exhaust bolts


fishon79

15+ Year Member

Joined
Dec 2, 2008
Messages
13
Points
3,101
City
vancouver wa
Vehicle Year
90 and 94
Transmission
Manual
having trouble with removing the exhaust bolts to a 4.0 at heads. have been using penetrating oil and striking them hasnt helped. anyoneknow about using heat where and how hot any help is appreceated
 
Don't heat the bolts heat the exhaust port flange where they screw in.

But I'll warn you with a tight fitting socket and an impact gun you can usually get the bottom three out on each side.

I've done that job dozens of times and if I get ONE of the upers out I consider myself lucky.

My best ever is getting two of the uppers out (I still snapped a lower)
And I broke all six on the other side of the engine.

Frankly and bluntly when doing that job I expect to have to drill and
heli-coil all six bolt holes before reassembling the exhaust, UNLESS
I've already been there and heli-coiled the holes in which case they'll
come out almost effortlessly.

AD
 
nice info allan
 
on my 90 i made all out but one witch was on top aply heat to the threads surounding the bolt
 
I managed to remove all of mine without breaking a single one. Use lots of pentrating oil and let them soak a little. Use a quality socket and more ass!
 
One other thing I should note...

When I drill and helicoil the exhaust port flanges on
a 4.0 cylinder head I DO NOT use the original metric
threads.
I rethread and helicoil them for 5/16-18UNC threads
because generally speaking the english bolts are available
in the proper lengths without special ordering them

In this application I prefer Grade 8 bolts because they are hard
even if not necissarily strong, and this inhibits them from
frictionally/vibrationally welding to the 18-8 Stainless steel
material from which the heli-coils are made.

Even so I use the prevailing torque Heli-coils to keep the bolts
from vibrating loose (though compression of my header gaskets
is more of a problem) while they are smeared with never-seeze
to prevent them from corroding in place.

AD
 
I used the stock size 8mmx1.25. Instead of using the old crap, I got some bolts in that size and just used a hacksaw to cut down what I needed. Worked fine for me...
 
i got all 12 out- when the heads were on the bench. just like was mentioned, i got a tight fitting socket on the bolt, breaker bar, pulled all the slop out everything, then gave a really good solid hard jerk on the bar. once the bolt 'popped' i was able to go the rest of the way with a ratchet and going slow.

seems like more often then not, its almost technique rather then tools or oil that gets things apart.
 
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