Cleaning exhaust manifold for gasket

[Cujet]

Needs to be machined flat

 

[JHZR2]

Needs to be machined flat

Yeah that’s my fear seeing that daylight. Even if a thick graphite gasket would close it, I’m not sure it’s the best bet. Now I guess I have to check the turbocharger too…

I just don’t know what machine shops around do this kind of work (most that I’ve searched and found are precision specialty stuff or tool and die. Not many that are explicitly automotive machine shops. I can’t imagine it’s that hard of work though.

 

[dvblanch]

Know anyone with a large stationary belt sander? Not anywhere near as critical as a cylinder head or deck surface.

 

[JHZR2]

Know anyone with a large stationary belt sander? Not anywhere near as critical as a cylinder head or deck surface.

Nope.

 

[toxic]

Back in 2019 I replaced head gaskets in my 2011 lml duramax, I used the green 3m disks on a die grinder to clean the block and head surfaces. Block is cast iron and heads are aluminum. Heads were just cleaned on the bottom surface and visually inspected. I put them right back on with new mahle gaskets and never had another issue until the crank broke in 2023. At that point the block and heads went to a machine shop. Block didnt need any deck surfacing and heads needed like .002 to be perfect again.

 

[spasm3]

Time, money, not having one I know and trust…

Otherwise no. I’ve never done this before.

I actuallly do think it will be necessary. Look at the turbo flange:

View attachment 311716

When I put my straight edge there I see light. Feeler gauge says it’s 0.009”

View attachment 311718View attachment 311719

No way would i put that together with out resurfacing. Especially seeing the straight edge gaps and the pitting.

 

[wtd]

I have always used Scotch-Brite (3M) white bristle discs to remove excess gasket material and to prep the surface, clean with brake clean after. They do offer yellow and green discs, but those are a bit aggressive on aluminum. I use it on my 90 degree grinder at a low speed with minimal pressure applied. They last a really long time if used properly, maybe 2 years in daily use. Higher speed and more pressure just wears it out faster without any advantage to removal speed or surface prep. Do not get off brand ones, they wear out really fast and the bristles tend to break off easily.

I've even used them to prep the head and block surfaces (without sending anything to a machine shop) when doing lifters and cam replacement on LS engines, not a single head gasket failure yet.

https://www.amazon.com/Roloc-Bristle-Disc-Grade-Size/dp/B06WVJ4166/ref=sr_1_11?crid=1MFPBDIKWJA1K&dib=eyJ2IjoiMSJ9.rOTEsJKzs7qqz8u4WAbs-CchToydqD4V9rAGZQuepLNkxsqdOPcG68oOnLlE_g1S7iGa_DoMt22Wvy_id5pLygVg7FcgpvRAmuLGJ74FxlRkfoZyFprb1FgCP5aOqsAnm-BhXGUC2BPQJt0ngox_4czcfu1CV19xISEM1g9sRoj43jDsbxU8Ki-6FSZH6OWsrDtDWxmXnHlNCvI29Gqn0tIOBzeFNKw05Hr-z75edLU.W9765VPehSFeNGE2QGWmFn54jWctVLHNfDrMb23kXB0&dib_tag=se&keywords=roloc+bristle+disc&qid=1763205462&sprefix=ROLOC+BRISTLE+,aps,365&sr=8-11

These are what I use too.

 

[JHZR2]

No way would i put that together with out resurfacing. Especially seeing the straight edge gaps and the pitting.

Yes I agree. Wasn’t as convinced until I saw the gap on the turbo side…

 

[TacoFergie]

I’m not sure I’d be asking the same question, and probably try much more by hand if it was an area that touched oiled areas. While I see no sign of abrasive dust with the bristle disc, even tearing apart a scotchbrite pad results in dust that I wouldn’t want inside the engine. Production conditions may be a bit different, but I thought that was a nono. Maybe if parts are removed and can be washed after that’s different?

I understand the concern. But the amount of abrasive dust or other material that may end up in the oil isn't much. I think I've gone through 2, maybe 3 white discs in the last 15-ish years. So the amount of abrasive that may come off during a job is hardly measurable. Large chunks of sealant, of coursepick that off before getting after it. But even on timing covers where the oil pan remains on or the valley of an LS that the blocks was cleaned with those discs, I've never seen an issue. Though an oil change has always been done after heavy maintenance like that is done as well. Out of the hundreds of vehicles I have used those discs on, none have had an engine failure to the best of my knowledge.

