Volvo MD7A Replacement in Sabre 28
I re-powered my Sabre 28 #497 last year replacing the original Volvo MD7A whose water jackets were gunked up with salt causing us to overheat after 20 yrs. and only 1100 hrs.. We're not much for motoring as you can see. Here is my saga.... My marina in Oxford, MD is primarily sailboats with us being about the smallest. They build very high end picnic boats and others and work on all kinds of engines. They were more than qualified to do the job with one exception and that appeared selection of the correct motor. There suggestion was a Yanmar about 19hp which I pointed out to them would be a problem. The MD7A engine had a left hand rotation and consequently a left hand prop. Well after lots of research I found that Volvo is the only builder offering a left hand rotation engine so I thought we were home free. I talked the Westerbeake, Universal and Yanmar in this process. I bought their three cylinder 19hp motor, model no. escapes me right now, and had it installed. I might point out there is a fair amount of surgery required in the boat to fit this engine. Because my marina is not a Volvo dealer a rep. came from one of their dealerships came to do the sea trial. Everything was great and I could even use my old reconditioned Martec prop. Well it goes downhill from here. My wife and I sailed the boat a few times and the engine seemed noisier than I expected with a high pitched whine in forward. Then I noticed one day backing into my slip that the engine was practically silent. You know with your MD7A it is much quieter in forward and whines when backing. Well Volvo in their "infinite wisdom" reversed the direction of the prop rotation in the reverse gear/transmission so I was effectively using reverse to go forward. Well you can imagine how ticked I was having spent about $ 14,000 all in to find this out. And the idiot from Volvo approved the install after the sea trial. The fix was to put a right-hand prop on which I was sure would make the boat pull horrendously to port going forward. Got luck on this part the helm is a neutral going forward as was the old engine. Reverse is something of another story, with the left-hand rotation in reverse and propwash going against the rudder backing to starboard is something to avoid if you can. While I have never known a sailboat to do well in reverse this is worse than usual. Backing to port is considerably better. Another thing I learned during this processes is that some of the older engines had true reverse gears so the simple fix was to just reverse the linkage. Not so anymore, all the mfgs. I talked to have some kind of reduction gear for reverse or what's called a creeping reverse gear. Had I not picked up on this early I would have burned up the reverse gear running it way too fast at 3000 rpms or so. The long and the short of all this is all the current builders I talked with require a right-hand prop and you're stuck I would look for the engine that fits best, requiring the least surgery and subsequent expense. I didn't carefully analyze the fit issue as I thought the Volvo was my only alternative. I will say that we really like our new engine which is a Model MD-2020-DST, with transmission Model MS10A-A, and which I recall has an 8deg down angle to best fit the boat. The impeller is now easily accessible on the front of the engine and filters are not hard to get out. The engine is much smaller, lacks the huge flywheel of the MD7A and there is very little vibration and noise. And that extra horse power is a real plus when you need it Oh one pitfall, you still must pump the oil out via the dipstick, something I had hoped they would change. Hope this helps anyone trying to replace a great old motor. Mine never refused to start in 20 yrs.
