Well.. I've got another update. I was driving the other day and back up to 201 in traffic... with 70 degree outside temps. Once I started moving the temp would go back down to 190 / 194. I'm wondering if my previously stated temps were because I was running the heater as well. But the temperature did drop significantly with the new viscus fan.

I ordered a new water pump for peace of mind. We'll see.

 

 

I'm going to check the radiator tomorrow, but... do you think it could be an issue with my thermostat?
I've got the 180 degree one... with only 3,200 miles on it.
Is there a way to test it?

 

Dude, you've posted that you get cruising temps in the 180s. It's not the thermostat.

 

So here's the latest and I'm not satisfied...
I replaced my radiator as it was warm at the top and not the bottom. Looking inside at the hose connections it "seemed" to look ok though.
Once it was replaced, I was back to idling at 194. It took a while to get there as the weather has been cool. Everything was great.
But lately the temps have been creeping up to 195.8 then 197.4 then up to 201 today. Granted 195.8 is negligible ... but originally I was running 194 pretty steady.

The water pump seems fairly solid when shaken... with belt off. It also spins freely. I noticed in the expansion tank that coolant (I'm assuming) was shooting up or moving quickly in the back corner where the small hose (throttle housing return pipe) comes in from the bottom. NOTE... my throttle housing has been bypassed and the throttle housing return pipe attaches directly to the top of the motor... where I'm assuming the throttle housing inlet hose would connect. So I'm not sure if coolant would be shooting back into the expansion tank in my case or if that's normally how it would operate if it was connected to the throttle housing.

I have a new water pump on hand that's easy enough to change. I guess it wouldn't hurt and would eliminate a possible cause of overheating.

What are your thoughts? What's next? Any symptoms I'm not considering?

 

What do you run in motion, that is pretty similar to mine. Sitting at a light she will go up from 188 to 197.5 ish, maybe as high a 201 until the fan a clutch fully engages then back down to 190 - 194. In this state once I get moving the temp can drop as low a 183 for a couple of minutes. Moving I run a pretty solid 188.6 as long as my RPM are above around 1700. In drive at around 1300 she gets up to 190 -194 even at 60 KPH.

These trucks should be able to take as high as 215-220 without issue so if you never get above 203 you are fine.

 

That is how it is supposed to be. Hot coolant comes in the top of the radiator, filters through and cools, then exits the lower part of the radiator.

My thoughts are you should just drive your truck and not be super **** about the temps. They are going to fluctuate naturally and each truck will regulate heat differently than others.

It was in the upper 20's the other night and my temps were 194 but earlier today they were 186 in slightly warmer weather

 

Thanks guys. I am new to old L.R.s., and more of an old motorcycle guy. I can be pretty **** about stuff. I did build a 40 year old Harley that doesn't leak.

So, I'll keep an eye on it. My concern was that once I got my Ultragauge it never really went over 194. Then it started to creep up... I replaced the fan clutch and it was better for a bit... then replaced the radiator and it was good... then started to creep back up.

Also... I do know how a radiator works... just not sure how my bypassed throttle housing would effect things.

I'm also using this site for some input, which I appreciate, and to "talk out loud" for anyone else interested in the problem.

With the weather in the 40's... I've been cruising at around 194... then when I'm going through traffic and hills around Atlanta it will creep up then maybe back down to even 190. But recently the longer I drive it will go up to 201 when I stop.

 

 

I'll just second what Richard Gallant and Best4x4 stated. I've got a 180* thermostat and cruise down the interstate at about 186-188. Sitting in traffic or at a long red line it will get up to about 194. On occasion I've seen it creep up into the low 200s, but it always drops once I start moving down the road again.

After doing all this work on my D2 and really wanting to extend it's lifetime it's been hard but I've started to learn to trust it again.