air compreesor rebuild engine

[richardkillmon]

Hello,

I have an 1976 MCI 5B 8V71 Detroit engine 900,000 miles no rebuild. Burns a gallon  of oil every 4,ooo miles and no oil leaks on engine.
Air pressure builds to 60 psi and never increases.
I put on a new governor and still the same.
Some say compressor needs seals rebuilt
I have put a 120 gallon fresh water tank above the engine with bed (I know bad plan).
What can I try to narrow the search for the problem.
If the compressor needs to be rebuilt, do I have to remove the engine?
If I have to rebuild the compressor can I do it without removing the engine or out through the top?

next question: I have a single back axle,8v71 detriot, super charged, 4 speed Allison - should I be able to climb a %7 climb with ease? I was on SR 26 Asheville, NC hit hills and was at 20 mph trying to climb -- some say II should be easy - super charged need rebuild- what say you all?


Thank

Rick

[benherman1]

It's a bit cozy in there but according to the manual you should be able to remove the compressor without pulling the engine. Is the air compressor still pumping air at 60 psi or does it stop until it drops? Is it dumping any noticeable amount of oil into the air system? Are there any large leaks? Try hooking the bus to an external air source and see if you can build adequate pressure. You'd be surprised with how big of a leak the engine can hide. If you do end up needing to pull it I can take some pictures of that section on my manual for a 5A which should be similar enough,

[freds]

Your engine might be a little tired. Maybe find a class 8 truck dyno and get your power to the wheels measured?

Also the blower on your engine is part of the required functionality for a two stroke diesel, not a super charger.

[benherman1]

Here's the information on adjusting the governor. Hopefully it's that easy...

[buswarrior]

Find the leaks, stopping at 60 lbs is almost always big leaks in the auxliaries, so wipers, suspension, shutters, dampers...

As for your engine power, do the lazy stuff first... when were fuel filters last changed? How's the air filter? How heavy is the conversion? What automatic has been stuffed in there behind a V8, cuz mci didn't build it with one...

No more "supercharger" it is a roots type blower...

Happy coaching!
Buswarrior

[Scott & Heather]

I'll chime in:

Yes you can remove the air compressor while engine is in place and without going thorough the floor hatch. Also, the fresh tank under the bed isn't a bad idea at all. Lots of converters have done it. Just have an easy way to drain it and move it for engine access if need be.

Anyway, yes, first thing to do is find a way to plumb in a shop air compressor into your air system (usually in the back rear passenger side engine door) and pump up the system with the bus engine turned off. You'll be amazed at the leaks you can hear. I'm guessing you have a large one somewhere. Have you drained your air tanks underneath? Pull the rings and drain any liquid out of them.

Deal with your air pressure situation and then have a conversation about engine power issues. But a normally aspirated 8v isn't going to win any speed or climbing contests.

[luvrbus]

You need to know the HP rating of the engine,it is probably set at around 240 to 260 hp,900,000 miles with no rebuild on a 8v71 has to be a typo ,if the compressor builds to 60 lbs check for leaks and if air dryer equipped service the air dryer,not a easy job in a MCI 5 but the unloader valves can be changed with the compressor in place 

[Dave5Cs]

Ah yes it is easy to service the air dryer. It is not easy to get to. Front wheel well front wall. Big long tank looking thing. Block the bus or put up on stands etc to be safe.

[richardkillmon]

thanks to all