Help Needed - Volvo Engine Part

[tribologist]

After reviewing your files, here's what I think I've figured out and what still has me confused.

First, as I understand it, the MD3B crankshaft has a total of 7 journals. Three of the journals are for the pistons (Big end bearing kits - 3x 875491). While 4 are for the Main Bearings 2x 875483 & 2x 875484. Do I have that correct?
>That is true from what one can see in the documentation and also common sense/best practice.

Second, part of my confusion is that the parts drawing on the Volvo online parts store (see earlier post) makes it look like #8 (875483) is the top half while #9 (875484) is the bottom half of a set. If that was true, then 2 of each would mean I only have 2 main bearing sets. However, when I do a Google image search for these parts, each is shown as a complete top & bottom set. If that’s true, then #8 is a set and #9 is another set and I have 2 of each which means I have my 4 main bearings sets. Do I have that correct?

>If they would have drawn in every single bearing and all the caps you would not see the forest for all the trees. They only draw one instance of each part. This is very common in parts diagram. A jet engine might have 40-60 blades on a disc....

Third, I am confused by the two parts each labeled #10 (897223 - Bearing Front & 807497 - Bearing Cap Rear). Again, the drawing makes it look like one is top and one is bottom and that they are carriers for #8 & #9. Yet again, when I search for images, I find they are shown as a complete top & bottom set. Additionally, the description leads me to think that one goes on the front of the crank while the other goes at the rear. Given that the bearing are what wears out, the bearing caps do not normally need replacing. Do I have that correct?
>Yes, # 10 is the bearing holders. I cant imagine they ever needing replacement, (you cant buy them anyway..) On step 25 in the manual they talk about marking them. Not sure if they are same front and back. The two cylinder engine only use 897223

All that said, I’m still at a loss to identify the bearing-looking part to which #6 is pointing. Yes, I know #6 is labeled as a “Seal Ring” but what is the collar in the picture? Is it a collar or bearing that is placed on the front end of the crankshaft or a bearing that is pressed into bearing sealing cover? I’m wondering how closely this would match the MD3B. The MD2B drawing shows a “Bearing Cover” (#14) whereas the MD3B does not but, it does show a sealing ring (#28).
Any guidance or advice be greatly appreciated.
>Look at picture 70 and 71. You can see the seal and the bearing. If you search google for volvo 3588879 and select "images" you get gazillion radial lip seal images. Its just the illustration that is messed up. This is pre-cad stuff. Done by a illustrator with a pen... Probably a swedish one and we swedes like to confuse....

Here is some other assurance...

https://www.ebay.co.uk/itm/Volvo-Penta- ... 2490273623

https://www.ebay.co.uk/itm/Volvo-Penta- ... :rk:2:pf:1

https://www.ebay.co.uk/itm/Main-bearing ... ctupt=true

ULf

[stxray]

UPDATE: Mystery Solved
Man, it was tough going but with the help of tribologist and my parts supplier (Poseidon Marine Center LTD.) we solved the puzzle. The issue is with the exploded drawings as found on the various online parts suppliers (they all seem to use the same diagrams).

First, the parts listing for the MD3B, Crank & Related Parts shows the main bearings (#8 & #9) each with it's own part numbers. Additionally, the drawing makes it look as if #8 is the top while #9 is the bottom of the set. That is NOT the case. In actuality, each part number is a top/bottom set. The parts listing calls for two #8's and two #9's, that's a total of four main bearing sets.

Second, the drawing creates the same confusion with regards to the Bearing Cap (#10). The drawing shows the two halves, each labeled as #10 but with different part numbers (897223 & 807497) making it look as if 897223 is the top and 807497 is the bottom of one set. In actuality, 897223 is a complete top/bottom set and is the front bearing cap while 807497 is a second top/bottom set and is the rear bearing cap.

Third, when looking at the drawing, item #6, the sealing ring, is depicted more as a bearing than a sealing ring. It appears that Volvo didn't bother to detail this part for the MD3B. However, looking at the MD2B shows a much better detailing as does the same part for the MD17C drawings.

Thanks to all who participate in resolving this.

[tribologist]

Lol!! Glad you sorted it out. Still thinks it sporty to rebuild one of those old engines but others have done it with good results. My boat is on its third engine as it looks from the documents i got with it.

Ulf