Towing Temps

[Dkevdog]

Just got back from a decent trip up the coast with the new 5er. Things went real well, average MPG seems to be in the 13 neighborhood. I seemed to do better on temps too, keeping a closer eye on it and keeping my foot out of it and dropping out of OD and slowing down on grades. The only time we had any trouble was the pull up the Grapvine on I5. EGT's were not really too bad, they hovered at about 1150 or so, and stayed pretty constant. transmission temp warmed up, but never got above 200 maybe 210. The engine however seemed to get real close to overheating- about 220- Hard to tell exactly on factory guage. Ran the heater on high and kept it from climbing, and air temp was about 100 or so. I've heard a few people talk about auxillary fans and/or replacing the stock fan with a better one. Anyone have any luck with it??



Kev

 

[Archive]

Did your stock fan kick on? I tow some heavy loads, and have stock fan... have never seen those temps, even with my bugscreen over the radiator, which is alleged to reduce the airflow by 25 percent.

 

[dvieira]

same temps as you do

i get the same coolant temps as you do going up I80 to Reno, from the Bay Area, and this day, i'm heading to San Diego, so i'll be watching my temps over the Grapevine also, this is my 3rd thermostat and it doesn't seem to make a difference, still get high temps when pulling, i think that's the way it will be, i pull a 11,000lb 5er and i have a 97 with the usual engine/transmission upgrades.

dave vieira

antioch,ca

 

[SlyBones]

education

OK you all, I need educated here.



How does the stock fan kick in when the temps get too high? Are these connected to the thermostat somehow?



Unlike the electric fans that are temp driven, I thought these were clutch fans? When the engine speed is low, such as sitting at idle, the clutch engages the fan and draws air through the radiator, etc. When the engine speeds up the clutch disengages and fan stops. Cooling relys on the airflow from the movement of the vehicle.



Also I think that in the owners manual it shows a picture of the temp gauge and says whats normal and what is possible while towing a heavy load up a large grade. Your 220 may be normal under certain conditions. I assume it came right back down as soon as you reached the top of the grade. I have seen this once. Steep hill, several miles long, 2nd gear, with 8K load, only time I have ever seen the temp go over 1/2 way.

 

[Bob Wagner]

hehe

Originally posted by Rob Hanson

even with my bugscreen over the radiator, which is alleged to reduce the airflow by 25 percent.

https://www.turbodieselregister.com/forums/showthread.php?s=&threadid=22810



the debate continues

 

[Dkevdog]

I need a lesson too....

I am with Skybones here- I thought the stock fan only came in at lower RPM's and speeds. Maybe we're both wrong. Yes the temps came down as soon as we cleared the summit. I also have the Lund Stainless grill which I know does restrict airflow somewhat- but I have driven with it on & off and not seen much difference if any. If I am correct about the stock fan, (or even if I'm not) what can be done to increase the airflow to = lower temps??



Kev

 

[HEYBOSS]

Clutch Fans

I don't have all the theory terms/conditions of clutch fan operation in front of me, but if anyone wants to know the exact specifics, I can post them. Any way basically the way a clutch fan works is based on some type of fluid that's inside of the fan clutch. When that fluid heats up to a given temperature the fan clutch engages therefore causing the fan to spin at a much higher rpm. On our rams I believe the fan engages around 210 deg. and you will hear a noticeable loud noise from the the fan ( similar to an 18 wheeler when taking off ) when the temperature drops you hear the fan disengage and quiet down.

 

[Archive]

I don't have a manual to explain how the fan works, but I can tell you it goes into "overdrive" when you are pulling heavy and its hot out. It really roars, sorta like a jet engine ... first few times it will shock ya. You will then see the temp gauge drop significantly.

 

[Archive]

Forgot... my 92 Cummins did this also.

 

[chuck3]

Robs right when my fan kicks on I can hear it real well and Im half deaf. My fan engages a lot when towing but allso running empty in this 100f plus temp.

 

[Dkevdog]

I'm pretty sure the fan was running and doing its job, (I do remember it was pretty loud) But it just didn't seem to be enough for me. Do the fluid couplings in the clutch fans go bad?? Is there an easy way to check if its running at its peak? There doesn't appear to be much room for auxillary fans in there, but I might try and find a way.



