Rebuild. Main bearing question

[rcnotes]

Hi all, I'm rebuilding my 2.0 FI for my 78 westy. Getting ready for the Arctic Circle trip.

I have a reground crank .020 under and my the GD case that came with the bus.

The case has not been machined or align bored. As far as I know, it was rebuilt about 65k miles ago with probably 130k on it total. It had low compression on #1 due to a slightly recessed valve that would not stay adjusted, but nothing terrible happened before I tore it down. I had it checked by a vw shop and a local machine ship. The bearing bores are round and it measures ok according to both shops. The thrust surfaces are good.

I have a new Mahle main bearing set. .020 under for the crank, Standard size for the case. New dowel pins, the case is clean and looks good in every other way. (New heads, cam, solid lifters, etc)

The main bearing (full round, not halves) at the flywheel end fits nice into the main bearing saddle, but doesn't snap tight into place. There's no play, it doesn't wobble. It takes a slight push to fit it into place, but it doesn't take a lot of force. Everything I've read says that it should be hard to get it into place and should fit in tightly with a good "snap".

When the case halves are tightend shouldn't (will?) the bearing set tight into place?

Before I begin assembling the crank and fit the main bearing to it, I want to make sure that the case is right and the bearing fits correctly.

Any help on this? I just want to make sure before I proceed at this critical starting point. I have a neighbor with a lot of ecperince on VW's but he's a bit anal

I live in Ann Arbor, MI. is there anyone who might want to stop by and check it out with me?

[germansupplyscott]

#4 main is a snug fit, but it should not be "hard to get in". it is a very slight interference fit. if there is any discernable play the case is bad. from your description your case is good.

[rcnotes]

Thanks Scott! You've always been a great help.

Time to forge ahead, no looking back! (yikes!)

[DurocShark]

Updates yet?

[rcnotes]

Wassup Don? All that snow keeping you inside? there's no an inch here in SE MIchigan. In fact, the early spring bulbs are already poking their heads up. they're in for a rude awakening.

Main bearings fit good. Case is very clean. I dry fitted the crankshaft assembly, following Tom Wilson's book. Gears and bearing on before the rods. The crank is ready to assemble as soon as I plastigage the big end bearings.

The Mahle pistons and cylinders came in a box all together. I installed the rings, but in my haste, one of the pistons hung up in a cylinder ( tight fit) and as I was putting it back into the box, the piston dropped into the cylinder and when it slipped down it went "tink" and broke an oil ring! My stomach flipped flopped. I had my local vw shop order a new set of rings. I'll let them install them and fit inside the cylinder and check the end gap.

I plan to close up the case next week after I get another 5 gallons of kerosene for my salamander to heat my garage.

[bottomend]

You can put that new ring on yourself! I bet the mechanic at the VW shop will have super-duper dirty hands. You gonna let him touch your super-duper clean engine? It's time to "get anal" with your neighbor ( strange clue hidden in that sentence somewhere....) and let some of his 'tude rub off on you. Wait till you start get ready to start that new engine. You'll turn anal in a heartbeat wondering if you remembered everything... or if ' clean' was really ' clean enough".

Do you have a ring separator tool? It makes putting the rings on the pistons easy. practice a few times with an old ring and you'll be an expert in no time at all! Place the gaps at 8 o'clock, noon and 4 o'clock. Bingo! Your done! Becareful not to damage/scratch the ring "lands' in the pistons. Those areas hold the compression inside your engine for you!

The bearing should be fine. you should feel a little bit of resistance, thats all. you can also check by putting the case halves togather and bolting it togather. Stick your hand inside and see if you can spin/wiggle the bearing. I saw Greg from FAT do this on my case one time and pronounce it fit for service.

[rcnotes]

Actually, these guys http://www.donssport.com/index.htm are the best in the Detroit area. And my neighbor put himself through law school working on beetles. Does all his own work on 3 late model Benz's he owns. One's a diesel with 315,000 miles on it. Talk about anal, he's a perfectionist.

Have no fear, those jugs will be spotless

[bottomend]

That looks like a fairly trust-able shop. Just keep stuff clean and dont cut corners. You'll have enough problems doing things right! Limit the risks involved in engine building as much as you can within your control.

[Amskeptic]

The main bearing (full round, not halves) at the flywheel end fits nice into the main bearing saddle, but doesn't snap tight into place.

Not a big deal about the snap-into-place, but the dowel pin should do its best to not allow the #1(that's the flywheel end main bearing) main bearing to rotate in the saddle. You know that your case bolt-up will "crush" the bearing into the saddle, but only the dowel can keep it from rotating. If there is a little tiny bit of play, remove the bearing and add a dollop of red LocTite to the dowel hole in the bearing and even in the case hole if it is not secure in the case.

the piston dropped into the cylinder and when it slipped down it went "tink" and broke an oil ring! My stomach flipped flopped. I had my local vw shop order a new set of rings. I'll let them install them and fit inside the cylinder and check the end gap.

WARNING
Do not use aftermarket rings. Try to get an original one piece oil control ring. Do not replace any of the rings except for the one broken oil control ring. Check your #2 ring lands for any evidence of having been pinched at the time of impact.
Look at your top compression ring. Does it have a little black stripe in the middle? That would be the OEM Mahle molybdenum ring that requires the exact surface finish supplied in the kit. Most aftermarket rings demand a rougher surface finish that your average cylinder hone knocks out. I guarantee you the longest ring life comes from the OEM rings with original cylinder honing.
Colin

[vwlover77]

Most aftermarket rings demand a rougher surface finish that your average cylinder hone knocks out. I guarantee you the longest ring life comes from the OEM rings with original cylinder honing.

So did my engine builder do me another disservice when he replaced the rings and honed the cylinders on my engine? Sounds like they should have been left alone with only 28K on them.

[Amskeptic]

Most aftermarket rings demand a rougher surface finish that your average cylinder hone knocks out. I guarantee you the longest ring life comes from the OEM rings with original cylinder honing.

So did my engine builder do me another disservice when he replaced the rings and honed the cylinders on my engine? Sounds like they should have been left alone with only 28K on them.

That's a judgment call, Don, that I cannot claim to offer any insight on. At 28,000 miles, I would have just kept the pistons safely sitting in the cylinders if I had other engine work to do. But rcnotes has an original Mahle set-up that hasn't been run, and he needs to save it from a possible Great Stupidity.
Colin

[rcnotes]

I'm making sure that the rings are Mahle. They're due in this week an the shop said they'd call before they do anything. I want to be there when they install the rings to make sure and to see how it's done.

[Amskeptic]

I'm making sure that the rings are Mahle. They're due in this week an the shop said they'd call before they do anything. I want to be there when they install the rings to make sure and to see how it's done.

They need to be Mahle moly, as in the tell-tale black stripe embedded in the upper ring and the one-piece oil control rings. These want the fine honing of the cylinders that came in the kit. If you find cast iron rings and three piece oil control rings, cylinder walls will want slightly coarser finish. We, you and I, want the oem rings. Check that #2 ring land for consistent width all the way around the circumference.
Colin