Thread: 3.0 TDV6 broken crankshaft / engine rebuild

Originally Posted by Jeffoir

Heh Fab,
that’a a bummer.
however, you have demonstrated immense patience and superb judgement to get this Far. A solution will be available, it might just take some hunting down.
i wish you every success and will ask a metallurgist that I know, what he thinks?
Keep on swinging Champ!

he said try the Australian Welding Institute in Adelaide. They have a Technical Advice line at that phone number. Best wishes. Jeff

Shame. Welding cast iron is not easy but can be done, low preheat and very very slow cooling. The issue is the heat input converts the CGI to white iron, making it very hard in relation to the parent metal.

Mechanically bracing it could be done, but then the issue is where to drill and fit the anchor studs.

I'm thinking if you can face mill that part down, you can then get a filler plate machined up to bolt in, if (say3-4mm high grade steel / stainless, this may be stiff enough.

Hello everyone and thank you very much for all your tips and hints. After thinking about the pros and cons, I decided to use a retaining plate to hold the idler pulley. I have already started dimensioning and today I will make a prototype version of an easy-to-work material.

The staining in the crack suggests an old crack but was a crack-revealing product used to make the crack more visible and therefore it could be a recent crack?

Originally Posted by Fabsky

Hello everyone and thank you very much for all your tips and hints. After thinking about the pros and cons, I decided to use a retaining plate to hold the idler pulley. I have already started dimensioning and today I will make a prototype version of an easy-to-work material.

Don't weld it, plug it.

In another life 40 yrs odd ago I rebuilt many high performance and standard "cooking" engines and often found cylinder head & block cracks which were too difficult to weld due to access or some other reason. Both cast iron as in Lotus Cortina (Ford engine) and many alloy Jaguar heads.

I had a local cylinder head expert plug the cracks with a series of interlinking plugs, sometimes as many as 8 or 12 and which were roughly 3mm in diameter from memory.

The repairs were very successful and considering the expansion rate of a cast iron cylinder block compared to a CI or alloy cylinder head I doubt you'd have a problem.

Suggest you take it to a cyl head reconditioning expert to discuss.

Good luck with it, I am very much enjoying your posts!

As I mentioned earlier, I dimensioned the detail on the engine and drew a draft in Sketchup. I printed and transferred to 8mm MDF and precisely cut and milled.

IMG-1798.jpg IMG-1799.jpg IMG-1802.jpg IMG-1803.jpg

I will install the heads, camshafts and drive wheels to the end and check the belt guidance / alignment.


I will make final corrections to Sketchup and commission CNC machining from quality steel.
..I hope my imagination won't lead me into the forest..

The lower idler appears to be closer to the block than your top idler due to being mounted on the plate, so why wouldn't the belt foul on the plate?

Do you really think that there would be enough strength in the recessed part of the plate considering that the cast block of much greater thickness fractured? I suspect that the bolt would distort or break out the thinner part of the plate as the fracture progressed.

Providing a diagonal brace from under the head of a longer substitute bolt and spacer to the bolt hole directly below it would prevent the bolt from being able to twist the fractured area.

Originally Posted by Discodicky

Don't weld it, plug it.

In another life 40 yrs odd ago I rebuilt many high performance and standard "cooking" engines and often found cylinder head & block cracks which were too difficult to weld due to access or some other reason. Both cast iron as in Lotus Cortina (Ford engine) and many alloy Jaguar heads.

I had a local cylinder head expert plug the cracks with a series of interlinking plugs, sometimes as many as 8 or 12 and which were roughly 3mm in diameter from memory.

The repairs were very successful and considering the expansion rate of a cast iron cylinder block compared to a CI or alloy cylinder head I doubt you'd have a problem.

Suggest you take it to a cyl head reconditioning expert to discuss.

Good luck with it, I am very much enjoying your posts!

I agree the technique you describe is called metal stitching and there are two or three ways of doing it....Block Repair using Metal Stitching (secondchancegarage.com)

Repairs Without Welding: Cold Metal Stitching - Workshop Welding

Metal stitching - Wikipedia