Another Running Hot Post

[nhudson]

Greetings, new member here. Just picked up a '79 CJ7 with a AMC 304 and am loving it so far. The only real issue I have at the moment is that I can't keep it cool. If I could constantly keep the speed up above 45 MPH I would be set I think. Stopping at lights or for trains and the temp gauge jumps up pretty quickly.

Right after I got it, I had the water pump and radiator replaced with both new parts. The guy I bought it from said he had replaced the thermostat already a few months ago. While I didn't verify this by physically inspecting it, the gasket looks brand new. Also when I got it the clutch fan was missing it's shroud. So my 1st thought after replacing the radiator was to install an electric fan.

I removed the clutch fan and set the new electric fan up as a puller on the inside of the radiator. I can verify that it moves some air, but the Jeep still runs hot at idle or slow speeds.

I am going to take it to a radiator place this week and just have them inspect everything to make sure it's actually flowing good, but other than that I am not real sure what to do. I'm almost to the point to drop $1000 on the Aluminium radiator and electric fan setup from Novak, but that's a hard pill to swallow especially after I just paid to have a new one installed.

A few things I plan on doing next. Let it come up to temperature with the radiator cap off and then take an actual temperature of the fluid. I don't have a IR temp reader, but I have a really good probe thermometer I can use, its upper limit is 600F.

Just looking for any thoughts or ideas I could try. Thanks for any help!

 

[hole]

With few exceptions, I take PO's word and work with a grain of salt. That said, I'd pull and verify the thermostat is in correctly and right temp range, and while I was there just replace it. Cheap insurance.

 

[coldair]

A few things I plan on doing next. Let it come up to temperature with the radiator cap off and then take an actual temperature of the fluid. I don't have a IR temp reader, but I have a really good probe thermometer I can use, its upper limit is 600F.

Please dont pull the radiator cap off when your jeep is at operating temp. You will get burned.

 

[gert]

another thing to do while you are trouble shooting this is to use the radiator flush stuff in your n=motor to clean up the rust deposits in the block. i would think a stock AMC 304 would not have that much trouble keeping cool

 

[Lumpy Grits]

:ww:

I hope you are not depending on just the OEM temp gauge here.
Many things can cause a false temp readings.
One of the biggest factors to cause a false high temp reading of the OEM gauge is the dash panel's ground(GND)connection. Many of us run a dedicated wire from the panel to the battery NEG(-)post
The other, is mis-matched sender and gauge.
Unless the seller handed you a receipt for this 'new' radiator etc. Don't believe him.
Are you running a fan shroud? You really should.
Also-A lean fuel mixture will cause higher engine temps.

LG

 

[nhudson]

Thanks for the replies. I went and bought a mechanical temp gauge and new 195F thermostat. I'll get them both installed after I get back from vacation. I think I'm just putting too much trust in the 40 year old stock gauge, the new radiator and electric fan definitely helps cool things down. I'll know for sure exactly what the temp is once I get the new gauge installed. I'll report back. Thanks again.

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[JacksonLakeJeep]

What's the verdict?

Thanks for the replies. I went and bought a mechanical temp gauge and new 195F thermostat. I'll get them both installed after I get back from vacation. I think I'm just putting too much trust in the 40 year old stock gauge, the new radiator and electric fan definitely helps cool things down. I'll know for sure exactly what the temp is once I get the new gauge installed. I'll report back. Thanks again.

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[nhudson]

Funny you ask today, I finally did the following work over this past weekend.

1: new aluminum radiator with dual electric fans
2: 180f thermostat
3: FlowKooler Water Pump
4: New upper and lower radiator hose and heater hoses.

Still runs hot if I am not moving. I'm not really sure what else I can do at this point. I've taken it to a radiator shop and they told me what I put on should be sufficient to cool the jeep. I will say it cools much better while it's driving, but if I ever come to a stop or idle for too long it will overheat.

Nick

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[gert]

Funny you ask today, I finally did the following work over this past weekend.

1: new aluminum radiator with dual electric fans
2: 180f thermostat
3: FlowKooler Water Pump
4: New upper and lower radiator hose and heater hoses.

Still runs hot if I am not moving. I'm not really sure what else I can do at this point. I've taken it to a radiator shop and they told me what I put on should be sufficient to cool the jeep. I will say it cools much better while it's driving, but if I ever come to a stop or idle for too long it will overheat.

