Cummins ISL with turbo issue

[Evugrandtour]

Hi. I have a 400HP ISL 8.9L on my DP and I was told my turbo has this thing (it’s supposed to move when turbo is activated) that’s broken clean or cut clean. However I notice it drives fine and turbo sounds fine and no issues whatsoever with performance even when climbing. I was quoted several thousand dollar to put in a new turbo. Is that necessary or if I leave it like that will it cause any issue?

Thank you for your time.

[shootist]

Originally Posted by Evugrandtour

Hi. I have a 400HP ISL 8.9L on my DP and I was told my turbo has this thing (it’s supposed to move when turbo is activated) that’s broken clean or cut clean. However I notice it drives fine and turbo sounds fine and no issues whatsoever with performance even when climbing. I was quoted several thousand dollar to put in a new turbo. Is that necessary or if I leave it like that will it cause any issue?

Thank you for your time.

post the picture again without it blocked with the red circle. Also post the make model and year of your coach. It doesn't show on a android if it's there.

[Jon_C]

That looks like a Holset HX 400 variable geometry turbo. (VGT) see pic.

If this is correct, that shaft is what moves the turbine blades to achieve the variable geometry.

So with the shaft broken, the turbo is now a fixed geometry turbo and apparently it is in a position mostly open which would develop full power but should be somewhat laggy on spoolup.

Im not familiar enough to know if running it this way will cause any damage or not. If the blades are fixed and not moving it would be the same as a fixed geometry turbo but if somehow they are continually moving or flapping that may cause catastrophic failure of the turbine

Best thing to do is repair or replace it for sure.

[153stars]

I believe most VGT in motorhomes are part of engine braking, instead of Pac exhaust brake. The trans may still downshift but no engine braking.

[Evugrandtour]

Originally Posted by shootist

post the picture again without it blocked with the red circle. Also post the make model and year of your coach. It doesn't show on a android if it's there.

Here you go. It is an 05 Alfa gold. Thank you.

[Evugrandtour]

Originally Posted by Jon_C

That looks like a Holset HX 400 variable geometry turbo. (VGT) see pic.

If this is correct, that shaft is what moves the turbine blades to achieve the variable geometry.

So with the shaft broken, the turbo is now a fixed geometry turbo and apparently it is in a position mostly open which would develop full power but should be somewhat laggy on spoolup.

Im not familiar enough to know if running it this way will cause any damage or not. If the blades are fixed and not moving it would be the same as a fixed geometry turbo but if somehow they are continually moving or flapping that may cause catastrophic failure of the turbine

Best thing to do is repair or replace it for sure. Attachment 377757

Thank you. I’m just not ready to drop $4k as the shop quoted :/
very disappointed to know the shaft can’t be replaced or repaired. I will ask couple other shop around to see if that can be repaired instead of putting a new turbo

[Evugrandtour]

Originally Posted by 153stars

I believe most VGT in motorhomes are part of engine braking, instead of Pac exhaust brake. The trans may still downshift but no engine braking.

We were coming down steep grade towing a van behind and the engine brake worked flawlessly. But I’m wondering if there is a way to tell if it’s engine braking or transmission is holding the coach?

[wolfe10]

Originally Posted by Evugrandtour

We were coming down steep grade towing a van behind and the engine brake worked flawlessly. But I’m wondering if there is a way to tell if it’s engine braking or transmission is holding the coach?

Simple:


Use the Allison down arrow to choose a gear that puts your engine toward the upper end of its RPM range.


Toggle engine brake ON/OFF/ON


Any difference you feel will be due to the engine brake, as your transmission is a "constant".

[Tha_Rooster]

It’s a shame shaft can’t be welded together.

[Jon_C]

The real question is why did it break in the first place. That’s a substantial looking shaft, seems would take quite a bit to break it. I suspect some internal issue caused it to break and if not repaired properly may do the same to a new shaft.

[RV Driver]

This version of the ISL has a Jake (compression) brake. The turbo is not involved at all in engine braking.

[jacwjames]

Suggest you create an account on the Cummins Quickserve site, then register your engine. The site offers a lot of information on your engine including the turbo. This might be a replacement part of the turbo.

https://quickserve.cummins.com/info/index.html


There may also be some useful information in the manuals as the working of the turbo. Lots of information but it may take time to find it.

[Rob_M]

Turbos are sometimes rebuildable. You probably have a good core to repair or rebuild. Few shops do it any more because they’d rather just sell you a new one and send you down the road. Also maybe there’s a re-manufactured turbo available. With a good core to trade in your cost should be quite less than 4k.

[96 Wideglide]

Originally Posted by RV Driver

This version of the ISL has a Jake (compression) brake. The turbo is not involved at all in engine braking.

May or may not!

My 400 hp ISL has the VGT exhaust brake!