Fuel Filter Adapter Problem

Yesterday I decided to change the fuel filters. Simple job, right? Spin the old ones off, fill the new ones with fuel, spin on, maybe bleed a little just to be sure, done.

Not with MY luck.

The PO was kind enough to put on the adapter to change the old CAV (cartridge) style system to take a spin-on filter. Good idea.

There's no room between the filter and the heat exchanger below it to remove the filter. Bad idea:


I suspect the adapter is a DP-1000


I can see the pipe with the circular hole in it sticking way down into the filter, which prevents me from sliding it out at an angle (#7 in the parts list).

There's the head of a bolt (#1) on top of the filter bracket, but it just turns without much resistance. I assume the nut on the bottom (#8) is just turning.

Two bolts will remove the bracket, but I still have four metal fuel lines I'd need to disconnect to get it out far enough. I tried to see if there was enough play in them leaving them attached, no luck.

Two questions:

1) Is there something I'm missing here? Any other way to get these out?

2) After breaking all 4 fuel lines, should I replace the adapters with the narrower screw-on kind that don't have the pipe sticking down into the filter? I've heard they sometimes spin off with the filter, but that would still be easier than breaking the fuel system at four locations.

Wow! That's a wanky problem. You'd think the PO would have done something about that when they were installed. Short of breaking loose all the lines (which kind of defeats the purpose of spin-ons in the first place), I would have no advice without seeing it in person. But by the looks of all the paint chipped off of those lines, it looks like that is what the PO did to replace them.

QQ though... Would it be easier to loosen the heat exchanger?

The long term solution, I would suspect, would be to extend (ie: replace) the those hard lines and fabricate a sort of offset to get them out of the way of the HE.

That's all I got... Sorry.

A little searching might find a shorter profile fuel filter that would work fine. Of course you still have to get those off.

How about just trying to change the filter on the left first before you remove or disconnect hoses or brackets? You'll know then exactly what you have.

It looks like it bolts on to the engine with those to big bolts in the center? So the whloe unit can be lifted up? Can’t see/tell!

Do you have primary filters, Racor, before them? How many hours are on the filters? Do they really need changing?

Tom B, believe me, I thought about disassembling the heat exchanger, but in the end that means draining and re-filling two systems, water and fuel, instead of just one.

Anode, good thought on trying to cross-reference a shorter filter. I'm afraid I'd need a LOT less height though. Still, I could bring the photo and the new filter in to the parts store and see what they suggest.

Larry, the photo is deceptive, I think the filter on the left is just as bad as the one on the right. Worth a try though, I've got nothing to lose!

Phil, I do have Racors ahead of these. According to the PO he just changed these last year, and there is a date of 1/12 written on them. They probably don't need changing. But now I'm glad I started this project. Not only will I know for sure how many hours are on them, but I'll know what it takes to change them. I'm glad I didn't have to do this while underway!

Here's what I was thinking of replacing the adapters with once I get the old ones off:

A quick search says the Napa 3361 in your photo is a replacement for a Donaldson P550678. Dimensions on are on this link. It appears to be much shorter. Anyway, the link will give you the thread and gasket data.
https://dynamic.donaldson.com/webc/WebStore/search/item_detail.html?section=10166&item=1381738

Tom, after you figure it out, this is worth a drive to the PO house to leave a flaming bag of dog poop on his doorstep

Baggiolini said:

Tom, after you figure it out, this is worth a drive to the PO house to leave a flaming bag of dog poop on his doorstep

Click to expand...

LOL, Thoughts like that HAVE crossed my mind several times in the past few months.

Anode said:

A quick search says the Napa 3361 in your photo is a replacement for a Donaldson P550678. Dimensions on are on this link. It appears to be much shorter. Anyway, the link will give you the thread and gasket data.
https://dynamic.donaldson.com/webc/WebStore/search/item_detail.html?section=10166&item=1381738

Click to expand...

Thank you! I could/should have looked that up myself, I appreciate you taking the time to do my homework for me.

The Donaldson filter would (on paper) be almost 7/8" shorter than the Napa, that just might be enough.

Capt Tom

Not sure why you need these two filters if you also have Racors inline. If you want extra filtration just use 2 micron filters in the Racors and eliminate the problem screw on set up. I have used 2 microns when "polishing" old fuel. I have the type with sight bowls so its easy to visually inspect. The two microns can easily last a whole season if your fuel isn't real dirty.

You may have to cut those filters to get them off. I wonder how the PO got them on?

I ended up ordering the Donaldson's, thanks to all who posted.

I've put everything back together for now, I'll try again when the new filters come in. I'll probably have to loosen at least some of the fuel lines to get the old ones out.

I'm no expert on fuel systems. Maybe the filters the PO put on are as good as new, and may not even be necessary. Still, I don't see a down side to having them, so I might as well start with a known entity. I've also bought those vacuum gauges that sit on top of the Racor and show the highest value since the last reset. So clean filters will give me a baseline reading that I'll compare all future readings to.

I'll post again when the Donaldsons come in and I've had a chance to try them.

After thinking about it why not just cut the filter to make them shorter as you are going to replace them.

BillMFl said:

Not sure why you need these two filters if you also have Racors inline.

Click to expand...

The on engine filters are called last chance for a very good reason, I'd leave them on. It is amazing how much junk the last chance catch, a lot of it from changing the filters in front of them. A normal 2u filter will catch about 80% of the minus 2u particles, that per cent number is called the "beta number." So you still have some passing through the Racors to the last chance.


But as Anode suggests a shorter low profile (very common) on engine fuel filter may be the ticket. BTW, a good read of diesel filtering can be found on boatdiesel.com

Sorry to dredge up an old post, but I wanted to publicly thank Chip and add closure for any poor sap who needs this thread in the future.

I wrestled the oversized filters out after removing the mounting bracket bolts and gently prying it out at an angle, bending all the fuel lines attached a little in the process. I equally gently pushed it back in place and bolted it back on. The Donaldson filters spun right on, only one needed a little jiggling to get the right angle.

I now have new elements in the Racors, four new engine-mounted filters, and the vacuum gauges on top of the Racors so I can keep an eye on things. One last loose end is to order some spare filters (now that I'm confident I can get them off and on.)

I also learned that sometimes the engine will stop with the fuel pump cam at the top, and then the manual pump lever doesn't pump anything, so you can't bleed the air out until you bump the engine a little. Thanks to a passing mechanic at the marina for that little tidbit of knowledge!

Greetings,
I know about the fuel pump cam situation. In order to facilitate "bumping" the engine I purchased one of these:
12 Volt Remote Starter Switch

RT Firefly said:

Greetings,
I know about the fuel pump cam situation. In order to facilitate "bumping" the engine I purchased one of these:
12 Volt Remote Starter Switch

Click to expand...

AKA an "inch button".