Volvo MD7A Rebuild

[weephee]

I am in the process of rebuilding my md7a volvo penta. Marine Parts Express sell a ring set for $160 per piston. I looked on ebay and found only one vendor that sells the same ring set for approx half the price.
Piston Ring Set Fit Volvo Penta MD7A 76mm Kolbenring | eBay

Piston Ring Set Fit Volvo Penta MD7A 76mm Kolbenring | eBay

The difference from what I can see is that the oil ring has a coil spring on it. Has anyone used these Caber rings. Any comments are appreciated. Thanks

[gjordan]

Good info to write down for future work. Somewhere on a thread about Volvos there was a mention of the MD7 using the same rings as a Renault engine. I dont think it gave a part number, or model number, but I will have to go searching. Thanks for the info. _______Grant.

[hpeer]

I wonder if we could start a subforum for these old beasts. Seems to be some frequent threads and lots of past interest. Would be nice to have info in a more compact form.

[gjordan]

GREEN DEMONS UNITE! yes we could use some kind of a club or forum to keep the old beasts running. What scares me is the (I think) wrong information I got from one of the most well know Volvo dealers. I looked for the Renault/Volvo ring connection but didnt see anything, but 76mm is a very common piston size so there must be other diesel rings available. ____Grant.

[jeffjd]

I had a shop teacher friend look at my pistons and cylinders when my head was off this weekend. We measured the bore and it was original. He seemed to think that I could get custom rings made for about $200. This means that custom pistons and rods could also be made for probably less than penta $$.

I remember someone saying Nissan rings work.

How are you sourcing the seals and bearing. Please keep us posted on what you find.





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[gjordan]

I disassembled my spare water pump">raw water pump today. It was still attached to the plate that goes on the back of the engine. The bolts were so rusted that I had to hack saw the heads of and then use an edge grinder to do the past bit of removing the bolt heads. The clamps that actually hold the pump to the plate were so rusted that I had to use a hammer and chisel to just break the chunks off. Even then, I had to sandblast around the bolts before anything would let go. My point in telling this is that even if you carry a spare pump, unless you have made sure that you can get the bolts out before you leave on a trip, it would be almost impossible to change out a pump at sea. Raw water pump is on the back of the engine, out of site and often neglected, and in a horrible place to work on. I was surprised when I pulled the impeller , and the shaft came out with it. I am used to splined shafts. The impeller had a rather poor fitting set screw all of the way through the shaft. I dont have my manuals handy, but I am going to check if that is normal. The good news is that the shaft looks fine and the bushing is nice and tight, so I will pull the seal and go to my local auto parts store and get a replacement. I will probably buy several. I will post a part number when I get it. Probably $50 from Volvo, but a few bucks from Napa Auto. I suspect that the whole MD series of Volvo would have similar problems with changing the pump, due to the bad location and neglect._____Just something to look for on your Green Demon. ______Grant.

[jeffjd]

If I recall correctly the Volvo rebuild kit was well over $100. I bought one from Sierra for around $100. Include a shaft and all new seals. The shaft allows the impeller to be removed without the shaft.


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[hpeer]

I bought a whole brand new pump last summer. Can't recall the cost, maybe $250? I also put new seals in an old one and cleaned up the bearings. That's in the boat, the new one is a spare.

In any case they are available and not from volvo, Jabsco maybe or Johnson?


There are a couple of different types. One type does not have bearing, just rides on Babbitt material. That lasted about 30 years I think. But others have ball bearing sets.

The boats PO had a pretty complete rebuild done just before selling her to me. I think I have a detailed receipt listing all materials with costs, maybe part numbers, don't rightly know. If my aged brain allows I'll photo and post if there is any interest. There may or may not be useful info there.

[hpeer]

Maybe, if we can't get a space here, we could start a yahoo group?

[gjordan]

I went thru a box of spares I got with the MD7, and found another water pump. It has the shaft with the notch in both ends, so you can change the impeller without removing the shaft. Maybe it has already had the rebuild kit installed, or the pump I opened up this morning had a machine shop built pump shaft. This mornings pump came off of an MD6B, so maybe they are different. I cant find my manuals, so I am guessing. Both have bushings, not bearings, and seem nice and tight. Posting a rebuild parts list would probably help for many of us. I belong to an aviation group on Yahoo, and find their format much less user friendly than CF. But I am a computer dinosaur, so maybe I am not doing it right. THE CONTINUING SAGA! _____Grant.

[gjordan]

Learned that the MD6 and MD7 raw water pumps are somewhat different. The 6 has regular threaded pipe nipples for in and out. The 7 has pipes that slip in and have a wire clip that keeps the tension on the joints. I think they both pump the same amount, but to have the wrong one as a spare would mean you would have to have a variety of plumbing parts to connect up the cooling . I have heard much complaining about the slip joints on the later 2000 series Volvo, but I have never heard anyone complain about them on the MD7,MD11,MD17. I have never heard any complaint at all about the MD7 other than cost of parts. I wonder why slip joints work on one engine, and not another??? _______Grant.

[hpeer]

I've heard lots of complaints on another board (YBW?) and from my mouth.

The fit relies upon the copper not being deformed. I had a hole in the copper to the transmission and i had to piece it out with hose. The pressure side copper has given other folks fits.

The cylindrical washers are hard to find, it I found something at Loews in the sink spares department that would work. Bought all they had.

[gjordan]

Interesting! I had never heard any complaints, but I can see that the copper pipes would have to be perfect to keep a seal. __________Grant.

[jeffjd]

Weephee

Are you going to do a rebuild or overhaul. I.e. Replace pistons and bearings or replace the items as needed. I am interested in hearing where you find the parts and cost.

I may be in a similar situation and looking to find a decent price on replacement parts. I think boring the cylinder would be the best for my peace of mind... just to make it like new.

I called on custom pistons and got a quote for $130 each, but I need to buy 4.


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[weephee]

In my case, I had low compression. I removed the head and found one valve need to be work. The machine shop is doing a valve job on it now. The cylinder walls look OK but are glazed so I will have them honed and there was one ring on one piston that was seized so I am going to replace the rings. Thats about all I intend to do. The compression before disassembly was about 180 lbs and should be in the 200 plus range. Wrt the rings, I will bring in a piston to the machine shop and they will try and find a match. If not then I'll buy a set from the ebay site I attached in my initial post. I am going to need a new head gasket, valve cover gasket and oil pan gasket. The cheapest place I found is this site and I've ordered them
http://www.powerproductsystems.com/p...?pid=&Pageno=7#
If you don't see what you need, call them. They were most helpful and had what I needed.
I will post when I get more information on the rings. I would hate to spend $150 x 2 for a set of rings.
BTW, I think a separate sub forum would be great and I'd certainly contribute to it will any information I might have.