All of the hoses and fittings on my 502 MPIs were 1-1/4.

- incoming from sea strainer
- Merc pump in/out
- transmission cooler
- power steering cooler
- engine oil cooler
- thermostat housing inlet

The above is a what was stock on the starboard engine (no power steering cooler on the port engine).

All of that has changed since dumping the MPI, but it’s still 1-1/4 all the way through.

Agreed on not using aluminum. I think I’ve seen in brass as well as plastic.

I think I can make it work with Marelon fittings. Now I'm trying to determine if I can bend the 1-1/4" steel reinforced hose enough or if I should put in a pair of 90s after the pump as it goes back under the motor.....Gonna grab some hose today and find out.

The steel-reinforced hose will bend pretty well. It will depend on how closely you want the hoses tucked around the engine. Do not use the steel-reinforced hose on anything that you need to easily take apart. The steel wire will make removal of the hose from fittings quite frustrating especially if space is tight (ie twin engines). I'm using it from the strainer to the pump, and then the pump to the transmission cooler (for added stability). Everything after the transmission cooler is soft-wall with 90-degree fittings to keep things close to the engines.

yes I’m doing it right now. You can buy the supports, and balancer adapter from marineenginedepot.com (where I got all my stuff from).

i was facing some pretty similar situations not long ago and found some 90 and 180 deg 1 1/4’ aluminum pipe. What an inexpensive and very practical way to go and looked good. I’ll see if I can find a pic and post. I know you could use multiple fittings to achieve the same but why when these are available. Just an FYI.


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Keep in mind you can always utilize your local muffler/exhaust shop to bend up whatever you need. Very inexpensive and nonrestrictive.

I’ve gone to local plumbing places to buy brass fittings (not Home Depot or lowes, you need a Ferguson or plumbing supply shop those big box stores should be able to tell you who the big guy is in town). You can make anything that way just beware of weight and cost…

my raw water is 1.25” from seacock through strainer to pump and to heat exchanger(s) From the main heat exchanger is 1” hose routed around to exit manifolds b/c of the fittings on the exchanger itself.

Yes. I run the F6B-9 with truck accessories but I can't post a pic, don't have enough posts for that privilege.

Only takes 10 I believe. Suck down a 12 pack and post. Hah… 😂

Allright. I have a question in regards to that alternator bracket Mercruiser part# 862778. It appears that the only place for that to mount to, has a tube connected to it that goes to my heat exchanger (Horizon motor with FWC). Am I right on that? Is that where it would go? I think I could grind/modify the bracket to fit but before I do that I wanted to confirm if that is where it is supposed to bolt to. See red circled bolt in pic.


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S

Not sure of what you’re asking. The alternator bracket goes to the head and then the heat exchanger brackets appears to go over top of the alternator bracket. It’s similar on the Gen VI big block.

You got it. I realize now that is just a bracket. From my cell phone flashlight it looked like a cooling tube. So then to use this alternator bracket I just remove that bolt and slide it in behind the heat exchanger bracket then?

Got it. I understand now. Yes, alternator bracket then heat exchanger bracket.

I put a crank mounted pump on a Westerbeke genset because the stock pump was against the starboard hull side in my Sea Ray with less than an inch of clearance. It also required crawling behind the Cat diesels over the top of the sea strainers and steering gear, squeezing between the exhaust verticals and the transom to even touch the accessory end ig the generator.. After 3 tortuous impeller swaps, I went to the Johnson pump.
there was no great way to locate the center on my Westy so I slotted the 3 holes and used a dial indicator to tap it around until it was close. First time in I hit the end of the slots and stoll had .030" total runout (-.015 to +.015). I fired it up and crawled back on there to see how it acted. It was "good enough" but not perfect. I sighed and took it all back apart and lengthened the slots. Thus time I got it inside of .002" (-.001 to +.001). TOTAL GLASS. Zero movement or vibration. Just crap tons of water pumping thru there. If your pump has any visible shake/wobble/etc to it, try to work with it to eliminate that. The pump bearings will thank you.

So that bracket just isn't going to work for me. It doesn't fit over or under that support for the heat exchanger and that clearly seems to be where it needs to be. No big deal. I've got it together with the old bracket.

Now I have a dumber question. I'm fairly certain I know, but I want to verify because the consequences are severe. LOL. Since we are rotating clockwise when looking at the belt side of the motor, the input is on the right as circled in red, correct?

https://cimg9.ibsrv.net/gimg/www.off...6300d3e19d.jpg

duhhhhh :p

Hahha. I know it seems super obvious but I have a habit of getting all the complex things right and overlooking the small stuff. Lol

Hahha. I know it seems super obvious but I have a habit of getting all the complex things right and overlooking the small stuff. Lol

She's done and running. I am satisfied with the almost imperceptible movement of the pump. The tiny amount of movement is only present at the farthest point out and you really have to look to see it at all. The base does not move. I guess that points to runout in the pump itself. I'm calling it a win. It pumps water quite nicely too.

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Anyone notice loss of water pressure or water temps rising. I installed them on my 12 m with NA 565’s. I like the way they plumbed in and easy access but noticed rising temps when I was on the pins. First time out last fall and only couple runs to do a shake down.

The impeller size is much smaller than traditional also.

