http://www.dieselplace.com/forum/uploads/Z1B_2005front.png


Notice the difference? Anybody?

Looks identicle to me.

Yeah it was a trick question (assuming the source is actually an 05). Did find some interesting information with it:


The new cooling system advantages:

• A reduction in parasitic losses due to disengaged fan speed with a corresponding increase in
combined city/highway fuel economy.
• A significant improvement in idle A/C performance (driver/passenger comfort) as well as an
ability to idle with A/C on for extended periods in very high ambient temperatures.
• A reduction in customer complaints normally attributed to unusual engine noise or
transmission noise/delayed shift, which are actually fan noise issues.


I think they are talking about a new electro-viscous clutch. If so hallelujah! Uses a solenoid instead of bimetal strips. It would be logic enhanced, cut out at high speed, on with AC, (always off if you live in Canada http://www.dieselplace.com/forum/smileys/Approve.gif), on with increasing trans temps, etc
Edited by: masterp2

If we all deluge the dealer with fan noise complaints maybe we can get a TSB.

I am willing to bet that is for the light duty trucks. I think the HD's still get a clutch fan.

You tell me:


http://www.thedieselpage.com/duramax/2005MY.htm


I don't believe everything I read. I saw an announcement by GM on this, not mentioning the 2500/3500, it is a clutch fan, that takes logic input. But if the fan is the same size, I'm gettin one, as long as I can interface it. I assume the clutch and fan will be sold together.Edited by: masterp2

We'll see but that article isn't specific to the Duramax equiped truck. I don't think GM would change to electric to solve the problem. I am pretty sure that the clutch fan can move more air then a couple of electric fans would be able to. We will have to wait for someone to confirm one way or the other.

You are reading too fast! It is a fan clutch, an electro-viscous type that still has 300 HP driving it, no current. Solenoid replaces bimetal heating strips.

More information, I am speculating.


http://www.gmtechlink.com/arcv_pdf/7_02_e.pdf

http://www.dieselplace.com/forum/smileys/Embarrased.gif

OK I see now. You are speculating.


You could be right. Now I will speculate. http://www.dieselplace.com/forum/smileys/Approve.gif I think GM will switch their gas trucks to dual electric fans and they will leave the duramax alone. This is just a guess, you might be on track. Again, we'll have to wait until someone can confirm one way or another.


The last two points are what lead me to believe that they switched to elecrtic. Reduced noise, better idle a/c performance etc.... The system you are talking about would not have any reduced noise or improved idle a/c performance. Electric fans should improve both. Again, just a guess.Edited by: Max Power

Reduced noise, better idle a/c performance etc.... The system you are talking about would not have any reduced noise or improved idle a/c performance. Electric fans should improve both. Again, just a guess.





Look at it again


By making the fan clutch "controllable", you can turn it on with AC activation, defeat it over a certain speed (In Canada, you may have never experienced the 20-30dB this puts in the cabin at 75 mph), on according to oil temp if you want! Have it on basically only when it is necessary per logic algorithm. The noise most people complain about is when it turn your truck into a cessna at high RPM. Yet, often sitting in traffic the darn thing stays off, when the AC condenser needs it most. That is my basic complaint, it is stupid, yet effective, but only in a stupid way. Anyway, that's why I labeled this vol 1.


But you are right on in defending this truck against an electric fan, it will never happen. An electric cannot touch it for CFM. And I would be suspect as you were.


I saw you respond on a post once that you thought this fan enhanced flow at 70 mph, and you may be right, but the benefit at that speed must be small.Edited by: masterp2

The wording still has me at the same conclusion. IMO the fan is adequate and does its job as it should. This is just my opinion.


There is no doubt in my mind that the cooling fan increases flow at highway speeds. If you had a digital engine temperature display, I am quite sure you would agree with me.


