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Install an electric fan, 2008 Colorado

Posted: Sat Jun 20, 2020 9:16 pm
by Speeder
The fan clutch on my 2008 Colorado went out, and I have a set of factory fans off a 2007 Silverado. I've cut one of the fans off the Silverado assembly, and it fits pretty nicely inside the fan hole on the Colorado fan shroud. But here I need some advice -

What should I use to permanently attach the Silverado piece to the Colorado piece? It'll need to be structural type support, not cosmetic, because this will need to be strong enough to hold a spinning, vibrating fan in place while bouncing down the highway. My initial thought was fiberglassing them together, but from what I can tell fiberglass and plastic don't play well together. Thanks for any advice on this, I do have a few other ideas but I figured I'd ask the giant brain first. It's just a work beater and I don't want to put much money into it if I don't have to, but worse comes to worse I'll pony up for a proper fan. I just want to see if I can make this work, as the 2008 Colorado allows for PCM fan control.

Posted: Sun Jun 21, 2020 8:22 pm
by Bushwacker
I don't have any experience with bonding fan shrouds. But I have bounded plastics before and I used some 3m epoxy, I scuffed up the plastic with sandpaper I think I used 40 or 60 grit on both pieces then I used super glue to position it then coated the seams completely with the epoxy. 3m makes all types of epoxy for different materials and strengths. Keep us posted with what you come up with.

Posted: Sun Jun 21, 2020 9:37 pm
by Speeder
Thanks, I'll look into those and advise the final outcome. I'm also looking at a few other options that will cost money, but want to try this first.

Posted: Tue Jun 30, 2020 11:40 pm
by Speeder
I wasn't able to find the 3M stuff locally, but was able to find JB Weldit (JB) plastic bonder. Their plastic bonding stuff is probably fine for fixing cracks or attaching patches together but it's no good for filling holes as itself as it's way too runny going on. It also gets very hot while curing, hot enough that it went through the tape I was using as a backer.

I wound up using L brackets and bolts to hold the Silverado shroud part to the Colorado shroud. The L brackets, bent to match the different angles, worked well to secure the two different shroud pieces together. The brackets are holding the three pieces (the Colorado has a 2-piece shroud) together securely. The regular JB was strong enough to fill in the holes and seems to be sticking to the shroud plastic pretty well. I was able to use regular masking tape as a backing over the larger holes between the two, and it peeled off the cured JB with no problems. I didn't have enough JB for the whole job, 2 more sets of tubes and it will be done.

It also looks like I'll be able to control the fan with the Colorado computer.

Posted: Sun Jul 05, 2020 10:32 am
by 97k15004wd
Good to hear it was successful. Fixing plastics is hit or miss for me

Posted: Tue Jul 07, 2020 8:51 pm
by Speeder
Stupid GM, changed the pins between the Gen3 and Gen4 computers. The old ones were round, new ones are square. Now my cache of computer pins is worthless, and my truck is sitting out there needing one stinking wire connected before the fans will run. Parts run tomorrow.

Re: Fix a fan shroud

Posted: Fri Jul 24, 2020 6:31 am
by 97k15004wd
Did you get the parts and is it fixed?

Re: Fix a fan shroud

Posted: Sat Jul 25, 2020 4:24 pm
by Speeder
Yup, visited a salvage yard and cannibalized a TrailBlazer with the correct computer in it, so I now have a cache of E67 wires. The plugs are shot though, as they'd been in direct sunlight for who knows how long.

Anyway, it ran great in the test run. When I direct connect the relay control to power and ground, the single fan comes on and is more than enough for ice-cold air at idle on a 99 degree day. I let it get hot before running it up (but not to the point of overheating) and as soon as the fan comes on it takes about 10 seconds to draw the temp back to normal. Unfortunately, EFI Live won't let me turn the fan on as they aren't supporting it and it doesn't have all the tables needed to make it work. I ordered HP Tuners, and it's on its way so I should have it up and running early next week. What sucks is people have been asking EFI Live to support the fans on the E67 computers, and EFI Live's response (on their own forum) is that they're not interested in supporting it. Seems to be their answer on a lot of stuff these days, if it's not diesel related. Disappointing, really.

