2002 Chevy Silverado-Transfer Case Overhaul
Mark: Hi, it's Mark Bossert producer of the Pawlik Automotive Podcast. We're here in Vancouver this morning in an increasingly chilly October, with Mr. Bernie Pawlik of Pawlik Automotive in Vancouver. How are you doing this morning Bernie?
Bernie: Doing very well.
Mark: So we're talking trucks today, 2002 Chevy Silverado that had a transfer case problem. What was going on with this Chevy truck?
Bernie: So this vehicle came in for service. We do a lot of work on this particular truck, and the owner had taken it on an exceptionally long trip across Canada and back. If you look on a map, you'll see it's a long ways. It's a lot of driving. He came back, there was a few issues with the truck. We looked at it, and one thing we found was that there was a leak in the transfer case. There was an actual fluid leak in the transfer case, and the fluid level when we checked it was exceptionally low pretty much right off the edge.
Mark: So where was the fluid actually leaking from?
Bernie: Well interestingly enough, we found a little hole in the transfer case near the top there was an actual hole, and we'll look at some photos in a minute and I'll show you that. But that's basically where the fluid was leaking, it was actually a hole in the case housing.
Mark: So how do you think a hole like this could develop?
Bernie: Well we'll look at that in pictures in a minute, but there are a number of ways holes can develop. You could hit a rock, you could actually hit something with the transfer case. Or a strange circumstance, a rock could actually fling up. It's pretty thin aluminum. The case of this one, it was actually wear from a part inside that had been moving back and forth over, this truck has 300,000 kilometres, so over 300,000 kilometres this part, it's the oil pump, was moving back and forth back and forth, and eventually put a hole through the side of the case.
Mark: So once you opened it up, was there any fluid in the case itself?
Bernie: Pretty much nothing. As I mentioned, we check the fluid level and we basically found nothing in there. When we took it apart there was oil in it, but no appreciable amount. There's supposed to be two litres of fluid in this case, there was probably if you could scrape very drop of oil off the bearings and everything, there's probably a couple of tablespoons at most. It was basically surviving with just lubrication that was on the bearings themselves.
Mark: You have some pictures.
Bernie: I do. Let's go right into those right now. To start, there is the rear cover of the transfer case. You can see that okay?
Bernie: Now if you look, it's an old dirty case, but if you look in this are a specifically you can see it's a little cleaner, there's a little more dirt and it's got some clean patches. So basically the hole is right over here, and I'll just close in a photo that shows a better view of that hole, which is right there. There's our hole. Tiny little, almost looks like it's meant to be there in terms of how nicely shaped it is. But that was our hole, that's where the fluid leak. And it was at the top of the case, which is fortunate because it had probably been leaking for a while and splashed out over a long period of time. So we'll go back into some other photos. So here's the inside of the transfer case. This is after reassembling it, so this is the transfer case chain. This is one of the main components of a transfer case, this is the chain that basically allows the drive to go ... This shaft here will go to the rear wheels. This connects up to the front drive shaft to drive the front axle, so that's how the. Again, the chain and these gears are one of the main components of the transfer case once you switch into four-wheel drive. To switch from high to low gear, down in this area of the case there's a planetary gear there's a shift fork and that'll make an adjustment. So that gives you the low gear range that transfer cases, most of them have. Here's the inside of that new housing. We were able to replace this housing. And the wear was basically occurred in this region here, from the oil pump, which sits in these four places here, it just has a little bit of movement and over time, 300,000 kilometres, it just moves around a tiny bit, tiny bit, tiny bit eventually it just wore a hole through the case. This replacement case is actually made of a better grade of aluminum than the original, so it theoretically should never happen again. But the ironic thing is they actually put these clips in, and we found one that was broken apart. There's a couple clips, they're called case savers, and they're actually meant to prevent this from happening. But strangely enough, they don't. It actually slapped around enough and wore the case saver and a part, and then just wore it through the case. So this is kind of a useless piece, it's not really important to replace. It doesn't come with the rebuild kit, you can get them but they're really not an important item to use.
Mark: So how could the unit survive without fluid in it?
Bernie: Well gear boxes do, they do get hot they get warm, but they're not hot like an engine, so they can survive with just lubrication that's on the surface. It's hard to know how much longer this case would've gone, but they can survive for a long time without actually being full of oil. We've run into a number of transfer cases over the years where a customer brings a vehicle in, it's basically got almost no fluid in it whatsoever, and we fill it up and away it goes and it's no problem. I'm not saying I recommend that at all, you should always keep it full because of course there was some wear inside this case, nothing major though. We replaced all the bearings of course because we were in there, but there was nothing major worn. All the gears were in good shape, the chain was in good shape. We replaced it anyways because it's a good thing to do with that kind of mileage on it, it'd be kind of crazy not to change the chain because they do stretch over time. But nothing really severely worn. The only other major component we found, was one of the shift forks was worn and it has plastic tabs on it. So over time that had worn, it's hard to say whether, chances are it was well lubricated it probably would've been in better shape, but you never know if we would've taken it apart we might have found it was still equally worn.
Mark: So what are the most common problems you find with transfer cases?
Bernie: There's a variety of things that happen, and there're different types of transfer cases. So this one, for instance, is a fully manual two speed transfer case. It's kinda common on a lot of heavier duty type of trucks. So this is the one that has the shifter on the floor where you have to mechanically move the shifter. A lot of transfer cases are electronic. There are some, let's say you got a BMWX drive vehicle like an X5 SUV, that has a transfer case that's very similar but it's all electronic. You don't even push buttons. It's all computer controlled, so it'll shift the four-wheel drive or all-wheel drive, it'll make adjustments computer controlled. And then there are other versions that are sort of semi-automatic. I've got a Suburban and it has basically a push button, you push a button on the dash, it'll switch into four-wheel drive. And then you can switch into low range, and again it's push button. And the way that's done, instead of having the lever on the floor it basically has a motor. It looks kind of like a windshield wiper motor, and it basically actuates the, moves the forks back and forth. That's actually a pretty common problem. The actuator motors will go bad. The chains will stretch. Those are common things, and from time to time bearings will wear also. But fluid leaks are probably the most common we see in it and repair. And of course, if you fix a fluid leak you're preventing other damage. This is surprising we caught this transfer case at the right time. Had he driven it for another few months, it for sure catastrophic damage would've occurred.
Mark: And are there any transfer cases that are worse than others?
Bernie: They're all pretty much, I'd say they're all fairly equal, at least as far as if we think of a North American truck style transfer cases. A lot of them are made by New Process, which is a transfer case manufacturer. So there're different grades in these transfer cases depending on if you have a half ton, three quarter, or one ton vehicle. There are other brands as well, but there doesn't seem to be any particular, Chevy's are better than Ford's or Dodge's, they're all kind of created equal, even amongst the imported vehicles. But when things go wrong say with those BMW type of transfer cases, they're much more expensive because the gear mechanisms are the same but the intricacies of how the other components work are the shifting mechanisms are much more complicated. So I'd say they're all, if you're thinking I'm only going to buy this vehicle because the transfer case is better, then don't worry about. They're all created pretty much equally.
Mark: So there you go. If you've got any issues with your four by four in Vancouver, the guys to see are Pawlik Automotive. You can reach them at 604-327-7112 to book your appointment. You have to book ahead, they're busy. Or check out our website, pawlikautomotive.com, we have hundreds of videos on our YouTube channel, Pawlik Auto Repair. Thank you very much for listening to the podcast. Thanks Bernie.
Bernie: Thanks Mark, and thanks for listening and watching.