ISB 300 Power loss / Turbo Failure

[gschob]

I have a 2004 Newmar Kountry Star with 69k miles. It's been a great coach and I have had no problems to date. On my last trip I noticed significant power loss, especially when climbing hills or taking off from a dead stop, it's as if there is no turbo. No engine lights have come on to indicate problems. I changed the fuel filter but it made no difference. Finally took it to the Freightliner shop who told me they found 250+ codes related to the turbo. They have to do some more diagnostics tomorrow but they think the turbo may need to be replaced. I asked...what causes a turbo to go out and they said "heat". This makes no sense on a rig with such low mileage. Anyone have any experience with this? If I do need to replace the turbo is this the time to replace with a banks or some other aftermarket turbo for more power? This is going to cost me 😞

The most confusing part of this is that the power loss was noticed immediately after I refueled at a Flying J in Wells NV with brand new pumps....

[hershey]

Kidoo wrote:

hershey wrote:
The easiest thing to check first is: The 1" hose that runs under the intake manifold from the bottom front of the intake manifold and back to the air compressor. I had the same symptoms you described and a forum member gave me the same tip. My hole in the hose was at the bottom of the hose right where it connects to the air compressor just as it was described to me. A new hose is $43.00 from Cummins' or an 18" hose from NAPA about $10 bucks.

Which hose would that be? Where exactly is it connected? Inlet or intercooler maybe?

Its located below the intake manifold and connects to the intake manifold right at the bottom front. It makes a 90 degree bend towards the rear of the engine (radiator side) and connects to the air compressor. Very easy to see from the top. Run your hand over the hose all the way around it from one end to the other and you might find a hole in it like I did. Mine was on the bottom of the hose right at the air compressor connection. 15 minute job to replace.

[Kidoo]

Ivylog wrote:
OP you may want to read kidoo's posts on his turbo woes.
The hose above is the supply for the air compressor.

OK, good point, so if you are loosing air, you are loosing power. There are so many things that can go wrong, many are just not obvious.

[Kidoo]

One more question, is you Exhaust brake (EB) working? Did you find any difference with the EB braking power? This turbo is using the VGT for exhaust brake, so if it is working, it means the VGT is working, but for some reason it would not modulate for the turbo.

[Ivylog]

OP you may want to read kidoo's posts on his turbo woes.
The hose above is the supply for the air compressor.

[Kidoo]

hershey wrote:
The easiest thing to check first is: The 1" hose that runs under the intake manifold from the bottom front of the intake manifold and back to the air compressor. I had the same symptoms you described and a forum member gave me the same tip. My hole in the hose was at the bottom of the hose right where it connects to the air compressor just as it was described to me. A new hose is $43.00 from Cummins' or an 18" hose from NAPA about $10 bucks.

Which hose would that be? Where exactly is it connected? Inlet or intercooler maybe?

[hershey]

The easiest thing to check first is: The 1" hose that runs under the intake manifold from the bottom front of the intake manifold and back to the air compressor. I had the same symptoms you described and a forum member gave me the same tip. My hole in the hose was at the bottom of the hose right where it connects to the air compressor just as it was described to me. A new hose is $43.00 from Cummins' or an 18" hose from NAPA about $10 bucks.

[Kidoo]

Start with the filters, this is the most basic thing to do when you start loosing power, especially if the problem came on after refuelling. Also check the air filter, never know.

250 codes is a lot of codes. Ask them which codes, otherwise this is a shot in the dark. Then ask them what are the codes related to. At least, if they are not sure, ask them to clear the codes and run the engine or test drive the MH, then recheck the codes.

You have the same engine as mine, cummins ISB 300 HP 2003. Might be turbo sticking but I doubt it because this problem would likely cause an intermitent problem, sometimes it would stick, sometimes it would let go and work again.

The second thing on the turbo could be the electric motor that drives the VGT, variable vane, or the position sensor that tells the ECM what is the position of the turbo VGT. The VGT sensor can be replaced, if they do not have the sensor, they can take the one from the EGR to test it, same sensor. The electrical motor could stop working completly or could be intermitent. The wires to the turbo could also be at fault. If it is electrical, you should have a code that says low voltage/low current or no voltage to VGT.

