MD11C Mysterious Pipework????

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thesaintlyone

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Can anyone tell me why the previous owners may have hooked this pipework up to their MD11C in a Westerly Longbow 31 She doesnt draw water through the system and trying to figure out why. The yellow pipe just seem to be vented through the step into the cabin. I have tried disconnecting the lot and just placing a pipe to the thermostat housing. Engine runs well but no water.

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I have just tried to do that by connecting part of the pipe between the thermostat and the pipe where it is connected at the rear but still no water somone mentioned it might be a heat exchanger
 
I agree with pvb

Plumb it as it was originally


  • From the inlet seacock and strainer to the gearbox cooler
  • From the gearbox cooler to the pump suction
  • From the pump discharge to the inverted Tee under the exhaust manifold
  • From the Tee to the bottom connection on the thermostat housing
  • From the top connection on the thermostat housing to the exhaust outlet bend
  • If desired a vented anti-siphon loop can be incorporated in this last section
 
Cooling water enters the engine via the inverted Tee and flow to each head via passages in the manifold ( these may well be blocked causing over heating)

Water leaves via other passages in the manifold leading to the thermostat and then to the exhaust bend when the thermostat opens

A secondary flow runs from the Tee to the bottom of the thermostat housing creating a "bypass" flow to ensure that there is water cooling the exhaust gasses when the thermostat is still closed

The water injection into the exhaust bend may well be blocked. This will totally stop all water flow
 
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Heat exchanger looks likely, however, I have no Idea what one is tho and the yellow pipe was only poking out through the conpanionway step unconnected

So where can I get one and how do they plumb in
 
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Well, this is the thing there is no evidence of Hot water system on board except that it has these additional pipes that may or may not have at some point connected to something in the cabin because that is where the yellow pipe led to a point just above the companionway step. I got the boat 2 years ago and know she had been in the same position from as early as 1996 which is the last log entry.

Could it have been some type of cabin heater fed by that pipe???
 
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No-one here can tell you what the oddball pipe is for, it could be anything. You've already been told what to do, revert to standard piping. Vic has given you the layout, so just buy some new hose and replace all of the decrepit old stuff thst's there now, including a water pump rebuild.

Considering you just did a rewire, the wiring around the engine doesn't look great. What's with the messy battery cable across the engine ? Get rid of the hose and tatty tape, that won't last five minutes, just put the cable across the face of the lifting eye and secure it with a cable tie.
 
thesaintlyone said:
Well, this is the thing there is no evidence of Hot water system on board except that it has these additional pipes that may or may not have at some point connected to something in the cabin because that is where the yellow pipe led to a point just above the companionway step. I got the boat 2 years ago and know she had been in the same position from as early as 1996 which is the last log entry.

Could it have been some type of cabin heater fed by that pipe???
Click to expand...

If there is no tank/ calorifier, plumbing or taps for a HW system, or cabin heater, forget about it until you want to add a hot water system. Just re-plumb the engine cooling system as was originally intended.

Note that originally the pipes around the engine were rigid metal pipes. If they are missing then you will have to connect it all up with suitable hose unless you want to make up new metal pipework.
 
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PaulRainbow said:
No-one here can tell you what the oddball pipe is for, it could be anything. You've already been told what to do, revert to standard piping. Vic has given you the layout, so just buy some new hose and replace all of the decrepit old stuff thst's there now, including a water pump rebuild.

Considering you just did a rewire, the wiring around the engine doesn't look great. What's with the messy battery cable across the engine ? Get rid of the hose and tatty tape, that won't last five minutes, just put the cable across the face of the lifting eye and secure it with a cable tie.
Click to expand...

I did have a cable tie on that hose through the lifting eye but it restricts the Manual crank Handle operation
 
I notice that the presence of the extra pipework does not allow the fitting of the air inlet filters. You will need ear muffs when the engine is running :-)
 
Bilgediver said:
I notice that the presence of the extra pipework does not allow the fitting of the air inlet filters. You will need ear muffs when the engine is running :-)
Click to expand...

The hoses looped round the front of the engine and over the top of the engine will be replaced by one direct connection ( or perhaps via a vented antisiphon loop) from the thermostat housing to the exhaust outlet bend when it is all re-plumbed so there will be no restriction on refitting the air intake filters/ silencers. ( one has the crankcase ventilation connected to it anyway)

I reckon those two hoses and the Y piece connecting them could be some misguided attempt to install/improvise an anti siphon vent
 
Is it possible that the black hose and junction were assembled as an anti Syphon device and the antisyphon valve now sitting beside the heads was supported above the engine where the orientation would be correct and the yellow pipe was from the anti syphon valve. There would have been better places to put this than above the saloon step!
 
Bilgediver said:
Is it possible that the black hose and junction were assembled as an anti Syphon device and the antisyphon valve now sitting beside the heads was supported above the engine where the orientation would be correct and the yellow pipe was from the anti syphon valve. There would have been better places to put this than above the saloon step!
Click to expand...

You are thinking along the same lines that I am. In fact looking at the picture more closely I'd think it very likely that the Y piece is in fact an antisiphon vent.
Its not necessary on a MD11C in a Longbow. The Berwick I used to sail did not have one.
If I fitted one, or refitted the existing, I would led the vent out to one of the cockpit drains, which are conveniently at the front of the cockpit, and make it one that pees.
 
Yes it looks like one and even has the mounting holes but is lying on its side. In the current set up the best fruit bowl would need to be put below the yellow pipe to catch the drips. :-);-):-)
 
My best assessment of the pipework is as follows. The "Y" piece is an anti-siphon device and should be fixed to a surface above the engine with the smaller diameter pipe uppermost. I have seen similar set ups where the small diameter pipe is used as a tell tale, the drips from it showing that water is flowing through the cooling system when the engine is running. I have also seen situations where such a pipe is lead to the vent on a DSS.

It's nothing to do with a FW heat exchanger.

+1 for taking care that the manifold is not silted/rusted up. The one on my old MD1b crumbled to dust as soon as I tried to remove it.
 
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