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Old 10-30-2020, 01:47 PM   #1
Mini-Skoolie
 
Join Date: Oct 2020
Location: Wasilla Alaska
Posts: 52
Year: 1991
Coachwork: Blue Bird
Chassis: TC2000
Engine: Mechanical 5.9
Rated Cap: 35 Feet
12V 5.9 boost

How much boost should i see on a 91 12v 5.9. It is showing 6-8 psi on the gauge at 2000 rpm. This bus is new to me and that seems low. If so, what should i check first? Waste gate?

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Old 10-30-2020, 01:55 PM   #2
Mini-Skoolie
 
Join Date: Jul 2020
Location: Ohio
Posts: 34
Year: 2003
Coachwork: Blue Bird
Chassis: All American RE
Engine: Cummins 8.3L ISC - 315HP
Rated Cap: Lots of kids.
That does seem a bit low. I think the stock wastegate for those were like 17-19 psi. I’d start simple first and make sure all clamps and charged air couples were firmly sealed then pressurize the system and check for leaks and then go from there. You can also check the fins on the turbo and look for shaft play. Hopefully it’s just a big leak somewhere and your turbo isn’t shot.
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Old 03-20-2021, 05:38 PM   #3
Mini-Skoolie
 
Join Date: Oct 2020
Location: Wasilla Alaska
Posts: 52
Year: 1991
Coachwork: Blue Bird
Chassis: TC2000
Engine: Mechanical 5.9
Rated Cap: 35 Feet
More information

OK, please bear with me. First I work 600 miles from home (where the bus lives) and spend way too much time at work thinking about this. Second it is winter and cold outside!!

This is a 12v cummins 5.9.
Boost only reaches 6-8 psi
No smoke at any time.
It will NOT start cold. If I plug it in and warm it up, it starts after about 30 seconds of cranking. After it starts the first time, it will restart right away.
All the start attempts are with a strong battery and good starter operation. Not slow cranking. Originally I thought of turbo or induction leak issues, but with the no smoke and very long first start, I am wondering about fueling issues.

Does this ring a bell to anyone?
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Old 03-20-2021, 07:14 PM   #4
Almost There
 
Join Date: Jan 2016
Location: Alberta
Posts: 69
Year: 1992
Coachwork: Blue Bird
Chassis: Ford B700
Engine: 5.9, Spicer-5
Rated Cap: 44 Big butts/66 Lil ones
6-8 lbs boost is not uncommon for stock older 5.9. My 97 Dodge struggles to reach 7! Makes one wonder why did they even bother with a turbo! If you haven't done so try pressing throttle all the way to the floor,( this sets the fuel rack) let it up, then about 1/4 down when cold starting.
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Old 03-20-2021, 07:20 PM   #5
Almost There
 
Join Date: Jan 2016
Location: Alberta
Posts: 69
Year: 1992
Coachwork: Blue Bird
Chassis: Ford B700
Engine: 5.9, Spicer-5
Rated Cap: 44 Big butts/66 Lil ones
Don't know what your buss is, but my 92 Bluebird has no intake air heater, so has to be plugged in for cold starts. Dodge put grid heaters in the air intake on the 5.9s. So they are much better at cold starting. My old 97 Dodge will start down to about -12c without being plugged in.
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Old 03-20-2021, 07:23 PM   #6
Almost There
 
Join Date: Jan 2016
Location: Alberta
Posts: 69
Year: 1992
Coachwork: Blue Bird
Chassis: Ford B700
Engine: 5.9, Spicer-5
Rated Cap: 44 Big butts/66 Lil ones
Sorry, just checked your profile and see you have a 91,so it's probably just like mine with no intake air preheat.
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