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Topic: Replacing turbo and adjusting kick-down cable (Read 661 times) previous topic - next topic

Replacing turbo and adjusting kick-down cable

We had an exhaust gasket fail on us while we were on ou way to our last destination in Kentucky.  The mechanic that was doing the repair showed us that the turbo had some play in the shaft and some light damage to the turbine. He recommended that we replace the as soon as possible.  We knew from the engine rebuild invoice that the turbo had a small crack somewhere on the housing and we had started getting some smoke at low rpms so we were planning on replacing the turbo once we got to our main destination.  On our way through West Virginia yesterday we started losing power and was having a lot of trouble climbing the mountains.  The coach started getting hot on us in one spot so we pulled over and let it idle for a while to cool down.  I got under the coach to check everything out and noticed that we had developed an engine oil leak coming from around the oil filter.  We shut Pearl down so I continue the investigation and I discovered that what I think is the kick down cable that slides up and down with the actuation of the throttle was completely loose and not moving.  I had noticed the the transmission  was not downshifting like I thought it should have been and was causing us to try and climb the mountains in too high of a gear.  I at first thought the power loss was from the turbo giving up which in turn was causing the heating issue but now I'm thinking that the shifting issue is a contributing factor. 

The engine returned to normal temperature and we resumed our journey without further issue.  Now that we're here I'm going to be replacing the turbo and addressing the other issues before we head out again.  I've been searching for a remanufactured holset turb but am having trouble finding anything but what appears to be no-name Chinese turbos and I'm not sure of they are of high quality or not.  The holset turbo has lasted 26 years so I'm confident that they're well made and would like to replace it with the same unit if possible and the cost isn't triple. 

Does anyone know where I could find a replacement turbo?  The assembly number is 3529466. I plan on contacting holset tomorrow.

Does anyone have experience with adjusting the kick down cable (if that is indeed what it is)?  I feel like it might be finicky to get set properly.
Hannah and Tyler Phillips
1993 U280 Grand Villa AKA Pearl
Basement Air
Cummins 6CT8.3
Build Number 4196

Re: Replacing turbo and adjusting kick-down cable

Reply #1 –
Lots of turbo rebuilders online so give one a call for a recommendation. The Chinese now own the aircraft engine manufacture, Teledyne Continental Motors. These engines are OEM in Cessnas, etc. They are now manufacturing aircraft diesel engines and while most of the engines are still made in Alabama, the "Made in China" turbos should be fine. A lot of racers use Kinugawa turbos
http://shopping.kinugawaturbo.com/turbocharger.aspx .

Some people are still badmouthing Chinese solar panels.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Replacing turbo and adjusting kick-down cable

Reply #2 –
Can't help with replacement turbo sourcing - haven't had to cross that bridge...yet.

The "kick down" cable to which you refer is more properly termed the TPS (Throttle Position Sensor).  If it needs adjustment or replacement, may be beyond the capability of typical shade tree mechanics (like me).  Might require visit to Allison shop.

Link below to another Forum and discussion of same subject.  Thread (2nd post) contains a link to a TPS adjustment guide.

Throttle Position Sensor MD3060 - iRV2 Forums


1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Replacing turbo and adjusting kick-down cable

Reply #3 –
Quote from: Pierce & Gaylie Stewart –
Lots of turbo rebuilders online so give one a call for a recommendation. The Chinese now own the aircraft engine manufacture, Teledyne Continental Motors. These engines are OEM in Cessnas, etc. They are now manufacturing aircraft diesel engines and while most of the engines are still made in Alabama, the "Made in China" turbos should be fine. A lot of racers use Kinugawa turbos
http://shopping.kinugawaturbo.com/turbocharger.aspx .

Some people are still badmouthing Chinese solar panels.

Pierce

Thanks for the information, I'm not trying to badmouth anything.  I'm leery of spending a $1400 on something that may or may not be manufactured with high qc standards. If people have had good luck with the knock off turbos I will look into them as an option.
Hannah and Tyler Phillips
1993 U280 Grand Villa AKA Pearl
Basement Air
Cummins 6CT8.3
Build Number 4196

Re: Replacing turbo and adjusting kick-down cable

Reply #4 –
Quote from: Chuck & Jeannie –
Can't help with replacement turbo sourcing - haven't had to cross that bridge...yet.

The "kick down" cable to which you refer is more properly termed the TPS (Throttle Position Sensor).  If it needs adjustment or replacement, may be beyond the capability of typical shade tree mechanics (like me).  Might require visit to Allison shop.

