New crankcase?

Hi folks!

So I'm brand new to this forum, and brand new to major engine repair in general, so please be kind. I'm 38 and have worked on my own cars for years. I recently bought a couple of parts Nighthawks and put together a working bike, so I thought the next natural step in progression would be to tackle a major engine project. Boy, I sure got what I was asking for, and now I'm wondering if I'm in over my head.

I purchased a '96 Vmax that had about 32k miles on the motor, and what I was told was a busted con rod. The project quickly became more than I was bargaining for when I realized that I needed to cut the exhaust off (some homebrew hack job), but that's a whole 'nother story.

They were right, totally has a busted con rod, but it looks like it banged up the crankcase quite a bit when it went. The rod is bent in half, piston head is totally smashed up, and it looks like took out the neighboring piston head along with it. It also looks to have banged up the inside of the case a bit too, from what I can tell so far. Oh, and it smashed the oil sensor as well, but I already have another of those on the way. The other two rods and pistons look to be ok at this point.

The ends of the spark plug wires look cooked, and the paint on the heads is flaky, so I think that means it was running hot. I'm guessing that I can have the heads resurfaced and they'll still be good.

So the question I have for you guys, is how much do you think I need to replace on the inside of the case? It looks like I need a new con rod (I have one on the way), and probably two piston heads for sure. But what else do I need to look for/consider here? I guess the big question is, do I need a new crank case? Do I need to take the whole engine apart, or is that unnecessary?

You should be able to see pictures of the inside of the case here:

https://www.facebook.com/photo.php?fbid=10208080951639030&set=pcb.10208080956599154&type=3&theater

Thanks!

tim

I used to rebuild engines with bad bottom ends but don't do that anymore (unless there is a lot of money already in there from a chain drive and or big bore). You're WAY better off getting a replacement engine case set.

I'd sell you a good short block (crank/rods/pistons and block) for $600 plus postage - move over your trans, heads/cams, covers and misc. Save you a shit ton of work and heartache when you have a follow up failure. I've probably got a stack of 50 sets of shit cases sitting out in the scrap pile. I do have bare cases I would sell for less then that (Keep in mind PCW charges $400 for a good bare set of cases). A crank/rods is $400 with good rods, crank and bearings.

Sean

Thanks for the reply, Sean. Help me to not feel like it's just a sales pitch though; tell me a little about why you think keeping the case is a bad idea. It looks to me like the rod banged a couple of scratches into the sidewall of the interior, but so far I can't see anything that makes it look like it has damaged the structural integrity (without having the whole thing apart yet, something I'd prefer to avoid unless I absolutely have to at this point) - tell me what to look for to determine what could fail so I can make a better assessment.

Since having to drop $350 into replacing the exhaust, my supply of funds for this project is running dry and I've only got about $300 in credit left. I need to figure out a way to make that work.

Sadly, you have a 'pig in a poke.' This is going to be a long costly journey for you, there's no way around that, given what you've told us. And while Sean isn't the cheapest, he is gracious enough to assist you with advice, and apparently has the patience of a saint in answering his customers' many questions.

A bad set of cases can quickly ruin your other reciprocating components. If the case bearing thrust surface is damaged, that's another costly repair that might be better put to use in procuring a known set of good cases from someone who should know what a good set is, and what they look like.

Given the extent of your damage described (I didn't check the pics) you should completely tear-down the engine, split the cases, and see just what you have for damage, I suppose you could use Plastigage before splitting the cases to get an idea of main and rod clearances on what you suspect are undamaged areas. But, you had a lot of damage, and the correct way to my way of thinking is to disassemble completley the engine, clean and inspect everything, and then rebuild, w/known new or good used components as required.

About the exhaust, you probably should be able to get a used stock entire exhaust for less than your named price, especially through the forum. It may not have the pristine appearance of a new one, but when the $ are scarce, it's a way to return to the road with a future upgrade in mind.

Since you have the bike engine apart, I suggest you research Sean's heavy-duty oil system upgrades, reasonable insurance that your bike will not have an oil-related failure, which isn't uncommon in these bikes.

Another alternative would be to get a good used engine from one of the members here, not cheap, but it would have you going again soonest. Bottom line, I suspect your budget is unrealistic for where you are now and for where you want to be, given what you have to work-with. I am not a profssional mechanic, I am only a hobbyist. However, there are many others on here who are earning livings as mechanics, machinists, and engineers, and you should listen to their advice. I think you need more $ in your fund to complete repairs. "Begin with the end in mind," and this includes financial considerations.

