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Old 05-01-2020, 09:47 AM
Livermoron Livermoron is offline
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Location: Livermore, CA
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Default Cooling question - a little different

I have a bone stock 2002 LB7 4x4 crew and often pull a 10K 5th wheel while carrying a full size dirt bike on a carrier on the front of the truck. On long climbs (NV to CA on 88 most recently) in warmer weather I approach over heating (warning cluster says to check coolant temp) near the top of the hill - so far it is within a 1/4 mile or so and as soon as I crest the hill the temps begin to drop, etc.

I am planning on doing this trip again in a couple of weeks and have been looking at available options for increasing my cooling. My original theory was that the bike was blocking air from the radiator (obviously) - but I have read that the fan with the clutch engaged should be sucking in air at an equivalent rate as driving around +60mph. So... if I move the bike to the back of the trailer will I likely see the same high temps? I have looked at all aluminum radiators but I haven't seen anything definitive on increased heat rejection and have seen lots of leaks reported within a year of install. I have looked at electric fans but that just looks like something for increased HP/MPG - not increased cooling over the stock fan with the clutch engaged.

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Old 05-01-2020, 09:54 AM
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gmduramax gmduramax is online now
Shits broke
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When was the last time the fan clutch was replaced?
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Old 05-01-2020, 10:02 AM
Livermoron Livermoron is offline
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Don't know but it makes the proper loud fan type noises when it engages - I will look at replacing.

You think if operating normally moving the bike won't impact cooling?
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Old 05-01-2020, 10:12 AM
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Bdsankey Bdsankey is offline

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How many miles on the truck? A good place to start would be making sure the thermostats and fan clutch are in good shape as well as cleaning the cooling stack. Just because the fan kicks on doesn't mean it is transfering the power properly like it should be, they defintely get weaker as time goes on. IMO the best "bang for the buck" is the Kennedy fan clutch. They plain work. Also after ~18yrs all the bugs/dirt/etc gets built up in the radiator and intercooler fins. If the radiator isn't super dirty you could try replacing it with a brand new GM radiator in the event that there is some internal blockage (not complete, but lets say there is some x% flow restriction after 18 years).

As for the bike, I would recommend getting it off the front of the truck as it definitely can impact cooling system efficiency. Once you're moving on the highway the air going through the radiator is more a result of vehicle speed vs the clutch fan. Electric fans do not move the same amount of air as the factory fan/clutch setup so I would not go that route especially if you're towing heavy.
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Old 05-01-2020, 10:28 AM
Livermoron Livermoron is offline
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The truck has 182K with new thermostats 2K ago. No cooling issues with the bike on it when towing 95% of the time - only issue is near the top of grades. I think the radiator fins are pretty clean but will look at them again and will also look into a new radiator and clutch - I replaced almost everything else over the last 18 mos so no reason to stop now lol
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Old 05-01-2020, 11:49 AM
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Dozerboy Dozerboy is offline
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I would probably pull the cooling sack apart if you haven't. I blew mine out once a year. This year after 190k I pulled the stack apart and got a bit more stuff out of it after blowing it out and cleaning it with coil cleaner. Chevy 1925 and Malibu796 have both posted quite a bit about trying to keep their trucks cool. But that can take you down a heck of a rabbit hole.

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Old 05-01-2020, 01:31 PM
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I was having trouble with the fan running a lot of the time on my LBZ while pulling my fifth wheel. After cleaning the cooling stack, I don’t think it ever kicked on again even in 100 deg temps. There is a thread here somewhere of how to do it without taking all of it out of the truck, which is how I did it

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Old 05-01-2020, 04:25 PM
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DAVe3283 DAVe3283 is offline
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The bike isn't helping anything. When I put my bike in front of my radiator, the fan kicks on all the time, even just on rolling hills. But it is such a convenient place for a motorcycle!

Fan clutches rarely just die, rather they slowly get weaker and weaker so you don't notice. When it kicks on it should sound like a jet aircraft trying to land on your head. If it isn't uncomfortably loud inside the cab, it probably isn't working right. Mine drowns out my billet S371 turbo and 4" exhaust like they aren't even there.

I would personally start with a new fan clutch and deep clean the cooling stack. Pull the radiator out (easy when the fan is already off) and use coil cleaner on it and the intercooler. I bet that will sort things out, and you might not even have to take the bike off the front.

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Old 05-01-2020, 04:46 PM
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Worse case, cooler towing makes an auxiliary radiator that mounts behind the bumper and with the additional fan you can add to it, it will keep that thing cool. Not cheap but it works very well.
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Old 05-02-2020, 10:18 AM
Livermoron Livermoron is offline
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Location: Livermore, CA
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I appreciate everyone's advice and comments.

When the clutch engages it does sound like a jet talking off - but don't know if that jet should sound closer or not.

So I've decided to move the bike to the trailer (our fifth wheel is a bunkhouse and has large access doors on each side and will easily fit one full size dirt bike and not so easily 2) and clean the stack as best I can. If no improvement I will move onto the fan clutch, etc. I am also talking to a guy about welding a receiver to the back of the trailer but that has a lot of issues that would need to get figured out. I'll report back after our next trip.

Thanks again!
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