Diesel Crank replacement

**smithy010** · 05-08-2006, 05:30 PM

What about that manual brackie?

**smithy010** · 23-08-2006, 03:53 PM

She's up on my home made frame ready for a bit of a pre-surgery scrub-up.
Once my housemate takes his washing off the line, i'll get into it- wouldn't want to get grease all over his gear.

brackie · 23-08-2006, 07:56 PM

I've got one...pm sent

**Golf Loon** · 23-08-2006, 08:44 PM

Nice frame Smithy. Got a bit of Diesel black on there. Show us an "after pic"

**smithy010** · 23-08-2006, 09:08 PM

Actually that's half cleaned- scraped, but just not washed... darn- it would've been more effective if i'd taken proper before pics...

**Golf Loon** · 24-08-2006, 10:13 AM

Originally Posted by smithy010

darn- it would've been more effective if i'd taken proper before pics...

Ha Ha, I always get to excited to take before pics too.

**smithy010** · 26-08-2006, 05:47 PM

Hi all,

I pulled the crank out of my diesel today, and realised something strange. Obviously i locked the pump and camshaft with the flywheel at top dead centre. When i pulled the sump off, i realised that 1 and 4 were at the bottom of their stroke, and 2 and 3 were at the top.... SHouldn't 1 be at TDC when the flywheel is at the tdc mark?

**smithy010** · 27-08-2006, 12:10 AM

Spot the difference between the two cranks....

That's besides the stuffed journals on main no.4 and big-end no.3

The one with red tape (bottom) is out of a 1600 petrol, and the top one is from my 1500 diesel.

The only differences i can find, is the diesel crank has unmachined counterwheights, but the petrol crank is machined all the way up the counterweights, leaving a sharper edge on the counterweights.

**smithy010** · 27-08-2006, 12:18 AM

Just a thought.....

If the pistons are differently sized from the petrol to the diesel engine, would the counterweights be of a different size?....

If the crank is balanced taking into account the piston mass, this would be true, in which case if i put the 1600 crank in the diesel, it would be unbalanced..

Anyone know more?

brackie · 27-08-2006, 06:25 AM

Originally Posted by smithy010

Just a thought.....

If the pistons are differently sized from the petrol to the diesel engine, would the counterweights be of a different size?....

If the crank is balanced taking into account the piston mass, this would be true, in which case if i put the 1600 crank in the diesel, it would be unbalanced..

Anyone know more?

Yes the crank would be balanced in accordance with the weight of the pistons and conrods (diesel and petrol use the same conrods but the pistons have flat crowns and are heavier).

No, I don't believe that the difference in mass would be significant. If you have a diesel and a petrol piston and gudgeon pin assembly out on the bench weigh them and see. Remember that it's common practice to fit flat topped pistons to petrol motors (so increasing mass) and boring out the same and fitting oversize pistons.