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Old 02-02-2010, 02:35 PM   #1
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Need some help/info on Cummins 350 ISC

Hoping someone can help with basic advice...

I have a 2004 Winne Vectra with the 350 Cummins ISC, side radiator and a Banks system. Owned it a couple years now, bought used, and has not needed anything other than basic maintenance to this point.

My issue - low power when accelerating. Probably about 1/2 of what it used to be and seems to have hit all of a sudden. I've also notice the turbo pressure is gone, per the dash gauge. Exhaust appears normal, no black nasty smoke or anything. Idle is smooth, no idiot lights, just the low power.

Checking various online sources it seems like there are a couple possibilities - a loose hose/clamp at the turbo, or possibly a problem with the exhaust brake. Have also read that there is a rubber inlet/gasket that can sometimes come loose around one of the turbo hose inlets. All others seem to be major and out of my league.

So before driving 90 miles to the nearest Cummins shop I'd like to check the obvious, like the hose stuff. My problem is I need some advice as to what to look for and where to look for it.

I do know my way around a screwdriver but while I've had my day of maintaining my car I've never touched a diesel. I do what I can, but not a trained mechanic. Yeah, go ahead with the bricks...

I'm assuming the turbo is at the top front of the engine and that I'll have to access it through the floor panels in my rear closet. Is that correct, or do I need to crawl under and come up from the bottom? Is there anything else that I can check? I'm not afraid to take it to a shop, just don't want to drive 2 hrs for a loose hose or something...

Thanks for your patience and any advice!

Ed
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Old 02-02-2010, 03:31 PM   #2
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Ed, you should be able to access the engine from the top through your closet. You'll find the turbo on the right side (you're looking to the back of the coach). Connected to it will be the exhaust brake. They sit right next to each other. Finding those things, you can follow the exhaust piping around and down the back of the engine.

The obvious stuff applies....splits, cracks, separated pipes.

You said you didn't get any boost...but can you hear the turbine spin up? When was the last time you got fuel? Have you changed your fuel filters yet? Any leaking fuel on the ground?

When the engine is running can you hear air leaking? Have you checked the radiator/charge air cooler pack to see if it's plugged with debris? Check your air filter and it's plumbing to the turbine as well. See if the filter is wet or has deteriorated.

Good luck with this. Hopefully, it's a simple thing.
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Old 02-02-2010, 07:55 PM   #3
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Jim, thanks for the advice. It's a big help.

I had fresh fuel and filters were both changed (I have 2) last summer. No sign of leaks.

Weather permitting I'll be going out this weekend to take a look at it (Michigan winter) and I'll listen for air leaks and take a look at the other things you mentioned.

Much appreciated!

Ed
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Old 02-07-2010, 01:09 AM   #4
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CHeck your filters and then it's a trip to the Cummins shop to have the lift pump and injector pump checked. Low lift pump pressure will cause the injector pump to work harder and will cause low power.

The older ISC's with the mechanical injector pumps operating with low lift pump pressure would damage the injector pumps. The lift pump pushes more fuel than is burned and the extra fuel is used to cool the injector pump and this extra fuel is returned via a bypass to the fuel tank. I don't know if the Cummins CAPS, or CARS based injector pumps, which you would have in your 04 Cummins work this way.
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Old 02-07-2010, 02:33 AM   #5
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If the lift pump is a problem, the injection pump (big bucks) will suffer. But, the report is normal engine operation other than low power, and specifically no boost per a dash gauge.

You can follow the air path from filter to engine intake. Turbo as noted is high on the driver's side. From the turbo you will see large diameter pipe to the intercooler which is in the sandwich of radiators, then pipe of equivalent size back over to the passenger side of engine for intake to the cylinders. Every joint is suspect till you find what has come separated. If all the joints are tight, check any rubber elbows for a blow-out. There may be one real close to the turbo which should be a high temp elbow (500 degrees) but Winnie might have cheezed and used a cheaper 350 degree part. IIWM, I'd replace any between the turbo and intercooler that have issues w/the high temp elbows from Purofil (do a search here on IRV2, I know the part number is listed on the Alpine Coach forum at least); they cost a bit more but are more suitable to the hot location and should last better.

If you can't find a joint or flexible elbow or straight flex part that has come undone or broke, you may be looking at an intercooler that has broken open or whose gaskets (if you have the gasketed type) are blown out. Hopefully it is a rubber part that is easily replaced. Blown out elbows are pretty common, and some carry a spare in case this happens while on a trip. Intercooler R&R is spendy, and replacing one is more spendy, $3-4G.