Many people are seeing the fan come on at highway speeds without even climbing a hill when towing. This tells me that the fan does aid in air flow at highway speeds and it does increase cooling. The temperatures falls quite fast and the fan does eventually turn off. So it is doing something. It also leads me to believe that this is the noise that GM is trying to reduce. If I am correct, the design you are talking about will not get rid of this noise. (The fan will still come on because it will be necessary) You are assuming that the fan isn't necessary at highway speeds. I am quite certain it is necessary. A necessary evil.

BTW, In Canada we don't see temperatures quite as high as you would in AZ however it is not uncommon for it to get over 100 in the summer months so I am no stranger to cooling systems. This summer has been unusually cool but I am still seeing a lot of the cooling systems complaints that other people in warmer climates are complaining about.


There isn't too much sense in speculating as we will all know soon enough anyways.Edited by: Max Power

Did you read at what temps the fan is fully engaged? Water temps of 264 F and above locks the fan 100 % (or transmissiontemps over 304 F). Thats NOT for our diesel engines.

Did you read at what temps the fan is fully engaged? Water temps of 264 F and above locks the fan 100 % (or transmissiontemps over 304 F). Thats NOT for our diesel engines.


Why not? That is basically the emergency fail-safe mode. It doesn't mean the clutch is disengaged for all other conditions. That is an ECM algorithm for another vehicle, I wasn't focused in on the ECM controllers, just the concept that there is vast improvement potential for the existing clutch. Edited by: masterp2

We made a run to Sacramento and back on Labor Day weekend. We were hauling my wife's Sptifire out there for some restoration work. A 4500lb load out, 2500lb load coming back. When we left San Jose, the outside temp was 95 degrees. In Sacramento, it showed 99.

The truck had no problems keeping the interior a chilly 68 degrees. In fact, we had to turn the temp up about 1/2 way because it was uncomfortably cool. At the same time, the engine temp gauge never budged off 1 tick below midpoint. This is where it runs all the time regardless of outside temp so far. We had some mild climbing, the longest being about 3 miles, 3% and the truck's gauges stayed put.

I'm satisified so far with the truck's cooling system.

When I drove from georgia to alaska across the states... I never had any cooling issues. Whatever GM put on my 04 lb7, works just fine.


I don't mind the noise. It's a dang diesel!

Forget the noise....fix the dang A/C problem. Noise is absolutely no issue as my LLY is a ton quieter than my old 6.0L PSD. Now, the A/C on the other hand is worthless in Texas. Come to any stoplight....nothing but hot air. Go in the mall for a few hours, come back out, truck couldnt cool itself if the fate of the world depended on it.

I've watched theese trucks go down the assembly line and can tell you that the electric fans are for the LD trucks only. The DMAX did not change one iota for 2005.....except for the bump in power.

masterp2
that was NOT meant as argument against your idea. I just wanted to say that for this particular application (the GM letter) temps were on the high side. I like the idea also, but it won't get rid of the noise at highway speeds. The silicone fluid coupling currently used is very reliable and fool proof. It comes on only if needed, if that thing is running than the engine is hot. Any other fan moving that much air will be noisy as well, electric or whatever.
To aid with cooling while the vehicle is standing (for A/C) is no problem at all, just put a nice electric fan in front of the radiator. If any electric fan would be moving enough air to cool the dmax companies like flex-a-lite would sell them - they don't. Of course they would custome made one if requested...

TEXMudder


There is a TSB to fix what you have experienced, print it off and bring it with you to the dealer. The parts are on national backorder, so you will want to get in line.


ALL


I like things that are simple and work good and reliable, I know the fan we have does that. But in our world of intelligence there is no reason my dog should poop in the back seat because a cooling fan kicks on. If the fan clutch modulated, like a transmission, instead of behaving as an on-off switch, then the biggest noise would never be necessary, the truck would stay cool with less shock, and as JK points out, the rapid temp swings this creates is BAD for metal parts. That's all I'm saying. I agree it does the job, I just prefer not to drink from a firehose, (we are in a severe drought, water seems to be in all my analogies lately). But good to know the firehose is there.


Nassdmax, you know we are not talking about electric fans, right? What in your opinion is changed then for 05 to accomplish what GM printed?


