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Flash rust on the head gasket surface


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So I've been carefully prepping my block for the past couple months in order to rebuild my L28ET. The block was hot tanked, rebored .50mm over and the gasket surface was trued. Since then I've been carefully cleaning every passage, wiping down the bores and keeping it coated in WD40. Two days ago I cleaned off the outer surfaces to remove the oil coating so I could paint the block, and taped the machined surfaces to protect them from overspray. The head surface was particularly hard because I left a thin film of oil that made the tape a little challenging to stick. Eventually I succeeded and painted the block and its been drying in my heated garage for the past 24 hours.

 

This morning I removed the tape and found this. I'm furious. No matter how careful I've been, it looks like flash rust STILL found a way to work its way in and piss in my cheerios. I'm hoping I'm not completely screwed and have to get the gasket surface redone at the machine shop. Its bad enough that I have to find a way to clean it all off and then was the block off AGAIN to get rid of any residue. I guess what I'm asking is, is there any better method I can use to clean the surface without messing it up, and dry it so it won't flash again? And, at the same time, how can I remove this stuff without destroyed the gasket surface?

 

So far every time I've pressure washed it, I've immediately coated it in WD40 to disperse the water, blasted it with compressed air to shed the water, then wiped the surface with a cloth and applied another coating of WD40. So far its not working. :huh:

 

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Edited by Oddmanout84
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dampen a cloth with some sort of rust remover, like clr. Or have you elbow greased it with a good clean cloth... you could even take the green scotch brite and lightly hit only the areas that are troubleing you.. others should chime in don't loose sleep all is not lost..... Unless you would send it all to me if it is all lost then it is send it to me lol.... no really though you'll be fine...... I've never surfaced my block, and I know I've had some impuritys and I always seal up nice

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I wouldn't use WD-40... I remember sanding down a BMW hood and coated it with WD-40, a week later it was all surface rusted. WD-40 is actually a degreaser, I think. I remember seeing something like someone was trying to preserve a rear end so they filled with WD-40 and it got pretty messed up.

 

What I did on mine was just get typical motor oil and wipe down everything. At our shop we have a squirt bottle with whatever type of oil, anything from motor oil to Marvel Mystery Oil. Squirt some of that good stuff on a lint free cloth or on your hand and go from there....

 

Sounds kind of dirty. :icon14:

 

I think a Scotch Brite pad would do well, like STP said. It shouldn't be rough/hard enough to scratch the surface.

Edited by josh817
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scotch brite pad lightly on the surface.

In shops techs use a similar pad to clean up the surface. Your really not going to hurt that surface with a scotch brite pad even if you rub it in... As long as you end up with a semi-rough but true surface the gasket will seal just fine. You'll notice that the machine surface isnt polished smooth. That is on purpose. It helps the seal from what Ive been told. You should be able to confirm this with your machine shop.

 

If you get worried about messing up your surface use a straight edge and a feeler gauge to check it.

 

WD40 = "Water Displacement formula # 40"

It works to keep water out for the most part. For shelf life tackier oils work better and can be cleaned off with brake cleaner.

 

I like to use assembly lube or pneumatic tool oil to coat stuff. Its messy and removing it in your case with brake cleaner would most likely result in paint damage.

 

I find it easier to leave the deck coated in oil, cover the bores, and then paint. A new razor blade easily takes the over spray off and the oil prevents it from sticking to the deck surface.

 

Ray

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Thanks for the tips guys!

 

I have worked with scotchbrite before, and was afraid it would be too aggressive and messy for the application, but it worked just fine. You can't really even tell the stains were there anymore, and now the surfaces are coated in Marvel Mystery oil. Smells minty.

 

The surface is so true that I can't fit anything under my straightedge. Not even light.

 

I'll probably end up flushing the oil passage again though just to make sure no bits got in there...

Edited by Oddmanout84
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Lol I had a hunch I was wrong, thanks for correcting Ray.

 

I still had some pretty horrible experiences with trying to store things using WD40. Probably the hot humid summer week in Texas. Never had a problem with lubing everything liberally with regular motor oil and put a trash bag or engine bag over it. I guess any oil will do, just something to keep moisture off.

Edited by josh817
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WD 40 is a WATER DISPLACEMENT COMPOUND and is NOT a preservative oil. It's that simple. Anybody using WD40 as a 'preservative' is guilty of 'not reading the directions'...

 

It will get water off, but it's a light aromatic that evaporates. As water displacement oils should. Do not preserve items with WD40. Use a good motor oil, preservative oil, or for longer storage cosmoline or other wax-based preparation to keep a dry surface from exposure to oxygen or other corossive or active elements.

 

WD40 'does not' attract water. That phrase should be edited out of the prior post. Where does stuff like that come from?

Edited by Tony D
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I use a Moly grease, wheel bearing packing grease. I've stored a motor in a damp hayshed down the back of the farm and it's held up for several years with zero rust on the cleaned & greased surfaces.

 

Just use the grease gun to lay beads all over the surface and rub it over with your hand in a cotton glove to smear it all over. Try to avoid touching the surfaces with your bare hands/skin, your skin oils and sweat are a slightly acid salty secretion.

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Doubtful, lots of thermal mass there. More likely simply exposed sections of particularly oxidation prone metal reacted in the air as it was exposed. Compound it by putting fingers on it with salts from your skin, and some humidity in the air...salt, water, exposed fresh iron....

 

Most people never see high-end engine assembly rooms, but rarely are they using bare hands to touch components. It's not out of fear of getting their hands dirty, but the possibility of putting salts on the surface from sweat and starting a potential corrosion based stress riser on critical components.