Kev

 

[John Berger]

That explains that roar when the truck is really hot. I always thought the clutch fan ran at a speed relative to the crankshaft speed. Good info.

 

[SlyBones]

Still learning

So the fans are two speed fans, so to speak... ...



I guess I have never heard it go off then. So far only once I have had the temp gauge go up over 1/2 way. I assume I should have heard it them. Maybe it was working and I just didnt notice ????



Like Dkevdog asked, can these go bad?



So does this mean the fan has two gears normal gear that I see while the hood is open and its sitting there idling, and "overdrive" when the temps get too hot?

 

[chuck3]

SlyBones, I guess thats one way to put it. All I know is when the temp. gets around 190 deg. I hear that baby kick in and like I said before I dont hear so good anymore, getting old ya know.

 

[Steve Campbell]

These viscous drive fans are activated by a bi-metalic strip, bi-metalic "clicker" or a bi-metalic spring(only types I know of. I have not looked at mine to determine which we have). When the temperature leaving the radiator starts to rise the dis-similar metals are expanded at a different rate and the metal deforms allowing a pin to move that opens a "valve" to allow the fluid coupling to take place. Visa-versa on the way back down in temp. I hope That was clear as mud!

 

[Dkevdog]

S Campbell, that makes sense to me. Assuming then that the fan is functioning correctly (like I said I do remember it being pretty loud) should I be concerned with the temps I saw?? And should I look in to auxillary fans or another way to increase airlflow??



Maybe I am hallucinating (sp?) but I seem to remember hearing about or seeing an aftermarket fan that replaced the stock and provided better airflow. Am I confused on this or is this possible??



Kev

 

[Steve Campbell]

Dkvdog, I had a 1982 Chev Diesel I bought used. The radiator was so plugged with bugs that the fan would not turn on until 225 deg. I kept trying to bad mouth the fan when the cure was to take the radiator out and pressure wash the bugs out from the back side. Problem solved!!! I see yours is a 96. How many miles and bugs on the rig? I would make sure that the radiator flows plenty of air before spending big bucks on a new viscous fan or going for the Horton on/off fan. The problem with the viscous fans is that they can't turn all the way on or off. Off is about 20% coupled and on is (depending on the style(clicker bi-metalic strip is best))between 85-95% of engine speed.

 

[Dkevdog]

S Campbell, the radiator is pretty clean, at least that I can see, and there is 47k on the truck. I was reading about the Horton Fan and it sounds pretty good, although it sure isn't cheap. Just for fun I'm gonna remove the lund stainless grill next time I pull it up the grapvine and see if it makes any real difference. I had not noticed any difference before and after the installation, but this is the first time I've had them on whil pulling the 5er on a grade. Ironically, the weekend before we pulled it up over the mountains at 7200 feet and didn't have the heat problem. The air temp wasn't quite as warm though. I found this while I was searching around last night, seems pretty interesting.

Evans Cooling



Kev

 

[mbrolin]

Kev,220 deg should be considered normal. Besides the engine coolant,in your case,you are also cooling transmission fluid. I have pulled with an auto and the temps can rise with the auto transmission working hard. My 01 HO pulling 19k never rose above the 0 on the 190 mark. That was going up the grapevine heading out of LA.

 

[Vaughn MacKenzie]

When running fast, 80+ mph in 110 heat my fan engages fully at highway speeds. I noticed it roaring away for several miles at a time. It seems to only operate in 2 modes, engaged or disengaged. Not really an in-between speed.



My temps would always creep up as soon as I pushed it up to 80 or so, to about 200-210 if I kept on it. But I think my cooling system could do better because I saw 2 or 3 other Dodge Cummins pulling HUGE trailers ( and a big boat on 3-axle trailer) doing close to 70 in those high temps. I noticed almost all the large loads were towed by Cummins power on my road trip



I am going to change out my T-stat in hopes of improving the cooling, but by the time the one comes in I ordered, the 100s we've been seeing for a week will have subsided.



Vaughn