How to know if something is flat

[BLOHS7844]

Not sure where to put this thread but I have all the studs off my head for the exhaust manifold because its leaking between there. I think one of them might be warp a little bit. How can I tell if something is perfectly flat?

[DSMnoobsause]

Use a straight edge

[knochgoon24]

I use a machinist straight edge, one ground to 0.001" tolerance.

Sandpaper on glass can help smooth high spots out, but shouldn't be used for precisely flat surface. But it may be enough to get that gasket to seal better.

[Justin_l_]

As they said, a machinist straight edge, or surface plate. Any machine shop can do it in a couple minutes.

[Bud92gsx]

Leaking oil or coolant? If your leaking oil the middle bottom exhaust stud has an oil gally behind it, so make sure that one is in there.

[BLOHS7844]

I'm just leaking exhaust gases.

I can take my exhaust mani in to get checked but I'm not taking my head off just for that. I was looking for something to check it while its on the car. Are machinist edges cheap by chance?

[Bud92gsx]

Ohh your leaking exhaust...Well thats easy..Retourqe all of your exh studs.But again like mentioned you can always use a staight edge, like they do to check heads for warpage..Make sure you do a good visual inspection as well.

You could run some seafoam thru the intake manifold..And wait for the smpoke shoe..That should narrow down where your exhaust is leaking.

[BLOHS7844]

I can feel exactly where my exhaust is leaking and its not as easy as retorquing the studs. The DO strip and thats a bitch and a half to deal with

I just had my head off so a machinist could fill in a stud hole with a weld and retap it because it was stripped so bad. No amount of redrilling and tapping a bigger hole was working. I think this welding my have warped my head and thats why I'm asking

[Bud92gsx]

Ahhh you got it welded..There is a good chance the heat may have warped it.

[3kgt2nv]

I can feel exactly where my exhaust is leaking and its not as easy as retorquing the studs. The DO strip and thats a bitch and a half to deal with

I just had my head off so a machinist could fill in a stud hole with a weld and retap it because it was stripped so bad. No amount of redrilling and tapping a bigger hole was working. I think this welding my have warped my head and thats why I'm asking

if a machinist couldn't retap a hole or install a helicoil i would quit using his services. thats some pretty simple metal working to no be able to do.

and if it wasnt welded properly he most likely warped the head

[Blurred Talon]

IMO, a surface table is the best thing for find out if a surface is perfectly flat/straight/true.

[BLOHS7844]

Is it possible that the bottom of my head is also warped?