roaring truck

[Paul L]

Has anyone experienced this?
When it is warm outside there is a loud roaring noise when I accelerate, 1st gear mostly, trannie shifts late
please let me know!!!

[Paul L]

Has anyone experienced this?
When it is warm outside there is a loud roaring noise when I accelerate, 1st gear mostly, trannie shifts late
please let me know!!!

[Paul L]

Has anyone experienced this?
When it is warm outside there is a loud roaring noise when I accelerate, 1st gear mostly, trannie shifts late
please let me know!!!

[kboring]

Thats your fan turning

[DRTYFN]

Actually, it's because your a/c compressor is on.

[H2Finally]

PaulL, been at the dealership TWICE for EXACTLY this problem. The second time they swapped my fan clutch and the problem went away for a month. Now that the weather's real warm, it's cropping up again!! PLEASE LET ME KNOW YOUR SOLUTION (IF YOU EVER FIND OUT)!!

[Yetti]

yep, the fan clutch is bad, they suck up power ,and mess with your shift points because your leaning on the gas harder.

[kboring]

The fan is suppsed to come on when it gets warm outside. Otherwise the truck would run hot. All I own is GM vehicles and all of them do this sometimes

[KenP]

H2F, get an electric fan so your sweetie won't have to her that noise.

[H2Finally]

How can the NEW fan clutch went bad (again) in 1 month?? Too, this is So Cal beach city temperatures -- where "hot" is only 90degrees.

KenP, guarantee the electric fan would work, I'd do it in a heartbeat!! I even have to drive with "tow" button engaged on the hills around here to get decent performance! (Btw, Mike of Cerritos Hummer said they have new programming just release 2 weeks ago, that would improve shift points in lower gears)

Anthing else you guys can think that could have caused it? Maybe water in where it shouldn't? (Problem seemed to first crop up after I washed the engine with pressure washer??)

If anyone think I know nothing abt cars... you're right!

[PARAGON]

Kboring is right. It does it on both my Denali and H2 and has done it on both from the beginning. The fan clutch is somewhat variable. It also does it when you first crank up in the morning as some type of test.

The clutch mechanism is not mechanical in nature but is a magnetically reactive fluid. GM calls the clutch "Magnetorheological Fluid (MRF) Fan Clutch". The fluid in the clutch changes viscosity to turn the fan on and off.

When the engine is at temp the viscosity of the fluid is at max and the fan is fully engaged and moving alot of air, that's what you are hearing.

[Hummer Man]

Guys, There has always been that feeling of hesitation as the H2 shifts from 1st especially on a cold start. The problem is as you identified - The Fan clutch eats up torque - So much that they are not using the same system on the 2004 H2 SUT and also did a modification on the 2004 H2. Read the details below!

Hydra-Matic 4L60-E/4L65-E (M30/M32/M33) Car and Truck Transmissions


2004 MODEL YEAR SUMMARY
? New application for compact pickup (GMT355)
? New application for Parallel Hybrid truck gets transmission RPO M33
? New application for HUMMER H2 sport utility truck
? Improved quality of neutral start backup switch
? Improved efficiency for torque converters


FULL DESCRIPTIONS OF NEW OR CHANGED FEATURES

NEW APPLICATION FOR COMPACT PICKUP (GMT355)
The 4L60-E will be used in the new Colorado and Canyon pickup trucks, which are powered by 2.8L inline four and 3.5L inline six cylinder engines. For four-wheel-drive applications, the bottom pan of the 4L60-E was modified so that the prop shaft from the transfer case to the front differential can clear the side of the transmission. As a result of the new bottom pan, the 1-2 accumulator housing, the valve body, and the fluid filter had to be redesigned for clearance. The fluid filter, which is housed inside the bottom pan of the transmission, was also redesigned to fit the new pan. The torque converters for both four-cylinder and five-cylinder models have been tuned to match each engine, with the four cylinder getting a 245-mm torque converter and the five cylinder getting the 258-mm torque converter. The two-wheel-drive pickups will use the conventional 4L60-E.

