Sluggish 4 hi

[2tornadoes]

Hi all, I just purchased a 2002 Chevy Tahoe, haven't had it but a few days and still putting in some work to clean it up and figure out everything that needs to be addressed. She runs and drives, seems to start just fine and no real issues other than cosmetic that I've found until today.

I was puttering around my street and went to check 4 wheel drive, put it in 4 hi. Seemed to shift with no issues but it seemed like I had to give it more gas than usual to get it moving and the forward progress was significantly reduced the moment I let off the gas. I haven't had time to check out the front diff to make sure nothing is binding it or if the fluid is low or anything, and of course the weather is going to turn to crap again here soon, but thought I'd ask while I have some time to mull it over. Any thoughts?

 

[SnowDrifter]

Well

That's not good

Get it in the air, see what spins, or doesn't spin freely. Both in 2wd and 4wd. Trans in neutral.

Check fluid, though that much friction would be..... Unlikely. But you should still check

Check your diff gear ratios too. Spin and count. I'm wondering if someone swapped a diff at some point with an oh so slightly wrong ratio

 

[2tornadoes]

Well

That's not good

Get it in the air, see what spins, or doesn't spin freely. Both in 2wd and 4wd. Trans in neutral.

Check fluid, though that much friction would be..... Unlikely. But you should still check

Check your diff gear ratios too. Spin and count. I'm wondering if someone swapped a diff at some point with an oh so slightly wrong ratio

Definitely the plan once the weather gets a little better, thanks for the feedback. Really hoping no one messed with the gear ratios!

 

[rockola1971]

Definitely the plan once the weather gets a little better, thanks for the feedback. Really hoping no one messed with the gear ratios!

Your gear ratio would be the same for the front and rear diffs. So 2wd will have the same ratio as 4wd. If its only doing it in 4WD then I would look at the front diff and the Tcase. You should already be able to rule out rear diff, both front CV halfshafts and front hubs since they would provide the same problem in 2wd or 4wd which is the excessive friction problem you are feeling if those parts were at fault.

Check your fluid level in the Tcase! These Tcases are notorius for pump rub which rubs a hole in the rear case and slowly leaks the Tcase fluid out. There is a plate that fixes it but the Tcase has to be removed and the back half case has to be replaced if it has a hole in it. Its not an expensive fix and actually fairly easy.

 

[2tornadoes]

Your gear ratio would be the same for the front and rear diffs. So 2wd will have the same ratio as 4wd. If its only doing it in 4WD then I would look at the front diff and the Tcase. You should already be able to rule out rear diff, both front CV halfshafts and front hubs since they would provide the same problem in 2wd or 4wd which is the excessive friction problem you are feeling if those parts were at fault.

Check your fluid level in the Tcase! These Tcases are notorius for pump rub which rubs a hole in the rear case and slowly leaks the Tcase fluid out. There is a plate that fixes it but the Tcase has to be removed and the back half case has to be replaced if it has a hole in it. Its not an expensive fix and actually fairly easy.

Thanks for the info. I do a lot of my own work so this fix doesn't sound too complicated and I'm sure I can find plenty online about it so I'll add it to the list of things to check once I get a chance to get under it. Appreciate the feedback!

 

[rockola1971]

Thanks for the info. I do a lot of my own work so this fix doesn't sound too complicated and I'm sure I can find plenty online about it so I'll add it to the list of things to check once I get a chance to get under it. Appreciate the feedback!

If your Tcase has leaked enough fluid out to cause excessive friction that is slowing the vehicle down then you will have to do an overhaul to the Tcase because of a bad bearing(s) ruined from the lack of lubrication. Luckily the 246(E) Tcase is stupid easy to rebuild and the chain, bearing and seal kit, clutches if you have Auto 4wd are very affordable.

 

[2tornadoes]

If your Tcase has leaked enough fluid out to cause excessive friction that is slowing the vehicle down then you will have to do an overhaul to the Tcase because of a bad bearing(s) ruined from the lack of lubrication. Luckily the 246(E) Tcase is stupid easy to rebuild and the chain, bearing and seal kit, clutches if you have Auto 4wd are very affordable.

This is what I was afraid of, the moment I felt that friction and how much more power it was taking to push the vehicle forward I immediately thought the tcase might be crapped out. Good to know it's inexpensive to repair, from what I've seen in a quick search, rebuild kits are not pricey at all and it'll just take a little time on the work bench to get it back to new. Thanks for the advice!