Loosing bolts

[Fstued]

How can I get the bolts lose and get the flange off. I need to build a new exhaust system. from the exhaust manifold to the water muffler. Got the piping system off no problem, it fell apart. But the flange that bolts to the manifold does not want to come off, the bolds are on there . How can I get them loose or can I just screw the new piping configuration to the flange and build the system in place. It would be better to remove and put on a new flange.

https://www.moyermarineforum.com/forums/attachment.php?attachmentid=16396&d=1682895243

[Dave Neptune]

You can soak with Liquid Wrench or equivalent for a few days. Or using a mix of acetone and ATF also works well. When soaking soak the bolts and the flange joint too as some may penetrate to the threads.

The bolts look to be a golden color in your photo, if so they are Grade 8, heat treated steel and very strong. After they have been soaked for a while you can use a 12 point wrench and lightly hammer in BOTH directions. Even striking the bold heads may shake some of the rust binding the threads allowing more penetration and movement. They will not come loose all at once and may take more than a couple of days. Also look closely at the "washers" if they are lock washers with a split they will be even more difficult as the split allows moisture to get in and on the good side the penetrating oil too. Work at it with patience and time not a big hurry. If they start loosening constantly work the bolt in BOTH directions, patience patience and patience.

When reinstalling use Grade 8 studs if you can find them and star style lock washers NOT THE SPLIT type.

If all else fails the heads of the bolts can be cut off. Then you can knock the flenge off and work the bolts out.

I suggest you do go for the new flange as yours looks bad and could prematurely fail with the new exhaust IE a very short life.

Dave Neptune

[msmith10]

Best to use the time-honored and proven technique: Apply a penetrant (50-50 mix of acetone and ATF is very good) liberally. Tap-tap-tap on the head of the bolt with a ball pein hammer. Wait. Apply more penetrant. Sometimes a little tightening on the bolt head helps loosen things up. An impact wrench is very helpful but use it on a light setting so as not to shear off the head. Apply more penetrant. You can also apply a propane torch to the head, allow to cool then apply more penetrant. The object is to work the penetrant into the threads. Just be patient and keep trying. It's a lot less work to wait, apply penetrant, tap-tap-tap on the head, light impact wrench, repeat, than dealing with a sheared off bolt. Worst case, both heads break off then the flange will lift off and you're using a stud extractor or vise grips to remove the remainder of the bolts, but now you are closer to the threads and the penetrant will work better.
Once you get those bolts out, you can replace them with studs (sold on the Moyer site) so as to prevent this problem in the future.

[W2ET]

Another MVP!

Thanks, Mark!

Bill

[TimBSmith]

Ultrasonic Battery Operated Tooth Brush to Help Penetrating Oil

I have wondered if an ultrasonic tooth brush base held against a stuck bolt might help with penetrating oil after a good soak. Or maybe some other source of point focused vibration. Best with the flange bolts.

[Al Schober]

Dave,
I have to disagree with you on the 12 point wrench. A 6 point wrench is much less likely damage the heads of the bolts.
My go-to penetrant is a 50/50 mix of kerosene and ATF.

[Al Schober]

Dave,
I have to disagree with you on the 12 point wrench. A 6 point wrench is much less likely damage the heads of the bolts.
My go-to penetrant is a 50/50 mix of kerosene and ATF.

[msmith10]

Agree, Al. Don't try to use an open-end or even 12 point socket. A 6 point socket is the only way to go.