Good morning from Cincinnati!

I have a 2000 D2 with 141k. The only thing it needs (today anyway) is help running cooler. I've owned it since November 2012. I thoroughly read your collective posts prior to buying. I was able to verify it had the rebuilt prop shaft and new head gaskets. All service records were available through 80k. Pretty sure the previous owner dropped some $$$ keeping it on the road. Now it's my turn I guess. Since November, I've converted to coil springs from sls, new thermostat (oem, should have done 180), new upper radiator hoses, new Toyo Open Country tires, an ultra gauge, and I just did the fan clutch Saturday. Also, I've checked all fluids, greased fittings, etc. I really enjoy driving it. It's a second vehicle I plan to use for hauling mountain bikes, camping equipment, flannel shirts, my beard, etc. I hope to get to a point with the truck where I can balance the ratio of hours driven to $$ and time spent servicing/maintaining. We'll see...
So I decided to go ahead and register/post today as I may need to ask for help soon. As I mentioned earlier, I changed the fan clutch Saturday and did not get the results I wanted. Engine still running much warmer than it should. About 208 on the highway, 217 under higher engine load. Temps stay consistent, but consistently high. My plan is to try the motorad 180 T stat next, possibly next weekend. If that doesn't do it, I'm afraid it may need a radiator.
Either way, I've got to get it running cool before summer gets here. I'll jump in the correct thread to discuss.

Thanks to all of you contributors who help so many more than you know. And...

Hello, I'm John and I'm a D2 owner.

 

Welcome. I'll move you to the D2 section.

Agree on the 180F stat.

There are only so many things to check on a cooling system. And there can be more than one problem. For our diagnostics today we'll need your truck keys and your Mark I Palm Reader (right or left hand, we don't discriminate). And a paper towel.

Open hood, engine cold.

Coolant level at same place on reference mark on jug? You need to have a frame of reference for how much is being lost, if any.

Use key or other slim object to spin electric fan mounted to AC condenser (the front radiator). It should spin freely. Any binding indicates a siezing motor, and it can blow the fuse (F5 - 40 amp) in the under hood fuse box. You should have heard the fan coming on at times with your heat.

Now examine the fins of the radiator and coolers. These form a sandwich in the air stream. If they are plugged with mud and leaves and road trash the air flow is restricted.

Next is the mechanical fan which is mounted on a viscous clutch on the water pump. With engine OFF, spin fan by hand and release. SHOULD feel like peanut butter inside, continues to spin maybe 1/4 turn or so when released.

Crank truck, and allow to warm up to a stable temp on the digital gauge. By now you have notice the stock gauge does not care how hot you are, it will lie as long as possible. 50% on the stock gauge can be 130F - 240F. Use a paper towel and see if airflow will hold it against grille, not blown away forward. Air should always be moving toward block. Fans can be mounted wrong, belts routed wrong, and electric fans wired reversed. Once warmed up turn off the truck.

Repeat spin test on radiator fan. May spin a little more, but should not go more than 1 revolution. Freewheeling indicates fluid has been lost from clutch, time for a new one. A cheap option is for a Chevy 2000 Express van, 4.3 liter, w/o AC. Will have to enlarge fan bolt holes slightly.

Locate a spot on radiator fins that you can touch, both top and bottom in a vertical line. If top feels much hotter than bottom, by 10F or more, radiator could have sludge inside, it won't clean out. The passages are too small, and the mud from old Dexcool is stiff. While the D1 era radiators were copper and brass, and easily rodded out, the D2 is replace. We will see more of this with the LR3 crowd, because the dealers follow a practice of life of coolant equal to years of payments times 2. Lifetime coolant is not a good idea. Now if guys had been flushing the radiator every three years and replacing coolant, never using tap or well water, then things would be better.

If you like, a digital IR thermometer will protect your hands.

The remote thermostat design of the D2 depends on a sample of hot coolant flowing into small holes on top of the stat to mix with cooled fluid returning from the radiator and "wake up" the stat. If those holes are clogged with trash it can shift temps higher. By changing stat you get a new clean one, and lower temps to begin with. But don't skip testing the radiator, one that is 66% of what it should be because of clogs won't help in summer.

 

Sometimes a plumbing plan flow chart is a help. Frequently the bleeder hole will become damaged, and there are brute force ways to adapt that.

 

Thank you very much! I'll look over everything this week. Going to pick up an IR temp scanner to check out the radiator.

Again thanks for the advice and warm welcome!

 

Just opened the two pics you sent... Changing thermostat and flushing tomorrow, so studying a little.

Is that a cast iron tee? That's awesome!

Thanks again.

 

Several members have made new T systems, this variant has the bleeder valve inclined so the hood won't bump it. Having a clear hose lets you bleed, rev engine up, etc., and force as many bubbles out as you like while the overflow goes into a bucket.

 

I'd be interested in buying one.

Changed to the motorad 180 T Stat today. Temps range from 190-194. That's down from 208-217. Amazing something that cheap and easy improves the cooling system so much.

Thanks again for all the info.