Crank mounted seawater pump plumbing - VP DP

[Dillon36]

Good morning,

As many of you may remember I've upgraded my old 350 to a new Votec 383 with a Penta duel prop. All is going well and I'm in the final stages. The last item I'm working on his running the raw water lines to the crank mounted Johnson F5B pump as recommended by someone on here. It looks as though the transom intake tube is 1 1/4 inch, the pump is set up to receive that same size, or i can thread in a barb. The hose connection on the engine and power steering cooler are 3/4.The problem is that those threads on the pump are a British thread pattern. (of course)

I guess my question is should I just find a 3/4 barb with those threads for the pump both inflow & out outflow, or should i keep the 1 1/4 inflow and use a 3/4 outflow?

Hope this makes sense. simple things are the biggest pain.

[builderdude]

Dillan, this will get more input in tech, I’ll move it there with this title:
Crank mounted seawater pump plumbing

[builderdude]

On my oem Mercruiser pump it is a 1.25” in & 1.25” out of the pump then bushes down to 1” between the PS cooler and the heat exchanger.

[Dillon36]

ok, thank you

I just realized that my OEM OMC intake tube is 1" (not 1 1/4 like i thought).

I run my 1" hose from the intake tube down to the new pump and get a 1" barb, from there I'll get a 3/4 barb and run 3/4 hose up to my PS cooler and on to the exhaust. That would work fine i think?

The real pain is that appears that the Johnson F5 pump is a metric thread from what I've read? Can anyone confirm that? Ive sent three emails to their customer service with no reply.

[dktool]

ok, thank you

I just realized that my OEM OMC intake tube is 1" (not 1 1/4 like i thought).

I run my 1" hose from the intake tube down to the new pump and get a 1" barb, from there I'll get a 3/4 barb and run 3/4 hose up to my PS cooler and on to the exhaust. That would work fine i think?

The real pain is that appears that the Johnson F5 pump is a metric thread from what I've read? Can anyone confirm that? Ive sent three emails to their customer service with no reply.

On my F6B (5 should be the same) pump the internal port threads are NPT not BSPT as you're eluding to. Are you SURE they're not NPT ?
My Cobra inner shield is the same as yours, I left the original flow connection which is inlet tube to ps cooler then to the crank pump. I used 1" hose and barbs for both in and out.
Soldered a sleeve over the out on the ps cooler to increase the diameter to 1"

McMaster has both npt and bspt hose barbs if you need them.

[Dillon36]

Here is what i found

Johnson 10-24140-4 Parts List F5B-9, 3/4" BSP (British) Threads, 2/3 Thickness Cam. Complete Pump Can Be Replaced by Johnson 10-24140-5 With NPT Threaded Ports.

Looks like i unknowingly got the bloody British version. WTH...

Adapters ordered and on the way. Geez

[builderdude]

Your getting bronze fittings?

[Dillon36]

Yes sir,

SPX who makes johnson pumps called me and confirmed that i was sent a metric version..

[2850Bounty]

As many of you may remember I've upgraded my old 350 to a new Votec 383 with a Volvo Penta Duo prop.
All is going well and I'm in the final stages. The last item I'm working on his running the raw water lines to the crank mounted Johnson F5B pump as recommended by someone on here. It looks as though the transom intake tube is 1 1/4 inch, the pump is set up to receive that same size, or i can thread in a barb.
Here's the problem.
Those female threads (within the pump body's inlet/outlet) are Straight Pipe Threads...... not TPT (tapered pipe threads).

The hose connection on the engine and power Assist steering cooler are 3/4. The problem is that those threads on the pump are a British thread pattern. (of course)
This will be on the "suction" side.
*** I would replace the oil cooler with one of a larger diameter Inlet/Outlet.

I'm holding a Johnson F5B-9 in my hand right now.
(see image below)
As mentioned, these internal threads are Straight Pipe Threads..... same thread diameter and pitch, but without any taper.

If your pump came equipped with the black inserts, those are to create a "barb" for the suction/supply hoses.
The threads do NOT need to seal because the hose ID covers the entire black plastic part!

I guess my question is should I just find a 3/4 barb with those threads for the pump both inflow & out outflow, or should i keep the 1 1/4 inflow and use a 3/4 outflow?
I would NOT restrict the pump's Inlet or Outlet.

Hope this makes sense. simple things are the biggest pain.

They certainly can be!


I just realized that my OEM OMC intake tube is 1" (not 1 1/4 like i thought).
This confirms that you are using the Volvo Penta DP-S drive.... correct?
With either the AQ series or the DP-S style (unlike with the Merc A drive), the seawater path does not help cool the transmission.
That said...... have you considered going with a Thru-Hull seawater pick-up that will allow the larger hose ID?

I run my 1" hose from the intake tube down to the new pump and get a 1" barb, from there I'll get a 3/4 barb and run 3/4 hose up to my PS cooler and on to the exhaust. That would work fine i think?
(see *** above)

The real pain is that appears that the Johnson F5 pump is a metric thread from what I've read? Can anyone confirm that?
No, these are US straight pipe threads..... not TPT.
Straight Pipe Threads are not intended to seal using the taper.
When used for liquid transfer, they are often O-ring sealed.

I've sent three emails to their customer service with no reply.
I'm curious....... who are you trying to contact?

In this image, I show a 3/4" TPT bronze nipple inserted into the supply port.
It threads in all the way, effortlessly, without any taper interference.

The black plastic fitting creates a barb for additional securing of the suction/supply hoses.

