Hi Richard,
There should be a reduced pressure in the return pipe from the radiators to
the water pump, so that sucks water from the stb side carb heater the small
pipe should be connected very near to the pump to maximise the depression)
Coolant flows from the port carb heater which is fed from the exit from No 1
cylinder, which should be hot. The trick is to ensure all the air is
evacuated from the carb heaters and associated pipes and make sure the carb
heaters get as hot as the No 1 cylinder return pipe. Hope that helps.
Best wishes,
William
----- Original Message -----
From: "R Holder" <rholder@avnet.co.uk>
Subject: Re: Europa-List: Water flow
>
> Cliff Shaw wrote:
>
> > The way I figured it out, the water is on its way back
> > when it goes to the little pot with the radiator cap.
> > That is the way I plumed up my "skydrive" carb heaters
> > .
>
> Rob Housman wrote
>
> > The "Operator's Manual for all versions of Rotax 914"
> > page 9-1 of version Dec 01/98 has a diagram (Fig. 4) at
> > the bottom of the page showing that the coolant flows
> > from the water pump UP to the cylinder heads, up to the
> > expansion tank, down to the radiator and back to the
> > pump.
>
>
> Thanks guys - you have confirmed what I thought. Which
> begs the question about the installation instructions for
> the carb heaters.
>
> As instructed the water starts from the water pump, goes
> through the starboard side carb, then through the port
> side carb and then to the header tank.
>
> HOWEVER. I see the starboard side as being the hotter side
> as the airflow is restricted by pipes and also by the oil
> dry sump tank, which itself is very hot. So the starboard
> side has a heat advantage already over the port side. So
> why doesn't the hotter water from the water pump get
> directed to the port side first and THEN to the starboard
> side ?
>
> I mention this as, even with the carb heat kit fitted, I
> am still getting the minor slight hiccups which I was
> getting before the kit was fitted and which I have decided
> (maybe wrongly) is carb icing. Today the outside temp was
> about 12 degrees C and I got the hiccups. I shall do some
> careful tests, recording ambient temps, carb body temp,
> and oil and CH temps in the cruise after settling down to
> see if there is any consistency about it.
>
> The hiccups are quite minor but I hate to hear anything
> which is not a continuous note from the engine.
>
> Richard
>
>
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