4108 Oil Bath Air Cleaner

richard5933 · July 25, 2018, 06:42:15 AM

Looking for a little advice on servicing the oil bath air cleaner on our 4108. It doesn't look exactly like the one in the book. It's larger, and doesn't have the exact same setup.

One picture shows the bottom oan and removable screen. I know what to do with these... Clean and refill the oil to the mark.

The other photo shows the bottom view of the upper section. This is where I have a question. The screen doesn't appear to be removable. I can't imagine that the entire upper unit is intended to come down at every service. Does that mean that the upper section doesn't get touched?

lostagain · July 25, 2018, 06:48:14 AM

The upper section is a steel mesh that catches oil mist. The oil mist drips back down into the bottom. If it looks dirty, you can clean it with diesel fuel or solvent once you remove the housing out of the bus. It not too dirty, leave it.

JC

lostagain · July 25, 2018, 06:52:16 AM

It is important to not fill the oil above the mark. I did that once on a stationary Cummins power unit for a saw mill. It revved up quite fast and rolled coal for a few minutes, while sucking the excess oil out the bowl.

JC

richard5933 · July 25, 2018, 07:07:06 AM

Quote from: lostagain on July 25, 2018, 06:48:14 AM
The upper section is a steel mesh that catches oil mist. The oil mist drips back down into the bottom. If it looks dirty, you can clean it with diesel fuel or solvent once you remove the housing out of the bus. It not too dirty, leave it.

JC

Nothing looked particularly dirty. There was a very slight amount of dirt in a ring around top face of the bottom screen, and a few spots of accumulated dirt at the bottom of the oil pan. It's only been about 2500 miles since the last service, but since we've run on some gravel/dirt roads this past week I thought it was important to check. The upper screen seems to be clean of everything but golden oil droplets.

This thing is really fascinating. There are remnants of the original label on the side of the oil pan/lower section. Enough to see that Donaldson made the filter for GM. And it's huge - not like the four little ones on a 4106 - just one massive filter.

Once the remaining solvent evaporates I'll put it back together and carry on.

Thanks for the tips.

luvrbus · July 25, 2018, 07:16:40 AM

On the 4905 I have seen both oil and paper OEM from GM wonder if the 4108 had the same option

richard5933 · July 25, 2018, 07:19:58 AM

Quote from: luvrbus on July 25, 2018, 07:16:40 AM
On the 4905 I have seen both oil and paper OEM from GM wonder if the 4108 had the same option

The book shows both oil and paper. What confused me is that the book showed the bottom section only having two wing nuts, not three like I've got. It also shows a cone-shaped screen in the upper section which easily drops out, not the built-in larger screen I found.

luvrbus · July 25, 2018, 07:33:31 AM

You never know what you will find ,I have seen the oil bath filters same as yours on MCI's will have 2 or 3 wing nuts on the bottom,with screens you could remove and some that weren't removable