Volvo Penta MD5a

[JohnBeck]

Hi There, I have recently acquired a Volvo Penta MD5A engine, a really nicely made single cylinder diesel. It had been replaced with a more powerful unit and is in good order. It is a sail drive engine and the the job I have planned for it has a conventional drive with gearbox. Has anyone done this conversion? I would like to be sure it can be done before I spend too much time and effort into getting it back into service. The next thing will be be to look out for a second hand gearbox, I guess that is going to be a quest. Does anyone have any ideas? I might be looking for a unit where the engine is beyond economic repair but the gearbox is still in working order. Thanks for reading this.

 

[Nudge]

Hi JB, Yes I have carried out that very conversion. This was over 20 years ago so memory may not be comprehensive! Best thing to do is get the right gearbox which served that series of small Volvo engines - MD5 & MD7 etc. first. That will allow you to sort out the correct dimensions.

I had bought an MD7 to replace my MD5 so needed to graft the MD7 box onto the MD5 to sell it on. I used a large hunk of steel solid steel plate to make the adaptor. You will need to work out the thickness but it was a standard size as I didn't need to face it off to fit. Might be 50mm? Got a friend to cut it out roughly to the OD with margin using burning gear! Milled the centre out with a rotary table on the milling machine - tidied up the OD on the lathe and drilled in the flanges. Had a powder coating plant at the time so coated it. I believe it is still going to this day!

I also had to make the adaptor for the MD7 to Saildrive and that is also still going!

Hope this helps and good luck.

 

[JohnBeck]

Hello Nudge, Thanks for that - yours is proper work of engineering which I do not have the resources to do I am afraid. I think what I am after is an MS gearbox, perhaps from a boat where the engine is uneconomic to repair but the gearbox is OK. I can't help thinking there must be a one of these little engines tucked away under a tarpaulin some where or at the the back of someone's shed that I can buy for handy money.
The forward engine mounts on mine have two M8 holes tapped in them and from photographs of the gearbox version it has front engine bearers held in place with 4 countersunk cap screws, I am not sure what size. Did yours have that? I can always drill and tap the extra holes
When I got it the crank would only turn about 300 degrees and I thought a valve was sticking but no it turned out to be a bit of carbon on the top of the piston and the head and valves and bore are perfect, amazing. I was thinking about drawing the piston now I have got so far with it but the rest of it is so good I don't think I will bother.
What about spares? Does anyone have any ideas where best to go for them?
Volvo say £150 for a top overhaul gasket set and you you can find them on the internet for £40 hmmm.... Has anyone tried the cheapies? What do you think?