Exhaust manifold cleaning

Hello, I am doing a head gasket repair on my 2004 4Runner V6 (1GRFE).

My problem is, in all of the videos and instructional posts I see, they never discuss cleanliness of the sealing surfaces other than on the heads and in some cases it looks like they don't even clean them at all.

How clean do I need to get my exhaust manifold surface? I had the heads re-surfaced so they are perfectly clean. The exhaust manifolds have some rust and pitting but the areas around the sealing surface (i.e. the edge of the holes) are quite clean after some fine-grit sanding.

Attached are some pics. I'm wondering if they are good to go or should I try to get all of the rust off in the non-sealing areas? These areas are still under the gasket, they are just not in the compressed area of the gasket.

Thanks for any help!

 

Run a wiz wheel on there and your good to go.

 

It is your time make them look really good if you want .

If you were paying would you want another hour of labor or more added to clean exhaust manifolds

 

I have some roloc discs but they’re too coarse for my taste. Is a wiz wheel the one with paddles?

 

Well, if they use an electric tool to do it then I'd say do it but all I have are some roloc discs of varying grit but when I tested I didn't like the scratches they left. I'm wondering if they use those 3M bristle discs which are hard to find and rather expensive.

$21 S SATC 46PCS Sanding Discs 2" Roll Lock Quick Change Discs 1pcs 1/4'' Holder Surface Conditioning Discs Fine Medium Coarse for Die Grinder Surface Strip Grind Polish Burr Finish Rust Paint Removal

https://www.amazon.com/SATC-Sanding...dchild=1&keywords=roloc&qid=1597337178&sr=8-3

I've just been hand sanding like crazy but you can see there are still some raised rust areas that I'm not sure what to do about.

 

Those are the discs I used when I was a Toyota mechanic. The red ones.

 

Use the blue if you like.

 

You would hit the entire area with those discs or just the rusty areas? It seems you would have to hit it all evenly.

 

If it was me... and it has been, I'd use the green or red scotchbrite wheels on cast, either of them will be smooth enough for an exhaust gasket as long as you don't sit in an area too long and make a depression. Could also just hit em with a file too

 

Thanks, this seems to be the consensus. I've just been too paranoid about it and in reality the manifold doesn't need to be as smooth as the block/head deck.

 

Yeah the Toyota and aftermarket exhaust gaskets have a good amount of give, they know you're working with a heat warped, possibly crusty, manifold flange haha

 

Yep. Just hit the entire surface.

 

So like get all of the crusty rust off as well, probably using a file in conjunction with the discs? I just hit it with a red disc and they look fine, still quite smooth but the raised/crusty rust seems to just get polished - probably needs a file.

 

The gasket only makes hard contact around the holes, that's why there was even room for rust around the other areas. If those are clean you're more than good.

 

Awesome, thanks everyone!

LOL my friend (who has only ever installed new manifolds/headers) told me to treat the sealing surface the same way I would a head/block deck. Well, the block is aluminum and the manifolds are cast iron so obviously it can take way more of a beating, should have though more of this. Regardless, I've been super extra paranoid with this head gasket repair, probably unnecessarily so - but in the end we choose how much risk we are willing to take. I think that developing that intuition is what makes a good/efficient mechanic. Anyway, I went from 1000 to 800 to 600 to 400 grit sandpaper, then to the roloc discs, green then red, and finally in the end to just using a file in some spots. Completely unnecessary but I will never let a non-majorly rusted cast iron manifold slow me down again. Lesson learned, time get this sh!t done already!

 

Most of the time unless the rust and dirt build up is really bad seldom are the exhaust manifolds given any thought what so ever.

Use permatex #2 great for exhaust gaskets

 

Wyoming09,

I seem to remember seeing a special gasket for warped manifolds, it might crush a bit too take up hi/low areas of the mating surfaces.

I might need to do this as my old manifolds are just as rusty or more than the gentleman who started this thread.

Don't they go on dry though?