Join Date: Sep 2005
Location: New Westminster, BC
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Re: old engine, new engine
The issue of 'push' is likely prop related, IMO... However if the engine overheats at normal RPM then there's another symptom. At this age the most likely culprit is the mixing elbow (where the cooling water renters the exhaust system) plugging up. (However this usually also limits RPM).This can be removed and cleaned out, or replaced if corroding and becoming thin. Other overheating causes would be a damaged impeller on your water pump (assuming Raw (sea) water cooled?) Is plenty of water spitting out with your exhaust.
You say you can 'hear' the motor is running too fast - I suggest you get a second opinion on that.
Yet another possibility is that the gearbox is not engaging and slipping.. this would account for 'high revs', and lack of stopping/starting push that would not come back to the propellor, but it is a bit counter-intuitive regarding overheating - there would be little load.
In any event if the engine starts reliably and easily the compression is likely fine.. I expect your problems to lie outside the engine itself - ie.. prop, water pump, gearbox, exhaust system.
1984 Fast/Nicholson 345 "FastForward"
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)
Last edited by Faster; 04-03-2016 at 12:47 PM.