OK, curiosity got the better of me, I checked the pics, and the correct way is to entirely disassemble the engine, and to wash the components to flush-out all the debris that is floating around in your engine. You got the big chunks, but there's no way you can be sure of having removed the smaller stuff without a teardown. It only takes one metal sliver working its way into a critical clearance area to ruin your rebuild. I didn't see any blued components in what you posted, signs of critical overheating. That crankshaft has to be removed and inspected for damage and clearances, You should just consider starting over w/one of Sean's short block lower ends, and his heavy-duty oil kits. Or, if you think you can source better components elsewhere, have at-it. Be aware that Sean is very patient when servicing his customers' needs including rebuild questions, and you should then have reasonable access to that when you become his customer.

It might sound like a pitch, but it's just a bunch of facts. You could try eBay for the parts you need, but you've got a bad situation. Many of us have bought basket case bikes before. Some get parted out. Some get revived. I would put the rest of your budget into fixing the problem the right way (all the parts Sean listed). You can get it from him or a few other guys ok here who have piles of parts.

Whatever you do, keep us posted. There are always guys helping each other out on here with parts, Pics, and knowledge.

My information was gained the hard way from experience building these engines for my customers and losing money when I had to do it again under warranty. We used to repair and rebuild engines with spun bearing damage and other types of damage you have found and it just simply wasn't worth the risk anymore. You've got less then 50/50 chance of the block not being deformed in such a way as to cause binding and premature bearing failure. It won't be something you can easily measure.

As I said, the risk is your own and if you are lucky then you may be ok to reuse your cases. Check specifically for damage to the thrust surfaces (which do not have a replaceable bearing) and crankshaft endplay. Either way this is not a risk I would take for my customers here.

You don't have to buy anything from me at all. You can find parts on ebay or craigslist though with me you'd have a warranty on the stuff.

Another option you may not want to hear is to part it out. These bikes part out pretty well and take those funds and buy a Vmax that doesn't have any issues.

yhtomit313 said:

Hi folks!

So I'm brand new to this forum, and brand new to major engine repair in general, so please be kind. I'm 38 and have worked on my own cars for years. I recently bought a couple of parts Nighthawks and put together a working bike, so I thought the next natural step in progression would be to tackle a major engine project. Boy, I sure got what I was asking for, and now I'm wondering if I'm in over my head.

I purchased a '96 Vmax that had about 32k miles on the motor, and what I was told was a busted con rod. The project quickly became more than I was bargaining for when I realized that I needed to cut the exhaust off (some homebrew hack job), but that's a whole 'nother story.

They were right, totally has a busted con rod, but it looks like it banged up the crankcase quite a bit when it went. The rod is bent in half, piston head is totally smashed up, and it looks like took out the neighboring piston head along with it. It also looks to have banged up the inside of the case a bit too, from what I can tell so far. Oh, and it smashed the oil sensor as well, but I already have another of those on the way. The other two rods and pistons look to be ok at this point.

The ends of the spark plug wires look cooked, and the paint on the heads is flaky, so I think that means it was running hot. I'm guessing that I can have the heads resurfaced and they'll still be good.

So the question I have for you guys, is how much do you think I need to replace on the inside of the case? It looks like I need a new con rod (I have one on the way), and probably two piston heads for sure. But what else do I need to look for/consider here? I guess the big question is, do I need a new crank case? Do I need to take the whole engine apart, or is that unnecessary?

You should be able to see pictures of the inside of the case here:

https://www.facebook.com/photo.php?fbid=10208080951639030&set=pcb.10208080956599154&type=3&theater

Thanks!

tim

Click to expand...

Take the whole engine apart.

Ok, so I had someone sell me a case with sleeves and bearings intact for $100, just waiting for it to get here.

The heads are off and I've started taking the pistons out. At this point I really need to know what to look for to tell whether the three other piston heads and con rods are still usable - how can I tell if they're junk and need to be replaced? I realize that the best thing is likely to buy a brand new set, but that is beyond my capacity at this point.