 

Most stuff is bathed in oil, lightly for similar reasons. If you do touch it, the oil seals anything there away from oxygen... no oxygen, no corrosion!

 

Hydrogen...lets not even go there!

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It really is amazing how much the littlest thing can contaminate something. Usually I'm pretty good about not touching the surfaces, even if they're covered in protective oil. To be honest though, I think what HowlerMonkey mentioned is probably closer to what happened. The garage WAS heated during most of the drying time, but I unplugged the heaters before I went to bed the second night to preserve electricity. Temperature dropped from about 60 degrees to about mid 30's or low 40's. Though it LOOKED dry when I removed the tape the next morning, water had probably condensed on the surface under the tape. I've since bought better oil for the job along with another 100 count box of nitrile gloves to replace the one that went mysteriously missing a while back...

 

I had always thought about storing my stuff in cosmoline, or some other grease readily available. Are you sure using moly isn't overkill though? I was under the impression that the molybdenum additive was mainly for lubrication.

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I bet the glue on the tape or the tape itself just "wicked off" the WD40 in the places where you pressed it hard. Condensation or not, there is moisture in the air that hunts all things Datsun. I am going to say that an evenly, lightly, rusted surface might give a good "bite" to the head gasket. Of course I am just surmising. But that amount of rust should cause no trouble at all. Even if you left it alone. Of course, you did the right thing. Scotchbrite by hand will hardly touch the surface finish of the super duper Japanese cast iron. BTW..masking surfaces with grease, that you don't want to paint, is good practice.

Edited by cygnusx1
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I bet the glue on the tape or the tape itself just "wicked off" the WD40 in the places where you pressed it hard. Condensation or not, there is moisture in the air that hunts all things Datsun. I am going to say that an evenly, lightly, rusted surface might give a good "bite" to the head gasket. Of course I am just surmising. But that amount of rust should cause no trouble at all. Even if you left it alone. Of course, you did the right thing. Scotchbrite by hand will hardly touch the surface finish of the super duper Japanese cast iron. BTW..masking surfaces with grease, that you don't want to paint, is good practice.

 

 

I have tried masking with grease as my uncle taught, but have had very limited success. Perhaps I've just been using the wrong grease or technique. It always seems to "seep in" and mask the areas that I don't need masked.

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I have tried masking with grease as my uncle taught, but have had very limited success. Perhaps I've just been using the wrong grease or technique. It always seems to "seep in" and mask the areas that I don't need masked.

 

Yeah that can happen, and then cleanup can be messy too. BTW the block looks great. What paint did you use POR15?

 

Here is a great 101 article on gasket sealing, including surface finish.

 

http://www.rlengines..._L_Engines.html

Edited by cygnusx1
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Yeah that can happen, and then cleanup can be messy too. BTW the block looks great. What paint did you use POR15?

 

Here is a great 101 article on gasket sealing, including surface finish.

 

http://www.rlengines..._L_Engines.html

 

Thanks! That was a pretty good read.

 

Actually, its Duplicolor/Rustoleum 500 degree rattle can engine paint (with "ceramic"). I've used it to great success a number of times, as has my uncle on his 944. It seems to hold up on the block surface and valve covers really well, though I wouldn't dare trying it on anything hotter. Finish is durable and shiny as long as the surface is prepped well.

 

My uncle actually uses it on just about everything under the car, including suspension pieces.

Edited by Oddmanout84
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60 to 30 would made a condensation point only if the humidity was favorable. What was the ambient temperature outside when you were at 60 in the shed? The heat of a lamp would cause a lower dewpoint in the shed at 60, but if the dewpoint of the air outside was still 32 outside, you wouldn't condense when you lowered the temperature. Your breath would have some additive effect to the humidity in the shed, but chances are good it's not 'airtight' by any means and that moisture would be 'sucked out' into the outside air as well.

 

I once had a guy complain that I risked condensing moisture from the air by heating a block with a heat gun to well upwards of 170F. My comment was that with an ambient temperature near -40 at the time, there wasn't enough moisture IN THE AIR to condense as it cooled.

 

I was right.

 

My bet lies on the finger salts and other things that got to it. As for "Moly" grease...what you want really is a thick NGLI2 or higher lithium or other metallic based soap grease with a high slumping factor. Something that is persistent and doesn't slough off, a high temperature grease like Wheel Bearing will keep oil from wicking out of the soap base and making everything around it oily and a dust attractant... There are some great clear greases out there like this, Lubriplate 630AA is white and not so thick but gives a clear indication that it's covered something! Vaseline would work, but it's almost body-temperature reduction ( :blink: ) so it will get everything greasy around it, the stuff is just hard to contain to a specific area. It doesn't have to be moly, but I'd say 'wheel bearing grease' of NGLI2 or thicker would work---a high heat application grease will be fairly 'dry' to apply, it will stick well and STAY PUT at room temperatures. I got some red stuff from an old garage sale in a 35# tin that I have been using for years to smear gaasket surfaces and pack gears in... It doesn't have to be 'good grease' it just has to do what you want it to do!

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I just use Moly grease since that's what I get for the the farm workshop and have a good stack of on one of the shelves, a high viscosity agricultural grade moly grease designed for tractors and farm equipment with excellent stick-ability and water resistance properties so it doesn't wash off when fording streams and working the tractors in the rain.

 

The agricultural compound is an excellent storage formula, and I have LOTS of it :D Any high viscosity grease will do the job.

 

Works great on packing up an old rifle I don't plan to use for a few years as well.

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