Time delay module

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Time delay module

Post by gizip » Fri Jan 29, 2010 2:45 am

Driving a 86 Humvee yesterday, smoke started coming out from under the hood and a terrible smell. The time delay module had melted on the firewall. I unpluged it and continued on. This is two recent failures on two different vehicles. (a) What makes these things meltdown? Are some better than others?........I have several different new ones.
(b) Second vehicle........once the fan turns on, then it will not turn off. Replacing the time delay module seems to fix this, but months later it happens again..........Wayne
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Re: Time delay module

Post by dunsbr » Fri Jan 29, 2010 2:55 am

There is a known fault for TDM's.
IIRC the early SSI modules were removed from service for causing electrical faults.
Not sure where I read that, maybe PS Magazine.

Anyhow, make sure you get the latest Part No TDM's

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Brad Dunstan
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(with 4L80E Trans, 242 T/case, 12K hubs, CTIS, A2 wiring, Air Con, A2 ebrake, 9k Winch,
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Re: Time delay module

Post by gizip » Fri Jan 29, 2010 4:24 am

Brad........so when I'm buying new TDMs off epay then I probably am getting the old faulty ones.......my failures have come from several mfgs. Does anyone know the manufactured time period that these units were improved? Wayne
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Re: Time delay module

Post by STUDENT-DRIVER » Fri Jan 29, 2010 5:27 am

I also have problems with my time delay modules.
I also had new ones that turns the fan off but never agin on others hold the fan on.
That's horrible with these things.
Other time I chleaned the engine compartment with water and few minutes later the TDM also failed... :evil:
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Re: Time delay module

Post by gizip » Fri Jan 29, 2010 5:38 am

Student Driver (Alex?)..........yes, I just washed the engine compartment to get the snow chemicals off everything, then the next trip was when the TDM melted down...........I did take a air hose and blow off all excess water before starting, but that may have been partly to cause for this recent failure. However the vehicle that fails to turn the fan off after coming on has never been washed since I owned it and I have put three different TDMs on this vehicle.........Wayne
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Re: Time delay module

Post by STUDENT-DRIVER » Fri Jan 29, 2010 5:44 am

Wayne,
for the non washed vehicle:
is the fan shutting off if you apply 24V to the hydraulic valve?
I had the problem in the desert. The clutch was stuck on becaus sand blocked it...
If the fan don't disangage when applying power to the solenoid.
You may have the same problem:
Lossen the small screws on the back of the clutch don't remove them just loosen so that you can turn the fan by hand easily. Then turn the negine on...
Let it run for a minute or so. Tighten the screws and chek the fan for proper function.
Alex
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Re: Time delay module

Post by actionpaintball » Fri Jan 29, 2010 6:35 am

I had the same problem. Replaced the temp sending unit, time delay module, and cleaned all ground wires (I have aux grounding kit installed) I also made sure there were no hydraulic obstructions on the hydraulic switching valve...there are small particles that accumulate in there...I want to think there was a small screen or at least a small orifice.

Mine melted and smoked/smelled: surprised that much smoke came from one small module.

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Re: Time delay module

Post by Action » Fri Jan 29, 2010 10:29 am

It sounds like you guys need to get a newer Humvee that doesn't use the TDM...
It uses a viscous fan drive. I guess it is temperature controlled.

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Re: Time delay module

Post by cpl brown » Sat Jan 30, 2010 7:30 am

i myself have thrown tons of fan clutches in the trash, until one day i got a huge hit in the back of the head from my gysgt. (years ago) he then told me how to clean them out (as alex pointed out), but i have never had a tdm problem,

what is the correct manufacturer part that we need so we wont have this problem?

you loose up to 15hp every time the fan comes on.

jason, has it correct. let's remove the fan system and put in electric fans. i don't beleve the electric fans will draw 15hp worth of electricity.

not to steal the thred, but what does everyone think about removing the fan and installing electric fans?
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Re: Time delay module

Post by dilvoy » Sat Jan 30, 2010 9:45 am

Ya! The part number of the "non catch fire" TDM's would be greatly appriciated. My biggest worry about starting up newly refurbished vehicles is fire from fuel and electrical problems. It's a bad way to loose your vehicle and maybe your house at the same time.

