Nikasil block

[Matt80]

Hi, I recently saw a Nikasil plated steel alloy block that had the cylinder deck awfully looking.
I was told the deck it was ok and it just got that looking for the plating
Is that normal?

[bentvalves]

those marks are from a rotary abrasive tool of some sort, used to "prep" the deck for HG replacement.

they prepped it alright... for a trip to the resurfacing machine!

edit: looking closely I am seeing no circular marks as would be left from a rotary tool, but it looks very similar in nature. almost looks like a belt sander was used on it to be honest.

[exhaustgases]

Looks like someone just sanded that area with something unsupported, like hand held emery paper or?

[Roundybout]

In those pictures the cylinders have been Nikasil plated and the deck looks like that after Nikasil treatment but before any cutting of the deck, correct? If that’s the finished product (decking included) that’s just plain wrong. A MLS gasket is not going to like that finish. If it’s ready for decking I’d be suspect on what procedures they used to clean the deck. That looks like someone with a chisel worked on that. I work on a lot of Nikasil coated Kohler tractor engines and the only think touched is the bores. I’ve never seen anything like that after treatment.

[peejay]

Looks like when someone hits a deck with sandpaper or a "cookie" because they don't like the look of the stains in the metal from where the old gasket was or wasn't.

It can be ugly as long as it is smooth and flat... and that deck is now neither!

[MotionMachine]

If the nikasil goes all the up to the deck, it probably should not be surfaced or the nickel will chip off. Maybe that's why it got cookie dusted.

[Matt80]

He just told me that the block deck is perfectly flat, but he isn't able to understand if it needs any machining on it.
If yes, is the Nikasil really going to chip off??

[MotionMachine]

I do some blocks using iron Mahle nikasil sleeves. They warn to do no machining after installation for this reason.

[Matt80]

I do some blocks using iron Mahle nikasil sleeves. They warn to do no machining after installation for this reason.

Sorry, are you referring to machining the block deck? Have you any email address to directly contact them about this? Thanks

[MotionMachine]

Yes, they say to not deck the top of the sleeve because the nickel goes all the way up and it might fracture if machined. I hone them of course but no decking. This was through engineers I do work for and their contact at Mahle Germany so I do not have any direct contact info for them.

[midnightbluS10]

Looks like when someone hits a deck with sandpaper or a "cookie" because they don't like the look of the stains in the metal from where the old gasket was or wasn't.

It can be ugly as long as it is smooth and flat... and that deck is now neither!

What are cookies? Those little Scotch Brite Roloc pads that go on angle grinders?

[ptuomov]

When the whole block goes to Nikasil/nicom plating, I think they mask the deck and it’s not plated. I think there’s a small chamfer still the top of the cylinder bore, and the plating ends somewhere there. At least for our blocks.

[englertracing]

Ive personally chipped a nikasil coated cylinder for a honda 450 single with a 3/4" carbide end mill taking 0.005" off the deck to tighten up the quench. Knocked a 0.020" x 0.020" or maybe less off. Was well short of the top ring. I ran it anyway with no issue.

[BillK]

What are cookies? Those little Scotch Brite Roloc pads that go on angle grinders?

https://www.enginerepairshop.com/abrasive-disc.html