91 Mini Cab running hot

Just bought the above mentioned truck and it gets all the way to the high end of the temp gauge after about 20 miles of running at around 80k speed.

The thermostat was replaced shortly before I bought it.

Added approximately 20 oz water to the radiator so it wasn't low or dry.

I have checked the radiator for a drain valve but can't locate it. I was going to drain a sample to see if there was excess rust, sediment ,etc in the fluid.

There is a little bit of coolant in the overflow tank and that looks normal to me.

Surely there is a drain valve for the radiator but it is artfully concealed.

Can anyone tell me where the drain valve is located or give me any ideas on what the problem might be?

Thanks

 

Is your fan working? make sure it is not spinning backwards

 

Running Hot

strick4,

Welcome, as for your truck the drain plug would be on the bottom of the left side of the radiator (as you are sitting in the truck). It's kinda hard to see but get under and look up you will find it.

Your overheating could be one of several things. It could be air locked. These trucks are finicky about refilling the radiator and keeping the air out of it. It could also be a weak/tired lower radiator hose collapsing (due to heat and rpms). Another overlooked but simple thing is your radiator cap (this can also cause a hose to collapse).

Tidbit of info:

A radiator cap has several functions. (1) It keeps the cooling system sealed from outside contaminants. (2) By keeping pressure on the cooling system, it raises the boiling point. (3) The radiator cap allows coolant to go to the expansion recovery tank when coolant gets hot, expands, and pressures increase. (4) As the system cools down, it allows coolant to return to the engine from the expansion recovery tank. A bad radiator cap can cause the engine to overheat at lower temperatures. This will cause the coolant to boil over to the expansion tank. A radiator cap that is faulty could also prevent coolant from returning to the engine. This would create a vacuum and cause the radiator hoses to collapse.

If you replace your cap you need one with 11-15lbs (psi) or for our Canadian Brothers 75-105kPa.

I've found that a Geo Metro cap is the same......Hope this helps..........later, slim

 

starpuss the fan is blowing a hurricane in the correct direction.

I am checking trying to find the correct method of bleeding the air out of the system now as I am thinking it may have an air lock since the thermo was changed lately and I opened it to add water.

Thanks for the response.

 

Hey Slim thanks for the response.

There is a valve mounted on the thermostat housing that has to be the bleed off valve but not sure how to do it.

I am thinking that I get the temp up to normal and then open the valve for a time but not sure. There is a hose on the valve that goes out of sight over the engine and not sure where it ends......don't know what else it would be though. (I am looking at some manuals on ebay now for the truck...........I hate trying to "dope" out the function of the various parts......LOL)

If that fails I will replace the cap ....thanks a lot for the tip on a replacement.

 

Also, listen for bubbling or gurgling. Sign of pressurizing the cooling system (bad head, head gasket, cracked block, etc. )

And again, check for hoses getting sucked flat. The rubber deteriorates and actually will suck down, blocking flow in some instances.

 

To ALL:

The problem has been solved!
>
> Turns out that the overflow hose from the radiator to the tank had a
> worn spot that leaked. It would blow the fluid out when hot but could
> not pull a vacuum when refilling due to the leak.

The fluid would hit the hot motor and evaporate and I couldn't see. I found it while flushing the radiator and happened to open it when it was a bit hot
>
> Thanks for the tips on what to check. I found a few things that will
> bear watching.
>
> Strick

 

93 suzuki running hot then not

When I got my 93 suzuki the first night it would heat up to almost redline then drop down, the heater would only blow warm air right after the temp would drop.

Opened my radiator the next morning and wow, almost solid rust/sediment colored liquid. Ran some flush, heavy duty cleaner through it and flushed it a bunch of times with tap water (filled it, capped it, started it, ran it, shut it off, emptied it, repeat), when finally clean, put some anti-freeze coolant in it and now runs at constant temp, and heater works fine. The hose to the overflow tank was almost completely clogged.

Also replaced my radiator cap, but my original that came with my truck was marked for only 9psi. Found a match at my local parts counter, I don't know what it was intended for, but was marked for 9psi as well and fit, seems to work.

My drain for my radiator was also 'hidden' on the bottom, back side of the radiator opposite side of the lower hose. And thanks to whoever posted on another thread that to remove the front clip from a suzuki look for the clips on the inside of the cab by the accelerator and opposite side! B