New (to me) Roadtrek 170 with a rear end problem

[heatlamp]

Hi, Just bought an 04 Chevy Roadtrek 170, 42K mi. I'm an ex Pleasure Way Excel owner, wanted something smaller. This van is cosmetically in very good shape, and is the right size for us.

Sad that this vehicle gets worse gas mileage than the old Pleasure Way (about 14.5 mpg on a recent trip), but the Pleasure Way did have a smaller engine as was noticeably less powerful.

In checking the vehicle out, turns out that the whine coming from the rear is not the tires (as I had thought), but a the rear end issue. Has anyone experienced differential issues on a van of this vintage? Seems very early to me, looks like one of previous owners may have towed something?

Now I'm wondering if the transmission may be compromised, guess I should have the fluid checked/changed?

Any other hints appreciated.

Tx, Jim

[booster]

We had two rear end failures in 25k miles in our 07 Chevy 190P, but from what we have seen that was something that happened in 07 time frame to quite a few Roadtreks do to defective axle housing castings. I would call it unusual for an 04 at that mileage.

Is it a constant whine, or more when you accelerate or decelerate. Better or worse at different speeds? Does coasting in neutral make a difference?

If the transmission fluid hasn't been changed, it certainly would be due. You would also then be able to switch it over to the synthetic Dexron 6 fluid, which is generally considered a big improvement.

[heatlamp]

The whine is constant from about 15mph up, increasing in frequency as the speed increases. The tire dealer raised the rear end and ran the van in gear, it was clear the noise was coming from the diff. Interestingly the noise seems to subside somewhat when turning a corner, I assume because there is less stress on a specific diff gear?

Question is whether to have the diff repaired, or to change the fluid and wait until the noise gets worse.

[booster]

The whine doesn't change with power on or off?

The style of rear end they use (semi-floater) puts all of the cornering force on the differential carrier bearings and gears (not on the wheel bearings), so if they are loose the carrier could move a bit from that force. That would also move the ring gear with the carrier. If that happens, the backlash between the ring gear and pinion gear will change, and that can affect whining. It would probably be a different change depending on which way you turned.

It is very possible that it may only need to have the carrier bearings adjusted to get the right backlash on the ring and pinion and the correct preload on the carrier bearings.

I would take it to a drivetrain specialty shop, if you have one around, to get the fluid changed and have it looked at. Those guys tend to be able to tell a whole lot by the sounds, and to change the fluid, they have to remove the cover, so they will get a look besides. The carrier bearings can be adjusted with just the cover removed, so they could do the adjustment then if they feel that is the problem.

[heatlamp]

Great info, thanks. There is a shop specializing in rear end work about an hour's drive away, sounds like it would be worth the additional effort to go there. The local shop's best answer was to replace the rear end with a junkyard version.

[mkguitar]

one failing with US owners is not servicing the tranny and rear end ...

could be water or something got in there are the bearings themselves can rust...adding grit to attack the other bearings.

rear end service is not tricky and for cost this would be the time to replace the axle and wheel bearings.

get the tranny fuild and filter changed at the same time- if you are a DIY you could get a new tranny pan which has a drain plug...

most US vehicles do not...makes for easy clean fluid changes ( many jiffy type places suction the fluid out of the dipstick tube, which is incomplete)

your 170 may have the 4.8L which is the smallest v8 in the vortec family- it is good for about 270 HP.
This motor is marginal for pulling it doesn;t have a lot of torque so when moving from a stop, the revs have to be higher than a 5.3 or 6.0. so a smaller motor can be less effective in some uses- hopefully you'll see better economy on the open road.
I have that motor in my 2001 pickup- I would't tow with it. I have since new gotten 20 mpg on the highway ( 65~70) and about 15 in city driving.
under any load like hills esp if loaded with "stuff", the tranny will hunt between 3rd and OD, tow mode doesn;t help, so I usually shift to 3rd until the road levels out.
When I have had to tow I have borrowed my Pal's same truck with the 5.3- marked difference in that motor ( it's not only the displacement but also the cam design controls when the power comes in)

the good news is that 165K has only cost a water pump, fuel pump and idler pulley/serpentine belt...all under $1000
tranny and rear end services, oil and filters not included in that figure

the 305 hp 6.0 in my pleasure way lexor is well matched to the almost 9000 pounds weight the 6.0 makes good torque- we are getting about 16 MPG cruising hwy- tranny doesn;t hunt up the hills and just has "more power" when needed



mike

[heatlamp]

Tx for the info. I have the 6.0L in the 170, seems a bit overkill but it is nice. Transmission definitely 'hunts' much less than with the 5.4L Ford in my old Pleasure Way Excel.

I've made an appt to take the van to a rear end specialist about an hour's drive away. Their comment over the phone was that given the whine from 15mph up its unlikely to be only a bearing adjustment, but I'll let y'all know.

[mkguitar]

6.0...interesting.

You may consider taller gearing if the rear end needs work- you could pick up some mpg

Mike

[heatlamp]

Final update on this. I went to the rear end shop, after driving and hoisting the van they diagnosed the problem as a front wheel bearing. So much for my (and the other mechanic's) diagnostic abilities!

A key diagnostic trick here was that the sound was reduced when going around a corner (e.g. freeway cloverleaf entry) - apparently this is a pointer to wheel bearing issues.

C'est la vie, thanks again for all your help.

[booster]

Originally Posted by heatlamp

Final update on this. I went to the rear end shop, after driving and hoisting the van they diagnosed the problem as a front wheel bearing. So much for my (and the other mechanic's) diagnostic abilities!

A key diagnostic trick here was that the sound was reduced when going around a corner (e.g. freeway cloverleaf entry) - apparently this is a pointer to wheel bearing issues.

C'est la vie, thanks again for all your help.

I guess you can count your blessings on that one. Much cheaper than a rear end job. The turning is normally a symptom, and you were lucky you had noise to warn you. We, and several others, had no warning from noise, with the first clue being that the wheel locked up after a highway drive and sitting a few minutes.

[markopolo]

Just adding the Wheel Offset topic: http://www.classbforum.com/forums/f8...hevy-1985.html

Might be useful info and/or applicable.