The core of this for me is the apparent lack of modulation. The chart is borrowed from Kennedy's site, thanks JK. It indicates 6.5 engine fan modulation but I don't get it on my truck. One second it's quiet the next I feel like I am a B-17. I'm not sure how to interpret the chart, but I would like a smarter fan clutch.http://www.dieselplace.com/forum/uploads/7DA_fanclutch.pngEdited by: masterp2

TEXMudder


There is a TSB to fix what you have experienced, print it off and bring it with you to the dealer. The parts are on national backorder, so you will want to get in line.


ALL


I like things that are simple and work good and reliable, I know the fan we have does that. But in our world of intelligence there is no reason my dog should poop in the back seat because a cooling fan kicks on. If the fan clutch modulated, like a transmission, instead of behaving as an on-off switch, then the biggest noise would never be necessary, the truck would stay cool with less shock, and as JK points out, the rapid temp swings this creates is BAD for metal parts. That's all I'm saying. I agree it does the job, I just prefer not to drink from a firehose, (we are in a severe drought, water seems to be in all my analogies lately). But good to know the firehose is there.


Nassdmax, you know we are not talking about electric fans, right? What in your opinion is changed then for 05 to accomplish what GM printed?


The core of this for me is the apparent lack of modulation. The chart is borrowed from Kennedy's site, thanks JK. It indicates 6.5 engine fan modulation but I don't get it on my truck. One second it's quiet the next I feel like I am a B-17. I'm not sure how to interpret the chart, but I would like a smarter fan clutch.http://www.dieselplace.com/forum/uploads/7DA_fanclutch.png














The cooling system statements are the blanket variety Silverado upgrades, just like the 17" wheels, platinum spark plugs etc. The HD series gets the 16" wheels, and the clutch is conventional.





Those who have been on the wrong end of a cooling problem (6.5) can appreciate the roar of a fan clutch coming in as they KNOW that it is for good reason. Mine seldom comes on unless towing heavy or it is very hot, but I KNOW it is needed.

I like the idea also, but it won't get rid of the noise at highway speeds. The silicone fluid coupling currently used is very reliable and fool proof. It comes on only if needed, if that thing is running than the engine is hot.


I hope you don't think I am splitting hairs, but there is some errors in your statement. A fan clutch that modulates according to actual engine conditions, cools only as much as required, engaging enough to meet cooling demand. This is less noise. The E-V clutch has this potential, and operates on the same silicone fluid coupling principle. When our fan comes on, it is not because the engine is hot. It comes on only when the air temp across the fan reaches a threshhold temp. So it doesn't care if the AC is on/off, or if the oil is 300 degrees. If you turn off the AC, and plug the radiator core with debris, the fan will never come on, because the clutch will never get hot enough. Don't know if that has ever happened.


My point is, i think it is possible to have an EV clutch that is every bit as reliable, with many advantages for the severe conditions user. Didn't mean to start a debate, I know there are lots of people out there with my complaint, who are also happy to have noise instead of boiling water. I don't know why that ever was a reason to not question improvement potential. If I had a life, I'd be in bed nowhttp://www.dieselplace.com/forum/smileys/Embarrased.gif

JK, why are these charts at 3200 RPM engine speed?


For the red curve, where is clutch engagement? 165 or 180?

I think if they go with a electrically controlled fan clutch it should work on water temp, not air temps like most electric fans do. This way you know it will work when water temps rise regardless of free air temps. It would be a lot more reliable and predictable too.

His point is that if they have an electrically-controlled clutch, you can turn it on any time you damn please, via the ecm logic. Thus, you can watch A/C status, road speed, water temp, oil temp, ambient temp, block/head temp, trans temp, engine load, or anything else and any combos thereof. You can also probably put in an overide switch to have manual on-control, something I was always fond of after my very first fan thermoswitch died in the 80's. On the other hand, the old-fashioned bimetal clutches rarely fail...

