AQ125/270 weird plumbing question

[yellosn]

1984 Bayliner 1950 capri, 2.1L/270 drive. I was wanting to flush out my raw water cooling system after saltwater use with a garden hose. Read an old post about attaching hose directly to the rubber coupling that ran from the chrome pipe to the copper pipe. This is what my setup looks like. The hose from the chrome pipe is capped and the copper pipe is fed from a hose which originates from the bottom of the bilge. It attaches to a coupling with a valve. I'm lost-what's going on here? Boat runs great @ 180deg. F all day. Thank you for any help.

Troy

 

[RandyJ]

Re: AQ125/270 weird plumbing question

Wish I could help. I've got the same set up (used in freshwater only)... it runs dead set at 192 degrees all day long... No freshwater tap on mine.

 

[johnmorgan]

Re: AQ125/270 weird plumbing question

one hose is for sure a through hull water intake and the other looks like it comes from the leg. If I am wrong maybe it was raw water cooled then some one tried to fresh water cool it idk kind of hard to tell

 

[yellosn]

Re: AQ125/270 weird plumbing question

Yes-the capped hose comes from the leg. I don't really know the difference between fresh vs. raw water. It's got a closed system and a system which draws water from the lake, etc., and the latter is the one I'm interested in tapping into. Good thing I didn't try running it with muffs if it's picking up water through the hull and not the leg.

 

[wellcraft19]

Re: AQ125/270 weird plumbing question

You are right on.

Someone modified a "standard" set-up (water pickup via the outdrive) to a water intake via a thru-hull fitting with a seacock.
Maybe someone had problems in the past with the pump sucking air from the outdrive, resulting a poor cooling, and could not fix it. Taking water via a thru-hull is the "classic" way of doing it, so to say and eliminates one known problem point on Aquamatic drives.

If you want to flush, you still need to "introduce" water into that copper pipe. I would run the engine and let it suck up water at its own pace (from a bucket), rather than "force feed" it and risk pushing some rubber seals out (it is debated whether that caution is necessary, but that's the way I would do it). There are also single "muffs" you can buy that allows you to feed water to the water intake on the outside of the hull.

 

[bruceb58]

Re: AQ125/270 weird plumbing question

The raw water pump will not suck water out of a bucket. When the boat is sitting in the water, the level of the water is actually higher than the pump so the pump gets primed that way. When you are planing, and the water level is lower, the movement of the boat is forcing water up to the pump.

 

[paperklip]

Re: AQ125/270 weird plumbing question

You could plumb in a T fitting with a shutoff valve to attach a hose to when rinsing.

 

[Mullin]

Re: AQ125/270 weird plumbing question

A t-fitting would be great, but I looked a couple of months ago and could never find one to fit a 1" hose. If you know where to find one, I'd really like to know!

Interesting setup, wellcraft19 described what's going on there well. I haven't seen that modification before but that would solve the hole air-leak issue and should work perfectly fine for the motor. That cap for the outdrive is really ugly, but I guess it works fine.

 

[wellcraft19]

Re: AQ125/270 weird plumbing question

The raw water pump will not suck water out of a bucket. When the boat is sitting in the water, the level of the water is actually higher than the pump so the pump gets primed that way. When you are planing, and the water level is lower, the movement of the boat is forcing water up to the pump.

Not to argue but I have had that very same pump suck water out of a bucket a few times. This when bucket has been next to the engine on the deck, so that pump easily will "hoist" water out up over the edge of a large Home Depot bucket. Like for normal operation, one have to ensure no air leaks, and if using a transparent hose, very easy to follow the water, part from seeing it disappear out of the bucket.
As for the water being "forced" into the pump at plane, we know that is only a theory. Far too many have issues with the water hose connection on the top of outdrive leaking a bit, allowing the pump to suck air, leading to overheating. If (enough) water truly was "forced" up while on plane, that would never be an issue.

 

[paperklip]

Re: AQ125/270 weird plumbing question

A t-fitting would be great, but I looked a couple of months ago and could never find one to fit a 1" hose. If you know where to find one, I'd really like to know!

Both Home Depot and Lowes have 1" poly tee fittings (they are a dark grey color).

As for the water being "forced" into the pump at plane, we know that is only a theory. Far too many have issues with the water hose connection on the top of outdrive leaking a bit, allowing the pump to suck air, leading to overheating. If (enough) water truly was "forced" up while on plane, that would never be an issue.

I'm sure there's a bit of a venturi effect happening with a the air leak problem. I would expect it to suck air in from a leaky gasket no matter what force is pushing the water.

The thru-hull scooper fittings typically have a bow-facing clamshell, so the water is forced in (when running forward).

 

[bruceb58]

Re: AQ125/270 weird plumbing question

Not to argue but I have had that very same pump suck water out of a bucket a few times. This when bucket has been next to the engine on the deck, so that pump easily will "hoist" water out up over the edge of a large Home Depot bucket. Like for normal operation, one have to ensure no air leaks, and if using a transparent hose, very easy to follow the water, part from seeing it disappear out of the bucket.
As for the water being "forced" into the pump at plane, we know that is only a theory. Far too many have issues with the water hose connection on the top of outdrive leaking a bit, allowing the pump to suck air, leading to overheating. If (enough) water truly was "forced" up while on plane, that would never be an issue.

That is a lot different than pumping up from the ground. It only needed to pump a couple of inches of head. If there was just a little water in the pump allowing it to prime, you then had a siphon after that which helped you. The problem is if the water pump is dry when you start as they may not prime.

 

[yellosn]

Re: AQ125/270 weird plumbing question

Thanks for all the info. Clears up some of the mystery. I think I'll bag the driveway flush and just remember to drop it in the lake on the way home next time to flush out the salt. Here's a picture of the intake on the bottom of the hull.

 

[sqbtr]

Re: AQ125/270 weird plumbing question

You could take a toilet plunger and cut the handle to length, install a hose fitting in the plunger part and flush away. I kinow at least one inboard guy that does it that way.

 

[RandyJ]

Re: AQ125/270 weird plumbing question

You could take a toilet plunger and cut the handle to length, install a hose fitting in the plunger part and flush away. I kinow at least one inboard guy that does it that way.

That sounds weird... I'd like to see it...

 

[bruceb58]

Re: AQ125/270 weird plumbing question

You mean to make it look like the one you can buy?

http://www.jetskiofmiami.com/eshopp...uct_347062.ALLOY_FAKE_-_A_-_LAKE_ENGINE_F.htm

 

[Don S]

Re: AQ125/270 weird plumbing question

Here is a trick I used to make a flushing attachment for thru-hull fittings.

Get a standard Mercruiser flusher, part number 44357Q2.
Take it appart except for the hose fitting. Throw the one rubber part away, put the clip on the other end of the wire, put the wire through half the muff and bend a hook in the end of the wire. The hook will catch the strainer and as you tight up the wire, it will hold the muff up against the thru-hull fitting.

Make this

Look like this.

 

[Mullin]

Re: AQ125/270 weird plumbing question

I think I'll bag the driveway flush and just remember to drop it in the lake on the way home next time to flush out the salt.

Or you can just attach the garden hose like you had planned. Pull out the homemade plug to flush the outdrive, then use that hose to attach to the copper pipe to flush the engine, and you can squirt some water through the other hose to flush out the thru-hull pickup. Going to the lake sounds more fun though

 

[bruceb58]

Re: AQ125/270 weird plumbing question

Or put one of these in. You could run a hose to fitting at your transom if you like.

http://www.perko.com/catalog/category/underwater_hardware/product/62/