A test can be done. If they are not able to make the VGT working with a test equipment, try this: While someone is turning the Key in the ON position but not starting the engine, as the key comes on, you should feel two cycle on the VGT, just put your hand on it. If you feel nothing, then there is a problem either with the motor or the wires, hope not the ECM.

If you have the DC electrical motor on the VGT, the motor is not servicable, according to cummins. Common cause to electrical motor is they get coolant bypassing the seal in the VGT mechanism, very poor design from cummins and very poor in solving recurent problems.

Turbo must be replaced as an assembly if motor is shot. The last price quoted from cummins to me was $3500.00. I would say it takes about 4 hours to replace. I could have a rebuilt one for $2000.00 and the other for $2600.00. I am checking right now to see if a VGT assembly can be bought separatly from the turbo.

Good luck, keep us informed.

[dakdave]

P Kennedy wrote:
Cummins don't run strainers just fuel filters, residual heat in the turbo exhaust housing cokes the oil on the bushing/bearing. Only a pyrometer can tell you when the turbo is idling below 300F so as not to coke the oil around the turbo shaft. 5 minutes idle time should normally cool an engine enough to prevent this but coming to the top of a mountain pass or long hill requires more time. 2nd biggest reason for power loss is air to air hose leaks, loose clamps etc. which will be observed on your turbo boost guage. ISB Cummins also had issues with transfer pumps the little guy that supplies the main injection pump. C9 Cat dump the EGR, DPF and reprogram around the junk and the little Cat will become a cool running killer with improved mpg and power.

Well sir I just changed the fuel strainer on my 5.9 ISB cummins so I would have to diagree with you.

[JamesBr]

Most common power loss issues I would start with new fuel filters. After that check the exhaust manifold. I know the ISB is known to have a failure of either the exhaust manifold gasket or the exhaust manifold itself has cracked on a friends 2001 HR with the ISB.

I know I had siginificant power loss when I got a bad load of fuel that clogged up my filter, it had all sorts of codes but new filters fixed the issue. I saw power loss as well when the exhaust manifold gaskets started to leak, but thankfully the manifold had no cracked.

[P_Kennedy]

Cummins don't run strainers just fuel filters, residual heat in the turbo exhaust housing cokes the oil on the bushing/bearing. Only a pyrometer can tell you when the turbo is idling below 300F so as not to coke the oil around the turbo shaft. 5 minutes idle time should normally cool an engine enough to prevent this but coming to the top of a mountain pass or long hill requires more time. 2nd biggest reason for power loss is air to air hose leaks, loose clamps etc. which will be observed on your turbo boost guage. ISB Cummins also had issues with transfer pumps the little guy that supplies the main injection pump. C9 Cat dump the EGR, DPF and reprogram around the junk and the little Cat will become a cool running killer with improved mpg and power.

[moisheh]

moparmaga2: You are having problems because that engine has an emission system that never worked properly and Cat will not do anything that will correct the problem. Your DPF is also problematic. When Cat left the OTR business they stopped doing any fixes for their problems! There may be some trucker hackers that can eliminate that junk!

Moisheh

[dakdave]

Check to see if yours has the fuel strainer in the fuel line usally on curb side above rear axle.

many owners and service people are not even aware the strainer is there.

[Tom_Barb]

gschob wrote:
I have a 2004 Newmar Kountry Star with 69k miles. It's been a great coach and I have had no problems to date. On my last trip I noticed significant power loss, especially when climbing hills or taking off from a dead stop, it's as if there is no turbo. No engine lights have come on to indicate problems. I changed the fuel filter but it made no difference. Finally took it to the Freightliner shop who told me they found 250+ codes related to the turbo. They have to do some more diagnostics tomorrow but they think the turbo may need to be replaced. I asked...what causes a turbo to go out and they said "heat". This makes no sense on a rig with such low mileage. Anyone have any experience with this? If I do need to replace the turbo is this the time to replace with a banks or some other aftermarket turbo for more power? This is going to cost me 😞

The most confusing part of this is that the power loss was noticed immediately after I refueled at a Flying J in Wells NV with brand new pumps....

Do you have a boost gauge on the engine?

[journey_indiana]

Check/change the fuel strainer. I had the same problem, service dept hadn't changed the strainer when the yearly maintenance was done. Problems started later.
The flow chart/troubleshooting for the turbo starts with turbo replacement, then the lift pump, then the fuel strainer.
Good Luck
Journey Indiana