NEW APPLICATION FOR PARALLEL HYBRID TRUCK GETS TRANSMISSION RPO M33
The 4L60-E will be used with the Parallel Hybrid pickup truck, which uses an electric motor/alternator sandwiched between the conventional engine and transmission. The electric motor assists the engine during acceleration, and generates electricity to charge batteries at other times. The torque converter is a 258-mm unit, but it is modified to take the extra torque of the V-8 engine. The input shaft on the torque converter is stronger, and the lockup clutch is also more robust. Generally, V-8 engines are matched to 300-mm torque converters, but the smaller unit was used to allow space for the electric motor.

NEW APPLICATION FOR HUMMER H2 SPORT UTILITY TRUCK
The new HUMMER H2 SUT will use the 4L60-E, but with a specially tuned 300-mm torque converter. This torque converter will produce slightly more torque multiplication initially, for quicker vehicle acceleration.

IMPROVED QUALITY OF NEUTRAL SAFETY BACKUP SWITCH
There is a switch on the transmission that signals to prevent the engine from starting in forward and reverse gears, and it also signals to turn on backup lights. The switch was redesigned to eliminate one electrical connector and to better seal out contaminants.

IMPROVED EFFICIENCY FOR TORQUE CONVERTERS
The torque converters used in V-6 and V-8 applications have been redesigned internally to be more efficient. Specifically, a torque converter is a circular fluid coupling with three sets of fan-like blades inside. The input blades force fluid through the stator blades into the output blades as the coupling turns. New shapes for the stator blades increase the efficiency of the fluid transfer, and contribute to measurable fuel economy improvements.

LOW MAINTENANCE
The 4L60-E/4L65-E uses Dexron III automatic transmission fluid. For severe use, fluid changes are the only maintenance recommended. For normal use there is no fluid change scheduled. One aim of continual development of the 4L60-E/4L65-E is to increase high-mileage longevity.

Another contribution to low maintenance is the ability to match the transmissions to each of their broad list of applications. Performance efficiency and ideal cooling are achieved by using one of five sizes of torque converters and that contributes to long-term durability.

OVERVIEW
The Hydra-Matic 4L60-E/4L65-E owe their rigid structure and quiet-running attributes to their design. The 4L60-E/4L65-E are state-of-the-art transmissions for rear-drive cars and trucks because of their adaptive shift electronic controls and GM’s proprietary electronic controlled capacity clutch (ECCC) technology. The ECCC allows sophisticated variable clutch slip to dampen engine pulses, providing smooth shifting and driveline feel. The transmissions also take directions from vehicle powertrain control modules to avoid hunting between gears when climbing hills.

An extremely versatile transmission, the 4L60-E functions in a wide range of applications. Its sophisticated electronic controls and high-torque capabilities allow it to serve in the high-performance Corvette as well as pickups and SUVs ranging from the compact Chevrolet S-10 to the roomy GMC Yukon XL.

The 4L65-E was introduced in the 2001 model year as a heavy-duty (HD) version. It features a host of more robust parts that provide increased strength, which allows owners of luxury sport utility vehicles to enjoy excellent powertrain performance at a reduced overall vehicle weight. For 2002 and 2003, some of the technologies from the 4L65-E applications that add durability were incorporated into the 4L60-E, such as the shift solenoid inlet port screens and more robust bushings and bearings.

FOUR-WHEEL DRIVE OPTIONS
The 4L60-E is mated to 10 different transfer cases used by four-wheel-drive applications. The Astro and Safari L-vans use the New Venture Gear model 136, in which an electrically operated clutch pack sends torque to the front wheels if rear wheel slippage is detected. The GMT 330 pickups use either the New Venture model 233 or 236. The 233 is a part-time conventional transfer case, but engages through an electrically operated solenoid. The 236 can be used full-time, with an electrically operated clutch pack engaging the front wheels when rear wheel slippage is detected. The Blazer uses either the New Venture 126 or 226 models, with the 126 featuring an electrically operated clutch pack between the axles, but without a low range, and the 226 using a low range. The GMT 800 pickups use the New Venture models 246, 261, the Borg Warner 4482 and T150. The 246 has an electrically operated clutch pack to send torque to the front axle, and the 261 is a conventional part-time transfer case.

