Engine/Transmission (1998.5 - 2002) Need second opinion

[DonSimpson]

It started last summer while pulling my 5th wheel, when hitting a hill I would get a roaring noise from under the hood (sounds like a small jet engine taking off) then at top of the hill when I leveled out it would go away. This happened only while pulling, in hot weather and on inclines. This year it seems to have gotten a little worse, it doesn't happen all the time, but has started while driving normally without a trailer. I was told it could be the fan drive (fan clutch) getting hot and sticking, but I really don't need to blow $200 right now on something I maybe don't need. I was wondering if any of you might have had this happen to them before. Any replys on this will be helpful.

Thanks, Don

 

[R-N-R]

Not sure about your roblem, but my fan turns on at odd times as well.

 

[DonSimpson]

Thanks to the post maybe it's all in my imagination, think I'll wait till to see if it gets worse before I start spending $ on it.

 

[nps]

It's the fan clutch kicking in - not sticking - but normal operation unless you hear it coming on in cool weather.



Uphill the engine temps climb. In hot weather, the underhood temps rise and engage the fan clutch even though at 55mph the cooling effect of the fan is questionable.



I've thought of getting a flex fan but haven't done any investigation. Even in the Vegas heat I really don't see temps climbing while driving, however when the truck has been run, then parked in the sun, on startup it is hot enough to engage the fan for the first couple of blocks.

 

[SnoKing]

Cycling of the cooling fan is normal under heavy pulling conditions. You did not say what year your truck is. Excessive cycling could indicate a need to service the radiator (boiling it out) or need for replacing the themostat. Also make sure the the front of the coolers are not plugged up with bugs. The first time the fan clutch kicks in, just about everyone things something is wrong. May think there transmission in slipping, but it is all part of working hard. SNOKING

 

[DonSimpson]

Thanks for the replys on this, glad to here it's normal operation, it's not cycling an extensive amount and had the rad. flushed out about two months ago, and yes the first time I heard this I thought there was something major wrong. Again thanks. DON

2001 2500 EXT. CAB AUTO SLT 4X4

 

[BillGotthelf]

Yes it is your fan clutch.

 

[ata]

You more then likely have a 195 degree thermostat. Go to Cummin's and get a 180 degree and the fan will hardly ever come on. Anyhow that's what I did and that fan robs a lot of horse power when it comes on.

 

[I-6DZL]

best thing i've found for bugs in the front of the radiator is a big chunk of screen door screen. Does not affect cooling negatively, only positively, by keeping the radiator fins clean.



Each time it rains while driving, you're cleaning the screen. I've had mine screened now since i've owned it.



Sounds like you also need a coolant flush.



Curtis

 

[R-N-R]

You can pick up a window screen from most hardware stores, a perfect size (18x36?)is available for the 2nd gen (if not more), it compresses by sliding together to install past the curved bumper, then can be expanded to stretch across the full radiator. I tossed mine after a couple of years because the metal frame (wood pieces on the sides) started to rust. The best thing about it..... approximately $7!

 

[Loren]

Several members have mentioned on other posts that if the fan clutch starts to cycle more than usual, the problem is often debris in the radiator(s).



The very first thing you should do is clean them. Then, and only then, spend money to fix this problem.



I understand that a good blast of water from back to front will do it.



Loren

 

[GBrock]

I heard the EXACT same sounds from under the hood of my 2500 while towing my boat last week. Also only occurs while towing heavy and in the hills. Glad to see the adviceon here of what it is and how to better deal with is.



On that note, what is the best way clean one's radiator fins, i. e, how much water pressure is too much?

 

[PC12Driver]

I just had my radiator out of my truck and could not believe how bad it was plugged. Easily 25% blocked (I've got pics that I'll post when I get home of my 100 watt shop light behind the radiator and you can barely see the light). Considering that my crankcase vent has been relocated almost since the truck was new and that I flush the fins with water, I was really surprised. Apparently, just hosing it out with it in the truck isn't enough.



After I found that on my truck, I checked out my Dad's truck (an '01 with 25k miles) for comparison. He's got 1/3 of my miles, but his breather bottle is still in place. His radiator was just as bad as mine!



So now part of my maintenance on my truck is to pull the radiator every 24 months when I change my coolant and (carefully) hit it with the pressure washer. Great time to change the belt too, since there's plenty of room to work with the radiator out.

 

[PC12Driver]

Here's the pics. The close-ups turned out pretty blurry, but the one of the front and the one with the backlight pretty much sum it up. There's no easy way to clean between the intercooler and the radiator 'cept to pull the radiator out.

 

[DonSimpson]

Thanks for the pic's, it looks like I might have to pull the rad to see the real story, might try to tackle that job next wkend. I appreciate all the info.

Don

 

[TRAMPLINEMAN]

Look at the front fins on the rad. and make sure they aren't bent over. If so, straighten them with a small screwdriver or similiar object. I've had a screen on mine since day one also and has kept out a lot of debris. With the engine off, try to spin the fan. It should only spin freely a couple of inches. If not, fan clutch may be going bad. Mine makes the same sound you described under heavy load.

 

[R-N-R]

Speaking of Radiator Problems....

Check out these pics of my 2002 @ 40k radiator



I am amazed at the amount of dirt on the bumper side of the radiator.



I developed a small leak that grew overnight into a major leak. It turns out that I had previously dropped an oil filter strap wrench between the radiator and the intercooler, which in turn poked into the radiator.



Anybody happen to know if this can be repaired or will I have to get a new core? Also, what $$ ballpark will this type of problem run?

 

[Moose Truck]

Ok, I have to pull mine this weekend. Tried the Foam Engine Brite cleaner, She still runs a "little" Hot. It looks like there are two bolts at the top for the Radiator, and the drain as on the Pass side. Does the Fan need to come out, or is it easier to pull out the shroud 1st?



I then plan to hot water & Simple Green it, then pressure wash it. Should be good for the trip to IRP Oo.



Thanks guys, Moose00

 

[PC12Driver]

I just took the fan shroud off the radiator and pushed it back toward the engine (two bolts on each side and remove the clips on the top). I also took the coolant and the washer tanks off the shroud too, but now that I'm thinking about it, I'm not sure if I had to. Then pull the two bolts on the radiator (and the hoses of course) and it pulls straight up.

 

[Moose Truck]

Thanks PC12Driver, I was thinking to take the fan off, But then your way looks the quickest. It looks like there should be room to take the shroud off after the fan. The shroud is a mess too. I have the hose and elbow to route the breather towards the back of the Transmission area. My 1st gen did do this, can't see way they changed it. Thanks again, Moose