Nick

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How lean is running? Ignition timing?


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[Lumpy Grits]

Could be lean fuel issue.
Need to check for vacuum leads.
Confirm your ign timing is correct.
Did you install the mech temp gauge and sender?
LG

 

[gert]

My 360 is pretty hot as well, it will get to 180/195 and stay there with the fans running the whole time. I got to run some errands in it the other day and I found myself having fuel boiling issues after cranking it up at one of my last stops, I have an aluminum water pump I want to install on it and a new 180 degree thermostat and I am tempted to install my 1 inch phenonalc carb spacer as well to help hope yours gets better

What does your coolant look like? Need to run prestone radiator flush thru the motor?


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[coldair]

You can run a 50/50 distilled water/white vinegar to flush your cooling system.

 

[nhudson]

How lean is running? Ignition timing?


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Good question, I don't know. I don't have any tools to check lean/rich on my carb or check timing. I got to find a place to take it locally and get it checked. I will say I do smell fuel sometimes, which I can only assume is because it's boiling at times.

 

[nhudson]

My 360 is pretty hot as well, it will get to 180/195 and stay there with the fans running the whole time. I got to run some errands in it the other day and I found myself having fuel boiling issues after cranking it up at one of my last stops, I have an aluminum water pump I want to install on it and a new 180 degree thermostat and I am tempted to install my 1 inch phenonalc carb spacer as well to help hope yours gets better

What does your coolant look like? Need to run prestone radiator flush thru the motor?


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Yeah I ran Prestone flush through it and flushed it twice with water and air before adding back 50/50 anti-freeze and distilled water.

I do smell fuel sometimes, I am assuming its due to boiling fuel.

Can you explain what he carb spacer is supposed to do to help keep it cool?

 

[nhudson]

You can run a 50/50 distilled water/white vinegar to flush your cooling system.

This is good to know. I used Prestone Radiator flush and the flushed it with water twice then used compressed air to blow as much water/flush out as possible. I then filled it back up with a 50/50 of anti-freeze and distilled water.

Don't know if I will be done to do all that again. I already have no where to take the stuff that came out the 1st few times. No place local seems to want to dispose of it.

 

[nhudson]

Could be lean fuel issue.
Need to check for vacuum leads.
Confirm your ign timing is correct.
Did you install the mech temp gauge and sender?
LG

Yeah I need to find a local place that can check timing and carb. I have never done it nor have the tools to make sure it's right. It's something I plan on doing soon.

As for the mech gauge, I bought one but I think I have to drill/tap into the block to install it. I don't know if I am up for that task. I thought I could place it in the same hole as the temp port is now, but it's way too small.

 

[gert]

Yeah I ran Prestone flush through it and flushed it twice with water and air before adding back 50/50 anti-freeze and distilled water.



I do smell fuel sometimes, I am assuming its due to boiling fuel.



Can you explain what he carb spacer is supposed to do to help keep it cool?

The phenolic carb spacer is a plastic type spacer that does not transfer heat as well as metal, so that will help keep my carb cooler and the fuel inside the carb cooler, the factories started adding thick paper gaskets under the carbs in the 70s to help do the same thing


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[gert]

.



As for the mech gauge, I bought one but I think I have to drill/tap into the block to install it. I don't know if I am up for that task. I thought I could place it in the same hole as the temp port is now, but it's way too small.

The intake should have a 3/8 pipe plug in it that’s where you want to put it or in the thermostat housing has a 3/8 plug as well that’s an ok spot



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[hole]

Yeah I need to find a local place that can check timing and carb. I have never done it nor have the tools to make sure it's right. It's something I plan on doing soon.

As for the mech gauge, I bought one but I think I have to drill/tap into the block to install it. I don't know if I am up for that task. I thought I could place it in the same hole as the temp port is now, but it's way too small.

You can get a brass reducer bushing to be able to use the same port.

 

[tbone3636]

I just bought a CJ7 with a AMC 304 , I was having issues with it overheating as well, new built motor. It had a new electrical gauge that didn’t work well. I put in a auto meter mechanical gauge( edelbrock intake) and just needed a bushing for it to work. Changed the thermostat, the old one was stuck open. I also put in a 180. I then bought a fan shroud and installed it. Mine now runs 180-190 no matter what I’m doing. Been happy with it.


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