• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

Hayden 2886

Potluckslammy

Member
Messages
77
Reaction score
86
Location
Arkansas
@Will L. excellent, detailed, and well considered post, as always! Two things came to mind...if a wind speed meter was used in front of the cooling stack, behind the grill, would that not give the best representation of air movement? Or perhaps, better yet, a meter mounted between the a/c condenser and the rad, with a remote display. That way values could be recorded at idle, and at all engine speeds while actually moving, and under load. Maybe three or four meters are needed, one at each position in the air stream? Maybe this was stated, and I just didn't fully comprehend what was being read.
Second, measuring both fans under same conditions, calculating the difference between the two values, and then coming up with some kind of determination as to how much that difference actually impacts the cooling efficiency of the whole system.
And maybe it's apples and...not oranges....but maybe Red Delicious and Granny Smith? Because they both do the same thing, the same way....but there's a difference of diameter, number of blades, weight, blade pitch...and, as someone said, the blades on the plastic fan may flex somewhat under load, making it more or less efficient at different speeds. So, maybe...either one is good enough, so long as it works.
 

Will L.

Well-Known Member
Messages
9,510
Reaction score
10,522
Location
Boulder City Nv
Yes, either one works for a lot of people. For some getting an extra few percentage points of improvement can make a big difference.
It’s never just which one component- its combined use.

What I am after is if i can recreate the test of the 2 fans, without fanclutch or weather variations- we could know which fan out performs the other. All indicators point to the metal one being best currently.

Comparing the best fan with the best viscous clutch against the one AK Diesel Driver put on his wiuld be interspersed too.
Because then you could know if the same air movement occurs at X rpm.
Then you could also determine how much being able to set engagement and disengagement affects it.

Hmmwvs for instance having the 100% lockup so no loss of rpm, and the instant on, so far less delay of cooling once demaded have amazing impact. Having seen fanblades on hmmwvs that are same diameter, and same pitch yet 2 blades less and can cool in less time once high level is set- means there is massive difference.
I am sure Twisted Steel Performance can testify to the much faster cool down periods of hmmwv fan clutch vs viscous.

My idea of wanting to test all aspects independently would be for all future users.

Theoretically comparing 15% better airflow because of complete lock up at speed, vs same airflow yet 25-35% better heat rejection from the radiator itself from coatings.

The other hummer owner simply found the best of each he could readily buy, and got it regardless of cost. Great for him, but for most of us choosing where to spend the money needs to be put on a scale and decide what to get and what we pass on- wether economic requirements or wanting best roi.
 

THEFERMANATOR

FRANKENBURBAN
Staff member
Lead Moderator
Messages
9,700
Reaction score
3,580
Location
ZEPHYRHILLS FL
Also keep in mind GM used s different fan shroud with the "good" metal fan than earlier trucks used. This was found when people with 99/00 trucks swapped in dmax fan blades and found it set differently in the shroud(more blade was visible). A few people swapped in earlier 6.5 shrouds to there late trucks with dmax blades, and said they got better cooling. So it's the whole system that needs evaluated, not just 1 piece.
 

THEFERMANATOR

FRANKENBURBAN
Staff member
Lead Moderator
Messages
9,700
Reaction score
3,580
Location
ZEPHYRHILLS FL
I have used the 2886 / DMax fan combination.

From what I could tell, the DMax fan did the job it was supposed to do.


The 2886 was a bit more of a wild card.

Remain convinced that first one I got (new) was stuck in a partially locked stage. Symptoms were that on hot days the ECT was lower than I expected (IIRC, low 180*'s F with 195 T-stats) and took longer than expected to get up to that lower than normal operating temp. When towing, I struggled to stay cool on anything but flat ground.

A second new 2886 worked like it should. The annoying thing about the 'good' clutch was that it periodically disengaged while pulling hard and I wanted it to stay locked-in. It was definitely not comfortable to hear the fan spin up / down while pulling the 8K# trailer and a lot of 6% uphill grade still in view . . . If there was a way to force the clutch to stay locked, am certain I could have asked for more power. But, that is less a fault of the 2886 and more of a thermal spring thing.
True medium duty fan clutched operate like you describe, and never fully unlock. They don't care about emissions and milage, and want to maintain constant airflow to prevent temp spikes before the clutch kicks in. I've ridden in a kodiak 4500, and the fan never fully unlocked like you describe in it with the oem fan clutch.
 