Mine dropped temperature when getting on them though I wasn't on the pins. Water pressure was 25+ psi at anything above 40 MPH. I'm closed cooled with idle temps right around 170, 150 running hard.

Merc impeller vs crank mount


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The Merc impeller is larger yes but not as many fins. Not sure how that equates to total volume but I know it works for mine.

What rpm are you turning? Most crank mounts max spec is 5k....

6k.

What I noticed on water temp gauge last fall was much above 4k temps jumped up quickly. I’ll find out soon. Although I love the concept just not certain they’re for my builds etc. possibly something else but I’ll find out. 330/365 under 5k likely perfect.

Dry to the tip should be pretty apparent water dumping but not. I believe the dumps at end of tips are 1/2”-5/8”

Hey John,

Just checking in... Did you do get to the bottom of your rising temps? Curious to see how you made out.

I know it's already midsummer here, but I have not been out yet this season to test it out more. Weather, schedules, and a new driveway (with weather delays) have kept the boat on the hard. Next weekend hoping to be out and about.

Just getting back on the water myself likely this weekend. I had called cp tech and questioned him about the crank mount pumps and he said perfect for their application but went in to say with my current builds, hp, rpm and dry exhaust/headers they wouldn’t be adequate. I just got the bravo style pumps on and re-routed plumbing etc (pita).

I did increase exhaust hose size to 1” so it’s not going to be a true comp. I almost left one side the way I had it.

weather here all messed up and lake mi just getting comfortable to run any kind of speeds without needing winter gear on. Lol

I do have two used only an hour of run time at best crank mount pumps for sale. I really like the concept and simplicity of install and impeller replacement of these. That’s for certain.

To be perfectly honest though the one thing I never did was verify my water pick up hoses from boat bottom to sea strainers were 100% clear. Going to disconnect both on each side and stick a garden hose in them to be certain. Boat sat for a few years before last fall.

Abones gave me a heads up on that one! Mud bees etc?? You’d think would’ve cleared out after 10-15 min of running but rather be sure. I have two 2 1/4 inlets per side.

Cool beans.

I was surprised to hear that you were having issues really. I could be wrong but my understanding is that once you’re really moving, water pressure is being provided by the movement of the pickups through the water with the pump helping things along. I know mine was maintaining good water pressure at 68 mph and 4700 but I wasn’t pushing her that hard either. If I started trimming and getting some more rpm, then maybe it would have shown something different. Time will tell. Max rpm for me will be 55-5600.

Hope you get out get to enjoy her!

Mud bees/wasps. They build some really strong nests that can break up into chunks that stay together. They make their tubes from mud, saliva, and sugar - they can be pretty strong. I’d definitely check.

I ended up flushing pick up hoses and turns out stbd side was about 50 % clogged however I believe that was from trip out last fall and over nighted in a mucky area of the lake. Hope to hit the water today if all goes well. 20 plus beers last night and hot and sticky working in the bilge just isn’t a good combo. Lol

Yup. Bringing up an old thread. Good reason too.

My VP damper/pulley (one piece) is rusted to hell. VP doesn't have an ETA when the part will be available again. I have an 8.1L with crank sea water pump for closed cooling via HE.

Questions:

1- Do the 8.1 dampers come with or with out the pulley?
2- Do the dampers already have threads or do they need to be threaded to hold the crank pump?

If I'm thinking of this correctly, I can pick up a new standard damper and pulley from AC Delco and add the the spacer and bushings.

This is what I have below. All one piece. The damper and pulley do not separate. This thing was eating belts. Thanks for the help.

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Looking at RockAuto for harmonic balancer for 8.1, the balancer and pulley is one piece as well with no holes to bolt the crank pump to.

Ive struck out with all the local auto part stores:

NAPA
AutoZone
Advanced Auto
O'Rielys

None have a harmonic balancer that I can bolt on a sea water pump to the crank. None had the 3 holes to bolt on the sea water pump.

Now looking for used or racing type dampers. Anyone have any suggestions?

Find out what the balance the 8.1 uses fornthe balancer in oz. Find one the same balance for a BBC. Mount a flush ribbed pulley and the water pump.

If you can't find the correct balance...get tje closest one and have an engine machine shop add the correct balance to the balancer.

Lots of room for solutions with the $5xx + cost of a new one from Volvo.

Or...get one from an 8.1 auto engine...and have a machine shop drill.and tap the holes. Easy day.

There doesn’t seem to be a market for Gen 7 BBC. All the BBC dampers are for the older versions especially early versions. That in itself has been difficult. Unless ANY BBC dampers will fit the GEN 7 crank.

I would reach out to Raylar. They are the 8.1 experts. They might have, or know a replacement.

The 8.1l Gen VI cranks use the same snout diamter as ll other BBCs.

1.5995-1.6005" tolerance

Balancers are 1.598-1.599"

some aftermarket auto 8.1l balancers spec out the bore at 40.6mm. (1.598")

Nothing special about the 8.1l balancer except likely the external balance offset for the larger crank swing 4.370", and they incorporated the pulley into the casting.

BBC balancers are sold based on their offset balance in ounces.

Lots of pulley manufacturers to sort out your needs. Bolt on your water pump.

Good info!!! Than you. This damper I took off had no keyway. Will putting a damper that has a keyway cutout affect anything?

Volvo Penta doesn’t publish any info on the balance weight. Any suggestions?