cooling fan

[oka065]

G,day all, well we have been struggling for some time now trying to get the engine fane to cycle, well today I fitted a trans cooler in front of the fan hub plumbed hot coolant through it & hey prestow the fan is locking up & all is getting better. It is about 95 deg f here in Perth West Australia. Still need to do some more mods, like slow the air down going through the cooler as I would like it to come in a bit earlier. But I am making progress at last.

Good to have summer here at last.

Cheers

Rod

[GMC Hauler]

That's interesting in how you did that. Where did you get the hot coolant from and where did you send it to?

[oka065]

Hot coolant came from the heater circuit mounted the cooler / heater in front of hub on engine side of the radiator.

Cheers

[DmaxMaverick]

Oka065

I've been following your issue with interest, and I remember commenting on another post.

It's good you finally got the clutch to engage, but I think your result is artificial. You shouldn't need to "augment" the radiator to get the clutch to engage. Although, adding the heater core does add to cooling ability of the system, it shouldn't be needed to get the clutch engaging if you have excessive heat. The heater circuit doesn't rely on the thermostat to release heated coolant. It is circulating coolant from the block exit to the core, regardless of thermostat performance, and may prevent proper function of the thermostat. Once the thermostat opens, less hot coolant will be forced through the core, as more will be passed through the thermostat to the radiator. This could also leave a significant amount of heat inside the engine, oblivious to the system, the temp sender, and the clutch. I've found a similar problem with the "rear crossover" mod that many folks have done.

Which radiator design are you using? Cross flow (side tanks)? Dual-pass cross flow (both inlet and outlet on the same side...current Duramax uses this, which I think is the root cause of fan clutch issues on the 2005's)? Verticle flow (top/bottom tanks)? Dual-pass verticle flow (both inlet/outlet on the same tank)? This could be very important. Each design has a different heat exchange "map". Perhaps you are just using the incorrect radiator design for your application. Simply reversing the tanks could solve the issue, if that's the case. Your radiator "hot spot" obviously isn't in the airflow path of the fan clutch, and you need to get it there.

[oka065]

G,day DmaxMaverick, the heater I have fitted is only a small tranny cooler so I dont thing there will be any further cooling or effect on the t/stat. The hub is sensing air from the very bottom of the radiator & the coolant is anywhere from 12 to 25 deg Celcius cooler depenting on t/stat opening & rpm.
The radiator it a vertical flow 5 or 6 rows staggered, coolant in the top LHS out RHS at the bottom.

The heater measures 10" x 6" x 1/2" so you can see its cooling effect will be very small!

Cheers

[Dvldog 8793]

Howdy
Hummers use a hydrolic clutch to lock the fan at a given temp. I think this was due to the radiator being at such an extreame angle to the fan. If you could find one of the hydrolic fanc clutches then you build a switch to either control in manually or have in close at a given temp. Just another idea....
L8r
Conley

[DmaxMaverick]

Originally posted by oka065:
....The radiator it a vertical flow 5 or 6 rows staggered, coolant in the top LHS out RHS at the bottom.

The heater measures 10" x 6" x 1/2" so you can see its cooling effect will be very small!

Cheers That could very well be your problem. A verticle flow radiator will have the hot coolant at the top, and the cooler coolant at the bottom. If the clutch is sampling air from the bottom of the radiator, it isn't very likely the air will be hot enough to engage the clutch.

Also, that small cooler will reduce the coolant temp in the small loop it's effecting to throw the temp out of the operating envelope, which is very narrow.

Ideally, you should either duct the radiator air path to provide a good sampling to the clutch, or switch to a crossflow radiator (same result).

Try placing a sturdy air deflector between the radiator and fan, room permitting. Imagine a piece of sheet metal channel attached to the top of the core, and angled downward to the clutch area. Be sure it's securely anchored. If the results are positive, consider making it permanent, or swapping the radiator.

It's obvious from your findings the current design wasn't meant to be used in your application.

[oka065]

Hi all, the original engine was a Perkins the was higher that the 6.5 as the hub was sensing air around the middle of the radiator. When we first fitted the 6.5 we left the OEM radiator in & you know what the fan clutch would cycle but I didnt like the temps I was seeing?So then I had a new radiaror made 4" longer & the staggered core.
Dmax I did think of what you suggested but getting in there is a real problem as it is a forward control truck ( cab over front axle ). If you want to see what an OKA looks like go to www.oka.com.au. (http://www.oka.com.au.)
Connely I had a quick look around on the web & couldnt find anything relating to hydraulic fans for Hummers, the Toyota Camry we get here in Ozz have on that was from the Lexus but I havnt seen one yet. I am trying to stick with a fan that I know will pull enough air through.

Cheers

[Dvldog 8793]

Howdy
Found this used on ebay. I don't think I would buy it but it gives you a good idea of what I am talking about. I did a Google search "hmmwv fan clutch" From what I've found, it needs the clutch, a solenoid, a control/temp switch and a hydraulic source(power steering)
L8r
Conley
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=6530572808&category=588

[oka065]

Thanks Conley, looks interesting. I thought it would be a speperate hydraulic motor.

Cheers

Rod

[oka065]

G,day I did a search & found KASCAR REAL 4WD they have the parts I just need to know if the poly V pulley will go onto the HMMWV water pump as mine is a late model motor with the spin on fan hub. So I would need to replace the water pump, pulley, fan & clutch.
The other thing I would need to know is how long the whole assembly is?

Cheers

Rdo

[oka065]

Gee you got me going now. Looks like the late model HMMWV has a poly v belt so one would hope the fan runs reverse.

Getting more interested but looks like the cost to do it would be around $1500 USD.

Might just run with what I have at the moment & see how it goes.

Rod

[Dvldog 8793]

Never realized it would be so much $$$! :eek:
Guess I shoulda figured anything built for the government is going to be spendy...
L8r
Conley