Volvo MD7A Rebuild

[mark maulden]

I rebuilt my 17 two yrs ago. Got most of my parts from Marine Parts Express in Maine and I did a lot of shopping but I did stick with OEM. My gaskets I got from French Creek Marina in NY at about half the price. Also my fuel delivery tubes had some rusty areas and are obsolete but they had some made up out of brake line. I think the 6/7 are also sleeved engines? Not sure id bore the sleeves out..


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[weephee]

Well, as per my original post, I just purchased the piston rings from Greece for $61 US per piston. My mechanic who does nothing but engine rebuilds in his shop looked and was unable to find any except the ones from Volvo. The ones I purchased were approx 1/2 the cost of the volvo rings so here's hoping they are OK. Also had the head cleaned and checked out. Valves needed grinding but apparently weren't too bad. The engine is in my garage and it's getting cold up here in Canada so the reassembly will have to wait until spring. Once it's together and running, I'll give an update

[Don C L]

Did anyone ever set up an MD7a rebuild group or website for those of us trying to scrounge up parts?

[hpeer]

It's a great idea. I'm don't know how it would be done here. On the Wiki?

[weephee]

It can be done on facebook. There are lots of different marine type sites there. I belong to a yanmar site on facebook that is very good

[Mongo_at_sea]

Hello MD7 A and B owners...
I am trying to rebuild the water pump on my md7b. I have it off with rebuild kit in hand.
I removed the circlip on the engine side, the impeller and wedge shaped impeller compressor on the impeller side. What are the next steps for removing the remaining pieces?
any help appreciated...

[hpeer]

My aged brain tells me there are at least 2 variants of that pump. I think one variant has bearings and the other just a sleeve with babbit material. IIRC the rebuild kit will work for both assuming the bearings/babbit are OK. Been too many beers ago to recall exactly.

I seem to remember wacking it pretty hard with a hammer and a piece of wood to avoid peening over the shaft. It’s a pretty generic Johnson water pump.

Take a peak at this link and see if it looks right.

https://marinehowto.com/rebuilding-a-raw-water-pump/

[Mongo_at_sea]

great response hpeer, thanks. I have the one with bearings. The Marine how to video is spot on...

[hpeer]

Wonderful. Glad to hear it helped.

[Compass790]

Originally Posted by weephee

Well, as per my original post, I just purchased the piston rings from Greece for $61 US per piston. My mechanic who does nothing but engine rebuilds in his shop looked and was unable to find any except the ones from Volvo. The ones I purchased were approx 1/2 the cost of the volvo rings so here's hoping they are OK. Also had the head cleaned and checked out. Valves needed grinding but apparently weren't too bad. The engine is in my garage and it's getting cold up here in Canada so the reassembly will have to wait until spring. Once it's together and running, I'll give an update

I'd be surprised if the piston rings you bought aren't ok.
Not a worry IMO.
I've been using aftermarket piston rings for 6 years now no problem as Yanmar is nearly as expensive as Volvo.

[Lou-In-NJ]

Originally Posted by Compass790

I'd be surprised if the piston rings you bought aren't ok.
Not a worry IMO.
I've been using aftermarket piston rings for 6 years now no problem as Yanmar is nearly as expensive as Volvo.

I don't know if the average shade-tree mechanic takes into account ring-slap, end-gap, bore honing, and piston skirt wear. There is a lot more to making compression reliably for years after a rebuild.
Here's a place that can help with piston skirt wear:
https://www.line2linecoatings.com/video1.html
I spoke to them and they are about $35 U.S. for skirt coating; as long as the rest of the piston is in tolerance, it is probably a good idea, especially if you're honing the bore and replacing rings anyway.