engine getting hot

[shrike]

ok, I searched through the forum but didn't see anything.

1970 with a 350, auto trans, Vintage Air A/C (orig had factory air), daily driver.

Stock fan setup (7 blade), stock water pump, new radiator shroud, new temp sending unit (on intake) new temp gauge.

Now the radiator I am not sure about. It looks to be in good shape, no leaks but it was on the truck when I got it. All I did was flush it out last year. How can I tell what size it is?

The truck runs fine as long as I am moving, temp sits around 200. no problems at lights. The problem is when it is hot out (like around 100 yesterday) and I get stuck in construction. Basically a worst case scenario. Had the AC on, got off the freeway at my exit and it was down to one lane. I sat, barely moving, for about 15 minutes and the temp was at 230 and rising.

I am thinking about replacing the fan clutch because it seems a little weak. Again, it was on the truck when I got it so not sure how old it is. Same for the water pump.

I really do not want an electric fan.

One thing Ive noticed is that the radiator shroud has a lot of gaps between it and the radiator esp at the bottom. Is this normal? Should I try and seal this up?

Thanks for any help!

[wwotr]

Originally Posted by shrike

ok, I searched through the forum but didn't see anything.

1970 with a 350, auto trans, Vintage Air A/C (orig had factory air), daily driver.

Stock fan setup (7 blade), stock water pump, new radiator shroud, new temp sending unit (on intake) new temp gauge.

Now the radiator I am not sure about. It looks to be in good shape, no leaks but it was on the truck when I got it. All I did was flush it out last year. How can I tell what size it is?

The truck runs fine as long as I am moving, temp sits around 200. no problems at lights. The problem is when it is hot out (like around 100 yesterday) and I get stuck in construction. Basically a worst case scenario. Had the AC on, got off the freeway at my exit and it was down to one lane. I sat, barely moving, for about 15 minutes and the temp was at 230 and rising.

I am thinking about replacing the fan clutch because it seems a little weak. Again, it was on the truck when I got it so not sure how old it is. Same for the water pump.

I really do not want an electric fan.

One thing Ive noticed is that the radiator shroud has a lot of gaps between it and the radiator esp at the bottom. Is this normal? Should I try and seal this up?

Thanks for any help!

This is a Temp solution, but I've seen they have an "Additive" that you dump into the Radiator that "Claims" it runs up to 30 Degrees cooler, and also Lubricates the Water Pump.
I live in a Hot Climate also and havent really had it out in the "Heat", but mine usually runs about 180-190 and if it sits for a period, it has gone up to 200. That was in about 90 degree weather. I'm sure time will tell this Summer.
Let us know what you do and how it works for you. Good Luck.

[68gmsee]

I had a similar problem on one of my vehicles but it turned out to be leaking head gasket.


You didn't mention the thermostat so if you haven't replaced it, that would be the next step. And for sure a weak fan clutch will cause overheating so definitely replace that.

Also take the radiator out and have it rodded and checked. Rad shops can tell you if it's a single, double or three row.

Do a leak down test on the radiator to see if you find leaks.

Fix or replace the shroud and you may also want to install an overflow tank. A lot of us have either bought or made our own. My 68 GMC used to overheat and stopped after I installed a new cap and overflow tube.

[shrike]

wwotr- oh yeah, I forgot about water wetter. Something to think about!

68gmsee- I hope it isnt a head gasket! New thermostat and I installed an overflow tank. The shroud is new, it just has a gap at the bottom between it and the rad. It looks as though this is how it is supposed to fit since the sides and top are flush. I just wondered if there was supposed to be something in there to seal the gap?

[Longhorn Man]

don't worry about the gap.

You have an air flow problem at idle.
Your engine produces more heat at speed. Since you aren't getting hot at speed, when the engine makes more heat, that tells us that your pump is moving enough water, and the air is removing enough heat through the rad. At idle, you produce less heat, but you don't have all the air blowing through.
A couple things to look at, is your fan 1/2 in the shroud, and 1/2 out? That's the best location for the fan.
Assuming your fan is located properly, I would suspect the fan clutch.
I would carry the clutch into the parts store if you have another ride to use. THere's a good chance that they'll try to give you the wrong one. If you have it in your hands and check the one they sell you, you'll save a lot of time and won't be so ticked off.

[406 Q-ship]

Where the fan sits in the fan shroud is important too. The fan should be about 1/3 to 1/2 inside the fan shroud with about 1" gap at the diameter of the fan to the shroud. You definately have a slow speed air flow issue. Fan clutch is a good place to start, get a good (ready expensive) thermostatic fan clutch if you need to replace the clutch.

[shrike]

Ok, so I ran out to the parking lot and looked. Fan placement appears correct, but I think the clutch has had it. It spins pretty freely and it looks as though it had been leaking at some point.
I'll pull it tonight if I can get a ride to the auto parts.

Thanks for the suggestions, I'll post a follow up when I get it replaced.
Scott

[fastwillie 696969]

evanscoolant
http://www.evanscooling.com/products/

[Longhorn Man]

coolant additives have there place, but a properly working system doesn't need it. At least, not in a stock, semi stock vehicle.

[cdowns]

i'd check the actual coolant temp with a known good themmometer prior to resorting to throwin cash or parts at the percieved problem

old gauges aren't that reliable and new sending units are worse

[shrike]

ok, so based on another post I got a Hayden 2797 from Oreilly. $60 made in the USA thermostatic fan clutch

The one I removed was a cheapie, rpm clutch. I could spin it with one finger and get almost a complete rotation of the fan. Once I installed the new one, it will move about 3 inches before it stops.

I took it for a test drive and it seems to run a bit cooler across the board. I'll know for sure tomorrow on the way home from work whether or not it fixed the problem.

[Longhorn Man]

it's tomorow.... how was the drive home?

[shrike]

Sorry! Didn't make it home till late last night.

The truck now runs at about 190 instead of 200, just driving around town.

I purposefully sat with it in gear and the AC running to see how hot it would get. With the outside temp around 100, it eventually got up to 220 but it took a lot longer. I'm not sure if it would have gone higher or not, I couldn't wait any longer.

How high is "normal"? Where should a healthy cooling system hold the temp at?

[Longhorn Man]

still a tic hot for my taste

[Boog]

How is the AC doing? With those kind of temps idling that engine fan ought to be blowing like crazy with the new fan clutch. It sure wouldn't hurt to take that radiator to a shop to be checked out. Too much running with excess coolant temps could lead to other problems like blown head gaskets and or cracked heads. I'm just sayin.

[shrike]

AC is doing fine, but yeah I think pulling the radiator may be the next step