fresh warer cooling

[Johnjo]

hi
I have a 1984 12hp petter mini twin unused,which i intend to fit this winter
As this is a mainly alloy engine i do not want salt water near it,I have a heat-exchanger-header tank.which i am fitting as a seperate unit.This model engine has no provision for a thermostat,is it possible to fit one in line between exchanger and engine preferably tight under exchanger to keep it tidy if so what temperature would it need to open at seeing it would be twofeet away from engine? I thought about having a small hole in it to allow for circulation.Which brings me to my next question.a circulating pump,as money is tight ,Is it possible that there is a car engine that is fitted with a indendant pump or will i have to get one modified for the job, At present the engine has a small salt water pump which i presume is big enough to cool the heat exchanger,I know i am going on a bit but i would also like to fit a tempature sensor would i fit it close to the thermostat or engine is there a clamp on type or would i have to drill and tap to fit so many questions,
many thanks Mike ps first post

 

[andyball]

You can certainly buy bolt on temp. sensors -fit on any spare bolt on an outboard to operate a guage where none is fitted as std.

But....if money's tight, get a car one (and the guage) from a breakers & drill & tap away. Some car t.stat housings have the sensor mounted there...so that might solve two problems in one.

Think I might look at flushing it regularly instead, esp. if petter think it's ok for salt water.

 

[pete]

Hi Mike
In August 1999 P B O number 392 Mike Parker wrote an article on this engine including converting it to fresh water cooling, building a pump based on a Ford Fiesta water pump and building a thermostat into the system I did this work to my mini twin and it worked well but I think the engineers drawing of the pump housing was printed in reverse.
As the heads are ally they are very prone to corrosion and very expensive.

good luck
pete

 

[Johnjo]

ANDY
Thanks for help,but engine is going to be fresh water cooled so no flushing needed
mike

 

[mtb]

Re:False economy

Fitting any thing but the pump meant for the job will mean the costs will be more in the long run.
But hillman imp water pumps are seperate and would be easy to bolt on.
Mind you the last time I brought one of these at an autojumble it cost £45.00

Cheers
Mick

http://homepage.ntlworld.com/boats
I want a big steel ex trawler / tug v / cheap or swap for tug

 

[Johnjo]

Mick
Thanks for the info,do you know of abetter pump to circulate hot fresh water that is belt driven and fitted externally,Ihave looked at pump sold by a marinisation company which seems the same as those fitted to a car engine only 2-3 times the price.Ihave looked at factory built cooling systems where the fresh water pump is electric but do notwant to take this route,Iwant to keep it simple,New to this computor larky, does my head in ,so i am going sailing for a couple of days will look at replies when i get back
mike

 

[david_bagshaw]

3 points come to mind

Thermostat

all automotive thermostats have a small hole in themm , often with a jiggle piece in it to keep the hole clear, operating temp 80 deg c is common.


running the engine that hot

If the engine normally is fresh water cooled ie about 52 deg, what will be the inpact on the designed running clearances, and also on the head gasket, as you say the head is alloy.

Sea water pump

be prepared for the pump to need uprating for although the heat input to the water will be nearly the same, the surface area in the tube stack / to engine interior surface will be very different, plus ther will be a sudden surge of heat removal when the thermostat first opens, similarly when shutting the throttle from highpower to idle.


good luck


David
<A target="_blank" HREF=http://www.euroboating.net>http://www.euroboating.net</A>

 

[dickh]

Re - thermostat and fresh water cooling - surely the running temperature should be more like 80ºC not 52ºC for fresh water cooling.
The lower temperature of 52ºC is for SEA water cooled systems - it it were any higher the water passages would clog up very quickly with salt etc.(and corrode faster) - hot salt water is very corrosive.
Perhaps you should talk to Petter direct to get a definitive answer on the water temperature.
Certainly looking at the article mentioned should help with your installation.

dickh
I'd rather be sailing...

 

[david_bagshaw]

sorry about the mix up

quite right, 52 for sea 80 for fresh, good job somebody reads the post!!!





David
<A target="_blank" HREF=http://www.euroboating.net>http://www.euroboating.net</A>

 

[seahorse]

How about?

I used Parkers idea in PBO on my volvo but pumped the fresh water thru domestic radiators!!
Free heat handy in scotland.
Used a commercial breakers ex truck heat exchanger.
If U can do DIY U can save loads of dosh!

 

[Gordonmc]

Re: How about?

Could you fill me in on the location of commercial vehicle breakers in Scotland? There are a few odds and sods I could do with.

Ta.

 

[Johnjo]

Thanks to all for the input,my apologies for not getting back sooner
mike