Foretravel Owners' Forum For owners and Fans of Foretravel Motorcoaches September 10, 2025 ...

Looks like oil. Turbo seals failure are usually accompanied by lots of smoke all the time. The seal failure also means high EGTs that can cause internal engine damage.

Oil causes blue smoke and a blown turbo the smoke is black.

Pulled the manifold off and five of the six exhaust ports have a sticky wet-looking residue on the inside.  The front two cylinders are real nasty, the third is a little better and the rest are not as bad.  The collector for the first three cylinders at the turbo has a wet glazed look. I'm going to take the manifold to the machine shop and then go to Cummins to pick up new gaskets.  Would fuel cause the residue or would it more likely be oil?

If that isn't it next thing they said to check was the over flow valve.

Got the manifold resurfaced at the machine shop and the new gaskets from Cummins. The service guys spent a lot of time going over things with me.  They both felt fairly sure that the injection pump drive gear slipped timing.  They said the residue in the ports would be caused by the over fueling.  They spent time showing me pictures and explaining how it all worked and how to correct the timing.  If that isn't it next thing they said to check was the over flow valve. They printed off 26 pages of instructions for me ha!  Ive got the engine barring tool, correct torque wrench and the injection pump gear puller ordered. Everything will be here by Tuesday and I can't check the timing until I get the barring tool to set TDC.  We're keeping our fingers crossed that this is the issue. 

I gotta say I applaud your gumption!  You obviously aren't afraid to dive in and get your hands dirty.  We appreciate that attitude around here. 

Of all the possibilities you mention, the overflow valve is the only one I know anything about.  I doubt it is the cause of your troubles.  Most overflow valve problems are caused by either a weak or broken spring, or a piece of trash on the valve seat holding the valve slightly open.  In either case, the result would be LOW fuel pressure (less than 20-30 psi at idle) at the P7100 injection pump inlet.  Doesn't sound to me like this would relate to your current difficulties or cause any of the symptoms you describe.

If you are interested in adding a engine compartment fuel pressure gauge to monitor the injection pump inlet pressure, it is pretty easy to do.  See the thread linked below.  The first post shows the pressure gauge installation.  Reply #7 discusses replacing the overflow valve.

Fuel System Science Project

The guy at cummins was saying something similar about the overflow valve actually causing under fueling.

If you have the basic mechanical skill set, you're better off taking care of this much yourself.  Last thing you want to do is turn your engine over to a shop that doesn't want your business.  Word of hard earned advice?  If you start to experience "get thereitis" step back and walk away.  Focusing too much on the end brings on its own form of tunnel vision.

Post Script.
From 1997-2007 I tried to build a hot-metal "society" press.  One night I was finishing up setting a job on the Linotype and my partner came in and said "It's getting late, you're getting frustrated it's time to quit for the day."  I was goal focused.  I brushed Lynn off, defeated a safety device and watched a cascade of type metal flow over the top of the mold and down the front of the machine.  What is known in the trade as a squirt.  We went home.

I've had the "get thereitis" a few times.  Luckily on these type of projects I have so many things to learn it keeps me from getting too ahead of myself. 

I can set hand type,

Boulder,have turned my engine over to run the valves without timing tool,take the 4 small bolts off the outermost pulley on the
harmonic balancer,you can then see 4 bigger bolts,you can turn the engine over with a socket on one bolt if you go slow or get 2
extra long bolts and use a prybar,go slow to allow the compression to dissipate.

The guy at cummins was saying something similar about the overflow valve actually causing under fueling.  I haven't done a lot of digging on the overflow valve yet but will definitely do some more research on it.  The fuel pressure gauge would be a nice addition for sure!

Tried to find TDC by using the harmonic balancer to rotate the engine.  I could not get the pin to locate in the gear.  Maybe the barring tool will allow us to rotate the engine more smoothly.  The timing in is between the injection pump and the air compressor and is a real pain to reach.  It was seized and had to be taken out and cleaned so it would slide back and forth smoothly.  Any ideas on getting the timing pin to seat?

The barring tool will make it easier to find the seat for the timing pin.  It's real easy to skip over the hole.