Thanks Chuck, it makes it much easier to get information on something if I'm using the correct terminology!  I'm assuming the tps works like a potentiometer, using the different resistance values to determine shifting points?  I'll try to mess around with it a little but I'll probably be looking for an allison shop nearby.
Hannah and Tyler Phillips
1993 U280 Grand Villa AKA Pearl
Basement Air
Cummins 6CT8.3
Build Number 4196

Re: Replacing turbo and adjusting kick-down cable

Reply #6 –
We were able to find a place called Turbo exchange in NC that had a lot of positive feedback.  They said they could have us a new turbo built by the end of the day for $795 with a one year warranty.  I'm going to take a chance and order from them.
Hannah and Tyler Phillips
1993 U280 Grand Villa AKA Pearl
Basement Air
Cummins 6CT8.3
Build Number 4196

Re: Replacing turbo and adjusting kick-down cable

Reply #7 –
Called Cummins to order a new oil supply line, a reman turbo for our engine is $1644 from them just fyi. 
Hannah and Tyler Phillips
1993 U280 Grand Villa AKA Pearl
Basement Air
Cummins 6CT8.3
Build Number 4196

Re: Replacing turbo and adjusting kick-down cable

Reply #8 –
I've been reading through our Allison manual and based on a cross-section drawing, the cable that I'm looking at goes to the modulated lockup valve which is only on the MT647, and not the throttle position sensor.  The MT647 has a throttle modulated lockup torque converter.  I should start with the manual next time!
Hannah and Tyler Phillips
1993 U280 Grand Villa AKA Pearl
Basement Air
Cummins 6CT8.3
Build Number 4196

Re: Replacing turbo and adjusting kick-down cable

Reply #9 –
According to the MT647 service manual the adjustment on the throttle side of the modulator cable needs to be set at max in one direction or the other depending on if the modulator has either a push or pull configuration for activation.  The modulator can be set in either a push or pull configuration depending on how it is assembled.  The throttle end of the cable has definite wear marks on one end of it so I'm going to replace the set screw and get it locked back into place.
Hannah and Tyler Phillips
1993 U280 Grand Villa AKA Pearl
Basement Air
Cummins 6CT8.3
Build Number 4196

Re: Replacing turbo and adjusting kick-down cable

Reply #10 –
Got the modulation cable reattached on Thursday.  There is a bolt that attaches the cable to the throttle, it was stripped and had to be cut with bolt cutters and replaced.  It was a tight fit, but from underneath the bus it was easy to get to with small bolt cutters.  The cable had to be connected so that it was able to rotate on the bolt freely otherwise it was causing the throttle to bind up.

Replaced the turbo on Friday.  Removing the old studs from the manifold was the most difficult part of the job.  Using one nut tightened tightly against another one, a little PB blaster and a handheld propane torch on one, they all came out cleanly.  Had to run a tap through all of the threads in the manifold because none of the new studs would thread in.  all of the threads on the old studs were rounded and kinda smooshed. It took me most of the day from start to finish but it was a pretty straightforward project.  I had to run  to the hardware store a couple of times. Once was to get a couple different long-handled magnets because I dropped a nut down the exhaust manifold. Guess what?  The nuts aren't magnetic and I got to fish for it for 30 mins with a piece of wire.  But if I hadn't of dropped the nut in the manifold or had to tap the threads it would have been a quick job.

We were surrounded by people all weekend and I didn't get to drive it until today.  We took it up the mountain to really test it out and the performance difference was really impressive.  The engine has a lot more power than it did and the transmission was shifting excellent going up and down the mountain.  I was really impressed by the amount of midrange power the engine had at around 15-1600 rpms.  It hasn't had that power since we've owned it.  All in all it was a fun project and doing it ourselves saved us a lot of money.  I think anyone could change their turbo by themselves if they wanted, just make sure to fill the new turbo completely with oil before starting the engine. :)

Thanks again for all the help!

Hannah and Tyler Phillips
1993 U280 Grand Villa AKA Pearl
Basement Air
Cummins 6CT8.3
Build Number 4196

Re: Replacing turbo and adjusting kick-down cable

Reply #11 –
Please add your engine specifics to your signature. Component replacement isn't rocket science, you did well.
Old Phart Phred, EIEIO
89 GV ored 36' #3405 300 hp cat 3208 ATAAC side radiator, mountain tamer exhaust brake

Re: Replacing turbo and adjusting kick-down cable

Reply #12 –
Boulder,what size was the tap and give us any other info you think the next one to tackle the job may need.
96 U270 BUILD 4810
85 380SL
Drummonds TN.

Re: Replacing turbo and adjusting kick-down cable

Reply #13 –
Quote from: John44 –
Boulder,what size was the tap and give us any other info you think the next one to tackle the job may need.
Tap size was metric M10-1.5.  New studs, nuts and gaskets are required.  A new oil supply line is also required for warranty purposes on the turbo.  Got everything I needed from Cummins. 
Hannah and Tyler Phillips
1993 U280 Grand Villa AKA Pearl
Basement Air
Cummins 6CT8.3
Build Number 4196
 

Re: Replacing turbo and adjusting kick-down cable

Reply #14 –
Sounds like you are a good mechanic, just the type to own an older Foretravel.
Jerry Whiteaker former owner 96 U270  36' #4831 Austin,TX-Owner Mods LCD TV w/front cabinet rebuild - LCD TV bedroom - Dual Central AC, either can cool coach w 30 amp - Skylights at roof AC openings - Drop ceiling for ducting of AC - Shower skylight white gelcoat/wood/epoxy frame - Air Springs/Shocks replaced - 2014 CRV - 8K Home Solar - Chevy Volt