A Three Hour Tour...

[The Chairman]

Well, three weeks later and I finally get to look at it. The fairly new impeller is toast. I put another one in, but something is wrong. I made sure the key was in the key way, but I think I pushed it out somehow. No water is exiting with the exhaust. I'll take a closer look after lunch. :-(

 

[RickyF]

Doc,
If that key is not fairly tight in the keyway, take a center punch and just punch the side of the key just enough to raise a little metal and put it back in.

 

[TSandM]

I didn't see this when it first went up . . . but I feel your pain. Our boat has never stranded us, but the first year we owned it, it seemed as though every time we took it out, we ended up with a thousand dollar repair bill. The most expensive diving I've ever done, anywhere!

 

[The Chairman]

A lot has transpired since my last post here.

It WAS the keyway! I took the pump physically out of the boat and put the impeller in on the bench. Water started pumping like it should, but something was wrong. As I might have mentioned before, I get a whine when I get the engine over 4k. The max should be around 5.5k, but the moan is just too much. As I approached 4k during testing, I got a loud rattle... it was too loud and high to be an engine knock, but it was one of those turn the engine off as fast as you can moments. The center of the pulley had actually broken out! Someone had stuck a plastic spacer under the pulley that did not go past the bolts. Crap!

Broken Pulley
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I searched the internet for a pulley, but I never found one. Since I had the pump in the workshop again, I examined it closer and realized that the bearing and seals were shot. It was hard to ID the pump, so I sent a picture to the manufacturer and they came through. This pump came off of an 8 cylinder Sea Ray. Here are the pictures of before and after...

Internal seal mess

Shaft (Before polishing)

Old and new seals side by side

Shaft and seals back together!

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So, after the whole thing is back together... I still can't find a pulley. So, in desperation, I welded the center back using oxy/acetylene. As you can see in the picture, it looks great, but looks can be deceiving. I mounted the pulley, put the assembly in the vice and measured the run out. The run out was 0.0.14" axially and 0.021" laterally. That's better than the other pulleys except for the alternator.

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Welded Pulley


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[The Chairman]

So, I assembled everything back on the boat and did a smoke test. It's pumping like mad and the pulley is running true, but something isn't right! If I sight down the back of the water pump pulley, it's obvious that the raw water pump pulley is not on the same plane. It's 3/4" of an inch or worse. You can even see the deformation of the belt as it comes off of the pulley. Whoever made the brackets for this pump guessed at the measurements or were blind. I understand now why they tried to shim that pulley. They only made things worse in my estimation.

Video of Pump



Water Flowing through the Exhaust

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When I first had it going it was quiet even over 5k. Then the howl started back, and I knew that I had to do something about the bracket if I am ever going to feel good about this engine. I pulled the pump and bracket. What should have been the adjustment bracket acts as nothing more than a poorly designed stabilizer. The only way to keep the pump from moving was to over tighten the pivot bolt. With everything apart, I started to measure. My first guess was not far off. The pulley was 15/16" out of alignment. While a V-belt can handle a 1/4" misalignment, this was too much. I cut the ears off of the bracket and started to devise how to create a new one from the old base. The biggest problem with any bracket is how to accommodate adjustments. You have to use steel that is thick enough to absorb any vibrations and has enough flat area for the bolt to have a purchase when tightened. It should also have a radius to handle the pump pivoting on it's axis. This is where I made my first mistake. That assumption is wrong and I'll get to that in a minute. I decided that I wanted to have a 1/2" wide slot and that I would bend 1/2"x3/16" steel bar edgewise. Working on my workbench, I drew two radii on a piece of asbestos cement board I have had for years. It was a toss out from when I worked as a machinist for Lab Science many, many years ago. I drilled 3/16" holes every half inch on the radii with two opposing screws about 3 inches further down to leverage off of. I screwed the board down to my work bench with #10x2 1/2" screws that protruded at least 3/16" above the asbestos board. FWIW, since the radius of the pump was 2.5" I drew them at 2.25" and 2.75" respectively. I took my time, but I heated up the steel to cheery red and carefully started the bend. After each tiny tweak, I made sure I flattened it on my 55# anvil. I didn't like the lower bend and couldn't get it right with bending, so I ground it down to keep the 1/2" space. I cut a 3" piece to be welded in between the bracket at one end. I had to grind to get the slot down to 1/2" and then I beveled all of the mating parts so I would have a deep weld. I then gas welded it together. I also made a 1.4" piece to act as a cap for the other end. It was while I grinding everything down that I finally realized my mistake. I needed to base the radius on the 5" bolt to bolt distance and NOT on the radius from the center. I will draw them with 4.78" and 5.22" radii. Here are some pics.
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Bracket next the stock steel it was made from.

Bracket next to the wrong and right radii!
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Don't let the shadow in the first picture fool you! I maintained that 1/2" spacing throughout. I think I will reduce it to 7/16" on the next one though. I found the bending process to be pretty easy to keep to tolerance. That will be in about a week when I get back from Cave Diving this weekend and a tech conference for NASE next week.


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[Capt.Gene]

Is the top pully running true?

 

[The Chairman]

Is the top pully running true?

Not as true as the one I welded back together. I haven't measured the actual run-out, but I think it's around 1/16" or better. Of course, that could be in the water pump flange or the pulley. Likely the latter, but I won't know unless I measure it. The real problem is in the almost inch set back of the raw water pump. V-belts can tolerate 1/4" and work fine. Much more than that and we have an issue.

Also, I had a solutions dream about the project last night. When I initially thought this through, I put the inner arc at 4.78" which is wrong. Since my jig is on the inside of the bar, I need to take into account the width of the steel (1/2"). The actual arc I need to draw is then 4.28". I don't know how many people have solutions dreams like I do... I have resolved a good many a problems in my sleep. Now I need to find a beam compass that will allow me to make such a large arc. The one I own won't quite make 5" and I need 5.22".

 

[D_B]

Pully looks great!
... I'm sure you'll get it all righted out

 

[The Chairman]

Thanks. It's kind of funny, but I would never put this much effort into a client's vehicle. On another forum it was suggested that I was trying to "cheap out" and I fully disagree. If I could find/buy the parts, I would. As it is, this is the only 140 that I have seen with an external raw water pump. Of course, it's the only one I have seen with a Penta-Volvo outdrive as well. The Mercruiser outdrives seem to have the raw water pump built in. I thought of going with an electric pump, and while I found a few with enough flow, they drew 10+ amps. That's a huge additional draw for this 55 amp alternator.

 

[captain]

Replacing the whole pump may be a better option. the one on my engine mounts directly to the front crankshaft pulley and needs no belt.

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