Blower Rebuild

[buddyten]

Based on info from a previous post, it appears that my blower needs rebuilding on my 8V71.    I have located a rebuilt blower for $480, and the rebuild kit for $182 (of course, plus shipping).   If I decide to get the rebuilt one, is this something that we can install ourselves without any special tools, etc.   Are there timing issues involved?    Give me all you can with description of how difficult this job would be.

[PSmith]

You're going to get some folks who will warn you that only a PRO will be able rebuild a blower.   

Just pay close attention to clearances and follow the steps in the manual to the letter.

Special tools may be involved- so do your homework and enjoy.

Now stand back -- there are flames nearby 

[luvrbus]

Takes a while Buddy but you can do it but the speical tools do make it easier only 15 pages in the book to tell you how lol ,the problem you may have if it is the small bearing blower those parts are getting hard to come buy there is also about 12 or more different blowers take the number and get the right parts and good luck.

You do know that the govoner and the rack needs to be reset ?

[buddyten]

I am not talking about rebuilding the blower myself....I was gonna get one already rebuilt complete.   Would not attempt to rebuild it myself.    I thought maybe if it came to me already rebuilt, that it might be just a "bolt on" type situation.   If governor and "running the rack" is involved, that takes me completely out of the picture.

I found out from the mechanic that when he did the "ring job" on it a couple years ago, the blower was not rebuilt.   That means it has been quite a while, and probably accounts for a large part of my oil usage.   I had a very weak air compressor and was told that would also lead to excess oil usage, but had a new one put on a couple months ago.    Before I spend the money to have an in-frame rebuild, I am gonna try the blower rebuild route.   

If that doesn't do the trick, will likely go ahead with a complete inframe.    Found a rebuild kit for around $1700, and gasket set for $100.   When injectors were rebuilt last time, I think it was about $200, so maybe I will be OK for parts around $2K.    Should I be able to get an inframe done (labor only) for around $3K?   

[bevans6]

Replacing a blower in the bus is getting on towards a big job.  You have to get the whole top of the engine quite clean, you have to take the blower drive cover off the back engine plate, remove the drive quill, loosen the drive housing (the big tube), take the oil feed off.  On top, you have to remove the air intake feed, and maybe the air manifold itself, for clearance.  At the front, you have to remove all the fuel lines going to the fuel pump, all the connections to the governor (fast idle, engine stop air lines, the throttle cable, anything else).  You have to take the valve covers off, take the top of the governor off, and remove the rack push rods.  Then you can undo the bolts that hold the blower on and lift it off.  You need to then get all the old gasket junk off while not letting any fall into the air box, you need to swap the fuel pump and the governor over to the new blower, and put it back on the engine, re-doing everything you took off.  Then you need to reinstall the rack rods and reset them, which means running the rack (although there is no specific need to adjust the valves or time the injectors, just run the rack).  Then, I would do a governor adjustment check (gap, starting aid, back out the buffer screw) and do a first-start procedure on it, set the idle and high idle (the first step to running the rack is to back the idle adjustment right out and back out the buffer screw), then adjust the buffer screw.

It's not a job for the first timer, but a good mechanic could read the book and figure it out.  So much of the work done on this engine is not complicated, just tricky, and best learned looking over the shoulder of someone who knows how to do it, then doing it yourself while said person looks over your shoulder.  People who can confidently do a job like this never having considered it or watched it done are fairly rare, in my opinion.   You do really need the tune-up tool kit to do the tune-up, unless you really like making special tools.

Edit:  just had the thought that if you put the kind of bus you have in your signature, it helps people know what advice to try to help you with sometimes.

Brian

[buswarrior]

buddyten, how have you arrived at the conclusion you should be changing parts?

From reading posts on this board?

Perhaps a bit more diagnosis should be conducted before you start acting like your local auto mechanic and throwing parts at the vague symptom of excessive oil consumption in the hopes that it will magically work?

Congregation, what easy checks should he be doing before spending all this time and money to not solve his problem?

happy coaching!
buswarrior

[bevans6]

Well, if you're going to have a quiz...

Run the engine with the exhaust off the manifolds and see if the smoke isolates to just one bank.  If it does, it's probably not the blower.  If it doesn't, it could be the blower or a generally worn out engine.

Run the engine with the exhaust manifold removed and see if only one cylinder is blowing smoke (only if it fails the "isolate to one bank" test.

Take the air-box covers off and look inside the air box.  If it is covered with gritty grimy horribleness, the engine is dusted and needs to be rebuilt.  Look for broken compression rings or something obvious with the pistons.

Run the engine with one air box cover at a time removed, and see if one cylinder is throwing oil more than the others.

Take the intake manifold off the blower and look at the blower lobes.  If they are dirty and horrible, clean them and run the engine again to see if the seals are leaking.  Look inside the air filter output hose.  If it is dirty and grimy, you have the cause of the dusted engine.

Measure the air box pressure with the engine running.  It should be around 2 psi at 1200 rpm.  If there is a greater pressure, it's possible that blow-by past worn compression rings is pressurizing the air box.  That would lead you to suspect worn oil rings also.  (I just dreamed this one up just now, I have no idea if it is true or not...    )

Brian