new radiator... still hot

[courage 80]

I recently was given a 65 step side from my father in law. The owner before him put a 350 from a 74 pickup in it. I have rebuilt the carb, and put new a suspension in it.

I just replaced the radiator with a new one from autozone (it is a 3 row). I told them that it was for a 65 c-10 pickup; HOWEVER, I forgot to tell them that it has a 350 engine. They put in their computer that it had the V8 ( but the only option for it is a 287 not 350)..... I just did the install today and figured that the 3 row would cool sufficiently since it only had the old half clogged one before.

I also replaced all the hoses, thermostat 190*, and the radiator cap.

I let it warm up and then took it out for about 15 min. The needle went all the way to the (H) and then stayed. It didn't overheat, but I didn't push it to see if it would leave me standing there.

SO, I guess I am wondering where to go from here. Thanks

[1966gmc]

Just for giggles what kind of gauge are you using? Are you using a mechanical sunpro type gauge and maybe the line is too close to hot engine parts? Any evidence of the coolant trying to boil?

[courage 80]

I am using the stock gauge cluster temp, with the sensor from the 350. The wire connects to the engine on the driver side just behind the 1 plug. I have enough wire that it goes straight to the inner fender then to the fire wall.

I haven't tried to see if it will boil over. I live pretty far from civilization and didn't want to have to walk. Maybe tomorrow i will see how long I can run it.

[Chevy Fleetside]

The omh are differnt in that 74 sending unit. The truck really isn't overheating. If you can get it hot and open the radiator, really slow so it don't boil on you, and stick a thermometer in and take a reading. If you they sell radiator caps with temp gauges built into them.. http://store.summitracing.com/partde...5&autoview=sku

[courage 80]

besides the cap, is there a way to set up the sending unit to work with the gauge inside, or is there a kit set up to put another gauge in the cab.

[1966gmc]

Just go to any parts store and buy a mechanical gauge.I think they are less than 20 bucks and very easy to install. I bought the Sunpro triple gauge set-up. Oil,volts,and temp for less than 50 bucks at Pepboys. I think they are wayyy more reliable than the stock gauges

[courage 80]

do you have to remove the sending unit in the block or is it a different type of temp sensor? if it replaces the current sending unit, do I have to drain the coolant to switch them out?

[1966gmc]

There is a fitting that you can screw into the intake and run your line from there.You can leave you stock sending unit in the block if you wish.It would be advisable to drain some of the coolant so you don't make a huge mess

[Chevy Fleetside]

If you put a 32 or 33 ohm resister on the wire that might get it right. You still have to stick a thermometer in the upper tank. You can run the engine with the radiator cap off and wait for the water to circulate.. You will be able to tell then steam comes out of the radiator. Watch the gauge also. I used a 32 ohm resister inline and it was close.

[PrerunnerRob]

I dont want to sound like a smartass, but are you sure the water pump is circulating coolant?

[courage 80]

as far as I can tell it is.... the upper hose gets pressure but I dont see a lot of movement of the coolant when I take the cap off ( before the pressure builds, and it gets too hot)... is there a sure fire way to tell without just pulling it and
replacing it

[rickf]

Originally Posted by Chevy Fleetside

The omh are differnt in that 74 sending unit. The truck really isn't overheating. If you can get it hot and open the radiator, really slow so it don't boil on you, and stick a thermometer in and take a reading. If you they sell radiator caps with temp gauges built into them.. http://store.summitracing.com/partde...5&autoview=sku

I've heard that before about the ohm rating. What year did they change?

I put a 71 GMC 350 in a 64 C10, I connected the sender that was there (no way to tell if it is OEM though, but it ws connected to the stock gauge in the 71 GMC it came out of) to my stock gauge, and it works fine. I have a second gauge connected to a second sender (in the thermostat housing), these are a matched set, and the reading is consistent between the two gauges.


As for the overheatig problem... there's been no mention yet about the fan and shroud. Is the stock fan (I presume clutch fan) in place and working? Fan shroud in place?

[courage 80]

Yes the stock fan is there with a fan shroud. As far as I can tell it is working.

[Chevy Fleetside]

If your engine was getting really hot when you were driving the power would go away. Also steam would come from somewhere. It takes a while for the coolant to flow so be patient. If you want you can remove the thermostate and boil up some water and make sure that it is opening. Sometimes they are defective.. Basically put a pot on the stove and when the water is boiling stick the thermostate in there and see if it opens. I hold it under with a pair of pliers usually...

[slepysal]

When I got my 60 it had an old Stewart Warner temp gauge in it. It read around 225 deg. ! I new the truck was not over heating., so I got a SunPro triple gauge set up ( cheep 30.00 autozone ) and sure as poop it read 180 deg. I wound up making a new dash gauge panel and installed the sunpro gauges along with an Autometer speedo and fuel gauge.