DJ, I'd love to get rid of the HMMWV Fan and have a water proof or water resistant electric Fan, if it could handle the air flow demands. Lots of cars have them, but is seems the heavy duty vehicles still have the belt driven Fans. Maybe a "larger" electric motor driving a belt that moves the fan?
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Re: Time delay module

Post by Ozhumvee » Sat Jan 30, 2010 11:29 am

The blokes over on the HML tried removing the engine driven fan and replacing with two electric fans, they found it doesn't provide enough cooling.
One of the Aussie owners tried as well with different combinations of electric and thermostatic engine driven fans and eventually succeeded in blowing headgaskets ;-)))
Because most of the Humvee's here in Oz are M1026's another of the Aussie owners tried different combinations of top and bottom grilles, fans etc and found that the best combination of grilles was the open mesh M998 in the front and the armoured grille in the top which tended to force incoming air down through the stack.
We all run the standard setup, TDM, Cadillac valve and standard fan clutch and the engines all run ok.
The biggest improvement you can make is to fit a 4 speed/4L80E trans, the engine revs slower so not as much heat, uses less fuel and when the fan does come on it is much quieter due to lower engine revs.
In 25 deg C ambient I can drive for hundreds of kilometres without the fan coming on at all.
I've never had a problem with a TDM, burnt out a Cadillac valve once (they don't like reverse polarity ;-))) and have changed the fan clutch once (due to constant leaks) but I've done over 150k miles now with no problems despite regular engine bay hose downs with Truck wash and the pressure washer.
Peter James
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Re: Time delay module

Post by dunsbr » Sat Jan 30, 2010 3:10 pm

I've gone back through the PS magazines since 1990 and can't find anything on TDM's.
I remember finding this out very early in my Humvee ownership.
When I got my truck the fan was on all the time (due to a blocked "Cadillac" valve) and it was during that time that I discovered that older TDM's were faulty and prone to fail and so I bought a new one by KDS.
Like Ozhumvee, Ive now done around 7 years and 30,000 miles with no problems.

Have you run through the fan diagnostics procedure in the TM?
It gives you a great step by step procedure with voltages and resistances to find issues in the fan control circuit.
We Aussie owners did a "field day" using this procedure many years ago to get all the trucks fan systems functioning correctly.

Regarding electric fans, I run two electric driven 12" condenser fans on my A/C condenser on top of the cooling stack.
They run when the A/C system needs them.
I noticed very early on how much better the A/C cooled when the engine fan kicked in than when the electric fans did.
So much so that I have now changed the fan system so that the A/C can now kick in the engine fan as well as the electrics.

There is NO substitute for an engine driven fan for normal driving operations. A compact electric fan just can't keep up.
The only time an electric fan is better is at idle.
Then the engine fan simply isn't turning fast enough to move as much air as the electrics.

Cheers
Brad Dunstan
RHD '87 M1026
(with 4L80E Trans, 242 T/case, 12K hubs, CTIS, A2 wiring, Air Con, A2 ebrake, 9k Winch,
Serpentine Belt Accessory Drive & Eaton e-lockers)

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Re: Time delay module

Post by GenBiltstein » Tue Feb 02, 2010 1:13 am

Since you guys are ahead of the power curve what's a "cadillac valve" ?

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Re: Time delay module

Post by dunsbr » Tue Feb 02, 2010 1:46 am

GenBiltstein wrote:Since you guys are ahead of the power curve what's a "cadillac valve" ?
One of these Carl:

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If you look closely you can see that they have "Cadillac" on the label.

Glad I could teach the teacher for once.... :mrgreen:

Cheers
Brad Dunstan
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(with 4L80E Trans, 242 T/case, 12K hubs, CTIS, A2 wiring, Air Con, A2 ebrake, 9k Winch,
Serpentine Belt Accessory Drive & Eaton e-lockers)

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Re: Time delay module

Post by STUDENT-DRIVER » Tue Feb 02, 2010 3:26 am

Brad you're getting started what I planned for end of this or beginning of next year.
Currently I've two elctric fans on my cooling stack.
I'm looking forward to add 2 more it's possible on the longer radiator / oil cooler setup.
With my turbo engine in my truck the fan kicks one very often even on low outside temperatures.
Especially on the autobahn.
What I want to do is to start a long term test over one year.
What I want to do is:
Installing 4 electrical fans which I'll have to switch on manually always 2 together.

After I've installed the 4 fans I'll install a data logger the should log the following parameters:
- ambient temperature
- engine temperature
- speed
- activation of the hydraulic fan
- activation of 2 electric fans
- activation of the other 2 electrical fans

I'll drive my truck over a period of one year and switching the electrical fans on and off in all different speed and temperature configurations.
After this year I'll analyze the data as to develop a self working control operated by a microcontroller that keeps the engine temperature as low as possible.

But something I recognized is that even the 2 fans keep the fan on at offroad operation...

-> Brad when I read that you connected your hydraulic fan solenoid valve to your A/C I'm starting to doubt if that is such a good idea. Now you're running the 4L80e that requires a down shift if you are towing a trailer the hydraulic fan is an additional burden that is applied to your drive train okay its in front of the transmission but I drove about 600km with a applied fan and afterwards I had a gear-hunting when driving up a slight pitch as you have on the highway…
I haven't analyzed the source of trouble but it could bet hat the problem is caused by the applied fan over a long term.
But also have to say that my transmission oil pressure was already a bit lower than it used to be before this problem appeared.

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