Running Hot - Help!

[J-Roger]

Hey all, I have a 93 Hardbody with the KA24E 4 cyl motor in it. Earlier this summer my truck went down while driving on the freeway. I took it to a shop and had them do a diagnostic on it. They said my timing chain had slipped or broke the guide and wore a hole in the timing chain cover as well as water pump (getting coolant and oil mixed together). Also the fan clutch needed to be replaced.

I got all the parts I needed from a friends hardbody (minus new gaskets and such) that he had recently replaced most the parts under the hood, then wrecked it and was preparing to take it to the junk yard.

Tear down and putting it back together went fairly easy. Truck fired right up and ran quieter and smoother than it ever has in the 6 years I've owned it. The only problem is that it runs very hot to where the water is boiling out of the overflow tank. Since I had put the original thermostat back in I thought this might be the issue so I got a new one, installed it and had the same issue. At that point I took it out, buttoned it back up and ran it...viola! No overheating at all, sweet! I checked both the old and the new thermostats in a pot of water on the stove and they both opened up around the 185* - 190* mark. I took the new t-stat back, got a third one and installed it...bam, back to running way hot!

Here's some other things I've noticed that will hopefully eliminate some possibilities or give you guys more info into what's going on.

- When a t-stat is installed the upper radiator hose gets hot while the lower hose stays cool. With no t-stat, both hoses are hot.

- Radiator gets hot near the upper hose while the rest of the unit is cool. It takes several minutes for the rest of the radiator to warm up

- Before the truck broke down it used to run very loud since the fan clutch was always engaged. Now that I have a newer fan clutch it always sounds the same...I dont hear it engage even when first starting it up. Not sure if this means anything

- While bleeding the system I had a hose in the radiator and the bleeder valve opened up. Water shot right through like a geiser (not sure if this indicates a good flow compared to a blockage somewhere)

- There is no white smoke, knocking or pinging that I can tell.

Thanks in advanced for the help. Just want to get my Stomper back up and running!

[RT22]

You have air trapped in the coolant system take to a radiator shop and let them pull a vacuum on it to extract air. Air pocket of air in a block will do this if system is not purged correctly. Some engines have bleeder spots to help in this. Not sure if this one does but a radiator shop can do it for little cash. Or first when cool open the cap and crank and as it heats up and thermostat opens it may pass the air pocket out.

[seang]

- When a t-stat is installed the upper radiator hose gets hot while the lower hose stays cool. With no t-stat, both hoses are hot.

- Radiator gets hot near the upper hose while the rest of the unit is cool. It takes several minutes for the rest of the radiator to warm up

This is because the cooling system is so efficient. With a Thermostat, the coolant eventually gets hot enough for it to open, causing the cool water in the lower hose to pass into the engine, where it can get hot again. The system is so efficient in fact, that the fan clutch can be considered overkill in my opinion. Personally, I run a small 3.75 amp electric fan, no thermostat, and 2 different size winterfronts for varying weather conditions, all help to keep the temp right where I want to see it, which is just into the normal range on the stock gauge. Sure, its more for me to worry about, but I'm just like that.

[RT22]

why not run it stock and get same effect and simpler and it was designed by Engineers LOL