Yes sir, SPX who makes johnson pumps called me and confirmed that i was sent a metric version..

I'm curious as to who is giving this info to you.

Look at my above image again.
That is a 3/4" TPT bronze nipple that has been threaded effortlessly into the supply port without any tapered interference.

There is also no chamfer for an O-ring seal.




A few side notes:

the suction hose must be collapse proof. It doesn't need to be wire re-enforced...... just collapse proof.

if the pump came with the impeller installed, remove it and check to see if the previously folded vanes will rather quickly straighten out.

the F5B-9 uses a very common # 1027 impeller..... keep a NEW spare on board.

lube the impeller with glycerin prior to your first start-up.





Post back and let us know how it went!



......

[builderdude]

Your pic of bronze barb threaded into the pump didnt show up
🤔

[dktool]

Here is my "6" with 1" barbs
There is no concern with downsizing to 1"

[Dillon36]

Thank you Bounty, although your picture didn't post.

I spoke with a Lina and Tim (engineer) from SPX last night to confirm what pump i had. They make a Metric and US version of the FB5 pump and it appears that I somehow received the metric version. They are looking into this today to confirm. Although frustration it's not the end of the world, i have an adapter i can use (pictured). My plan is to go 1" from the tube to the pump intake (suction), 3/4 from the pump (supply) to the power steering cooler as originally designed all with non-collapsible hose for sure. i can adjust and make changes later if needed. I have thought about a thru-hull for this but to be honest, I'm not a big fan of more holes in my boat. We will see how this goes before moving in that direction.

Johnson 10-24140-4 Parts List F5B-9, 3/4" BSP (British) Threads, Johnson 10-24140-5 With NPT Threaded Ports.

I'll locate a strait thread tonight and double check just to make sure as you suggested, but this adapter i have threads in perfectly.


Also, Linda told me that SPX will soon be making available a Minor and Major rebuild kit directly from SPX and provided the chart below. Personally I thought this was already available but i guess not.

[2850Bounty]

Dillon, that is weird....... the photos show up on my end.

I like the adapter idea!

I have a few questions: what type of threads are they, and how do they become sealed..... especially on the suction side?

[Dillon36]

Learning about something I never thought id need to know.

Here you go for your viewing pleasure.


BSP
BSP thread form stands for British Standard Pipe and is common in Australia and the commonwealth countries. It is based on trade size rather than actual diameter which can lead to some confusion when measuring ports.

There are two types of BSP threads;
- BSPP - Female & male thread are both (also known as G)
- BSPT - Female thread is parallel and the male thread is tapered (also know as R/Rp) (the female thread can also be tapered it is then Rc, these are fairly rare to find). Within BSPT it is also common to call the female thread BSPP (parallel) and the male BSPT (tapered) even though they are both technically a BSPT thread form (the female would be parallel and the male would be tapered).

Both threads have the same pitch, angle (55 degrees) and shape (rounded peaks and valleys).


NPT
NPT stands for National Pipe Thread and is an American standard thread. It may also be referred to as MPT , MNPT or NPT (M) for male external threads and FPT, FNPT or NPT(F) for female interal threads. A thread sealant must always be used to achieve a leak free seal (except for NPTF). It is also based on Trade Size rather than actual diameter (similar to BSP in this regard).

Both threads have the same pitch, angle (60 degrees) and shape (flat peaks and valleys).


BSP vs NPT
NPT threads are common in the United States and a few other countries, BSP threads (also know as the R subset according to ISO 7) are widely used in many other countries.

BSPT -British Standard Pipe Taper
BSPP -British Standard Pipe Parallel (G)
NPT -National Pipe Taper
NPS -National Pipe Straight
R - External taper (ISO7)
Rp - Internal Parallel (ISO7/1)
Rc - Internal Taper (ISO 7)
Rs - External Parallel

While the actual specified outside diameters of American National Pipe differ slightly from those of British Standard Pipe, either thread may reliably be cut onto a pipe of its respective trade size. BSPT equivalent is NPT and BSPP’s equivalent is NPS.

Never swap threads if it is a high pressure application.

NPT/NPS and BSP threads are not compatible due to the differences in their thread forms, and not just the fact that most sizes have a different pitch. NPT/NPS threads have a 60° angle and have flattened peaks and valleys (Sellers thread form) where as BSP threads have a 55° angle and have rounded peaks and valleys (Whitworth thread form).


I have a headache now

[Metrodriver]

Complicated Engineering 101

[Dillon36]

Confirmed from the SPX FLOW engineer


Good question! I revisit this drawing about 2-3 times a year for people calling in
The thread is R3/4” which is ¾ BSPT (British Standard Pipe Tapered).




Linda Hall
Western Region Sales Manager
SPX FLOW, Inc.
5885 11^th Street
Rockford, IL 61109

[Dillon36]

OK, one more post for today.

SPX Flow called me back and said that all F5B pumps have this "british" pipe thread but i also know that several of you have installed a barb type fitting without issue. Can someone please share with me what you used. I've looking into this way to deep and made a mountain out of a molehill i think.

I stopped by Home Depot, West Maine, Ace Hardware and even a tractor supply on my way home. Nothing seemed seems to fit right to me. I need to reset.

Thank you

[dktool]

Out of curiosity ask them if all "6" pumps are bloody British too.
I used a npt on mine (post #9) , brass from McMaster.
A wrap of teflon and green loctite. No leaky.

I know the Bronze police are on their way to my house now.

[Dillon36]

I sent them an email asking