Engine Operating Temperature

[chtr65]

Just fired up my 65 1/2 ton after having the original radiator recored, and I'm not sure what the operating temperature should be. It is a stock 283 with a 650 Holley. The temperature went up to 194 degrees in about 6 or 7 minutes of idle with the heater on. I just installed new transmission cooler lines along with the new radiator core. Thought maybe someone could shine some light on this. I thought the temp should be around 180. I did turn the heater off and the temp seemed to rise another 8 degrees. Would the temperature drop if I took it out on the road? Thanks for any help.

[cortcomp]

1) connect another gauge and/or sending unit because factory ones can often be off, or hit a hot spot on the head with a laser thermometer to make sure that the factory gauge is close enough to trust.

2) could be timing and fuel mixture, worn water pump cavitation, etc, etc. If you do drive it on the road and the temp drops, that's an air flow throguh rad at idle issue, or water pump at idle issue. I'd make sure i had a fan shroud with good side blocks, etc in place to make sure that as much of the little bit of air the fan is pulling at idle is going through the radiator and not from around it.

3) Did it run cooler before the rad recore? Did the carb or timing or anything else change recently?

4) Did you ever put a thermostat in? You might have a 180 or 195 stat in there. Get a 160 high flow (or drill a couple small holes in a regular stat to help let air out and so that it will flow if sticking). Even when i get a new stat, i get the thermometer out and put it in water on the stove and watch to see when it opens. You might just have a high temp (around 200) or sticking t-stat, or a vacuum leak so running lean, etc.

Definitely test drive it to see if it stays cooler to give you an idea where to look.

[chtr65]

Cortcomp, Thanks for your info. I just purchased the truck last Dec. I haven't put many miles on it since purchase. So, I don't remember what the gauge was reading. The previous owner installed a very expensive Stewart Warner gauge cluster in repacement of the original. I will be taking the truck for a drive this evening. Not far, but just enough to see if the temperature moves, and in what direction. It is mostly original, and has been very well cared for. I had started the engine with the heater on as a tip from a fellow that said it would help to circulate the newly added coolant. With the radiator cap off, so I could watch the coolant level, I noticed steam coming from the coolant in the radiator in a matter of minutes. Thats when I checked out the temperature gauge. I just didn't think the coolant would heat up that quick. But, then I never stood in front of the radiator and watched it before. As I try to remember from the few times I did drive the truck, I don't remember it being over 200 degrees. Anyhow, thanks for the tip on the different degrees of thermostates. I appreciate all your info. Again, I just didn't think an engine would heat up that quick. Thanks, Mike

[cortcomp]

Well, 200 isn't bad at all if it never went over, even in high heat, idling in traffic, etc. what you don't want is a truck that runs at 200 and goes for 220 in the summer. Let's see what that test drive shows, maybe a problem, maybe not.

[chtr65]

Looks like it went to 200 degrees on the temp gauge. Just 1 mile out the road and back. So I will check with someone locally that owns a mechanics garage, and see if he has a heat sensor gun. I might also pick up a new thermostat. I enjoyed jumping over to your thread and reading about your venture of driving your newly purchased c-10 home from the west coast. I can't imagine there are to many fellows out there that would do that. You must have had a great trip. And a good way to get to know your truck in a short period of time. Unlike myself, I purchased my 65 locally 2 weeks before Christmas. Drove it home and parked it. Roads weren't really suitable anyway for a couple of months. Now I finally have time to work out some of the bugs.

[cortcomp]

It was good fun but a lot of dreary driving in some areas, we were pretty beat! Other than the half a** paint job that was done some time not too long ago and some butchered underhood wiring, the truck was luckily solid so we could get away with that trip. Knowing now what i do about the truck, i would have paid a little less, and spent a day there putting tires on, brakes, connecting spare fuel tanks, etc. But i DO know that truck inside and out now you can bet!

If you have a harbor freight near you, you can get a cheap thermo gun there. Or you can go to any parts store, and buy a cheap temp gauge and sending unit and connect them up, just under the hood, to verify how hot you are before tearing things apart.

