HD fan clutch upgrade...

[ottexj2000]

So after reading through this thread I am a bit torn on doint this upgrade to my XJ. Its a 2000 with a stock cooling system except for a 3 core radiator. Have a lot of people with a 3 core radiator had clearnece issues with this upgrade? Thansk for any answers

 

[CharlesS]

I just discovered something. If you search on the NAPA website for a fan clutch for a 1999 XJ, you get 2 results. The PNs are TEM 272310 and TEM 272318. I googled the first one and got a thread, which says 272310 is the ZJ HD clutch http://www.naxja.org/forum/showthread.php?t=993344


Why would NAPA list the ZJ HD clutch as being for the XJ? Never heard of a parts store doing that.

http://www.napaonline.com/Search/Results.aspx?Ntt=fan%20clutch&Ntk=Keyword&N=599001+101999+50038+2038004

The AutoZone TorqFlo 922737 fan clutch is the heavy duty for the 98 XJ 4.0L and the standard duty for the 98 ZJ 4.0L.

http://www.autozone.com/autozone/pa...?filterByKeyWord=fan+clutch&fromString=search

http://www.autozone.com/autozone/pa...?filterByKeyWord=fan+clutch&fromString=search

 

[O-Gauge Steamer]

It is true that if you check napaonline for a fan clutch (mine is a 98) it will return both the stock clutch and the "ZJ" clutch. Do a filter by engine, i.e. eliminate the 2.5l, and only one shows. To me, that means the 272310 clutch is the stock clutch on the 4 banger as well. Maybe another way to find the thing...

 

[Ecomike]

I don't the 4 banger uses an electric fan, so that might make sense that it would have the ZD clutch and bigger mechanical fan, like the ZJ has.

 

[O-Gauge Steamer]

After flushing the life out of the system, mine will over heat only when the AC is on. Have picked up the 272310 clutch and will install. Also picked up anopther Tstat in case. I tested the one in it and it appears to be OK.

Test method; pan of water, thermometer, stove top, ticked off wife..., bring water to boil and watch.

 

[O-Gauge Steamer]

Clutch is in. Really do not mind the whisle the fan makes. Still over heats, but not nearly as bad. Installed a 180* Tstat, it now run from halfway between the mark BEFORE the 210* and 210*. I am in process of using the vinegar flush with distilled water method as I am still getting junk out of the radiator.

For thos tha are arguing the 180* Tstat will throw codes debate, no codes thrown. It is not complaining about coolant warm up time. Makes you wonder...

Again, it's a 98 Sport.

 

[Boostwerks.com]

:Soap Box:

A 180deg thermostat will do nothing in terms of cooling system efficency. It simply sets the target temp the system trys to keep. However, most engines will attain the best gas mileage around the 200deg mark. By swapping the stat to 180 will do nothing but hurt performance. Unless the engine was designed around a 180deg stat, you should always keep the same degree thermostat. All auto mfgs do extensive testing to find out the ideal engine temp for optimal efficiency.

We use the stock 200deg thermostat on our time attack road race car if that helps prove my point. We use a thick aluminum radiator and aftermarket oil cooler which both improve the systems heat transfer.

The biggest thing people tend to overlook is airflow. Once the air passes through the radiator, it has to exit. The easier that air can exit the bay, the more efficient the system will be. You can have a giant aluminum radiator, but if there is no airflow it will still be an inefficient system. This is actually what the main function of the factory "splash guard" is. Turbulant air doesn't flow. The guard straightens the flow of air allowing it to exit the bay.

 

[Ecomike]

One of the big mistakes people often make is not realizing how easy it is mistake a slow coolant flow radiator, partly restricted flow in the tubes, for a working, good radiator. One problem is that as the flow through the radiator slows down, as scale builds up on the walls of the thin tubes, or junk blocks the tube entrance, the slower flow through the radiator makes the cooler side of the radiator run cooler, making it look like the radiator is working and cooling!!!! Ane we have no way to measure flow rate in out systems.

I had 1 35% delta T across my 4 year old aluminum radiator. Replaced it with a 3 row all copper / brass CFS, and not the delta across my radiator is only 20 F!!!!! But the engine runs 20-30 degrees cooler now!!!!!!!!!!!!!!!!

Difference is the coollant flow rate is higher now. After 35 years of cooling system work, this even surprised me, but this time I had an IR temp tester to see what changed!!!!!

 

[OverlandZJ]

I pulled the fan clutch out of my 98 ZJ this afternoon to throw it in my XJ, what i thought was a nonHD now appears to be a HD clutch. It also differs visually from the pics in this thread.

