Originally Posted by CRABBIT
I notice in Blue Eagle's pictures that the same has occurred in his manifold. In mine the channel from the manifold into the lower part of the thermostat housing is completely blocked and I had thought it was cast that way!
Uh.... I think it might've been too! lol - I drilled the hole in the end of the manifold out when I rebuilt the engine - it was completely closed off on mine too (although it DID have a very manky rubber seal in there) However the tube it connects to in the housing doesn't seem to go anywhere
if this hole isn't open though, there would be no water flow at all with the thermostat shut so I opened it up thinking that the worst that would happen is that I'd create an additional leak risk if it wasn't supposed to be open.
Interestingly, my engine is raw water cooled, and although I am based in Hong Kong where the ambient water temperature gets up to 24 or 25 degrees celsius (centigrade, whatever) in the summer, I never have any problems with overheating - quite the reverse in fact, the engine never seems to get really warm - about 1/3 to 1/2 the way up the green band is the best I can manage.
If I were you, I'd deal with the wire-drawing on the cylinder head (assuming that it hasn't gone too deep, and remembering that the more material you take off the bottom of the cylinder head, the more shims you'll have to put under the cylinder to keep the compression ratio right (and to avoid having the piston smack into the valves at TDC) oops, big parenthesis) first. Then:
1) Check / clean your raw water through-hull inlet opening,
2) Check / clean the raw water filter,
3) Flush the heat exchanger if you have one,
4) Bleed the freshwater cooling loop of all air and top the expansion tank up (again, if you have a heat exchanger)
5) Replace the raw-water impeller,
6) Test / replace the thermostat - it should open at the temperature stamped on its body - about 70 degrees C?
I don't know how you plan on cleaning the waterways on the cylinders out, but when you figure it out, let me know! lol - I didn't bother and the engine seems to run ok.
It's a bit of a pig to start actually, but that's probably down to not having quite the right shimming under the mechanical fuel pump, or under the cylinders (I didn't have a depth-micrometer to hand for the rebuild) or the fact that the high pressure pump needs overhauling since I didn't do that at overhaul either, reasoning that I could save a couple of bob and some time and it wouldn't be difficult to do it later if necessary. As it turned out I probably only did save a couple of bob as the local Bosch agent turned out to be surprisingly cheap - about 90 US to have two injectors overhauled, one new nozzle fitted and two reground (I now have one emergency spare) - versus 250 odd pounds sterling (I seem to recall) from Volvo for a new one - however much it was it was more arms and legs than I could spare at the time!!