Defect in Nikasil Coating

[trond]

I seem to struggle with attaching pictures. Also with deleting posts...

[trond]

[Rebuilding my engine with newly coated cylinders I found this defect in the Nikasil coating. Is it something that need to be redone or not ? I am surprised it made it through QC

[Zuffenwerker]

Hard to say from a picture. Millennium who is a major nikasil plater considers pits normal. If that’s a pit though I’d say it’s too big. Is it a low spot? Will it come off with a scotchbrite?

[Jeff Alton]

That is not a high quality finish. Never seen a pit in a new Mahle cylinder. Intersting that the company that replates them says it is "normal". Normal for their process perhaps...

Cheers

[Dpmulvan]

Pits are not normal in freshly plated cylinders.

[trond]

It is a hole/pit. Nervous about it but the cylinder was plated twice already. First time too coarse. This time it came back with pit. Ra is approx 5 according to the note

Originally Posted by Zuffenwerker

Hard to say from a picture. Millennium who is a major nikasil plater considers pits normal. If that’s a pit though I’d say it’s too big. Is it a low spot? Will it come off with a scotchbrite?

[trond]

better picture

[Dpmulvan]

That’s not usable once the heat and friction happens that will start to fail. Who did your plating? Hard to tell from picture but that cross hatching looks pretty rough did you measure RA or just take their word for it.

[trond]

yes it looks a bit dodgy. US Chrome. I did not measure it

[Henry Schmidt]

Originally Posted by trond

better picture

Everything about that picture is ugly. I would send them back and request an RA factor of 8-10.

[trond]

this cylinder is supposed to be Ra5 (or 0.1 in metric) . Maybe it is the camera.... Also the coating company AND the third party that I got them through claim the defect is acceptable but I don't feel confident about any of it. This is second time I paid for Nikasil coating for these cylinders, plus re-building costs, shipping cost, VAT cost, frustration and months and months of waiting time. They even sand blasted the sealing surfaces and I guess there could be sealing issues both against block and against cylinders ?

[Dpmulvan]

If they’re telling you that defect is acceptable it’s time to call them out. Post their names. That whole area will fail. It’s an adhesion problem caused by contamination.

[trond]

good news; I decided to not trust the roughness measurements and had it checked today. It measured to Ra6 which is as promised more or less. Pictures don't look like a 6 but pictures and lighting exaggerates slightly

[LJ851]

I have installed Many bored and Nikasil plated aluminum Ducati cylinders both air and water cooled. The supplier primarily used was Millennium and I would guess approximately 1 in 20 cylinders would come back with a very small defect in the surface. Similar to what you show in your pictures except tiny, just the size of a pinhole. Those cylinders with the tiny defects never caused a problem for us but I personally would not use a cylinder with the size of defect shown here.

[Jeff Alton]

Why would anyone risk a defect? You paid good money for them to come back proper. If not proper, back they go to get done correctly.....

[colingreene]

I also have had cyls replated and they came back with pits like this.
The vendor assured me they would warrantee it and that it would be no issue in running them.

Did i just take the motor apart for consuming oil and the rings not seating. yes i did.

[Dpmulvan]

Originally Posted by Jeff Alton

Why would anyone risk a defect? You paid good money for them to come back proper. If not proper, back they go to get done correctly.....

I agree what’s it cost these days like $280 per cylinder?

[mepstein]

Originally Posted by colingreene

I also have had cyls replated and they came back with pits like this.
The vendor assured me they would warrantee it and that it would be no issue in running them.

Did i just take the motor apart for consuming oil and the rings not seating. yes i did.

Their warranty probably covers 1% of the cost to rebuild it.

[trond]

something is not right with the aftermarket industry. I was dismissed effectively by EBS after I had to take my engine apart because of the rough surface finish last time. Forget warranty. This time nothing has been concluded but thankfully it appears it is only one out of six cylinders that need to be replaced and I'll just consider myself lucky.

If anyone were to ask me now on advice on getting bigger bore cylinders I would advise to buy new Mahles and not take the chance with bored and plated cylinders at all. The cost of an unnecessary rebuild (2 rebuilds in my case) by far outweighs the cost saving of buying from lowest bidder

[Dpmulvan]

[QUOTE=trond;11891005]something is not right with the aftermarket industry. I was dismissed effectively by EBS after I had to take my engine apart because of the rough surface finish last time. Forget warranty. This time nothing has been concluded but thankfully it appears it is only one out of six cylinders that need to be replaced and I'll just consider myself lucky.

If anyone were to ask me now on advice on getting bigger bore cylinders I would advise to buy new Mahles and not take the chance with bored and plated cylinders at all. The cost of an unnecessary rebuild (2 rebuilds in my case) by far outweighs the cost saving of buying from lowest bidder[/QUOTE

If anyone wants to set up their own nikasil plating I’d be happy to share the process and chemistry.