The 4L65-E is mated to three different transfer cases used by four-wheel-drive applications. The New Venture 149 is used in the full-size sport utilities and contains a center differential for full-time use. A Borg Warner 4481 is used by the heavy-duty GMT 800 pickups, and a Borg Warner 4484 is used by the HUMMER H2.

[Hummer Man]

Just as Paragon stated The H2 Fan Clutch System operates on a slightly different system then a standard fan clutch.

The H2 fan clutch is a small fluid coupling with a thermostatic device that controls a variable-speed fan. The fan clutch ensures that the fan will rotate at just the right speed to keep the engine from overheating, and reduces drive to the fan when it is no longer needed.

The fan clutch has a fluid coupling partly filled with silicone oil designed for just that purpose. If the temperature of the air passing through the radiator rises, the heat alerts a bimetal coil spring to "uncoil" or expand. When it expands, it allows just a little more oil to enter the fluid coupling, so the fluid coupling starts to rotate the fan. If the air coming through the radiator is cool, the opposite happens; the coil spring contracts, the oil leaves the fluid coupling and the fan slows. Slowing the fan when it is not needed reduces fuel consumption, makes less noise and saves engine power.

Sometimes a flat bimetal strip spring is used instead of a coil spring; it bows out and in when the temperature rises and drops, letting oil in and out of the fluid coupling.

[Yetti]

I would think if the fan is doing it job the clutch should disengage when you get going(after 1 minute or so), and then the clutch should just be letting the wind coming through the radiator make the fan move, UNLESS its hot enough for the afore metioned spring to change the valving inside to applie the fan. OR the fan clutch never got the right part to begin with. I have seen dealers "throw on" what fits , rather then getting the right part.
good luck.

[Paul L]

its going in wed - I will post what happens
my mileage will be +/- 35,900
then I'm on my own

[Zing]

I think Drty's right. It has to do with extra load of the A/C.

[Limited Red Man]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Hummer Man:
Just as Paragon stated The H2 Fan Clutch System operates on a slightly different system then a standard fan clutch.

The H2 fan clutch is a small fluid coupling with a thermostatic device that controls a variable-speed fan. The fan clutch ensures that the fan will rotate at just the right speed to keep the engine from overheating, and reduces drive to the fan when it is no longer needed.

The fan clutch has a fluid coupling partly filled with silicone oil designed for just that purpose. If the temperature of the air passing through the radiator rises, the heat alerts a bimetal coil spring to "uncoil" or expand. When it expands, it allows just a little more oil to enter the fluid coupling, so the fluid coupling starts to rotate the fan. If the air coming through the radiator is cool, the opposite happens; the coil spring contracts, the oil leaves the fluid coupling and the fan slows. Slowing the fan when it is not needed reduces fuel consumption, makes less noise and saves engine power.

Sometimes a flat bimetal strip spring is used instead of a coil spring; it bows out and in when the temperature rises and drops, letting oil in and out of the fluid coupling. <HR></BLOCKQUOTE>

[H2Finally]

Update: Bad Fan Clutch -- again! 2 bad fan clutches in 2 months??

Brings a whole new appreciation to term "under warranty".. Paul L, update on yours?

[Paul L]

Update fan noise:
Tech could not duplicate
What else is new?
Now here is the scenario, when I dropped the truck off it had 35,975 miles on it, with no extended warranty. (HMan DO NOT RESPOND TO THE EXTENDED WARRENTY)
So they gave me paperwork to extend my warranty to cover the “ROARING NOISE” beyond the 36,000
I’m as content as I’m going to be without blowing a gasket & the other side of the coin if the roaring noise just happens to be an engine or trannie I’m covered beyond 36,000. How much beyond ---- I dono

On a side note they replaced the kaka “hummer thresholds” ……. No strike that, I meant the sh*t sma thresholds

[H2Finally]

Ask them to test the fan clutch. When I dropped off the H2 I did not believe it could be the fan clutch again, so asked them to test everything they can think off. They did that & conclude that it was ANOTHER defective fan clutch. He even said tounge-in-cheek -- "well it is a GM part...."!