Turbo boost gauge.

[Rob53]

Hi Folks
Looking at purchasing an 04 Cayman 36 PDQ. Already aware of the trailing arm issues, inspected them and there are no signs of cracks. I plan on getting the heavie arms installed (any advice).The coach has 30k miles. I test drove it yesterday and was quite pleased with the way it handled, much smoother than than my 34' gas coach on Ford chassis. One thing I noticed is that the boost guage stayed at 0. I'm new to diesels and am thinking the gauge would not register until the turbo kicks in is this correct? Any help and advice would be greatly appreciated.

[Drifter]

Gotta have Turbo boost, get it checked out before you buy. By a indpendant.....Cummins dealer!

[bdpreece]

On level ground just cruising you will see little boost but, if you put your foot in it the boost gauge should increase significantly and on a long hill should probably be up around 23 to 25 lb or better. I would definatly check this out further before purchasing the coach. If it felt like plenty of power it may just be the gauge but then again it it's a turbo problem we are talking big bucks.

[1ciderdog]

If the boost stayed at 0 when driving that is not correct. Could be as simple as the tube that runs from the fitting to the gauge has come loose from a fitting. What engine does this unit have? My 330HP Cat C7 seems to run about 8 - 10 at high speeds.

[Mike Canter]

ROb, on my 2004 Signature when I first bought it the boost gauge did not work. I thought it was an electronic gauge to start with but did some looking around and found a 1/4 whitish plastic tube coming off a fitting on the intake manifold. Took the fitting off and in the brass part I found a brass plug that is meant to look like a real porous filter. It is used to suppress spikes in boost going to the gauge. It was black and plugged with carbon. I tried carb cleaner and everything else to clean it and unblock it with no success. I finally took the smallest drill I had which is .050" drill and using a pin vise to hold the drill bit I made two small holes in the middle of the brass plug. Now my gauge works just fine. Monaco should have put that suppressor plug at the gauge end so it didn't carbon up.

[Rob53]

I only drove it on city streets highest speed maybe about 45-50mph. I was real easy on the throttle. After one stop I did give it a bit more pedal and am pretty sure the turbo kicked in as the coach got a burst of energy and really took off. Unfortunately I didn't have my eye on the gauge, too busy watching the road in an unfamiliar coach. It has the 300 hp cummings.

[Mike Canter]

Every time you start off from a standstill you are going to see good boost. Driving down the road you should see a steady low reading of about 5-7 lbs and if you push down a little you should see it climb.

[Bighammer]

My plastic tube from the turbo to the gauge was plugged up. After clearing the tube it worked properly.

[Mike Canter]

Was it blocked right where it attached to the intake manifold? I think the EGR system causes the diesel exhaust to circulate back into the intake manifold and causes that.

[RustyJC]

Quote:

Originally Posted by Mike Canter Was it blocked right where it attached to the intake manifold? I think the EGR system causes the diesel exhaust to circulate back into the intake manifold and causes that.

An exhaust brake can also contribute to this as residual high pressure exhaust gases ahead of the brake flow back into the intake manifold during valve overlap. It's pretty common practice on the 24 valve Cummins ISBs to periodically clean the MAP sensor as well due to this fouling.

Rusty

[Bill2]

The turbo boost gauge on my ISL 400 moves everytime I step on the excellerator.
Bill

[Mike Canter]

My MH does not have an exhaust brake, only a Jake and mine plugged up by 24K miles.

[RustyJC]

Perhaps not, but the OP's candidate 2004 300 BHP Cummins (a 5.9L ISB) would.

Rusty

[Rob53]

I talked to an authorized cummings service rep yesterday and explained everything in detail. His conclusion was that the turbo was working correctly and the line to the gauge was either plugged as others have indicated or it could have even be burned at the manifold since it is plastic. Anyhow, he said it was an easy fix, Now one other question, is there a pressure regulator on the entry step cover? Seemed to me it came out pretty hard when it was activted, I sure wouldn't want my foot in the way.