Over heating delemna??

[dillfarmer]

Yesterday on a return trip to Anchorage, I noticed a burning melting smell which quickly subsided but was followed by the unmistakable smell of antifreeze.
A quick check of my gages (running near dark at 11:00pm), I saw my alternator wasn't charging and my temp was rising quickly. I pulled the truck over as fast as I could and shut it down. A quick inspection revealed a broken belt and a bit of lost antifreeze through the valve in the radiator cap.
The nexty morning I secured a new belt and installed it... A quick trip down the road revealed rising temps (up to 220). I pilled i nto a parkinglot and (upon cooling) removed the thermostat...

Note: This is my 1968 chevy 3/4 ton pickup...

Another quick run lead to more high temps...
I purchased and installed a new water pump..
Upon an inspection of the old pump (out of curiosity), I found it to be in good condition internally....
This leads me to conclude that the problem may still exist??
Tomorrow I will install a new thermostat, and antifreeze...

Question: could the valve on the cap be causing the problem?
What else could there be??

Note 2: I'm currently stick 70 miles from home, with 3 dogs, limited funds... I really need a fix..
Any help is much appreciated...

regards...

[King Cary]

The thermostat could have jammed and removing it lets the water pass through the radiator too quickly not giving it enough time to cool. Removing the spring and all the guts from the thermostat will slow the water down enough to cool it... (Like a big washer).. It's just enough to restrict the water... Second thing... Does it have a clutch fan? If so that could be your problem because it's not pulling enough air...

[dillfarmer]

Yes it has a clutch fan.... I have watched it turn while running.. It looks good, but I don't really know enough about these things. I can swap out parts but I don't always know how they work.
This happened suddenly.. The truck always ran at about 185 degrees and was very consistant...
Also??... If my water pump was turning okay, and my power steering pump is okay.. thn what caused the belt to break? It appear in good enough shape other than the break.. No long term burning etc... I'll take a pic and post it....

[King Cary]

Sometimes belts just break.. Also check your bottom radiator hose and make sure it's not soft and sucking shut, it should have a spring inside to keep it from collapsing.

[72_Cheyenne_Super]

Depending on how long you ran it like this it might be something more serious but agree with checking the thermostat as a first step. If you havent already drained the coolant do a running test to see when the thermostat is opening; it should be much cooler on the outlet until it opens, if the outlet feels like it is warming up gradually it is a good indicator it is stuck open. It should have a very noticable change in temp when it opens, it should start to get hot on the outlet side about 10 degrees before full open temp (185 etc).

At the ambient temp it is in AK right now I am doubting one stuck open is the cause though; undercooling in the rad is generally only a symptom that is problematic in high ambient or when pulling a trailer...I have run a lot of performance engines with fixed orrifice setups which is really acting the same way as a t-stat stuck open. If you are lucky the t-stat is stuck closed; if you are unlucky you might have damaged a head or head gasket.

The most useful tool for troubleshooting this type of problem is an IR heat gun, during the run-up test shoot various areas of the cooling system and cylinder heads to look for hot spots and temp changes.

[dillfarmer]

I'm something of a gage watcher. This truck never ran hot before.. When i noticed he smell.. (probably of the belt) I started checking gages and when I saw the temp rising too, 240 I pulled over and shut her down.
I was running empty.. temps are cool, here (mid/high 60's during the day) so I thought removing the thermostat might work.
This is my short run work truck, but has always run extremely well, and never had a issue. If it is the head, them IK'm toast. I'm stuck 70 miles from home wih no shop and no resources. I work seasonally. And since it is still May, that means I'm broke. if it isn't something simple, I'm walking away... literally..
I'll try a new thermostat today. The hoses look okay but I'll check them too once I get it started...
Thanks y'all...

[King Cary]

Hello Dillfarmer, I wanted to know if you were able to get your truck running?

[Norcal72]

Dildfarmer, sending good karma and thoughts. Good luck buddy.

[dillfarmer]

Hi guy's....
As a matter of fact I did get it running. I did replace the thermostat as well. I refilled the radiator and fired it up this morning.
It started and idled great (as usual)...
I let it warm up good and the temp never rose above 190 degrees...
I have determined that it probably wasn't the water pump after all.. (well at least I have a spare now).. unless they can go bad while still being tight, and turning freely! (?)..
Somehow I have trouble believing it was the thermostat either...
However the problem seems to be corrected, at least for now.. I'm currently leaning towards it being a collapsed or vaporlocked lower hose?...
In any event I'm ordering a replacement..
Thanks for all the input....
This incident is proof positive that I don't need to be in the bush to live extreme.. three nights sleeping in my truck without any outdoor gear with, and temps near 40 degrees at night.. no heater to warm me neither!

Here is a pic of the ol gal... (Penelope)... until this episode she has been a solid runner since the day I got her started..

[72_Cheyenne_Super]

Glad to hear it worked out and at the lowest cost option...Murphy must have taken the day off

[dillfarmer]

Yeah... The water pump was only about $32.00 I had a flashback to the 1980's....

[SS Tim]

Good to hear you are up and running.

[King Cary]

Hello Dillfarmer, I glad to see you made it home and your truck is running good and you didn't hurt anything. Glad it was an easy fix and you will always have a wealth of knowledge at your fingertips. Between the C10 Truck family we can always put our heads together and figure out anything.

[brown7373]

If the thermostat fixed it, I'd think it failed. And not in the open position. If it failed in the open position, then it might affect warm up, but it would be in the correct warmed up running position, so it wouldn't cause any problem, unless it was very very cold and it was needed to restrict flow to keep the engine at operating temperature. If a clutch fan fails, it would only affect low rpm driving. Once the truck got moving down the road, a clutch fan disengages and free wheels. The airflow doesn't come from the fan, it comes from air flowing through the radiator because the truck is moving. If the clutch locks up, you would hear the rushing air when at speed.

I had a perfect running 69 Corvette have a thermostat go bad, but it wouldn't open. Like a light bulb, just because it works this morning doesn't mean it will work tonight. My t-stat was locked shut, or nearly shut and my gauge pegged. I had to let it cool, then drive a short distance repeatedly until I got it home. I had ben stuck in 4th of July Fireworks display traffic at the time.

[dillfarmer]

Originally Posted by brown7373

My t-stat was locked shut, or nearly shut and my gauge pegged. I had to let it cool, then drive a short distance repeatedly until I got it home. I had ben stuck in 4th of July Fireworks display traffic at the time.

That is basically what I did.. I was about 400 yards from the exit ramp to a wal-mart... It took me from 11:30pm to 4:00am to get there.....
It was a very chilly night.
In hind site I wished I had looked at the lower hose to see if it had been sucked in, but my mind was racing ore towards worst case scenario's, rather than anything simple....
I'm just glad I'm a gage watcher... When I smelled the burning rubber I knew it wasn't engine smell, but I smelled it before the antifreeze..
In all I lost 1.5 gallons or so, of fluid from the system.. including what I could not recover in the pan ( an old feed bucket I was using as a dog bowl on the trip), during the water pump change...
How much of that was lost during the initial venting of steam from my radiator cap, and the reservoir hose that had blown out of the jug is not known..
I'm sure I'll need some assistance in the future... But overall this old gal runs great after years od sitting in a parkinglot.. (2004)...
The best part was.... she was given to me....
I couldn't beat the price!