To install i would need to remove the studs and screw them in with clutch in place.. and i would not have much clearance from the rad.

Does anyone have the height of the non HD clutch assembly for me to compare?

 

[CharlesS]

The HD clutch used on the XJ which is the standard duty on the ZJ is 3 1/8" tall from the hub to the top of the clutch, the original clutch was slightly less and the HD ZJ clutch sill not work at all according to the Napa catalogue.

 

[OverlandZJ]

Thanks Charles.. i'll go measure what i have. Was hoping to save the $40 and use this for an upcoming trip.


Edit: The fan clutch i pulled off my 98 ZJ measured 3 5/8" tall. So this makes it a HD cooling clutch.

 

[Ecomike]

I found nearly a 1/8" difference betweens brands on the Standard duty ZJ clutches. IIRC the Emperial (hayden) had the lowest standard ZJ profile, and it left me 3/8" between the ZJ clutch face and the new 3 row Copper/brass radiator Wide core!! CFS brand) I am using.

 

[carves]

For thos tha are arguing the 180* Tstat will throw codes debate, no codes thrown. It is not complaining about coolant warm up time. Makes you wonder...

Again, it's a 98 Sport.

Nothing to wonder about really ... especially on an OBDII model where you can watch the scan gauge display - closed loop, within minutes of startup ... Engine temp is irrellevant but will probably be about 65'f from a cold start when it happens - depending on climate.

PO 125 "too cold" code should occur when engine temp is only 20'f and no speed signal from the sensor.

Closed Loop has nothing to do with thermostats temps, brands ... or even if one is fitted ... At least on OBDII.

Its all about the heated upstream O2 sensor reaching ITS normal operating temperature.

If you are running 160'f - 180'f temps instead of 180'f-200'f ... there will be some noticable increase in fuel consumption ... but it wont be an open loop scenario ... which would cause even higher fuel consumption.

:Soap Box:

A 180deg thermostat will do nothing in terms of cooling system efficency. It simply sets the target temp the system trys to keep. However, most engines will attain the best gas mileage around the 200deg mark. By swapping the stat to 180 will do nothing but hurt performance. Unless the engine was designed around a 180deg stat, you should always keep the same degree thermostat. All auto mfgs do extensive testing to find out the ideal engine temp for optimal efficiency.

Using a 180'f thermostat will have differing results depending on the efficiency of the cooling system.

For the most part they seem to be fitted as a band-aid fix .... hiding a real fault.

Others fit them in conjunction with better rads, fans and even driving techniques - to get a more stable engine temp, suited to particular driving conditions.

Optimal Eficiency .... Optimal fuel consumption and meeting of legislated emission standards ... more so than optimal efficiency I would think ...

Wonder if the 4.0l engine is also designed to run with an optional 180'f thermostat ... since chrysler lists one for XJs ???.

But then they also list 1row, 2row and copper/brass radiators .... So its a bit like suspension systems ... In the end - the choice of components is dependant on the owners driving requirements.

Good points on the airflow .... and theres a bit more to getting that right besides just banging holes in the hood ....

 

[Ecomike]

All good points carves, and I agree.

FWIW, the only reason I can see to remove a thermostat is get more flow through a partially compromised radiator (some scale on the tubes), until one can fix the real problem. I have wondered if lower temp thermostats have a larger flow opening, or perhaps some of them do?

I must agree, that in the winter, here in south Texas, my fuel efficiency does drop a little (about 10%) using a 180 F thermostat, then in the summer, when the engine runs at 200-205 F anyway, I get a little better fuel efficiency, so actual engine temps do affect mileage, the hotter the better, up to a point. I still run old API SL grade dyno oil, so I try to run mine a little cooler than newer engines with syn oil.

Nice to see that we have finally put the OBD-II open-closed loop legend to rest, that a 180 F thermostat does not affect closed loop operation!!!

 

[carves]

FWIW, the only reason I can see to remove a thermostat is get more flow through a partially compromised radiator (some scale on the tubes), until one can fix the real problem. I have wondered if lower temp thermostats have a larger flow opening, or perhaps some of them do?

Agreed ... best to have a thermostat fitted.

In the case of temporary flow help, or because it was sticking closed, causing high temps ... and depending on climate conditions - Its quite safe to drive in the short term ... remembering that the vehicle should be treated as if its in "limp home" mode ... untill able to purchase & fit a new one.

Generally its better to just cut the valve out, and refit the skirt ... because in colder weather - with a decent rad & fan, the opening will be too large allowing too much flow. If its only a short drive to a shop or somewhere for a new one ... Its probably not such an issue.

