Engine temperature change?

[Tony J.]

So, I'm getting ready to take my first towing trip this weekend with the "new" 6.5 we just got. It's already warmed up to upper 80's here in AZ. Around town, my stock temp gauge shows about 160-170. My 95 doesn't yet have the high-flow water pump, although I will be doing that in the near future. My question is, how much temp increase do you guys usually note when towing vs. not towing? I'm towing an ~8,500 lb. toyhauler this weekend, mostly flat interstate, only one good grade that's about 4-5 miles long. I'm looking forward to adding trans temp, EGT, and boost gauges so I can more closely monitor these things, but haven't gotten them in yet... Think I'll be okay this weekend??

[DBlake]

You should be okay for a weekend trip. I hauled my 7Klb 5th wheel to Organ Pipe Nat Mon. December 2002 without any mods or guages on my truck. Came back through the valley and then up towards WM via Payson without hurting anything. The biggest problem I've seen is EGT when towing. Maybe I'm just paranoid but I like to keep it below 1250F (preturbo) at all times. When pulling a hill while towing it can quickly exceed that number and push much higher if you let it. I think the PCM will shut you down to the "limp" mode if it goes too far, but I think you may have already done some damage if that happens. My suggestion is to just take it easy on the hill. If there is a headwind on the interstate - don't push it. I know it's 75 but that can also make you exceed a safe level. I think your tranny will be fine. The only time I ever had a problem is when grades exceed about 5%, I slow to lower EGT, and then it drops out of torque lock. Hope this helps.

[ucdavis]

Biggest trouble on a stock '95 is the accumulation of bugz'n'stuff between the radiator & AC condenser that can cause inadequate heat exchange doue to clogging of radiator airflow & elimination of good heat exchange to the clutch for the belt driven cooling can. If you start hitting over about 210 and haven't heard that fan kick in (you'll know it when it does, sounds like a jet engine under the hood) then you have some sort of inadequate airflow to the clutch. If you hit about 240 (and that means you are already in deep doo-doo) the PCM will shut down the fuel & kill the engine. PCM doesn't have an egt reading to follow so it uses coolant temp which is a proxy of head/exhaust temps that can crack castings, but coolant temp comes only after high egt's have pushed up metal temps quite a bit.
If you hit that long grade & have a gear where you can favor lower RPMs, do that. My rig will put out a given MPH and all the fuel I put to it after that won't give me more speed (meaningfully, anyway) but sure pushes up the EGT fast!! The extra fuel goes into pure heat, no go. And higher RPMs spin the turbo which pushes up intake air temp to add to the problem. Loser RPMs and less pedal to the metal will keep your temps in line.
My rig is currently parked @ a new resort @ Lake Havasu, so wave if you go by.

[Tony J.]

OOPS- I just got to looking at my water temp gauge, and I sit normally around 190, not the 160-170 I originally thought. Are there any sort of checks I should do to my coolant tomorrow that might help cool things down? I'm going to take a look at the bug buildup and see if I can do some cleaning before we go. I sure hope we don't have any problems! I'll keep an eye on the temp gauge for now, since it's all I've got.