Community Forums

heatseaker · 11-24-2016, 01:46 PM

Hello,
My '01 Fleetwood Discovery with a 300 HP Cummins has no boost or very little. Does anyone have a suggestion on what the problem might be ?

jacwjames · 11-24-2016, 01:55 PM

How are you measuring the boost, dash gauge. There could be a line broken/plugged that provides the pressure for the gauge. I installed a silverleaf monitoring system that gives me a very accurate boost reading.

Turbo or CAC failure or air line between the two.

If the CAC is bad it would reduce boost but I'd think you still would have some boost. I had to have my CAC repaired, it was leaking really bad, when they lowered into the test tank and put air to it it looked like a jacuzzi tub. After repair I did gain ~2 psi boost pressure.

dennis45 · 11-24-2016, 02:02 PM

Quote:

Originally Posted by heatseaker

Hello,
My '01 Fleetwood Discovery with a 300 HP Cummins has no boost or very little. Does anyone have a suggestion on what the problem might be ?

You turbo is an air compressor. What drives your turbo is heat from the exhaust. The higher the heat (more load) the more air it compresses until the pressure reaches a set point which is controlled by the waste gate.
So, if your turbo is not producing boost the turbo has failed, the waste gate has failed or, there is not enough load on the engine to produce heat out the exhaust.
You don't give a lot of symptoms but my bet is on a failed turbo.

twinboat · 11-24-2016, 02:08 PM

Does it have low power ?

As mentioned, it could be the gauge connection.

If it has low power look at and tug on all of the, 3" or so round, tubes and connection hoses around the engine. Any one lose or off will let the boost escape.

Have someone give a little throttle, while holding the brake, and listen for air escaping near the engine.

If nothing found, you can see the turbo fan by removing the hose that heads to the charge air cooler. Reach in and see if it spins freely, by hand. Do this with a cold, not running engine.

heatseaker · 11-24-2016, 02:12 PM

I noticed it when I lost power even going up a slight grade. My exhaust temp seemed very high and very little boost. Could the jake brake be a problem? I haven't noticed any difference in it but possible. What about the EGR valve ?

jimmy braden · 11-24-2016, 04:59 PM

shouldn't have an EGR in a 5.9 or 8.3 cummins from that vintage.

Waste gate, charge air cooler or plumbing. If it was a problem on the exhaust side you would probably get some additional noise.

harleyjt · 11-24-2016, 06:01 PM

Quote:

Originally Posted by dennis45

You turbo is an air compressor. What drives your turbo is heat from the exhaust. The higher the heat (more load) the more air it compresses until the pressure reaches a set point which is controlled by the waste gate.
So, if your turbo is not producing boost the turbo has failed, the waste gate has failed or, there is not enough load on the engine to produce heat out the exhaust.
You don't give a lot of symptoms but my bet is on a failed turbo.

Or it could be a leak in the system. Could be as simple as a loose clamp on one of the hoses.

jt

twinboat · 11-24-2016, 06:09 PM

If your getting high exhaust temp, EGTs, my money is on a stuck ehxaust brake.

Look for a cylinder and rod, just past the turbo hot side, before the exhaust pipe.

jimmy braden · 11-24-2016, 09:22 PM

And there is no she on that era Cummins . And it would not change that drastically...egr issues are usually accumulation of deposits

Check plumbing and waste gates/ ext brake

pcurt23 · 11-25-2016, 07:52 AM

Just had my turbo replaced as exhaust gate had failed in the open position.

heatseaker · 11-25-2016, 02:37 PM

Can you explain the exhaust gate please ? What is it ? Where is it located? thx

jimmy braden · 11-25-2016, 08:14 PM

Right near the turbo. There is a solenoid that has a wire that should trigger it. Is this an isc?

8TiresRollin · 11-26-2016, 09:48 AM

I believe pcurt23 would mean waste gate not exhaust gate. Waste gate controls maximum boost to prevent engine from going into over boost. If it is stuck open then you get low boost. If it is stuck closed it can damage engine unless one stays on the boost gage and controls boost by throttle position - not an easy task while driving.

select55 · 11-26-2016, 09:59 AM

Quote:

Originally Posted by dennis45

You turbo is an air compressor. What drives your turbo is heat from the exhaust. The higher the heat (more load) the more air it compresses until the pressure reaches a set point which is controlled by the waste gate.
So, if your turbo is not producing boost the turbo has failed, the waste gate has failed or, there is not enough load on the engine to produce heat out the exhaust.
You don't give a lot of symptoms but my bet is on a failed turbo.

wrong heat from exhaust does not drive anything let alone your turbo
your turbo is driven by the exhaust gas itself
assuming you have no power? therefore no boost it could be as simple as a blown CAC connecter boot or a failed waste gate or a exhaust brake stuck in the ON position to a failed turbo system