The Stovebolt Site Forums The Shop Area Engine Shop what's this crankshaft condition?

Now that I'm done with frame work and body prep for the winter, I'm starting to plan my engine rebuild for the winter / spring.

This 235 is has less than 400 original miles on it but had an oil pump failure. So it was taken apart by the original owner, never to be reassembled.

Having NEVER done this, have a ton of questions, but gonna start with the crank.

I cleaned up the parts where the bearings ride.

https://picasaweb.google.com/113636046886857960240/New235#5654613049585722482

Everything looks pretty shiny - and feels smooth enough. I PLAN to bring this to a shop to get the pro advice, but can the "free" experts tell me what you look for?

What I did notice was there pistons 3 & 4 ride, they're not shiny at all... and might be the reason why it needs to be machined right there...

https://picasaweb.google.com/113636046886857960240/New235#5654613133801090770


How do the others look?

https://picasaweb.google.com/113636046886857960240/New235#5654613092201566946

https://picasaweb.google.com/113636046886857960240/New235#5654613114043010626

https://picasaweb.google.com/113636046886857960240/New235#5654613152178067010

( I should note Fred "truckernix" advised me that these need to be machined when he saw them, and I'm not questioning you at all Fred! )

Also - what would one expect to have to pay to get this specific job done?

I just had a 235 crank ground and it was $120, and yes, that crank looks like it needs to be ground. My advice is to disassemble everything and take it all to a reputable machine shop and they can measure all the parts, block, crank, and head and advise you on a path forward.

Well, It looks like the lube failure wiped out the #3 & 4 bearings and the rods will be damaged also as the bearing spun and friction welded rod and bearing shell and shaft together.Notice the sign of overheating on the web between 3 and 4.The crank will be crooked from the heat but this is par for the course when a bearing has run to failure and the crank grinder knows how to straighten it.
The 3 & 4 journals may well have lost enough metal that you can't regrind without welding up.
Probably should look for a better crank.
Good luck

Have you done any measuring on the bearing journals? If it's still standard diameter, those two center rod journals might regrind to .010" undersize, but I'm going to guess they'll need to go .020" under. The main bearing journals will probably clean up at .010" undersize. Have your machinist check it for warp, and straighten it if necessary. Be sure and get all the rods reconditioned so any damage they might have sustained in the meltdown won't mess up the new rebuild.


Be absolutely sure you do a thorough pressure-wash on the block, including taking all the plugs out of the ends of the oil passages and using rifle brushes through every oil gallery. All it takes is one slug of crud in an oil passage finding its way into a new bearing to trash the engine again.
Jerry

It looks as though it was a Powerglide engine.

No I haven't measured - but are they not stamped?

https://picasaweb.google.com/113636046886857960240/New235#5613809205473110530

I believe that's standard right?

Yes, I believe it was - it also had the transmission cooler - how could you tell?

Overheating signs... the color of the web?

I'll let you know what the shop tells me - when I find one.

Yes, you've got a standard-diameter rod bearing there. The part number is a TRW item a 1953-63 rod bearing. The standard shaft diameter is 2.311-2.312 inches. If it's got TRW main bearings, the part numbers should be MB 1721,22,23,and 24. The main journals are four different diameters.
Jerry

While the bearing back is stamped std, once the oil failed to lube the journals all bets are off as to size. Measure the journals for wear to see what they have to be turned to. Just because the bearing says std, doesn't mean the journal is any more.

Mark,
I didn't actually notice 3&4 the day we were loading the parts. For the folks here, it may be interesting to see the shells from those two. Maybe there has been some metal transfer from the shell to the crank.

Fred

Mark, Pictures can hide things sometimes that will look different in actuality but the overheating sign I think I see in pic #28 is found between 3 & 4, where the oil appears burned off the crank counterweight.Also there looks like metal buildup on #3 journal.
Pic #14 shows the affected rod shells very thinned with a fin of displaced metal appearing on 1 half(probably both).
Pic #18 shows the rod/piston assemblys, and I think #3 pictured in the #2 position-no shells in #2 & #3 and the #2 looks rougher like we see in the last stages before the rod leaves the engines.Probably the 2 thinner,rougher shells had climbed atop each other and the knocking was diminished for a little while.
All this is characteristic of a "spun bearing" where the soft metal went away and the steel backing wore until the locking tang and crush couldn't prevent the shells from spinning in the rod-cutting off futhur the oil supply-welding to the crank or rod before the red hot big end gave up and the remains exited the block.
From the localized heat at the rod and crank, they may lose or pickup metal from the process and may have changes in metallurgy affecting hardness and strength.But for sure the things critical to plain (plane) bearing life, fit and finish, is gone.
I hope I read all pictures wrong and the crank is perfect or repairable.

https://picasaweb.google.com/113636046886857960240/New235#5654782661343951922

https://picasaweb.google.com/113636046886857960240/New235#5654782689968153010

https://picasaweb.google.com/113636046886857960240/New235#5654782707042676866

Thanks for your detailed analysis enginenut, I'll be sure to update this thread once I have a shop look at it.

So the heat build up could ultimately warp the crank - this would be my biggest problem correct? And if so, worth the repair or cheaper to replace?

Mark, As we said, straightening, pre-grinding the crank is something they routinely deal with and adds no cost or concern for the user.I was just using the heat indications to evaluate the severity of the failure.
Many times this severe failure results in enough metal displaced to put the crank out of the "regrind only" range.
I didn't look at all the pics initally or I would have seen the 3 last ones of the damaged shells which would have lessened my opinion of the severity.Still severe "spun Bearing" but not as extended as it could be.Jerry is probably in range with .020-.030 undersize needed.But the measuring will give the crank grinder a chance to better predict.There many times are surprises with these failures that the eye can't evaluate because you can't see where the metal was displaced.