[raiden7800]

On my I6, my temp gauge would run almost all the way to hot, but the truck still ran fine. I had no idea if the guage is correct, so I took the thermostat completely out, sure enough it was stuck. So I just put it back together without a thermo at all, and the hottest I have gotten it to go is about 3/4 on the gauge, whilst sitting in 100+ degree weather in traffic. :p

Sometimes they dont need a thermo, here in oregon, the weather isnt ever sever enough to really NEED one much at all. This will be the third vehicle that I have run w/o a thermo, and have had no problems. They still warm up to operating temp, and typically stay there.

[courage 80]

spent the day on the truck.... put in a sunpro electric temp gauge. The sensor fits in the bottom of my radiator into one of the secondary holes (it has 3, one drain and two others) The radiator is for a manual trans... I thought that if it was for a auto trans the holes would be for that, but its for a manual.

I also put a 33ohm restricter on the other temp gauge wire.

RESULTS....
sunpro gauge reads 125-150 when truck is fully warmed driving around.
original gauge reads about mid when "" "" ""
once I stop the sunpro and original read the same as driving.

Meat thermometer in the radiator top reads 190-200.
(thermostat is a 192*)

I checked all the connections on the sunpro and everything is fine. I don't quite understand why there is a 50-70* difference between teh thermometer and the sunpro.

[rickf]

Originally Posted by courage 80

I don't quite understand why there is a 50-70* difference between teh thermometer and the sunpro.

If I followed right, you have the Sunpro sensor at the bottom of the radiator, and you are checking with a thermometer at the top.

At the top is where hot water is coming in from the engine.
At the bottom is where the cooled water is going back out to the engine.

The 50 to 70 degree difference is the job your radiator did on the water.

[courage 80]

after pondering it for the last few hours I wonder if the radiator is a universal with the auto trans capabilities plumbed in (or even uses the same shell).... and I am actually reading the temp of that cavity???????

it is the transpro radiator from auto zone part number 433284. If anybody knows or has any ideas.

Tomorrow I am going to try to loosen the other cap on the bottom (not the drain) and see if coolant comes out, this should help me know whether coolant is in that cavity.

[19GMC63]

Originally Posted by raiden7800

Sometimes they dont need a thermo, here in oregon, the weather isnt ever sever enough to really NEED one much at all. This will be the third vehicle that I have run w/o a thermo, and have had no problems. They still warm up to operating temp, and typically stay there.

really? This doesn't make sense to me.
Because you have no thermostat, the coolant freely flows from the engine to the radiator, cooling the already cool coolant, right?
So in other words, you'd be running that engine below its normal operating temp, unless you let it sit and run for a while before driving. (usually not the case) Isn't that not a good thing, or am I way off?

[rickf]

Originally Posted by 19GMC63

really? This doesn't make sense to me.
Because you have no thermostat, the coolant freely flows from the engine to the radiator, cooling the already cool coolant, right?
So in other words, you'd be running that engine below its normal operating temp, unless you let it sit and run for a while before driving. (usually not the case) Isn't that not a good thing, or am I way off?

You are correct, it is a bad thing.

Anything under 180 is quite bad.
The oil isn't working right, wear is higher.
Combustion residue tends to be (more) corrosive.

[Chevy Fleetside]

Originally Posted by courage 80

after pondering it for the last few hours I wonder if the radiator is a universal with the auto trans capabilities plumbed in (or even uses the same shell).... and I am actually reading the temp of that cavity???????

it is the transpro radiator from auto zone part number 433284. If anybody knows or has any ideas.

Tomorrow I am going to try to loosen the other cap on the bottom (not the drain) and see if coolant comes out, this should help me know whether coolant is in that cavity.

Lke Rickf said.. The coolant at the bottom of the radiator is the stuff that is already cooled, it will naturally be cooler then what is at the top of the radiator. The top of the radiator is where you want to take your reading.

[63 & 64 Bowties]

No thermostat at all will actually make your truck run hotter. Without the restriction of the thermostat's reduced size opening the coolant actually moves too fast and doesn't spend enough time in the radiator to cool like it should. If for whatever reason, you have something against thermostats, you should at least put in a thermostat with the plunger removed so that you have the restriction.

Your gauge sensor needs to be reading coolant in the motor, not the radiator. And where you have it installed it's actually reading "air." There's no coolant in the auto trans cavities.

[courage 80]

I have the temp gauge in the motor that is hooked up to the stock gauge.... I wanted to have the sunpro hooked up as well to have a back up. I didn't know where else to put it except in the rad.......

Today I have to check out, but this is supposed to be a manual trans rad.

[rickf]

Originally Posted by courage 80

I have the temp gauge in the motor that is hooked up to the stock gauge.... I wanted to have the sunpro hooked up as well to have a back up. I didn't know where else to put it except in the rad.......

Today I have to check out, but this is supposed to be a manual trans rad.

I wanted the same thing, at least for awhile, until I trusted the stock gauge and "new" sender.

I bought a cast iron thermostat housing that has an extra port on the top, same thread as the stock hole on the head, something like $10 at Baxter's. This is where I put my brandX extra temp guage sender.

My intention is to eventually put the sender for an electric rad fan controller here, currently I am using a manual switch for the fan. It turns out with the new radiator I've hardly ever needed the fan, even mid-summer, so I am not in a hurry to change anything.