Gentleman,

I have a some cooling system questions I'd like to run by you. I've looked at JTIS and AllData but I could use some help.

I've got a well maintained '01 S-Type 4.0 Sport Suspension with 55K miles (my wifes car) that runs well. I have regularly maintained the cooling system flushing and refilling with 50/50 distilled water and Dexcool approximately every two years. The remainder of the cooling system is original. I changed the degaus bottle on the cooling system about a year ago due to the common cracking which was causing some minor, sporadic leaks. The car runs well.

Recently my wife indicated that several times after driving around (car fully warmed up and approximately 40 degrees Fahrenheit outside) the cooling system fan would remain running or several minutes after shutting the car down. The last time it happened she was home and came in to get me. The fan just shut off when I came out to look things over. Each time the temp. gauge was half way (where it always runs).

I've checked JTIS and All Data as well as searched around here but it is not clear to me what the issue may be. No check engine light or codes.

I checked everything mechanically under hood that I could see and don't see any evidence of leaks.

I figured due to age combined with mileage it is probably a good time to do some maintenance anyway. I'm in process of replacing the t-stat, waterpump (both Motorcraft) as well as the serpentine belt (Dayco) with parts I purchased from RockAuto.

I noticed that the lower left (near the alternator pulley) idler pulley has some play in it. Using the Gates catalog online I can find part numbers for the tensioner/pulley unit as well as the upper pulley. I see no reference to the lower pulley.

I called today and my Jag dealer can order me one for $84. I'd prefer to go aftermarket or this pulley due to the expense of this item but if necessary I'll definitely get the Jag pulley. I also see in All Data that there are two spacer/gasket plates for behind the waterpump. One is .40 mm and the other is 1.5mm I ordered the 1.5mm one from my dealer because don't think that the Motorcraft pump from Rock will have this plate (I'm guessing it will only have the o-ring).

I"m glad I pulled the pump. It has the plastic impeller and it is showing initial signs of failure (still in tact but starting to crack slightly on one vane -- not enough to impact performance of the pump from what I can see)

So to summarize...

1) Any leads on what is causing the fan to run after shutdown in 40 degree F weather (cooling system is in good shape, clean fluid, no leaks)
2) Is there an aftermarket Gates (or other) part number for the proper lower idler pulley
3) Just curious why the two spacers/gaskets. Obvious reason is or belt alignment but I would think that could be handled by properly sizing the waterpump housing (just curious on this one)

 

Wow! You've made a really good start. Might it be a temperature sensor, giving the wrong value and thus overall making the fan run when it shouldn't? A wiring problem might do that, too. You can probably find values for what the sensors should read at various temperatures in the data you have access to. (Or use OBD.)

 

Yes, I'm figuring it is probably an electrical issue but not sure at this point. My visual inspection didn't surface any wiring problems (chaffing etc.) that I can see. I also ordered a replacement coolant temp sensor (the one in the hard portion of the pipe near the front of the waterpump).

I'll probably take some readings with the old sensor to see if that might be the issue.

There are also two sensors down on the oil cooler/filter housing. I belive the green connector is the oil pressure switch. Any idea what the white one is? I con't seem to find it in JTIS (it's probably there but I can't seem to find it.. For some reason I find JTIS harder to work with than some other make manuals that I've worked with).

 

So I picked up a new lower idler pulley from my local Jag dealer today ($84 plus tax). Along with a Waterpump gasket (mine was the 1.5mm not the .40 mm version)

I measured my old pulley and I have been looking through the Gates catalog that I downloaded from gates.com. The pulley is 90mm OD and 17mm ID and it is 32 mm wide.

There are no exact matches from the aftermarket that I can see (based on size, flange configuration AND pulley material).

The gates 38001 which is the replacement for the upper idler pulley and the tensioner pulley might work but it is 1.5mm narrower and has no flange.

The Gates 38012 pulley is the exact size but it is thermoplastic rather than steel, and it is flanged on both sides. The pulley is flanged only on one side (the side away from the engine block). The gates pulley is $18 from RockAuto

In my opinion the best route is to either get the OEM pulley or if you have a press replace the bearing in the existing (old pulley). The OEM pulley has a *** (Germany) bearing. The bearing number is 559247.T.R 16.26

I'd replace the bearing in the old one and save it but changes are I'll never have to replace this pulley again.

I'm sort of curious why this pulley is flanged on one side. The belt rides the pulley 4mm away from the flange so the flange really does nothing. Must be a reason for it but it isn't obvious to me.

Now that the pulley is off I can definitely feel the play in the bearing. I'm glad I"m replacing it. The other two idlers seem fine so I"m leaving them as is...

 

6203-2RS is the bearing number that is used for all three idler pulleys. So if you need the lower idler obtain and press in a new bearing. The bearing costs about $4 or $5. The new lower idler pulley from Jaguar is $84.