Cummins 4bt -- uncovered opening

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paul-b

Member
Joined
May 12, 2013
Messages
7
Location
USA
I just purchased a boat with a 4bt 155. I was cleaning things up and found and unused opening on the engine. The two attached pics show it (same angle, just two different zoom levels).

What is it? What should I do about it? I'm sure it was not intended to be left open.

Also attached is a picture of the dip stick. There are no markings that I am familiar.. how to read oil level?

Is there a good online source of Fleetgard parts? The Cummins dealers nearby are all Mon-Fri operations, which rules out a visit to them.

Thanks guys. I've been a lurker here for a long time. Thought I'd give posting a try.
 

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I don't see any threads near the surface in the hole, it has a machined boss, no sign of fluid leakage, so I have a guess-
It may be a clearance hole for a missing or unused mounting bolt.
( I am a mechanic/technician but not on diesels, so take with a grain of salt)
 
No help on the hole, I have a few on my 6bt. Get a shop manual from Cummins. Spend a couple of hours on Seaboard Marine - Custom Marine Diesel Repower Specialists, Tony is the resident Cummins expert on boatdiesel.com and his tech tips are awesome. Boatdiesel.com costs a few bucks but the forums are awesome.

For the dip stick, pump all the oil, add the low capacity from the manual and mark the stick yourself.
 
Around here the local big truck parts store chain, Fleetpride, sells Fleetguard products. Check your local area for truck parts stores.
 
Thanks guys.

..someone gave me a clue that it may be a tachometer sensor on the flywheel bell housing.

The good news: an opening on the flywheel housing is not a crisis.
 
Around here the local big truck parts store chain, Fleetpride, sells Fleetguard products. Check your local area for truck parts stores.

Good tip.

I looked them up. There are two Fleetpride on my drive to the boat.

Now I have to make sure I have the right part numbers, translate from Cummins Truck, to Cummins Marine. I'm not experienced enough to know if there is a difference. [researching]

I imagine, for market reasons, truck "labeled" parts are less expensive than the same part labeled "marine." There may be a silver lining to me ending up with this funky engine.

Thanks!
 
Do yourself a favour and do as suggested. Look up Boatdiesel.com.
Also go to Seaboard Marine
www.sbmar.com
which is Tony Athens business and site. he has provided a huge amount of info available for the looking.
he also and through Boatdiesel is very willing to help with questions specific to the Cummins diesels. The 4bt is not so common as the 6bt but is a good engine.
The reading will be worthwhile.
 
There may be a silver lining to me ending up with this funky engine.

Not funky , they have a GREAT reputation.
 
There are TONS of 4bt engines on the road...Frito Lay trucks, UPS trucks, and many similar styles use the 4bt..and there are several oil and fuel filter numbers that fit.
 
There may be a silver lining to me ending up with this funky engine.

Not funky , they have a GREAT reputation.

I only say funky because of configuration in this case. The boat from the factory had an 85 hp Perkins...which the last owner repowered to 4bt. The more than 30% increase in HP not really needed, and the boat sits a bit lower in the stern since the 4bt is quite a bit heavier than the Perkins. Having said that..I'm OK with the Cummins. Nice part: if I decide to repower (this 4bt is an old one) I'm gonna put in another 4bt.
 
(this 4bt is an old one)

Age and condition are not the same.
 
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