Overheating dilemma....need input.

Here's my problem.
I'm currently running an older griffin aluminum rad with a newer style slant six shroud that I mated to it with a mechanical ridgid blade aftermarket fan....no clutch fan, just blades.
I also have an electric pusher fan for back up on hot days idling in traffic.
It seemed to work well until lately when it started running just a bit over 180 even on cooler days.
Well the other day I was driving it and I smelled rubber burning then noticed my temp started climbing hotter and hotter as I pulled into town in traffic.

I finally made it past a forever light at an intersection and pulled into a parking lot and she was steaming hot and pissed off.

Popped the hood and found my fan belt was gone.
I checked the fan pulley and it spun fine, smooth and bearing did not feel sloppy nor did it make any noise.

I had a spare belt and popped it on.

I noticed my lower hose was much much cooler than my top hose.

Anyways I let it cool for 20 minutes, and did not add any coolant because. I did not lose but about 3 quarts and lived only 1 mile away so I fired it back up and limped home but on my home street it pegged full hot again so I shut it down and coasted into my driveway and parked it for a couple weeks until I could get time to mess with it........so.

Finally I put a new 180 deg stat back in it, and fenangled a spring into the bottom hose just in case mine was collapsing at the middle.

I also found my pusher fan fuse popped, and who knows how long it was popped but I put a new fuse in and the fan ran fine again.....yes I m running a relay and I have it on a toggle switch for very hot day usage only.

I filled my radiator back with new 50/50 mix and fired it up.

Ran fine but seemed to warm up much quicker than usual sitting in my driveway.
While I gave it some rpm it held about 180 but when I let it idle it started climbing towards 195 deg so I switched on my pusher fan and it immediately dropped back to 180 deg on my temp gauge so I burped out the air about three times until it was no longer burping air.

it was doing fine as long as my electric fan was on but once I switched the fan off it would climb hotter even with my mechanical fan and it never did this before, but like I said, it had been creeping a little hotter than usual.

I took it for a short test drive and figured I still have a problem since my mechanical fan won't cool it off.

I pulled back into my driveway, shut it down and checked it out.
I noticed my top and bottom hoses were now hot but the top hose seemed a little hotter....just a little.
I felt my radiator and noticed it was pretty cool to the touch except on the very sides of the rad.

So given all this info, any thoughts?

I'm thinking my radiator is plugged up or my water pump may be toast.

If it turns out to be my radiator I am going to get a completely new set up and get rid of this used griffin that I don't know the history of.

This being said I am open to options on a kick a aluminum rad with a shroud but not sure if I want to go with electric fans/ fan or a mechanical fan, mechanical fan with a clutch but I never liked the idea of my pusher fan hindering my cooling but it was nice on really hot days and saved my butt numerous times.

I also plan on flushing out my cooling system really well.

Any thoughts?

Car is a 67 barracuda 360/ 4 spd manual, sure grip with 3:91 gears running roughly 450 horse with 11.0-1 compression, j heads, Holley single plain, big cam, crappy vacuum.

Is there any flow at the radiator neck with the cap off?
Are the hoses for the heater core hot? If not I think the pump is broken.

The burning belt being thrown off leads me to believe that the shaft broke or something bound up the pump for a second.

hmm, this is an odd one. If we're only dealing with one problem at a time, hot at idle is not enough air flow and hot at speed is not enough water flow. Even that points to the pump...not enough water flow at any speed...

I've run:
A stock /6 with stock cooling ( fan shroud and solid fan and stock radiator )
A turbo /6 with electric fan with shroud
A 360 with electric fan and alum rad
Only time it ever overheated was due to plugged radiator core... even here in FL
What kind of HP is your motor and what size radiator?

Checking for water flow at the rad with the cap off will tell you if the pump is working.

Garden hose in the radiator on full blast with the lower hose off will tell you if the radiator is flowing well. If the water backs up out the neck with the lower hose off and the garden hose at full, then the radiator isn't flowing enough.


sorry, message edited about 10 times as thoughts hit me. I'm trying to set a record

I hear that, I edited my story a few times.

You know my dumb *** forgot if I even grabbed the heater hoses to check if they're hot.

I didn't really check for churning under the radiator cap and yeah I agree I need to do some more digging when I get some time.

