front and rain for a large portion of the second day of travel and that helped keep things a little cooler.



Upon my return, I put the "Hawaiin Stat" back in to try to keep things cooler and also found using my Smarty Jr, I had code P0483 (Fan Speed). I reset the code. When I ohmed out between pins 2 and 3 (sensor and ground), I get an open and between 2 and 5 (sensor and 5v), I get an open on the wiring connector to the fan clutch. Am I doing this right? When I try to spin the fan by hand, the most it will spin is about 1. 5 turns and that was after multiple spins. The initial spin only moved about two blades widths. I also pressure checked the new cap and it held between 15 and 16. I pressure checked the pickups cooling system and it held as advertised. I took the truck on another trip this weekend with the TT and without the stat thinking it would run cooler and this would be better than running as hot as it did going to CO. It still ran a tad over 200 degrees and this time did not set a P0483 code. I understand that RPM would directly affect the cooling with the stat removed so I slowed to 60 MPH on this trip. What did I do or am doing wrong here??? I have a Cummins 190 stat on order to replace the Gates stat that I took out. I am at a loss here. The radiator appears clean and there is nothing between (debris) the coolers. I do have a screen on the front and have done this for years without issue. Please help!!!

 

[leaky gasket]

Dave, I don't think you have a cooling problem. that's pretty close to where my truck temperatures are when I'm towing my travel trailer. it sounds pretty normal to me honestly. I understand that the temperature gage might be reading differently since the fluid change. my only explanation there is that maybe the new fluid is denser than the old fluid and that causes the different reading.

 

[GCroyle]

Dave,



Just curious, how exactly did you do this



I checked the "status" of my coolant and found I was "heavy" to the coolant and light on the water. Meaning I was way over 50/50 mix.



I just did basically the same coolant, t-stat and hoses and just did some flat land towing last week (about 16K Lb combined) this weekend with AC on, no cooling issues to report.



One of my favorite tools to help look for heat issues is a digital thermometer, even used it to check my 30A plug at the campsite power post.



Gary

 

[Bill Stockard]

Could you hear the engine fan cycling on and off on those hot days towing your trailer? If you didn't hear the fan, that could be a good clue to your heating problem.
On 95+ degree days with the air conditioner on, the engine fan on my truck cycles regularly without towing anything.

Bill

 

[Teich]

Dave, my temp gauge does the same towing non towing with the OE cummins stat and the gates 190* , not towing it is just below the center mark (95 Canadian trk) just over towing, have an extra SW temp gauge this indicates 192* unloades and about 205* loaded quite allright i think. I installed a hose clamp on the line from overflow tank to rad wouldn,t draw coolant back to rad Laurie

 

[DaveHess]

Gary: I use two of those Prestone coolant testers you can buy at Wally World. I tested with two just to see if they match. They both read the same. I wish I had a Refractometer to say exactly but for my purposes I figured the Prestone deal would get me in the ball park for under $10. I do have one of those "touchless" thermometers but there is no way to use it while driving. When I have checked used the touchless, I use the laser pointer function of the tool and hold it about 1" from the thermostat housing. These measurements were only at idle and were considerably under 190 with the stat removed. I wish out temp gauges had more numbers on them for better guess. If using 190 as a reference since that is when the stat opens, this happens with the needle just to the left of the center of the temp gauge. So, my guess was that just to the right of the center mark should be 210 and directly through or slightly to the outside of the second "0" of 200, would be 220. Again these are guesses. My owners manual says as long as it reads in the normal range, which I assume is between 140 but not at 245 (Which has a red mark by it), I should be ok. The pickup has never ran, even towing in summer heat, with the needle over the second "0" of 200. At worst, slightly to the right of center.



Bill: I have never heard my fan cycle so I cannot tell you if it is or not.

 

[GCroyle]

Dave,



Thanks for the info. I know you can't use the IR thermometer while driving, but with the engine fully heated up, you sure can hit various points in the coolant flow path and look for temp changes, hot coming out, cooler going in sorta stuff, and the radiator end tanks if you can hit them.



With the engine at normal temp and getting hot, if you turned the heater on full blast, wouldn't that start to drop the temp as a test only?



What about a water pump that ain't pumping at full flow?



Good luck.

 

[DaveHess]

Thought of the water pump too but thought given the way it cools down with the stat out, I felt it was pumping as advertised. Checked belt and tensioner too. If I have to pull the fan, the tensioner assembly is coming out and new one going in with a new belt. Just looked easier without the fan. I also measure oil temp off the top of the filter head. It tracks with the water temp for obvious reasons. The reason I bring that up is as a check for the water temp sensor. Just racking my brain here.



Gary: The IR comment that I made was just an observation, not a personal shot at you! Just didn't want you to think that.

 

[GCroyle]

Dave,



No shot percieved, thanks.



I watched a Tech diagnosis a bad t-stat IIRC on a 1997 7. 3L (I was on the road) that we used to own here, he pretty much got it from observation alone, but when he pulled out the IR and started shooting the cooling system and following the flow and temps, well that did it, I bought one soon after. Does anyone have a similar truck that you could do a side by side comparison or speed and distance then shoot several fixed points to check his vs. yours?



Still wish we had a DIY quick check for fan clutch performance, tis a mysterious thing including its control system.



Good luck.

 

[DaveHess]

I ordered a Cummins stat and pulled the Gates version. It should be here today. I really wish the P0483 code would reappear so I would feel good about shelling out $400 on a Vistronic Fan Clutch. I see Geno's now has them for $385. I know everybody has someone but my brother is a diesel mech now parts guy for Kenworth in Buffalo NY. He is mulling this over and has me just about disassembling the front of the pickup and pulling the coolers. Not ready for that yet as this problem just suddenly appeared in early July thus prompting me to service the cooling system. I think the problem is still there lurking. I like your idea and I think what I will do is drive the truck to get it at least to operating temp and then stop and start shooting the rad with the IR and see what I find. I think even shooting the upper and lower hose should give some indication on the temp drop across the rad. I just don't want to start shotgunning money for unneeded parts.