Potluckslammy

Member
Messages
77
Reaction score
86
Location
Arkansas
...GM used s different fan shroud...found when people with 99/00 trucks swapped...

... it's the whole system
Well crap on me! My 99 sets me in with this lot. But this is good news...because it's exactly what I needed to know! Luckily I didn't scrap the metal fan...but I'll mount them both just to get an eyeball on it and make sure.

Absolutely right! As with anything, as systems approach is best.
 

Will L.

Well-Known Member
Messages
9,510
Reaction score
10,522
Location
Boulder City Nv
You guys are hilarious!
Dude, if you still have the metal, and don’t mind the 25 bucks or whatever the dmax fan goes for- try them both on your rig, then sell the one you didn’t like.
Just the 1 fan isn’t expensive
 

WarWagon

Well it hits on 7 of 8...
Messages
8,994
Reaction score
4,030
Location
AZ
I found both fan work well all out towing at speed. One difference on the 1993: The Dmax fan pulls more air at idle allowing higher AC fan settings during extended idle in a parking lot. Most don't consider how flexible the Dmax fan is and it's been suggested it can somewhat act as a flex fan. As fan RPM goes up the suction from the radiator stack restriction puts a load on the blades. What fan do you think is going to flex? I also recall the torque limits of fan clutches being a concern from KD for the Dmax fan.

Due to an engine mount failure starting to trim both the shroud and Dmax fan on their own... I ran the steel fan and the high side cut-out switch would shut down the AC system during extended parking lot idle times. (When the switch fails the high side blows up usually at the hose manifold to R4 compressor.)

Oh yeah, I am talking about a hot day. A 115-121 degree extreme heat day where a minor difference becomes a BFD.

A wind speed meter was mentioned. A single measurement point won't say much. You need to measure a grid pattern of the radiator and then average it out. The airflow can vary depending on what is in the way just sitting still. (Road speed can do weird things to airflow over the stack depending on vehicle airflow and is beyond the question asked). Bluntly 10,000 CFM isn't enough. A 21" fan capable of 10,000 CFM that I measured on a Trailblazer SS with a wins speed meter as described isn't enough CFM for our 6.5TD because the blades didn't have enough pitch and my 6.5 ran hot towing around Lake Havasu when I tried it. (Windows down, heater on high. Dealer on way home for a Dmax fan blade.)
 

WarWagon

Well it hits on 7 of 8...
Messages
8,994
Reaction score
4,030
Location
AZ
@Will L. I have both. Bought the Dmax fan because I thought it was an "UPGRADE"...and because the metal one was rusty.
How rusty? Cracking and flinging a blade off the fan is a known thing for diesel engines. Sometimes a new good shape fan is better than risking a blade being flung off when you are working under the hood.
 

Stoney

Lock-n-load
Messages
481
Reaction score
750
Location
Elmira ny
This is why I should have paid more attention in class... Because after reading wills explanation I am so confused it's not funny LOL... After yesterday's events I've been thinking I need to do something about my cooling system... Had to do a couple vehicles to an auction for a friend...and my temp gauge saw regions it has never seen before... Probably close to 220 to 230..it was only for a few minutes getting up the hill to his house which that he'll is a monster... But still if I'm out on the road hauling for somebody I never know how steep of a hill I might have to pull so I need to get my truck more prepared...
 

Will L.

Well-Known Member
Messages
9,510
Reaction score
10,522
Location
Boulder City Nv
I can complicate a glass of water. That said- at 220 you are taking temper out of your piston rings. 230 you are possibly scuffing pistons in cylinders 7&8.

215f should have huge red flashing light in the driver’s eyes and a loud alarm thatthe car behind you can hear.

Seriously, if you hit 220: PULL OVER AND LET IT IDLE BACK DOWN!

I have driven 6.5’s at 230 and above, but it was on the way to a hospital ER. I would have continued if there was ZERO oil pressure. Short of that type of situation- pull over.
 
Top