Replacing Cool Fuel III

[rondds]

The original (2007) cool fuel III module on my stbd engine was leaking raw water from the crummy plastic press-in fittings. So it was time to replace it. Ordered a new unit HERE and got it in 3 days. Headed down today to do the deed.

Here is the old unit. You can barely see the old fittings but the lower one was leaking. Note the crusty salt buildup. Also note the distinct lack of hose clamps. The old units have these odd fittings that push on and are virtually impossible to remove without destroying them. They are also prone to leakage. I had to break them out of the old unit to free it up.

This fitting was intact but it was a chore to get it out of the hose. I would up crushing and cracking it into pieces with a ViceGrip. The metal bracket sort of holds them in place. It is not used on the new model.

Crush, Kill, Destroy!

Here's what is left of the fitting after complete removal...

Here's the new unit. Note the female thread in the case. Also supplied were 3/8" 18 TPI NPT hose nipples that fit the existing hoses. You can also buy a replacement hose kit from Merc but not really necessary.

The only other difference from the old unit is there's a blue plastic wingnut/drain at the bottom of the unit. (don't have a pic of that).

Getting the unit off was a snap. Make all your disconnections, remove 4 bolts from the brackets and it comes right out. Put the new one on the same way.

The installation called for Perfect Seal so the nipplea got a healthy dose of that, as did the brass fitting on the fuel supply going IN. A bit more careful on the fuel side so as to not get any monkey snot in the gasoline.

Water hoses re-connected. Turned the ignition switch (not the engine) on and off several times over a 15 minute period (to fill the fuel pump). Let the ER air out for an hour or so with blowers on, vacuumed the water spillage out of the bilge and she started right up.

Had a small leak around the upper nipple so drained the unit of water (using the handy dandy wing nut - must less messy) into a bucket, loosened the hose clamp and tightened it (11/16" wrench). Also, where I was using the vice grip on the hose had some tiny weeping perforations. Had to cut that part off (about an inch) and stretch the lower hose to reach. Other than that, no problems encountered.

Hooked up to the ECM and checked all parameters. All was well. Funny, I don't see fuel pressure here but it comes up on the Garmin and it was within in normal limits.

The next step is an attempt to rehabilitate the OLD CF III unit. ie: convert it from press-on fittings to the same hose barb nipples. This will require tapping the existing holes. I will be sending this to upstate NY, to my buddy Dale MasterFab where he will hopefully work his magic.

As many of you already know, there were issues with paint peeling off the internals of these CF III units. I took the two filters out and emptied all the gasoline from the unit and dried it with paper towel. No a trace of evidence of peeling paint. I did not remove the fuel pumps from the other side of the chamber so I can't comment on what is going on over there. But the plan is to replace the CF III on the port engine with the re-habbed and modified old CF III. dc380 (Dave) tells me that his marina in Rhode Island has done quite a few of these conversions successfully.

BTW, you can also purchase just the bottom part of the CF unit and recycle your pumps adn the filter housing. That will only set you back about $450.

 

[villain style]

Nice job!!!!

 

[mawyatt]

Ron,Thanks for posting and showing the images. Did you know about the Mercury recall on the cool fuel modules a few years ago? BTW what do you use to get the engine data displayed on your laptop? Sorry about my formatting, my Dell laptop at work doesn't work well on this site, my Mac at home does. Cheers, Mike

 

[rondds]

There was never a recall. Just a "service bulletin" and a revision of the old design. But I am VERY aware of the problems with CF III.

Check out the software HERE

 

[carterchapman]

Nice Ron,

Thanks for posting. Are you going out this weekend?

 

[rondds]

Thanks Carter.

Heck yeah. Unless I have fuel issues.

 

[MasterFab]

Nice post, Ron. It should be very helpful to others with this problem. But, I see dirty water in your bilge........

Dale

 

[rondds]

God you SUCK! I KNEW KNEW you would say that when I took the pic. But the gas fumes were hanging low and I was NOT ready to run the shop vac. That's muddy water that dripped out of the old CF! Smelled lousy too. LOL!

