When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Intake Pipes gasket removal - opinion asked on scratches
I am cleaning an removing the old gaskets on my 16v intake pipes. On the first one i was a bit reckless with the razorblade and i got some scratches.
My question is can how big of a problem is this? And can i just polish this out with some fine sandpaper? Did not touch them after the removal just cleaned them.
Flat file will knock down anything standing proud of the surface, The soft gasket will take care of the scratches. Stuff the port before you work on it, vacuum any crud aand the stuffing out together when you are done dressing it.
Just get a 1/4" air angle grinder with a 2" backing plate for surface conditioning discs. Use the fine grade surface conditioning disc and lightly hit the surface, which will quickly remove all the light scratches caused by the razor and not take off extra material. You can clean up the flanges in 10 minutes so no need to put them on a sanding belt. Not to say a belt won't work as I use mine frequently, but IMHO it is an aggressive approach to a minor issue. I also had scratches on my intake runners as well as from removing the gaskets on the exhaust ports and the surface conditioning discs are the way to go.
Here is a link to the stuff at Harbor Freight so you know what I'm talking about.
if you dont have a machine for this job,
then get a few pieces of self stick sanding sheets 320 grit or 220 grit works pretty well,
place them on a flat surface a and then work the piece in a figure 8 this will restore the surface
In my experience, a few shallow scratches fro a razor blade are not an issue worth power tools. In skilled hands, a gentle touch with a disk sander or grinder is OK, but not needed. In unskilled hands, more damage is done than cured. The surface when done still needs to be really flat. It's way too easy to rock the manifold part as you move it across a belt sander, or use the tipped disc sander or grinder to make the face slightly concave. Instead, use spray gasket remover to get all any remaining remnants of gasket lurking in the rough surface. A flat file, drawn a couple times over the surface will remove anything sticking up. Then leave it alone. The new gasket will do what it was designed to do.
---
Most of the engines I "work on" these days are big enough to walk through, and I generally don't actually touch anything inside the engine itself. The precision surfaces and finishes receive the utmost care and respect. The folks who do this stuff all the time are incredibly good. There's no such thing as a sander or grinder. Small or large parts that "don't fit" are very carefully inspected to find out why. Still, no BFH or material removal or "adjustment". Think along the same lines when you work on your 928. Avoid damage as you take things apart if you possibly can. Certainly avoid damage when assembling, or even "restoring" or otherwise working on components. Use good sense, and Do No Harm.
A fine surface conditioning disc is not going to damage the surface unless your intent is to damage the surface and would require you to spin the disc at full speed and hold it to one spot. Just spin the disc at a slow speed and move it back and forth, which will only remove light surface imperfections. If you don't feel safe then get a green scotch brite bad and knock it down by hand. If you look at the pics below you can see where I used a medium surface conditioning disc (they were out of fine) to clean up the razor scratches when I removed the gasket material from the cam tower (took 4hrs per side...PIA) as well as the intake gasket. I did the exact same thing on the cam tower after removing the buckets and prior to rebuilding. Just wipe it all down with acetone when your done to remove any oils from the surface.
FWIW dont use any scotchbrite on the cam tower mating surfaces or any grinders,
only use a razor blade held perpendicular to the surface .
any slight deviations from the plane could spell an oil leak that will require new castings
A fine surface conditioning disc is not going to damage the surface unless your intent is to damage the surface and would require you to spin the disc at full speed and hold it to one spot. Just spin the disc at a slow speed and move it back and forth, which will only remove light surface imperfections. If you don't feel safe then get a green scotch brite bad and knock it down by hand. If you look at the pics below you can see where I used a medium surface conditioning disc (they were out of fine) to clean up the razor scratches when I removed the gasket material from the cam tower (took 4hrs per side...PIA) as well as the intake gasket. I did the exact same thing on the cam tower after removing the buckets and prior to rebuilding. Just wipe it all down with acetone when your done to remove any oils from the surface.
Just as a point of reference....from a professional 928 mechanic.
I throw away any heads and cam carriers thst have been attacked with a Scotch Brite pad, as you describe....almost always they are junk...and the amount of effort required to fix the damage from this approach isn't worth the effort.
You will completely understand this, when you put it back together an keep blowing out the cam carrier gaskets.
Just as a point of reference....from a professional 928 mechanic.
I throw away any heads and cam carriers thst have been attacked with a Scotch Brite pad, as you describe....almost always they are junk...and the amount of effort required to fix the damage from this approach isn't worth the effort.
You will completely understand this, when you put it back together an keep blowing out the cam carrier gaskets.
Congratulations on being a professional 928 mechanic, that is great. Using a Scotch Brite pad by hand will in no way damage the surface of the cam tower or head so not sure why you would make such a statement. Do you really throw a customer's head and cam tower away and make them pay for a new/used one if a Scotch Brite pad was used to clean the surface? BTW, my engine has been running since May 100% leak free and I used a Scotch Brite Pad.
Do a Wikipedia search on Scotch Brite. It feels like plastic, but it's impregnated with aluminum oxide and titanium oxide, which is hard enough to scratch glass.
Thanks for all the feedback! We are all in the same team ok, just different experiences.
The answer i will use is basically: do not scratch any goddamn peace of aluminium which needs a gasket. Then if you do, don't do crazy stuff because the gaskets will probably safe your **** when you are lucky.
Again: i appreciate all you guys for helping me through this whole "i am going to pull my engine and make it new again" thing, with almost zero experience
FWIW dont use any scotchbrite on the cam tower mating surfaces or any grinders,
only use a razor blade held perpendicular to the surface .
any slight deviations from the plane could spell an oil leak that will require new castings
Originally Posted by GregBBRD
Just as a point of reference....from a professional 928 mechanic.
I throw away any heads and cam carriers thst have been attacked with a Scotch Brite pad, as you describe....almost always they are junk...and the amount of effort required to fix the damage from this approach isn't worth the effort.
You will completely understand this, when you put it back together an keep blowing out the cam carrier gaskets.
Originally Posted by 240Z TwinTurbo
Congratulations on being a professional 928 mechanic, that is great. Using a Scotch Brite pad by hand will in no way damage the surface of the cam tower or head so not sure why you would make such a statement. Do you really throw a customer's head and cam tower away and make them pay for a new/used one if a Scotch Brite pad was used to clean the surface? BTW, my engine has been running since May 100% leak free and I used a Scotch Brite Pad.
You would do well to incorporate knowledge from folks that have worked on these cars for years.
You either are very, very careful, or very very lucky.
Perhaps what is missing information in this context, is that the 16v cam carrier seals are a high-pressure oil (8 BAR+) seal. A localized surface variation of 1/2 thousandth on the surface around the oil gallery will enable an oil leak.
Thus, it is very important to treat the cam carrier seal mating surfaces with extreme care.
02-01-2018, 06:49 PM
Intake Pipes gasket removal - opinion asked on scratches