Down here the common reason for fitting a lower temp thermostat in any stock vehicle is simply to get full coolant flow happening sooner ... A drop in running temps is just a bonus.

Local products are even catering to that requirement e.g.

The 195' thermostat Im currently using - is designed to be 1/4 open at 195'f and is fully open at 207'f .... but I dont think its much different to using an ordinary 188'f or 192'f thermostat.

Another same brand variant has similiar specs but a 30% increased flow rate ....

Whereas the chrysler factory 195'f t'stat specs indicate, a way too high temp (imho) of 220'f is required for it to be fully open ...

Wanting lower temps generally means better rad & fan ... and if thats whats wanted .... it seems a bit pointless refitting a factory OME original thermostat to an improved cooling system ... and forcing temps back up again.

I must agree, that in the winter, here in south Texas, my fuel efficiency does drop a little (about 10%) using a 180 F thermostat, then in the summer, when the engine runs at 200-205 F anyway, I get a little better fuel efficiency, so actual engine temps do affect mileage, the hotter the better, up to a point. I still run old API SL grade dyno oil, so I try to run mine a little cooler than newer engines with syn oil.

You fellas in the hotter states get that same, poor performing, winter mix fuel the northern states get ??? ... maybe without being told of it ??? ...

Could be something worth considering too ... I find variations in fuel quality all the time here ... even at the same pump.

Yep, I like cooler than the presumed 210'f XJ "normal" ...
20/50 dyno oil, 2row copper brass rad, 10/90 coolant mix, the 195' t'stat mentioned above .... and Im running 195'f temps in 30'f - 100'f+ ambients. The radiator is doing its job cooling ... and thermostat is doing its job - keeping the engine warm.

Finally got the balancing act right I think ... I do vary stuff a bit during our mild winters.
Welllll ... mild to you lot anyway .... :laugh:

And just to stay on topic a little bit .... Also running a heavy duty XJ USMW brand fanclutch ... whether its a stock ZJ equivalent or just different temp operation I dont know ... but certainly performs better than any stock XJ chrysler one I ever fitted.

Nice to see that we have finally put the OBD-II open-closed loop legend to rest, that a 180 F thermostat does not affect closed loop operation!!!

heh heh .... I first came across the factory 180'f thermostat in an OBDI parts manual ..... but since Im just a lowly OBDII owner .....:dunce:


I'll let some trouble making, thermostat/closed loop OBDI sceptic - sort that one out ... :laugh:

:cheers:

 

[Ecomike]

LOL, just noticed that your down under, south even of me, LOL.

While I have gotten a noticable MPG difference in winter/summer fuels over the last 10-20 years, I have not noticed it so much the last 2 years. Here in Houston we can have a 90 F week one week, a 30 F week the next, and back to the 80's the third week, so the MPG drop I see at 30 F, is easy to distinguish from any seasonal fuel changes. In fact, the winter fuel, IIRC, gets better mileage than the summer fuel, or use to anyway, as the summer fuel had more ethanol. I suspect the formula here is 10% ethanol year round now.

 

[iwannadie]

I pulled the fan clutch out of my 98 ZJ this afternoon to throw it in my XJ, what i thought was a nonHD now appears to be a HD clutch. It also differs visually from the pics in this thread.

To install i would need to remove the studs and screw them in with clutch in place.. and i would not have much clearance from the rad.

Does anyone have the height of the non HD clutch assembly for me to compare?

Just remove the upper radiator support and tilt the radiator back and that should give you enough clearance(it did for me).

 

[praetorian]

Just remove the upper radiator support and tilt the radiator back and that should give you enough clearance(it did for me).

I removed both my engine mounts and jacked the engine up until I had enough room to get it all in.

 

[O-Gauge Steamer]

OK, finally replaced the radiator and reinstalled the 195 Tstat. Now it only runs extra warm in town with the AC on. I [ulled the tanks off of the old rad and I am totally amazed it cooled at all. There was MUD in it. How the PO managed that is a great mystery. Oh yah, I also found a great slug of silicon sealant stuck in it as well.

 

[Ian Christiansen]

If everything in the XJ's cooling system is working properly, it should have no trouble maintaining the 195 degree thermostat temp. I just installed the NAPA (p/n 272310) HD fan clutch along with a Stant thermostat, Flowkooler water pump, CSF 2 row radiator, Mopar lower hose with the coil inside it, Goodyear upper hose, and 50/50 coolant mix. Before it always ran right at 210 and would creep up to maybe 215-220 sitting in traffic. Now it stays at 195 no matter what. It was 91 degrees here the other day and I let it sit and idle for 30 minutes and it never went past 195.