If you really are running hot, and the thermostat is good and a correct temp (under 180 i'm guessing is what you'd want, i run a 165 in my pontiac and it doesn't get quite warm enough to get nice heat out of the heater on cold days, so you can be too cool), and it's getting that hot that fast, i'm really thinking that you're running lean, maybe a vacuum leak or something, and i'd double check your initial timing just to rule it out. (I've had timing not be a big deal on some motors, but on one i did, changing it from 8-9 initial to 13 brought it down from running 210 all the time to running 170ish all the time. What a huge difference!)

I'm betting it's something basic, and we just need to cover the bases to find it.

[cortcomp]

You've done the quick check of pulling the dipstick to make sure it doesn't look like a milkshake from coolant leaking into the oil right? If that looks good, and you don't see a ton of white smoke out that back, that kind of rules out the likelihood of something big like a blown headgasket.

[Rich 5150 69]

Originally Posted by cortcomp

1) connect another gauge and/or sending unit because factory ones can often be off, or hit a hot spot on the head with a laser thermometer to make sure that the factory gauge is close enough to trust.

2) could be timing and fuel mixture, worn water pump cavitation, etc, etc. If you do drive it on the road and the temp drops, that's an air flow throguh rad at idle issue, or water pump at idle issue. I'd make sure i had a fan shroud with good side blocks, etc in place to make sure that as much of the little bit of air the fan is pulling at idle is going through the radiator and not from around it.

3) Did it run cooler before the rad recore? Did the carb or timing or anything else change recently?

4) Did you ever put a thermostat in? You might have a 180 or 195 stat in there. Get a 160 high flow (or drill a couple small holes in a regular stat to help let air out and so that it will flow if sticking). Even when i get a new stat, i get the thermometer out and put it in water on the stove and watch to see when it opens. You might just have a high temp (around 200) or sticking t-stat, or a vacuum leak so running lean, etc.

Definitely test drive it to see if it stays cooler to give you an idea where to look.

You really don`t want to put a 160 thermostat in, you`ll want to use a 180 or 192, this actually slows the water down in the radiator and gives it more time to cool down giving you more stability in the coolant.

[chtr65]

Everything like the major problems have been covered. Like engine oil level, no wild noises, no obscene smoke. It has been for the most part very well kept. I did talk with a local mechanic this morning. He advised me to stop by and he will gun the radiator, and then the engine for temperature. He also advised me to go to a 160 thermostat. I should have replaced it when I had the radiator out. So, well check temp first then move to a 160 thermostat. Also wanted to mention the work your doing to your truck is more than impressive. It's down right professional. Nice work! And thanks for all your help.

[cortcomp]

Thank you for the compliments, thats good to hear, especially since i havent done a lot of the body type work before, so im a little nervous.

On the thermostat issue, a lower thermostat doesnt flow more or less when open than a higher rated one, it just opens at a lower temp. In theory, if you had no thermostat, the motor should never heat up (i've had that happen on a 400sb). Putting one in prevents flow to the radiator until it hits its rated temp, then it opens and system cools down until it closes, then it heats up, but really it just finds its balance between the thermostat and cooling system, and stays steady.

However, i have also personally seen problems where no thermostat causes overheating. It is thought that the water moves through the radiator too fast to have the heat extracted. Thats my belief, not sure if thats why but putting a thermostat in fixed it. Some racers will use a restrictor in place of a thermostat to provide that slow down while running but not as much as a stat.

So what rich is saying can happen, but it's from having no thermostat vs one rated at like 160.
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[Rich 5150 69]

Chtr65 has not stated all his truck has such as a radiator shroud, what LB cap he is running and is it new, overflow tank, is the timming (centrifical and vaccum advance correct ) especially the latter will really affect temp, noting that his rose quite quickly I would investigate this first...!

[donthekawguy]

Sounds like you have air in the system. Try squeezing the hoses when it gets warm enough to open the thermostat.