Fan clutch or coolant flush first?

[red02tj]

I replaced the water pump in my 97 4.0. The rear bearing was going bad and finally leaked coolant. It would always run hot (210+) with the a/c on regardless of operating conditions in the S. Fl summers. The new Gates pump and HD fan clutch scrubbed at least 20 degrees. A little play in the shaft must have a huge impact on coolant flow. Water pumps are cheap.

I’m working my way around.
Did fan clutch and chemical flush
Next week is thermostat
I’ll move to hoses and water pump afterwards if needed.

I like 1 thing at a time.

Pics of the old tstat and housing.

 

[red02tj]

Thanks all for the kick in the pants specifically @Irun for not letting me let it slide and @PRNDL for putting up with my PMs. Changed the thermostat this morning and after driving it up to temps I let it idle for 45min and never saw 210. Was right in the 200-205 range.

When I started this I was 236… no jinx, I think this is done.

 

[red02tj]

I may have been premature in my celebration. It was 75 and sunny today so I wanted to see what temp would be since last week it was in the 40s.

Drove it around for 30 with the AC and then let it idle for 20min and temps have crept back up to 220.

I’m essentially back where I started.

1. New flan clutch Hayden 771
2. New stant thermostat - with burp hole drilled
3. Themocure treatment
4. New G05
5. Pressure tested cooling system- held ~16psi, no leaks found
6. New Stant rad cap
7. No loss of coolant

Issue is only at idle, where do I go from here?

Thanks.

 

[PRNDL]

Dang, sorry to hear this. I'm not expert enough to know what else to suggest. If a radiator isn't cracked can it go "bad"? Maybe sediment in the bottom? I'm questioning the efficiency of the radiator at this point since it only happens at idle.

I will reiterate my lack of expertise here though.

 

[JKP]

At idle it's either the fan clutch or water pump.

Since you have a new clutch, I'm going to go with your water pump impeller is not moving enough water. My buddy's 97 impeller almost completely eroded away and was hardly pumping any water due to never changing the coolant.

 

[red02tj]

At idle it's either the fan clutch or water pump.

Since you have a new clutch, I'm going to go with your water pump impeller is not moving enough water. My buddy's 97 impeller almost completely eroded away and was hardly pumping any water due to never changing the coolant.

You’re only about 100mi south of me, essentially the same weather. I could see outside temps going from 80-110 having an impact but not the mid 40s of last week to the mid 70s today.

 

[JKP]

You’re only about 100mi south of me, essentially the same weather. I could see outside temps going from 80-110 having an impact but not the mid 40s of last week to the mid 70s today.

Yep, 100 mi S.

My thermodynamics is rusty and I wouldn't hazard a guess at how much a 30 deg swing would make. However the general rule is: The greater the temperature difference, the greater the rate at which heat transfers.

So, at idle both your fan and your pump are at their slowest speed. Less air being drawn through the radiator and less water being pumped through it.

And if your impeller looks anything like this, it's not pumping enough. This is the result of neglected coolant.

 

[RMETeeJay]

I may have been premature in my celebration. It was 75 and sunny today so I wanted to see what temp would be since last week it was in the 40s.

Drove it around for 30 with the AC and then let it idle for 20min and temps have crept back up to 220.

I’m essentially back where I started.

1. New flan clutch Hayden 771
2. New stant thermostat - with burp hole drilled
3. Themocure treatment
4. New G05
5. Pressure tested cooling system- held ~16psi, no leaks found
6. New Stant rad cap
7. No loss of coolant

Issue is only at idle, where do I go from here?

Thanks.

From the photos you shared, your system looks like it has significant buildup of scale. I think it would be worthwhile to replace the radiator.

 

[TexasTJ2004]

I’m working my way around.
Did fan clutch and chemical flush
Next week is thermostat
I’ll move to hoses and water pump afterwards if needed.

I like 1 thing at a time.

Pics of the old tstat and housing.

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You need to run like 3 rounds of thermocure to get the rust out

 

[red02tj]

Checked my tstat hosing for leaks and the tstat change. …so damm close.