I'm pretty sure the crank is bad, it appears as though it was banging the ends of the rods up against the balancer shaft, rounding off the nuts that hold the con rods together. I'm guessing this was the initial problem? Something happened to the crank, which got caught up onto the balancer, shifting the rod which caused the piston head to stick on the inside wall, and the force pulling the rod downward ripped the piston head right off. Does that sound right?

More pictures:

https://www.facebook.com/photo.php?fbid=10208107970314480&set=pcb.10208107974914595&type=3&theater

When they grenade, metal shavings get into everything. Parts need a hot soapy scrubbing drying with air pressure and an oil or protective coating to make them usable. There are some pics of case damage to look for that Sean posted a while ago. On the thrust surfaces I mean.
Steve

yhtomit313 said:

Thanks for the reply, Sean. Help me to not feel like it's just a sales pitch though; tell me a little about why you think keeping the case is a bad idea. It looks to me like the rod banged a couple of scratches into the sidewall of the interior, but so far I can't see anything that makes it look like it has damaged the structural integrity (without having the whole thing apart yet, something I'd prefer to avoid unless I absolutely have to at this point) - tell me what to look for to determine what could fail so I can make a better assessment.

Since having to drop $350 into replacing the exhaust, my supply of funds for this project is running dry and I've only got about $300 in credit left. I need to figure out a way to make that work.

Click to expand...

My free advice from Sean, ratio to parts purchased, is embarrassing. His advice is
genuine and willing. That, you can count on. Many others on this site also have done the same for me. Damon, Dannymax, Mark Milne, Eric and all his shared dyno./tuning experience, and many more I missed, make this site the very best.
Steve-0

I would not use the mating rod. The other 2 rods can be checked for roundness on the big end and excess play on the small (pin) end. See if it wobbles laterally (up or down).

I would inspect the case thoroughly. The problem is rarely in the main bearings so your comment about the bearings being intact don't mean shit. NOW, if it included a crank with the rod bearings also intact then we're getting somewhere. If it ever had a crank that had a spun rod bearing I would seriously reconsider using that case set. Though no damage may be apparent they just don't seem to last when doing a rebuild.

Look at the case thrust surfaces. If you can feel where the crank was riding then it's junk.

Unfortunately it doesn't come with a crank.

Are those pictures of a good or a bad surface?

What causes the crank to go bad like that if it's not a heat issue? As I was working on pulling the case apart last night, I came across a rather large crack in the exterior of the case, same cylinder that went bad. There's some scarring on the top edge of the piston that went bad, as though it was caught up at an angle, making me think that's why it broke, but for me it's just a guess.

I've got about two weeks of free time left and it's making think that parting out and replacing it with a used motor might just be the best way to go at this point, but I'm still interested in learning as much as I can about it.

Your best bet (green)

yhtomit313 said:

Unfortunately it doesn't come with a crank.

Are those pictures of a good or a bad surface?

What causes the crank to go bad like that if it's not a heat issue? As I was working on pulling the case apart last night, I came across a rather large crack in the exterior of the case, same cylinder that went bad. There's some scarring on the top edge of the piston that went bad, as though it was caught up at an angle, making me think that's why it broke, but for me it's just a guess.

I've got about two weeks of free time left and it's making think that parting out and replacing it with a used motor might just be the best way to go at this point, but I'm still interested in learning as much as I can about it.

Click to expand...

Fire-medic said:

Your best bet (green)

Click to expand...

( I Agree ) The only thing I would think about using off of that Eng. would be the heads only after they were gone over completely.

Heads, Cams, and Trans plus other small parts. But, the head with the cylinder that broke might be suspect for valve damage too.

The earlier pictured thrust surfaces were of a good surface. You can just barely make out where the crankshaft has been riding.

More pictures.

First picture is 100% junk. You can see easily where the crank rubbed on the surface.
2nd picture is about the max wear i'd consider using. At the upper left edge you can just see where there is some minor material displacement.
last picture is a good surface.

Did you end up junking the engine? Looks like some parts found their way on ebay? I might be interested in a couple of them (though you may want to hold on to a couple of them just in case you get another engine with good bottom end).

Yeah, I just decided to part it out and use the funds to buy a new motor. I would've liked to do a complete rebuild but was a little shy of the funds to buy parts that I was comfortable with.

Contact Mike - vmax2extreme - he's got a good complete motor for sale - I have seen it in person and it's real clean.

I didn't buy it because I have way too many Vmax/motorcycle parts already.