Don't drive the coach too much, and certainly not where you have potential for dust. You need all the filtration you can get for the life of the engine and running for miles sucking in dust directly will affect engine life greatly. A hole in the system may be bypassing the air filter, hence the warning.
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Old 02-07-2010, 11:08 AM   #6
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I hope your problem is as easy as mine was. As EngineerMike mentioned, hoses can come off of the CAC tubes and connections. Early after purchasing my current mh with a Cummins and a side radiator, the cool air charge hose kept coming off. Your problem sounds identical to that issue (loss of power, no turbo pressure and black smoke) and typically easily fixed, even on the road. I have also heard that damage can be done if driven in that condition (perhaps unfiltered air as well as carbon buildup). Since it is a side radiator, you probably have elbows in the CAC hoses which are prone to misalign. There is a large 3" hose entering the cool air charge unit which sits on the engine side of the radiator. Check all of those hoses to see if one has slipped off. If it has, merely loosen the hose clamp, put the hose back on and tighten the clamp. What I found on mine was that the hoses were not aligned properly resulting in the hoses slipping off a few times before ultimately being aligned. It could actually be any of the issues previously discussed but this one is an easily fixed problem. Good luck, I hope it is this less costly issue.
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Old 02-08-2010, 08:09 PM   #7
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The original symptom is low power (perhaps 1/2 normal) and no turbo pressure. I believe you have an electronic ISC engine with a computer controlled injector pump. This system is the Cummins Accumulator Pump System (CAPS) and the CAPS is controlled by the ECM (Electronic Control Module). The ECM controls fueling and timing of the fuel delivery. The ECM incorporates an SAE J1939 datalink where it monitors the pressure levels in the accumulator through a pressure sensor, and also controls the operation of a single fuel control valve. Fueling and timing are handled by this valve, which sends the fuel to a distributor module. Any issues with these components will result in the ECM operating the engine in a reduced power mode which will not produce sufficient exhaust flow to adequately spin the turbo and produce turbo pressure to a point where the waste gate begins regulating the turbo pressure. No power, no turbo boost and then, with turbo boost, more power, and this is repeataed until the waste gate regulates the boost.

THe Cummins diagnostic equipment will provide appropriate read outs of all pump pressures, fuel demands, and more information.

As suggested, check the air connections at the CAC and elsewhere, also check the fuel filters. Then find a reliable Cummins trained technician to run the diagnostics.
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Old 02-09-2010, 08:12 AM   #8
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Roadking, Good post. It is surely a reason to read the codes on the engine. Buying a Silverleaf VMSpc cost a few hundred dollars but reading just one code can pay for it. I have had two cases where I had codes and once I knew the code the fix was simple and I could do it myself.
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Old 02-16-2010, 11:21 AM   #9
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A couple of things. If a clamp goes on one of the connector hoses from the turbo though the intercooler to the intake manifold then the connector hose blows off at that end and zero boost and not low boost. Just happened to me. The T clamp broke and came off. A loud boom occured and boost went to zero and I had to pull off the road. Thought I was going to find the turbo sitting on top of the motor. Took me a while to see the clamp missing and the hose looked normal.

The other thing that has happened is that I had the "black slime" in my fuel tank so I was going through fuel filters at a faster rate. I cut a filter open and was I shocked as to what crap I saw. Had this black slimey stuff. When my filters would start blocking up the turbo boost would start going down. A diesel is a little different from a gasoline motor because it takes fuel to make normal EGTs. A gasoline motors goes up in EGTs when the fuel goes away and it goes lean. In a diesel if no fuel and the EGTs are low then no hot exhaust to spin up the turbo and low boost. I would take your first filter at the water separator off and cut it open and see what is inside. If you have an algae then it will be obvious. I used an air grinder with a cutting wheel and cut all the way around the top so that outside slid off.
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Old 04-06-2010, 01:37 PM   #10
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Resolved - Need some help/info on Cummins 350 ISC

Thought I'd post a quick resolution, since so many of these "help me" threads don't do so.

Turns out I was 'looking for love in all the wrong places.' Nothing was wrong with the turbo, the hoses, etc.

It was the Banks Ottominder module that had failed. Putting in the by-pass jumper (didn't know there was such a thing!) brought the engine back to normal specs, and replacing the module has brought back the kick.

Seems like I learn something new every month... and I sure appreciate all the help and advice offered. Gave me a lot to remember to check if this ever happens again.
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