Volvo Md7a Rebuild or Repower

[Shawn67]

"(it's a bear to get to on the Sabre 28!)."

Believe me I know. The inspection cover the water pump is connected to has to be removed to take off the injector pump. My injector pump died last summer. Because of the leaky water pump the two lower bolts on the inspection cover were badly corroded. I had to drill one of them out. I'm 6'5" so that was an experience I hope not to repeat. Not a fun way to being ownership of my Sabre 28.

Regarding the head, are you lifting straight up or have you tried prying a corner yet? The head gasket might be stuck to the block and head and holding it on. Don't use a huge amount of force but see if you can sort of break that seal.

Good luck,

Shawn

[hpeer]

8 lots on my MD7A, just went through this myself.

No need to remove studs.

Be careful to not drop washers in engine. I'll be reporting on how to remove oil pan shortly!

For me half of my nuts came off () and half the studs came out.

Head came off easy.

Good luck.

[jeffjd]

Bob,

Just a update on my engine.... Someone else owns it now. I discounted the boat big time and now the green demon is someone else's problem.

In hindsight I could have taken the $2,500 I spent on parts and put that toward a beta. My 2 cents is to run the engine with the water (changing oil often) and save for another engine.... Parts are to expensive. Good luck!!!!

To get the head off try using a rubber mallet to loosen the rust in the water jackets. You should be able to put your fingers down the head and lift. If that does not work try removing the head bolts by using two nuts if you can. If that does not work you may be able to use the injector studs as a point to attach something to lift the head.

Best of luck.


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[BobCom]

Thanks for the suggestions. I tried lifting the head straight up using a lever (board with one end resting on the companion way and me lifting the other end) and lines tied beneath nuts I put back on the rocker arm studs but the head never budged. I would guess the mechanical advantage produced a lifting force of over 100 lbs.

I absolutely agree with going the Beta route. Worse part is my wife is already saying "I told you so" when I mentioned your advice! I got a quote earlier for the B14 that seemed pretty reasonable and nearly placed the order but didn't see how I could get it installed to give me much sailing time next summer so decided to see if I could keep the MD7A going for one more season and try to get things set up for an conversion next winter. Boats are packed in so tightly at my yacht club that there is no way to get an engine to the boat before they start moving them around in May.

Thank you all for your help,
Bob

[gjordan]

You might want to try putting the injectors back in, and putting a few of the head nuts back on a few turns and hit the starter. The compression may pop it loose. I have heard of this technique working, but have never tried it myself. It costs nothing to try. Just a thought. ______Grant.

[gjordan]

I just ran across a clear photo of an MD6B head, and it shows 9 nuts. I will look at my own 6B and 7A later today to find out if there is a difference between the two. I had thought that the heads were from the same original casting, but I may be wrong. _______Grant.

[gjordan]

Now I am really confused. I should clear up what I said in my last post. I should have said that it showed 9 boss,s for washers and nuts. I looked at both of my heads today, and they both appear like they are held by 9 studs and nuts, but there are only 8 studs in the block. I am not sure why it is that way. The heads do look like they are the same casting, but I know that the valve guides are different, and the machining to match the larger cylinder diameter must be different. Oh well, just another Volvo mystery. ______Grant.

[h the boat]

Originally Posted by gjordan

You might want to try putting the injectors back in, and putting a few of the head nuts back on a few turns and hit the starter. The compression may pop it loose. I have heard of this technique working, but have never tried it myself. It costs nothing to try. Just a thought. ______Grant.

Yes, that is the best way and normal method used on very many much larger engines. The problem is invariably caused by a previous removal and reassembly, using some form of gasket cement on both sides of the gasket, without applying a light oil or grease to the opposing mating surfaces. If a silicon compound has previously been used, even the above remedy may not shift it. In which case, you have to be drastic. Remove the injectors again and pour about a large soup spoon full of lube oil direct into the cylinders, replace the injectors and Bar the engine over slowly. As the pistons come to the top of the stroke, the trapped lube oil will hydraulicly lift the head. you must bar it over slowly and a considerable force may be required, but it will come apart. H the boat.