If your temps dropped down immediately when the pusher kicked on, it is probably not a problem with your radiator. Which means it's either air flow or coolant flow. Since nothing has changed about your air flow, that leaves coolant flow. I'd be willing to bet that your water pump is about to give up the ghost

challengergary said:

If your temps dropped down immediately when the pusher kicked on, it is probably not a problem with your radiator. Which means it's either air flow or coolant flow. Since nothing has changed about your air flow, that leaves coolant flow. I'd be willing to bet that your water pump is about to give up the ghost

Click to expand...

Yeah, the fact that I smelled burning rubber then lost a belt seems to be the giant staring me in the face but the fact that the water pump pulley spins freely with no noise kinda had me stumped.

Looks like I need to pull the water pump for a look see and it all kinda makes sense since it never did cool even after I put a new belt on.

Thanks for the input guys....nice to get a few more opinions.

With a 180 degree thermostat, the engine SHOULD be running between 190 and 195. This is how it works, it won't run right at the stat temperature.

Anything under 205 normally is fine and will not hurt the engine. Overheating, IMO is over 230 on a warm day.

Put a new water pump on (they are cheap and yours sounds sketchy), and check your belt alignment with a straight edge.

I have electric fans only - Ford Contour fans - and my fans come on at 195 and off at 192. Rock solid water temp and the fans usually will only come on when sitting at stoplights and turn off within 10 seconds of pulling away from a light. 180 thermostat.

To check your rad,, get it up to temp,, then touch your knuckles across the front of the rad,, about halfway down,, you're feeling for cool/cold areas across the rad,, those are plugged tubes. more than 20% area cool,, is time for to "rod out"/service the rad..

A heat temp gun is preferable

hope it helps..

Well I looked in my bypass hose hole and saw the impeller spinning but decided to pull the pump and inspect it anyways.
The impeller looks fine, the bearings look fine.

I think the rad must be plugged.

It's an older used griffin rad that I don't know the history on so I'm gonna just get a new one and be done with it.

Do you think your block is slowly shedding bits of rust into your radiator, cloggin it?

Maybe get a ganofilter?

goldduster318 said:

With a 180 degree thermostat, the engine SHOULD be running between 190 and 195. This is how it works, it won't run right at the stat temperature.

Anything under 205 normally is fine and will not hurt the engine. Overheating, IMO is over 230 on a warm day.

Put a new water pump on (they are cheap and yours sounds sketchy), and check your belt alignment with a straight edge.

I have electric fans only - Ford Contour fans - and my fans come on at 195 and off at 192. Rock solid water temp and the fans usually will only come on when sitting at stoplights and turn off within 10 seconds of pulling away from a light. 180 thermostat.

Click to expand...

It always stayed at 180 before, but it kept climbing and I turned on my electric fan at the 195 mark otherwise it kept climbing.

Rice Nuker said:

Do you think your block is slowly shedding bits of rust into your radiator, cloggin it?

Maybe get a ganofilter?

Click to expand...

Could be.
Gonna flush the block out and install a hose drain from Jegs.
My buddy also mentioned that ganofilter....seems like a good idea at this point.

A simple home flush is to take the radiator off, turn it upside down, and flow water in the bottom hose, which reverses the normal flow. I have rigged up a garden hose w/ fitting so I can clamp to the lower hose and build up pressure. With rad. cap on, I block the upper port (now on ground) with my hand, build up pressure, and release to get a quick gush of water. Keep doing that. However, don't build too much pressure or you could rupture the radiator. Minimal risk, since the force on your hand blocking a 1.5" opening at 20 psig is 35 lbf.

You can find posts here where people use citric acid and such to clean their radiators and the before and after photos of the internals are amazing.

Citric acid might be hard on an aluminum radiator? I don't know the chemistry regarding aluminum vs acid. The copper ones can tolerate quite a dose of acid.

I'm going the new route and I know for a fact this radiator was flushed before. I bought it.
I got it from a friend pretty cheap.

I will chime in here with a thought. Just because the pump pulley spins freely does not mean that the impeller is still attached to it. The fact that the pump may have locked up and thrown the belt tells me the problem is more than likely the impeller as I have seen cases where the impeller had rusted completely off and others where the impeller shaft had broken inside the pump.
Hope this will help.

DVO

Dam....I wish my car ran at 195.