 

[MasterFab]

You should have cropped the pictures!!

Dale

 

[rondds]

You'd STILL have spotted it with your bionic forensic bilge swill vision.

 

[mawyatt]

There was never a recall. Just a "service bulletin" and a revision of the old design. But I am VERY aware of the problems with CF III.

Check out the software HERE

Thanks

 

[rondds]

I emptied out (most of) the gas, packaged up my old CF3 unit and shipped it off to Dale MasterFab to see if he could machine the old holes for raw water to fit the new style Merc fittings. Unfortunately, the autopsy Dale conducted revealed pinhole failure due to corrosion of the aluminum casting interiorly. The seawater runs through jacketing that surrounds the internal fuel chamber, thus cooling the fuel. With such a failure, water can enter the fuel system. So in the words of the Masterfabricator, "this unit is toast."

The good news is that there was no evidence of paint chipping/sloughing. The strange paint job you see in the picture is purely a function of the paint guy at Merc missing.

Here's one area of corrosion...

Here's another. You can see the poor paint job here. Probably a blessing.

The holes were tapped to 1/2" diameter NPT. They were too large to be tapped to the 3/8" 18 NPT thread of the new merc fittings. So Dale bushed them down to 3/8"

New fittings and bushing in place...

So, what have we learned today...
1. if your CF is corroded on the outside, it's probably corroded in the inside as well
2. The paint flaking/dissolving was not an issue...IN THIS CASE
3. These things can be modified to accept the new fittings, as long as inspection reveals no internal issues with the casting. And Dale is the man to get the job done for you.

Dale, if I missed anything please chime in. And thanks for the post-mortem report!

 

[rondds]

I got a very good question from the audience. WHY WOULD DALE BOTHER TO MACHINE THE UNIT IF IT WAS DOA? Quite simple - to see if it could be done. That's the kind of guy Dale is. Never-ending quest for knowledge and the guy is a total gear head who loves messing about with machines.

 

[scoflaw]

Nice pixs, couple of comments, I'm in the middle of the same mod. The area of corrosion you show is where the old O ring was sitting on the opposite side, that area is paper thin, is that where your leak was? Not sure if opening up that even more to 1/2" will hold up over the long term. I think I'm going to weld some tubing in that area for the hose instead. I'm also coating the water jacket and that section of the gas area with a POR 15 product called U.S. Standard tank sealer. I've had excellent results in the past on old classic car gas tanks, pinholes, corrosion, works nice

 

[rondds]

Scof
I don't have the unit back in my hands so I'd have to let Dale answer the exact location of the pin holes if he finds this thread. My leak was from the crappy plastic press-on fitting of the old design. The sea water was not leaking out of the housing proper.

 

[MasterFab]

The casting is thin where the fittings are pressed in (on the old design), and it's aluminum - not much we can do about that. Now, in order to machine the thing for 1/2" NPT bushings, I don't actually make the wall any thinner on the inside edge. Instead, I offset bore the casting, in a milling machine, so I only remove material from the outside. And, I only remove a small amount of material. The existing hole is tapered, and machined to accept the push-in plastic fitting, so I am just straightening it out and removing the taper. This mod can't be done with a simple drill bit, because the depth has to be precisely controlled, or you'll penetrate one of the bosses that is threaded for the fuel pump retaining screws. A drill also can't remove material from only the outside, so drilling will just make it even thinner in the critical area.

Now, here come the "ifs". IF your casting is not corroded, and IF the casting does not suffer from porosity, I can machine it and tap it for plastic 1/2" x 3/8" NPT bushings. You can then install the 3/8" NPT plastic nipples from Merc, and keep on cruising.

Like Scoflaw said, these are thin castings, so your mileage may vary. If you have one that's only leaking on the outside, my mod will extend the life of the CF3. I also intend to coat the interior of the unit after machining, to prevent, or at least delay, further corrosion. But, it's a crap shoot. Each unit has to be evaluated individually. Ron's was on the edge of complete failure, so it was too late to save it.

