Broken Con Rod Bearing / Moving Crankshaft

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nms-georg
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Broken Con Rod Bearing / Moving Crankshaft

Post by nms-georg »

Morning!
First, happy easter to you all :)

Took a look at my engine.

First problem: con rod bearing broken at the 3rd cylinder. No big deal to change it. But! How do I find out, if it's the original size or already one of the three available oversized once?
Image

Second problem:
I can move my crankshaft (back to front / front to back) about 2-3mm (0.08 inches). I think this is not normal?! Took a look into the oilsump and found this inside:
Image
The small parts are plastik (don't ask me where they are coming from). And the big one is a thrust washer.

Did the crankshaft start to move because the con rod broke? How do I found out why the crankshaft is moving?

Thansk George

tom lad
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Re: Broken Con Rod / Moving Crankshaft

Post by tom lad »

good morning george

the images dont show up , not on my putter anyhow

my first instinct re. excesive end float on the crank shaft is worn thrust washers , if they've come out then thats prob the problem .
Question is i guess how did they pop out ?
to much end float will matter when u press down on the clutch , that pushs on the crankshaft .
Some mornings I wake up grumpy, but most mornings I let her sleep in.

tom lad
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Re: Broken Con Rod / Moving Crankshaft

Post by tom lad »

ow
i THINK , it should say on the outside of the bearing shell ( not wearing side ) the size , std. 10 th under ect. ones i've messed with did anyhow
Some mornings I wake up grumpy, but most mornings I let her sleep in.

nms-georg
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Re: Broken Con Rod / Moving Crankshaft

Post by nms-georg »

Sorry, wrong links. Here we go again:
Image

Image

nms-georg
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Re: Broken Con Rod / Moving Crankshaft

Post by nms-georg »

tom lad wrote:good morning george

the images dont show up , not on my putter anyhow

my first instinct re. excesive end float on the crank shaft is worn thrust washers , if they've come out then thats prob the problem .
Question is i guess how did they pop out ?
to much end float will matter when u press down on the clutch , that pushs on the crankshaft .
Have attached the pic now. If I take a look at the thrust wahser that fall down, it looks like new. So the question is, why did it come out?

What would you suggest: how can I start to check it?

tom lad
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Re: Broken Con Rod / Moving Crankshaft

Post by tom lad »

hi m8

was the other half of the thrust washer fitted on the crank ? do u think the loose one dropped out on a rebuild ??

re. the broken con rod photo , is that the little end out of the piston or the big end on the crank looks well worn either way , i guess the engine stopped suddenly :oops:

the plastic bits , does the dexta engine have valve cap seals ?? i dont know
Some mornings I wake up grumpy, but most mornings I let her sleep in.

nms-georg
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Re: Broken Con Rod / Moving Crankshaft

Post by nms-georg »

Hi!
First, I think I have a wrong title. Not the con rod is broken, just the bearing.

The bearing you see at the photo is the one out of the piton (the small one).

Engine was running till the end quite good, just a bit noisy...

I don't care so much about the bearing at the con rod - this will be easy to fix.

My biggest problem is the movement of my crankshaft. Don't know how to start to search for the fault. Think I have to check later where the thrust washer is coming from and if I can re-fit it again. And then, check again for the movement of the crank...

nms-georg
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Re: Broken Con Rod / Moving Crankshaft

Post by nms-georg »

Hi again!
Have been again under my vehicle to check, where the hell the thrust washer came from. Unfortuneately nothing to see or I'm just to stupid to look at the right place.
As the crankshaft and everything else is still in place it's quite hard to see something.
This guy has been found in the oilsump under the first cylinder - so he must be in place somewhere there.

Can anyone of you pleeeeeeeeeeeeeeeease tell me, between which bearings (main bearings) and con rods this thrust washers are sitting?

Thanks a lot
George

dexta roadless
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Re: Broken Con Rod / Moving Crankshaft

Post by dexta roadless »

i am afraid you have a slight problem. The trust bearing is placed on the rear bearing, and on that there is also the rear sealing bolted both to the cap and to the block. The only way to fix thi is to take split off the engine, remove the clutch and flywheel. then you gain access to the problem. :eyes: :cry:
6o Dexta Roadless
62 Dexta
63 Super Dexta
75 Shilter UT
62 Aebi

nms-georg
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Re: Broken Con Rod Bearing / Moving Crankshaft

Post by nms-georg »

Morning,
think you're right :( Took a look at my parts lists and they're really all next to the third cylinder. Don't know why I found it around the first one...

S***, that sounds like a lot more work :( What I'm wondering is - if its all screwed together there, why did it fall out. And also, when did it fall out. May be I'm drving since weeks or months with it.

Thanks guys so far... Have a good one...

nms-georg
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Re: Broken Con Rod Bearing / Moving Crankshaft

Post by nms-georg »

Hi!
Took today a look At the place where the thrust washers are sitting (inner side to the sump).
I placed them back in but they are not sitting very tight and falling out again. Once fitting them back, how are they hold in place? How do they stay where they need to stay?

Or will them stay there once i place the right ones and the crankshaft is Not moving anymore?

russelm
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Re: Broken Con Rod Bearing / Moving Crankshaft

Post by russelm »

The thrust washers sit in a groove in the block and rear bearing cap as per you can see here:

Image

The pic above also shows how they changed the thrust washer position, the early ones had the tab located at the 2 Oclock position (where the half moon cut out is) but you cant get those bearings anymore. I had to machine mine where the oil return holes are to get the later thrust bearings to fit.
Mark Russell - 1959 Standard Dexta - Work In Progress!

nms-georg
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Re: Broken Con Rod Bearing / Moving Crankshaft

Post by nms-georg »

Thanks for the pic. And what keeps them in the groove - is ist just the crankshaft?

russelm
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Re: Broken Con Rod Bearing / Moving Crankshaft

Post by russelm »

Yes, its a pretty deep groove!
Mark Russell - 1959 Standard Dexta - Work In Progress!

nms-georg
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Re: Broken Con Rod Bearing / Moving Crankshaft

Post by nms-georg »

Morning!
Just a quick update for you. Have finally fitted all back together. But it was a hard job to get the sump back in again - what a heavy piece....
And..... My baby is running again. Very smooth...
Thanks for your help.
George

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