[BobCom]

Thanks to you all the head is now sitting on my home work bench. The batteries were removed soon after hauling (after running it with fresh water for 20 minutes, an oil/filter change, and then running two gallons of anti-freeze through it). So I used the hand crank and after the third try (could never get over the compression peak) there was a little poof and then it was relatively easy to hand crank. A little prying at one of the corners and the head lifted and I was able to remove it easily. Given how much effort was involved in removing the gasket from the block I can see why the head didn't want to come off. I had to push a razor blade really hard to force it under the gasket. It really felt like it was glued to the block. Now all I have to do is get everything fixed and put back together again!

If I had know of jeffjd's experience and his advice earlier I think I would have followed it and just done frequent oil changes next season and done a Beta 14 conversion next winter. By the time I got the advice I was so far along with the head removal (every thing removed, all eight nuts off, and several attempts to pull the head) that I figured I was better off getting it off as I might have damaged the gasket in the process.

Regarding the number of studs the web site marinepartseurope.com has diagrams and parts lists for both the MD6A and MD7A showing that the 6 has nine studs while the 7 has 8.

Thanks again to everyone,
Bob

[Don C L]

I know I am way late on this thread but does anyone know the best way to connect with folks who have parts IF a person MIGHT want to TRY to rebuild or repair an MD7a? Or at least keep one running until a Beta 14 is bought? (Thanks jeffjd for all the blow by blow!) I have a friend who just got a Cheoy Lee 30 with and MD7a and I casually said, don't worry they are easy to rebuild. It seems to be running fine but it is an old engine... Now I am finding parts are not as easy to come by as I thought!

[hpeer]

Interesting, my manual shows torque sequence for both engines, and they are different, but not a clue why the 6 needs an extra bolt.

My nuts came off except where the studs came out. Didn't seem to be an issue either way.

Hope this helps.

[BobCom]

Originally Posted by Don C L

I know I am way late on this thread but does anyone know the best way to connect with folks who have parts IF a person MIGHT want to TRY to rebuild or repair an MD7a? Or at least keep one running until a Beta 14 is bought? (Thanks jeffjd for all the blow by blow!) I have a friend who just got a Cheoy Lee 30 with and MD7a and I casually said, don't worry they are easy to rebuild. It seems to be running fine but it is an old engine... Now I am finding parts are not as easy to come by as I thought!

I'm not sure I'm replying to this properly since I'm quite new to cruiserforum but it turns out after a lot of thought I decided to replace my MD7A with a Beta 14 and do have a lot of parts. In particular I have a set of unused gaskets in their original sealed package (all Volvo parts) that I'd be happy to sell for half what I paid if you pay for shipping (they don't weigh much so probably not that expensive). These include a head, exhaust manifold, intake manifold and rocker arm cover gasket. My total cost was $175.84 but I can give you a break down if you're interested in buying only some of them. I also have lots of other parts many of which I think are fine including a thermostat with gasket (replaced a year ago and I cleaned it up while still planing to repair), water pump (rebuilt two year ago. I would be willing to send you anything you want if you pay for shipping since I really don't have any use for the parts at this point. I made my decision to re-power because I want to take some fairly long cruses (Boston to Canada this summer I hope) and want to be very confident about my engine.

[Shawn67]

Don,

I think it is going to depend on the part you need. Some are easy, some are not, some take a bit of luck. Gaskets and such are still available, some things like the water pump are still available from the original manufacturer but others are made from unobtanium now. I ended up purchasing a pulled complete engine for spares.

I'm in the middle of swapping the exhaust manifold from the spare with the one that was in the boat and converting to fresh water cooling. The manifold that was in the boat was completely clogged up and the source of my overheating last summer. I'm a little concerned that due to how badly it was clogged my winterizing may not have been effective though.... if I have damage from that then I'll have lots of spares available.

Shawn

[jeffjd]

For new parts try marine part express.

The issue with keeping the engine going is once you open it up you may need to replace a few parts that cost 1/4 the cost of a beta.

Change the oil and save. When something goes wrong next year or 10 year replace the engine after you spend $500 on Penta parts.






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[gjordan]

Bobcom, Yes, I would like to buy the parts for the MD7. Please PM me(not sure if new members can send a PM) or Email me direct at <gjordan14132@yahoo.com>. It will help in my rebuild. Thank you, _____Grant.