As to welding a tube into the casting, I have to say I doubt that will work. Cheaper cast aluminum is notorious for porosity and inclusions, resulting in weld contamination and a potential leak. Also, without knowing the metallurgy of the casting, it is almost impossible to select the proper filler rod, so accelerated corrosion may result. If you're really good with a TIG, and the coating you apply post weld is 100%, you might get away with it, but you might wind up with a pile of useless slag too.

Dale

 

[mistercomputerman]

Dale is "DA MAN".

 

[rcmafgny]

Awesome Dale....

 

[rcmafgny]

Where is the paint peeling problem? Would it be in the top half? So is buying the bottom half even an option?

The original (2007) cool fuel III module on my stbd engine was leaking raw water from the crummy plastic press-in fittings. So it was time to replace it. Ordered a new unit HERE and got it in 3 days. Headed down today to do the deed.

Here is the old unit. You can barely see the old fittings but the lower one was leaking. Note the crusty salt buildup. Also note the distinct lack of hose clamps. The old units have these odd fittings that push on and are virtually impossible to remove without destroying them. They are also prone to leakage. I had to break them out of the old unit to free it up.

This fitting was intact but it was a chore to get it out of the hose. I would up crushing and cracking it into pieces with a ViceGrip. The metal bracket sort of holds them in place. It is not used on the new model.

Crush, Kill, Destroy!

Here's what is left of the fitting after complete removal...

Here's the new unit. Note the female thread in the case. Also supplied were 3/8" 18 TPI NPT hose nipples that fit the existing hoses. You can also buy a replacement hose kit from Merc but not really necessary.

The only other difference from the old unit is there's a blue plastic wingnut/drain at the bottom of the unit. (don't have a pic of that).

Getting the unit off was a snap. Make all your disconnections, remove 4 bolts from the brackets and it comes right out. Put the new one on the same way.

The installation called for Perfect Seal so the nipplea got a healthy dose of that, as did the brass fitting on the fuel supply going IN. A bit more careful on the fuel side so as to not get any monkey snot in the gasoline.

Water hoses re-connected. Turned the ignition switch (not the engine) on and off several times over a 15 minute period (to fill the fuel pump). Let the ER air out for an hour or so with blowers on, vacuumed the water spillage out of the bilge and she started right up.

Had a small leak around the upper nipple so drained the unit of water (using the handy dandy wing nut - must less messy) into a bucket, loosened the hose clamp and tightened it (11/16" wrench). Also, where I was using the vice grip on the hose had some tiny weeping perforations. Had to cut that part off (about an inch) and stretch the lower hose to reach. Other than that, no problems encountered.

Hooked up to the ECM and checked all parameters. All was well. Funny, I don't see fuel pressure here but it comes up on the Garmin and it was within in normal limits.

The next step is an attempt to rehabilitate the OLD CF III unit. ie: convert it from press-on fittings to the same hose barb nipples. This will require tapping the existing holes. I will be sending this to upstate NY, to my buddy Dale MasterFab where he will hopefully work his magic.

As many of you already know, there were issues with paint peeling off the internals of these CF III units. I took the two filters out and emptied all the gasoline from the unit and dried it with paper towel. No a trace of evidence of peeling paint. I did not remove the fuel pumps from the other side of the chamber so I can't comment on what is going on over there. But the plan is to replace the CF III on the port engine with the re-habbed and modified old CF III. dc380 (Dave) tells me that his marina in Rhode Island has done quite a few of these conversions successfully.

BTW, you can also purchase just the bottom part of the CF unit and recycle your pumps adn the filter housing. That will only set you back about $450.

 

[MasterFab]

Supposedly, (I've never seen one do this, but it may have been an issue on older units) the paint inside the casting softens, peels, and then clogs the fuel pump inlet screen or injectors.

You can't just buy the "lower half" of the casting - it's a single piece. The parts that unscrew on top are the filter housing and fuel pump assembly.

Dale