rangermonroe

Update. Got it licked!

Ran Prestone Radiator Flush+Cleaner in it for a couple days. Brownish water came out (like when you hose blood out of carpet), despite the coolant being new and clean. So I pulled the radiator, and rinsed it with vinegar and water. More crud came out including some chunky stuff.

Rinse, reinstall, and she is running as she should. The electric fan kicks in at about 215 and cools it back down while idling in the driveway. Yay!

Thanks for the input guys.

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94 GC, V8 AWD.

Noticed this last summer. Weather got cold, and the problem went away.

As I only drive to work and back, 14 miles, all in the morning, it really isn't an issue.

Now that it's hotter than blazes, I run the a/c and it runs up to 220-225.

Coolant is clean, and recently flushed. Heater works fine. Thermostat is new.

I figured the hillbillys who owned it before may have run straight sea water in it and eroded the impeller away. So I threw a new water pump in her. The old one was pristine.

Where should I look next? Fan clutch?

My thinking is that at speed it should cool it down, if the clutch is bad... and it does... but just down to 215-220.

What gives?

Bustedback

The fan clutch is where I would start. Also make sure there isn't a bunch of debris between the condenser and radiator.

rangermonroe

Thanks. will check in the AM

rangermonroe

No trash between the radiators.

I had the stuff, so I put an electric fan, with an adjustable t-stat. Dialed it in.

Still running hot.

Two things are left to examine: Lower radiator hose collapsing, or radiator blockage.

Before flaming me... I would have checked both today, but wife had to leave before all of my science-ing was completed.

Getting this fixed tomorrow and will describe how.


Soon.

wingless

Are all the parts in-place?

There should be flexible "rubber" parts on each side of the radiator that fill the gap between the radiator and the body. There should be a molded plastic fan shroud w/ a lower section to ensure the fan air is coming through the radiator.

A variable speed strobe light can be used to measure the fan blade RPM compared to the clutch hub RPM, to verify that the clutch is locked up when hot.

rangermonroe

Yeah, the air dams are in place.

I didn't put the shroud back on as the fan attaches directly to the rad.

I checked the lower tubes this morning, all seemed to be evenly hot. The lower hose didn't appear to be collapsed.

I also used my Harbor freight laser thermometer and it was showing 140 at the water pump inlet and 190 at the top of the engine. It will **** me off if this turns out to be a sending unit that is slightly out of round.

wingless

If the fan attaches directly to the radiator, does the fan have a shroud?

The shroud ensures the air flows through the radiator, instead of just looping around the fan.

Please post an image of the fan / radiator configuration.

dave1123

Yes. I agree. The shroud keeps the blade tips from cavitating and disturbing the air flow direction. It forces the air to move only in one direction. This is sort of irrelevant, but a "ducted" propeller on a boat is 4 times more efficient than an open propeller for the same reason. All the driving force is directed in one direction.

This is easy enough to prove. Put the shroud back on and see if it makes a difference. It was installed at the factory for a reason. Actually, if it's like my fan, the blades are connected at their tips with a ring. This not only stabilizes the blades, but helps with air flow.

AND it's entirely possible the temp sensor is at fault. After all, it's only a variable resistor. It's value should be around 10,000 ohms at 70*F if it's 2-wire. IDK what it is if it's 1-wire.

rangermonroe

This is the one I am usinghttps://smile.amazon.com/Heavy-Radia...T8JPQJ8DWWE4NY

It ran "warm" this morning on the way in. Probably 220 on the gauge.

It was 73 degrees ambient.

I will put the stock shroud back on tomorrow and see if that makes any difference

dave1123

One thing I'm going to ask that might sound stupid, BUT is it running the right direction? I have a friend with a Chrysler Town&Country van who complained about it overheating after he installed a new electric fan, but if you stood in front of it while it was running, heat was blasting out the front! DUH!

wingless

The factory 16" fan w/ shroud pulls air through the entire ~24" x 16" radiator. That electric fan zip tied to the radiator core forces air through a 16" circle. The factory fan uses pulley diameters to increase the fan speed above the crankshaft RPM.

Adding the shroud while keeping that electric fan attached to the radiator won't provide a benefit.

rangermonroe

Thats why I didn't put the factory shroud back on.

dave1123

So I guess you've made up your mind.

wingless

The factory designed a large radiator, w/ two-rows over a large surface area.

They then created a shroud to ensure that the fan pulls air through that entire surface area, so that the entire radiator core is working to remove heat from the coolant and transfer it to air.

There are also flexible air dams on each side of the radiator, to fill the gaps between the body and the radiator, so the airflow created by the vehicle moving is also forced through the radiator core.

The electric fan modification discards those design elements and instead pulls air through a 16" circle.

My suggestion is to revert to the entire factory cooling solution to quantify the performance and compare it to the existing cooling modification.

I am certain one will be better by an amount that can be measured.

rangermonroe

No, Dave. I am actually going to do as you suggested and pop the thing back on. It just slides in place and has two nuts holding the top on. Like you said, easy to try it out.

The reason that I went with the electric fan to begin with was the car was running hot. The replacement clutch was close enough in price to the "conversion Kit" that I decided to do that instead. I really hate to throw more money at it to "see if this'll work", before I have chased down other possible culprits.