The Stovebolt Site Forums The Shop Area Engine Shop Thermostat question

I have a 54' 3/4 Chevy and the other day I got in it to go for a spin. I let it warm up to operating temperature and took off. On the way down the street the temp started rising pretty quickly I pull over right away and it almost made to the "H" side of the gauge. I stop and then the temp dropped almost immediately to the normal range. So do you think that the thermostat was stuck and then opened up? If that is the case should I go ahead and just replace it? This was the first time it has ever done this. Also what temp should I get for a thermostat? They offer a 160,180 and 195 degree thermostat. Keep in mind this truck is all stock. Thanks guys.

I like the 180* myself. Run one in my 65 c-10. Stays around 190-195. best of luck to you.

I believe that could be your thermostat sticking. I have had the same symptoms in two of my trucks. In one, it resolved on its own without doing anything. The other still does it, a non Stovebolt, but never goes more than 10 degrees above and eventually settles down after 20 minutes. It is not that hard to replace the thermostat in any case. I would recommend 180 degree.
Kent

160 is what was oem for your truck, which is what I would suggest.

OEM is what I'm looking for I think. Thanks for the replies guys.

Keep close eye on it at first. About 1/2 the new therm we get are defective. I prefer the 180 degree myself in your climate.

OEM, original equipment manufacture would have had a brass accordian bellows. I don't think you want that one. I would look for a well known Brand Name t-stat. Find one with the small hole off to the side which allows air to be purged when you refill with coolant.
Carl

I replaced it with the 160. The book said 160 or 180 would work fine. It runs a little bit cooler now and it seems to have fixed my problem. Its about 42 degrees out here and the heat still felt hot. I wont be driving it for very much longer anyway, this truck will never see snow again lol.

180 is the normal temp on a thermostat unless there is a issue with the vehicle or extreme climates.

Exgie,

Welcome to Stovebolt.com

180 degree normal temp - operating temp or thermostat-rating temp?

What engine size, year, and size-truck?

The original poster referred to a 1954. One thermostat rating for that engine was 160 - fully opened at 185 degrees. Another thermostat for that year was 180 - fully opened at 204.

My 49 216 had an old Robert Shaw 160 bellows type stat in it when I got it.
I changed to a modern 180 to see if it would do away w/the condensation build up in my valve cover in the cold weather. It didn't....
With the 180 the temps avg a hair over 180, maybe 185 - 190 so I put the 160 back in it. Temps now avg 170 - 175 which I'm happier with.
My owners manual calls for either.

Dave

You won't have any creosote build up if you only burn hardwood and no pine. I agree with running any engine on the hotter side. Modern engines take advantage of higher operating temperatures for better performance. Hard for us to run at similar temperatures with a 4# radiator cap.
Carl

I suppose it's like everything else with these old trucks, that is whatever you think works best. The 180 degree thermostat ran just below the middle mark of temp gauge, while the 160 degree runs right between the 1/4 and middle mark of the gauge. Even though it runs 20-25 degrees cooler now, it still runs fine with no difference in the performance of the motor. I still have good heat in the cab for 40 degree weather. If I ran it in the winter time I would have more than likely put the 180 back in. This truck doesn't see rain let alone snow LOL!!!! Other the than the position of the needle on the temp gauge, I see no difference.

The down-side of higher operating temps is that it makes the motor more knock-sensitive, requiring;
1. less spark lead, initial and/or total
2. slower advance curve (more spring tension)
3. richer mixture
4. higher octane fuel

I have run a 180 for the last 2 tears. Downside is swamping at a short stop. Will go to 200 indicated, and it takes for ever to get it to cool down. This is in summer and with a new radiator. So I am thinking about a 160 just to give a bit of a cushion to the recovery. The truck does not like the higher temp. It will surge and Idle rough until it cools. 235 in a 52 1/2 ton and here in Utah with a lot of 90 degree days. It is my daily driver so it sees, rain and snow, but I do avoid the slippery stuff as much as I can. If I were to do it again, I would use the water pump relocation plate and move the fan up to the center of the Radiator. It has to work better in the right place.

Changing to a 160 thermostat won't make any difference. You have some other problem. Once the temp gets to 180 the thermostat stays open under normal conditions. Only thing that will change with a 160 thermostat is it will open sooner. If you put in a new radiator without flushing out the cooling system then your new radiator is probably got a bunch of crud in it from the block. Feel it with your hand. Start in the center and feel out toward the edges. If its cooler in the center and gets hotter toward the edges then its clogging up.

That is most likely your problem. There's a couple of things you can do to help the situation besides the relocation plate (though that would be the best solution). One would be to add a shroud around the fan to make it pull the air through the radiator rather than from the sides/bottom. The other would be to add an auxiliary electric pusher fan to assist the main fan, particularly when the truck is sitting still.

I am willing to bet my entire collection of salvaged clutch head screws (I am queer about them, BTW) that your over-heating problem is the water pump/fan location. Way too many people going through the trouble and expense of making that mod for it to be unnecessary.
Carl