As far as the flatness of the manifold, no way around that something will have to be done for a permeant seal. I have seen people use a hand held belt sander to backwoods DIY flatten cast iron manifold surfaces. I don't know what grit the belt was? Maybe 80 or 120? If you choose that route, be gentle, make a couple full passes, check flatness and repeat as required. Use the bristle disc afterward to knock down the straight sanding grooves from the belt sander. Is it ideal, no. But sometimes things just have to get done.

 

[JHZR2]

I understand the concern. But the amount of abrasive dust or other material that may end up in the oil isn't much. I think I've gone through 2, maybe 3 white discs in the last 15-ish years. So the amount of abrasive that may come off during a job is hardly measurable. Large chunks of sealant, of coursepick that off before getting after it. But even on timing covers where the oil pan remains on or the valley of an LS that the blocks was cleaned with those discs, I've never seen an issue. Though an oil change has always been done after heavy maintenance like that is done as well. Out of the hundreds of vehicles I have used those discs on, none have had an engine failure to the best of my knowledge.

As far as the flatness of the manifold, no way around that something will have to be done for a permeant seal. I have seen people use a hand held belt sander to backwoods DIY flatten cast iron manifold surfaces. I don't know what grit the belt was? Maybe 80 or 120? If you choose that route, be gentle, make a couple full passes, check flatness and repeat as required. Use the bristle disc afterward to knock down the straight sanding grooves from the belt sander. Is it ideal, no. But sometimes things just have to get done.

Regarding manifolds, or even simply the job of removing these studs, I know that I’m going to have at least two more jobs like this. One on the six cylinder version of this engine that I have in my other 1991 350SD, and I know that the manifold gasket on one of my two Cummins trucks also need to be replaced. Those manifolds are known to shrink and warp, so I wouldn’t doubt that minimum some work will need to be done on it.

I like to develop skills and learn how to do new things. Time in particular is a limitation, because time working on cars is free time away from my kids; between working and kids stuff, I don’t really have a lot of free time, and I love doing all the kids stuff, so I don’t really want the alternative. That means it as much as I love to buy a giant belt sander and learn to do this myself, I do think that paying the piper is the better bet. That said, I am also trying to make a reasonably decent wood shop, and suspected there are some good units on the used market and that might work.

The question really is if I trust the quality of my work…

 

[dvblanch]

Welding & Fab shops in your area? Lot of the metal working guys use industrial type belt Sanders for cleaning up or shaping steel. As far as straightening the manifold just put on a pair of gloves lay it on the moving belt and move it around a little bit. Done it a few times and surprising how fast it cleans up. Just hang on.

 

[The_Jeff]

If you have a granite countertop use it and your feeler gauges to judge your progress as it goes. Better to take off just enough. You could also rig up a light behind it and look for light getting through.

 

[Vexorg]

Regarding manifolds, or even simply the job of removing these studs, I know that I’m going to have at least two more jobs like this. One on the six cylinder version of this engine that I have in my other 1991 350SD, and I know that the manifold gasket on one of my two Cummins trucks also need to be replaced. Those manifolds are known to shrink and warp, so I wouldn’t doubt that minimum some work will need to be done on it.

I like to develop skills and learn how to do new things. Time in particular is a limitation, because time working on cars is free time away from my kids; between working and kids stuff, I don’t really have a lot of free time, and I love doing all the kids stuff, so I don’t really want the alternative. That means it as much as I love to buy a giant belt sander and learn to do this myself, I do think that paying the piper is the better bet. That said, I am also trying to make a reasonably decent wood shop, and suspected there are some good units on the used market and that might work.

The question really is if I trust the quality of my work…

Go to the orange store an buy a 16"x24" or so polished floor tile and glue it to a piece of plywood. get a sander belt in 120-150 grit and use 2 sided tape to hold the sandpaper flat. pull the studs out of that manifold and you can resurface the manifold and turbo yourself. Doesn't have to perfection here and you can use copper silicone sparingly as a gasket mount compound.