You didn't miss them, I only added them this morning when Truckernix suggest I show you guys.

Thanks for all the input, I've asked some local guys for recommendations on shops in the area that do this kind of thing.

On further observation of the discoloration of the crankshaft and the bearing shells, I tend to agree that the crank is close to junk condition. It takes a pretty long time of running in a knocking condition and little to no lubrication to cause that much heat damage. I suspect that the oil passage that lubricates those bearings is probably clogged, starving those two rods for oil. I saw a racing engine ruined in the first 5 minutes of operation after a quick assembly job because one of the crankshaft oil galleries had a mud dauber nest blocking it. The engine parts had been stored in a corner of my friend's shop waiting for assembly, and the mud wasps got to the crankshaft passage. The car owner scattered his engine, and quickly assembled the backup without doing a thorough inspection.
Jerry

Junk because the heat weakens the shaft? Please elaborate to the novice guy.

Running with limited lubrication and high heat long enough to discolor the entire counterweight means that the metallurgy of the shaft could have changed. Cast iron and even forged steel has a tendency to get hard and brittle when it's heated enough to change color after it cools. Stovebolt crankshafts aren't that scarce- - - -yet- - - -so if there's any question about its suitability, I'd try to find one that hasn't been subjected to the stress this one has obviously experienced. A good machinist's hands-on examination is your best bet here. We can make an educated guess based on the pictures, but nothing beats getting the input of someone with the ability to do a hands-on inspection.

Here's an example of one that would be a better choice, even if it needs a regrind:

http://cgi.ebay.com/ebaymotors/1954...arts_Accessories&hash=item3cbb5951eb

Quite often, a "crankshaft kit" with a reground crank and the appropriate bearings are available from machine shops that do crank grinding, and they will take your used shaft as an exchange item.
Jerry

Thanks Jerry - I took a quick look around online, and may have some available to me locally where I don't have to pay the shipping. (Cripes that thing is heavy!)

I'm going to continue to shop, and still bring the existing parts to a shop just the same.

When I was growing up in Toronto, Accurate Crankshaft was the big name. A few years back I used CarQuest shop services to do my head and they did a good job for very reasonable money. I think the pros could give you a good estimate. I would be very surprised if they said it was a scrapper. I think they work on a lot worse.

Many times a crank "kit" for a common engine will be more economical than a local regrind and bearings and I have a hard time getting a finish locally that compares with the kit.I am convinced that smoother finish allows tighter clearances and increased bearing life--in engines doing day to day duty.Now in performance engines, increased clearances give increased oil flow for better cooling but still the smoother the better for a good oil film.
I don't have a vendor yet that can give me a finish like the modern engines from the factory.
I have heard some of the big volume rebuilders have invested in machines that do the "micropolishing" or whatever it is called--but that don't help me none.
Columbus Engine and Crankshaft, in Mississippi, says their shop does it but I havn't used one of theirs yet.

Unfortunately, the machine shop where I worked part time in Nashville had to close its doors for various reasons, mostly related to Nashville politics. Standard Motor Parts specialized in heavy-duty engine machine work, Caterpillar, Cummins, etc. as well as basic automotive machining. They did excellent crankshaft work, regrinding, welding, straightening, polishing, etc. It's quite an art. They had two paid-for buildings located right where the city wanted to build its pro football stadium, and the business never quite recovered from the expense of having to relocate. It took 10 years or so for them to to finally go belly-up after the move, but the owner had to borrow 3 million dollars at age 70 to buy another piece of real estate and make the move. His sons and I worked our butts off to make it a go, but it was a lost cause. I don't know of another good machine shop in the Nashville area, at least not one that works to the standards they did!
Jerry

First I've heard of a "crank kit" - what is that, a DIY type thing?

Around here, most all the automotive parts distributors list "crank kits" for popular/common engines and will include a reconditioned crankshaft of a light regrind, and the high quality bearings to fit.
You are expected to return a regrindable crank as a "core" but I've seen some junk traded in as a core acceptably--depends somewhat on your relationship with the vendor and the rarity of the crank.
I've never received one that was not acceptable by me, and believe me, I do check dimensions and what conditions I can measure with common machinists tools, as well as visual quality(nicks,dents,welds,hammer tracks, etc.I have returned some to my local grinder(s) for correction more than once.
I think a lot of engine reman people with quality machines and processes and buying power are cashing in on their excess capacity by supplying these kits.
But they are limited to the available cores and bearings.They would laugh at me if I went in and asked for crank kits for some of the derelicts and orphans my friends and I resurrect.

Hi Mark

Thanks for the link. Did not realize how bad you crank was. My main concern at this stage is......
Do we know what caused the problem.... besides the obvious lack of oil....?

If this was a total rebuild with only 400 miles.... how come they have STD size bearings..... wasn't the crank turned and polished.... or just washed in gasoline and reassembled...?

Why would anyone run an engine that long.... it must have been making a racket.... which makes me think the rebuilder was not very experienced.... if that is the case what else might have been done wrong...?

I think the bore should be examined and carefully assessed as well.... was it honed or just deglazed with a stone bead mop...

Al boils down to have a pro look and measure it..... crank, block and as anyone looked at the cam/bearings....

Best bet in town I have heard of is an English fella running a machine shop at the back of Car Quest on StarTop road in the East end ..... he is old country and apparently reputable. Sad part is Ottawa being a "goberment" with no or littel induatrial base no longer have a full engine rebuilding shop. I am trying to tap in to the West end with contacts in Arnprior ....rural areas still have a few hidden gems.

Meanwhile I would keep an eye on local papers and Kijiji, etc for possible total complete engines they do come up regularly.

Stay in touch, will help you figure it out.

Bob C.