Changing Engine-Mounted Fuel Filter

[adt2]

Okay...how do I do this? Detroit 12v71 manual says drain the fuel, remove the bolt, change the filter, fill 2/3 with fuel, reinstall, then "remove plug on top and fill completely."

Which of these fittings is the plug?

 

[Captain Ralph]

That is the old & original cartridge type filter.
Looking at the hoses, that is your secondary filter.
Drain plug on the bottom. Drain near 1/2 gallon. 3 wraps of teflon tape and re-install the plug.
The hex head of the top cemter,, is the top of a long bolt that connects to the bottom of the bowl. This bowl will drop if your not holding it and ready. Good thing you drained it.
When it drops, keep it up-rite and place into an open (empty) 5 gallon bucket.
Take off the boat, invert the bowl and remove the filter. Leave the bowl upside down for a while for all the snot to drain out.
Further cleaning is desirable but messy, Good thing your off the boat.

The top edge of the bowl seats against a gasket (new with filter) that you may have to peel out of the filter head. Install new gasket.
You may also get a new flat washer, this goes under the bolt head.
That is a steel plug in the steel bowl. Not self sealing, that's why you need a few wraps of teflon tape.

New filter may look like a paper element in a can full of holes.

Install new cartridge reassemble in reverse order. Good snug tension on that bolt but not head boat tight.

Oh, there is no plug on top of that old assembly.
Looks like you may have a priming pump installed (small hose).

 

[adt2]

Outstanding. Thank you

 

[bostonhatteras]

you may consider swapping the filter base on both engines to spin on style. There is a hands down big improvement in maintenance ease and imo filtration. Same fittings connection and its a simple job. The photo is a primary filter base because that's what i had for the picture but the part number you want is DD 23539256. filter is accurate. With spin on replacement, you'd fill the filter and screw it on. Another consideration is a pressure gauge to monitor when to swap the filter but that's a different post.

 

[bostonhatteras]

looking closer at your photo, is that a galvanized tee fitting in the fuel system? Thats a big no no for diesel fuel systems. a brass or stainless is the metal of choice.

 

[Pascal]

looking closer at your photo, is that a galvanized tee fitting in the fuel system? Thats a big no no for diesel fuel systems. a brass or stainless is the metal of choice.

Even though I don’t think I ve ever seen or used galvanized fittings with diesel, I wonder why it would be a no no. After oil diesel is close to oil so you re not going to get corrosion.

 

[Boatsb]

Zinc plating will react to oils and fuels. High zinc alloys will too. Ignorance will not fix the injectors. Just think about how much time and thought went into the boats and systems before you think you can change it for the cheaper or more available product.

 

[bostonhatteras]

Even though I don’t think I ve ever seen or used galvanized fittings with diesel, I wonder why it would be a no no. After oil diesel is close to oil so you re not going to get corrosion.

The zinc supposedly reacts.

 

[adt2]

you may consider swapping the filter base on both engines to spin on style. There is a hands down big improvement in maintenance ease and imo filtration. Same fittings connection and its a simple job. The photo is a primary filter base because that's what i had for the picture but the part number you want is DD 23539256. filter is accurate. With spin on replacement, you'd fill the filter and screw it on. Another consideration is a pressure gauge to monitor when to swap the filter but that's a different post.

Where would the pressure gauge be installed? That sounds like a good idea. I refer to the pressure gauges on the Racors frequently.

 

[Pascal]

Where would the pressure gauge be installed? That sounds like a good idea. I refer to the pressure gauges on the Racors frequently.

Actually they re vacuum gauges. They are installed on the Racors, in place of the handle on single units or in between the filters on dual units