Install an electric fan, 2008 Colorado

Posted: Fri Jul 31, 2020 4:48 pm
by Speeder
OK, my fan is working now. Sorry, no pictures, while it's working pretty well I'm kind of ashamed at the build quality. This is a work truck, so my only care is does it work, not how does it look and it looks horrible. Anyway, since the information is kind of scattered and hard to put together, I decided to do a write-up showing what you need to do.

To install an electric fan on a 2008 Colorado using the E67 ECM to control it, there are two ways to go about it. You can use a PWM controller, or Discrete control. The PWM requires the use of a PWM controller for the fan, and while it is a better way to control the fan or fans, it is also more expensive and complicated than the Discrete method. There are also companies out there that sell complete setups to use PWM control, and will even activate the ECM for you as part of the deal. However, being the cheap beasturd that I am, and because this is just a POS work truck that I don't care much about, I went with Discrete control.

For mine, I cannibalized a GMT800 electric fan unit that I had laying around doing nothing and combined it with the factory Colorado fan shroud. My reasoning is that if the two fans for the GMT800 can handle a 6.0 liter engine under towing conditions, that one of them can handle a 2.9L engine that almost certainly won't be used for towing anything. If you do plan to tow, you;ll want to get a fan that pulls at least 3000CFM. I used JB Weldit and four L-brackets to lock the fan to the shroud. The fan shroud size was close enough to the hole size on the Colorado shroud that it almost fit within the lip around the Colorado shroud. With the brackets and the weldit, it made for a nice, solid one-piece fan shroud with the added benefit of mounting like it's stock.

To control my single fan, I used a relay and the E67 ECM to run it. For a single fan, you want to use Pin 49 on the grey connector, which is the low speed fan control. There are plenty of sites out there that will show you how to find the pins on an E67. You can buy specialized pins for the E67 computer, or you can go to the salvage yard and cut a junk harness up to get the wiring you need. If you think you can find it on my word though, on the grey connector there are two stacks of pins, two rows to a stack. One stack has a large round plug on one end, the other doesn't. On the stack without the round connector, but from the same end of the plug that the round connector is on, count down to pin number 6. You will want the inside pin, not the outside. This is the low speed fan control. Somewhere there is a high speed fan control as well, which you will want to use if you are running two fans, but that is outside the scope here.

When you wire it up, you will want to use a pretty hefty relay. I have a bunch of 60 amp relays that I bought for other projects, and used one of them. This is well below the amperage the fan pulls, so I don't ever expect to have a relay problem. Since it's a single fan, I wired the relay from the fan to the fuse box where I tapped on at the Megafuse GM uses between the battery and the fuse center, on the fused side. Since it's on the fused side, I used no other fuses on the fan wire although I may change that later. On the control side, when using Discrete the ECM will ground the control wire when it wants the fan to come on, so you will want to tap into 12V for the other side of the relay control. For this one I used an in-line fuse and tapped into a switched power point in the fuse box for an unused accessory. When the key turns off, so does the fan. The E67 (at least on my truck) also has wiring for the AC so it can turn off the air conditioner compressor for WOT driving (like trying to beat a bicycle stoplight to stoplight) or if the AC pressure gets too high so when the AC comes on, the fan also comes on.

When it's all installed, you will need to tell the ECM that it needs to control the fan. When EFI Live was asked to do this by multiple members, their response was it was too much work so they weren't going to do it. More and more, EFI Live responds to customer requests like this, so I've switched over to HP Tuners. Looks like HP Tuners has come a long ways since way back, and they support damned near everything on the road as opposed to EFI Live, who only wants to support GM and Dodge diesel trucks. Plus, they're now a lot cheaper than EFI Live for the unit, although license costs are about the same. Anyway, HP will turn the fans on for you, EFI Live will not. I turned it on for mine, and it worked perfectly. If you don't want to do it yourself there are companies that will just do it as a standalone, but considering it's pretty close to what HP Tuners costs to have them just do the fans, may as well buy it and do it yourself.

Anyway, I'm done with this one now. Don't mind answering questions, but won't be updating this thread otherwise.