His point is noted, but GM isn't doing it. So short of designing your own system, what can you do? http://www.dieselplace.com/forum/smileys/Geek.gif

It is kinda strange though because foreign cars have monitored water temp to control electric fans for over 30 years now and it is pretty reliable. My son has a 14 year old Toyota that they still works like new so it can be done. By monitoring the air temp only, in theory it is possible to overheat the car on a very cold day or is core is plugged up. My guess is they are try to minimize fan noise and therefore waiting for air to get hot but that is not good for under hood temps either.

My guess is that it is financially driven, a thermoswitched fan is entirely smarter, but a few pennies more. And up to now they have been electric fans (and we all agree that thier aren't any 20 HP elec fans that will do for this bad boy). The EV clutch uses the logic AND a 300 HP motor to drive it. Best of both worlds.


But if GM is NOT using one for 05, what explains the cooling improvements? Something changed! Or maybe they are referring to the other trucks, not diesel.

snowman


The Japanese do all this at the cost of premature trans failure. I can't tell you how many coolers I have had to install in these cars.


mike

JK, why are these charts at 3200 RPM engine speed?


For the red curve, where is clutch engagement? 165 or 180?








The stuff on my site is all geared toward the 6.5l. The cut in temp spec on the OE clutch is 190-200° for the 6.5. The Dmax is 195-200° My clutch for the 6.5 is 175-185°.





The cut in temp is highly influenced by the air to air intercooler, trans cooler, AC etc.





IMHO, the fan NEEDS to run when it kicks in. The underhood temps are hot.

I agree with you. Would love to see a replacement clutch that "blends" in with a broad temp range.


In hindsight, our clutch may do that some, but when spinning at highway RPM, the kick on is like a switch. Maybe RPM has something to do with the delay of fan activity, a centrigugal force that keeps it from behaving as it does at lower RPM. Just throwing darts here.

Emissions, both air and noise play a BIG factor in clutch specs...





I think it could pull a little bit harder more often and possibly circumvent full enagaement (like my 6.5 unit seems to do) which would increase the effectiveness of the IC and AC etc...

snowman


The Japanese do all this at the cost of premature trans failure. I can't tell you how many coolers I have had to install in these cars.


mike

I do not see how they are related. If water stay cool so will tranny unless it is abused. It would be far more likely to overheat tranny with cooling based on air temp thru core only.

I agree with you. Would love to see a replacement clutch that "blends" in with a broad temp range.


In hindsight, our clutch may do that some, but when spinning at highway RPM, the kick on is like a switch. Maybe RPM has something to do with the delay of fan activity, a centrigugal force that keeps it from behaving as it does at lower RPM. Just throwing darts here.

Actually, you are correct. Centrifical force does play a factor in its operation and it does take a bit more "signal" (input from Bimetal coil) to engage at higher RPMs than at a idle.

The stuff on my site is all geared toward the 6.5l. The cut in temp spec on the OE clutch is 190-200° for the 6.5. The Dmax is 195-200° My clutch for the 6.5 is 175-185°.





So the flat part of the curve on the left is freewheeling RPM?


Snoamn, thought I was imagining things when it would engage on the highway after picking my foot up a bit. Starting to feel like pavlov's dog.Edited by: masterp2

Ahhh... sorry for my ignorance, but I saw electric and thought you were mentioning the elec fans on the LDs. I know of no changes to the HD cooling system except for the different grille. Fan clutch still the same as far as I can tell...Bi metal strips and all!


Don't you love the generic statements used to get you thinking that you are getting something more and actually NEED to have the latest and greatest thing in the world....http://www.dieselplace.com/forum/smileys/Disapprove.gif I'll still sit with my 03 LB7 thank you very much... As proven here, there is still more power available for that motor than the new LLYs.http://www.dieselplace.com/forum/smileys/HiHi.gif

Ah pooh! But we are saving the environment, LOL.


It does seem that my truck gets sportier with time. The comparisons made are LB7's fully loose vs many LLY's still not broken in. Just a thought. I have also noticed slightly fewer hiway clutch sessions than I use to, probably due to less heat from friction in the motor.