lightly rusted cylinders - to re-hone or not?

[MTribe]

Hi everyone,

I recently took my block in for boring/honing, thinking it'd be 'hot tanked' and come back sparkling clean. To my surprise, when I picked it up, the same nasty water deposits were in the cooling passages of both the block and head. The machinist said the chemicals to clean that stuff out weren't common anymore (I'm here in CA FWIW).

After getting some great advice here to use muriatic acid to clean them out (worked amazingly well!), I discovered light surface rust in the freshly honed cylinders. I tried to capture it accurately in the pictures. You can't feel any imperfection with your finger, but it's definitely discolored and no longer shiny in places.

So here's the question--is this a big deal? Will it just come off after the first few miles of running, or might this spoil the rebuild?

I need to decided today if I'm going to take the block back in to get it re-honed. Any advice very much appreciated!

Thanks!
Steve

 

[BOXoROCKS]

I use muratic acid often, clean it off with a scotch pad and baking soda,and hot soapy water, real clean.Dry. Then spray fogging oil all over it until you are ready to assemble the engine. You did not hurt anything. Acid never dries. so bury it with oil.

 

[RomanH]

I wouldn't assemble new pistons into a block that looked like that. Before determining if it needed to go back to the machine shop to be re-honed I would try cleaning it. See if the rust can be cleaned off by using a new lint free rag soaked with fresh motor oil.
If it does not come off consult your machinist.

 

[YankeeTR]

You can run a cyl. hone thru it and that rust should clean off in a couple of passes...

 

[TFR]

As the above post suggests run a cylinder hone and lightly clean off the rust. If a hone isn't available just scotch bright and oil the cylinders. Believe me the metal would be hurt by the pad and the rust will be removed.

 

[vettedog72]

Sears (and may others stores) sells a tool that fits into a hand drill. It has 3 rock scapers connected with spring pressure to run up and down the cylinders; just the thing for your problem. Run that tool in ALL the cylinders as they likley have some rust too. The cylinders must be cleaned afterwards until you can run a clean lightly oiled cloth all through the cylinder and not get any discolration. If you can not get the tool and you decide to use the bright pad be sure you use circular motions and not up and down motion. You need to clean the top of the block with the pad too.

As said above after you clean it up get some oil on it so it will not rust again before assembly.

 

[Brosky]

You should never have to re-hone a block that came from a machine shop for the same work. That block (bare cylinders and deck, especially) should have been coated with oil spray or a protector after it was done. They should have asked how soon you would be building it and done this for you.

And I agree with wiping it with a clean, lint free cloth and clean motor oil to remove the rust. Any more than that requires the shop to make it right in my opinion.

But tell them first and let them make the call. I wouldn't touch anything until you notify them and let them decide what to do.

 

[startech47]

After you hone the cylinders, you must use soap and water to remove the metal pieces and the grit from the hone and than immediately oil the cylinders after you dry them. Any solvent will only drive the bad stuff into the pores of the metal and cause early wear of the engine.

 

[PeterK]

Same if you use Scotchpads. Little bits break off as you use them and can really mess up a new engine if they are left inside. Wash and then oil.

 

[RonMacPherson]

MTribe, What Brosky is telling you is true.


First have a little chat with the machine shop, advise them that if that is the quality of work coming out of their shop, they should consider changing vocations.

Then get a bottle brush type hone> I recommend them over the blade type for clean up, the blade types, if not held completely stationary and centered will eat at one side of the cylinder wall more than the other.

The hones are available at any tool truck or tool store.

When you hone use a light oil to lube the hone while you are cleaning up. Should only take a couple of passes to get that rust out.

Then when done, take warm soapy water and scrub the cylinder walls(a toilet brush is usually a good fit). Then wipe down with clean rags, hopefully lint free(baby diapers). Then coat the cylinder walls with a couple of good squirts of oil from a gun where it runs all the way down the wall.

This info is garnered from doing well over a thousand Honda head gasket/exhaust manifold/cylinder ring replacements over a number of years.

 

[AltaKnight]

You can also rent the 3 legged hones that fit into an electric drill at many rental places.

 

[MTribe]

Wow, thank you for all the advice! I can't tell you how much I appreciate it.

First, in defense of the shop, they did coat the cylinders with oil. I believe the muriatic acid fumes ate it away, though, and of course it rapidly rusts at that point. (The fumes also caused flash rust on a vice sitting nearby, and on the cylinder shaft of the engine lift directly above the block.) Of course, I would have *really* appreciated it if the shop advised that I should clean up the block before machining, but really that was in my court.

After getting the first couple replies, I went out and gently scotch brighted a small area in one of the cylinders. It worked very well--but it was creating a smooth spot and some of the rust was still visible, so I decided to stop!

I hence loaded the block back into the car, and will call the machinist tomorrow to ask about options.

Couple questions:

- What type of oil are you guys using on machined surfaces to prevent rust Weight? Brands?

- Just prior to final assembly of the motor, what's the best technique/fluid to ensure all surfaces are absolutely clean in the block, head, etc?... Brake cleaner? Oil?

- You mentioned diapers as lint-free rags. What are you guys using for rags on clean-critical areas? Are diapers really a good option?

Thanks again!

 

[PeterK]

I use Gibbs brand penetrant and/or Boeshield T-9 to protect machined surfaces until assembly.

 

[TFR]

Best way to clean the cylinders is to use WD40 with a clean rag. Cycle the method as many times as it takes to be able to wipe without the rag coming out with black grit.
Race proven...

 

[MTribe]

Larry, on the WD40, sounds great. Do you wipe everything down--cylinder walls, crankshaft journals, head, etc? Kastner's prep manual said something about not using rags on the journal bearings, but not sure how you're supposed to clean them otherwise!

Have you ever used brake cleaner? Seems that'd blast grit away without leaving any residue.