Active Active   Unanswered Unanswered

Removal of a broken engine plate drive screw

Keeping your powerboat under power is a lot easier with good advice. Post your power systems questions here.

Moderators: Al Benton, Don Ayers, Don Vogt

Post Reply
George Emmanuel
Posts: 153
Joined: Mon Apr 10, 2006 7:44 am
Location: Gainesville, Florida

Removal of a broken engine plate drive screw

Post by George Emmanuel » Wed Apr 04, 2018 7:39 pm

The drive screws that fasten the engine name plate to the manifold are hard. My question is, how do you remove ones that are broken below the surface? I can order a carbide drill but is there another way?

George

User avatar
Bilge Rat
Posts: 226
Joined: Thu Jul 16, 2015 4:02 pm

Re: Removal of a broken engine plate drive screw

Post by Bilge Rat » Fri Apr 06, 2018 10:56 am

You can try to drill these out but I believe they are a hardened steel and a small bit will want to wander off center, even if you tried doing it on a drill press. If you have enough real estate on the manifold, maybe moving the engine tag over a bit and drilling 4 new holes might work out better.
1966 Lyman Cruisette 25 foot "Serenity Now!"
1953 Chris Craft Sportsman 22 foot "Summerwind"

User avatar
Don Danenberg
Posts: 181
Joined: Fri Nov 18, 2005 9:30 pm
Location: Manistee, MI
Contact:

Re: Removal of a broken engine plate drive screw

Post by Don Danenberg » Fri Apr 06, 2018 7:10 pm

Actually, I don't know these to be hard, but quite soft 'Rivets'. These are generally 1/4" to 3/16" long and hammered into place. It is quite easy to just pry this plate off of the manifold if you are careful not to bend the corners of the brass plate. They can't be re-used because the spiral ribs are deformed when they are forced into the shallow hole.
They are available from "Restoration Supply Company" for like 20 to 30 cents apiece. Get out your calipers because sizing the hole in width and depth is most important.
You do not have the required permissions to view the files attached to this post.

kiitos
Posts: 19
Joined: Tue Mar 22, 2016 8:59 am
Location: Harsens Island, MI

Re: Removal of a broken engine plate drive screw

Post by kiitos » Sun Apr 08, 2018 6:38 am

If the broken pin is below the surface you can use a drilling tool made for drilling in the center hatch bindings and hinges. This tool is a "must have" if you are drilling piano hinges for engine covers or hatch bindings. If the broken pin is above the surface you could make a jig plate with a hole and clamp it to the manifold directly over the center of the broken pin. Then use the drilling tool. Go slow and easy so that you don't catch the drill point and break the drill bit. Here is a photo of the tool. These can be found on the Woodcraft website.
You do not have the required permissions to view the files attached to this post.
'78 Chris Craft 30' Sportsman
'49 Chris Craft 25' Sportsman - Twin "K"s

User avatar
Bilge Rat
Posts: 226
Joined: Thu Jul 16, 2015 4:02 pm

Re: Removal of a broken engine plate drive screw

Post by Bilge Rat » Mon Apr 09, 2018 8:29 am

Sometimes known as a VIX bit. They are the tool to use for hinges and rub rails.
1966 Lyman Cruisette 25 foot "Serenity Now!"
1953 Chris Craft Sportsman 22 foot "Summerwind"

User avatar
Don Danenberg
Posts: 181
Joined: Fri Nov 18, 2005 9:30 pm
Location: Manistee, MI
Contact:

Re: Removal of a broken engine plate drive screw

Post by Don Danenberg » Mon Apr 09, 2018 6:46 pm

Hey,
If it's even possible to 'break' a 3/16" long rivet, what would be left is tiny.
If you are going to try to 'drill' it out, you should use a "Reverse-cut" drill bit, so that it unscrews the super-tiny bit of the rivet left, by its own threaded rings.
Be VERY careful to not drill into the cast iron at the bottom of the hole, that would change length of the drive-screw needed and could even quickly get into the top water-jacket?

George Emmanuel
Posts: 153
Joined: Mon Apr 10, 2006 7:44 am
Location: Gainesville, Florida

Re: Removal of a broken engine plate drive screw

Post by George Emmanuel » Thu Apr 12, 2018 4:52 pm

There's no doubt on my end that this drive screw is hard. I'm well aware of using LH drills to back out threads, but I've gone through 3 bits so far and even using tapmatic I can't make progress. I'm thinking about using a carbide drill with a drill stop as my next approach and if necessary, tap the hole, install a flush plug and re-drill....but I'm not going to use drive screws. I'll drill and tap.
Thanks for all the input. I'll keep making posts on my progress.

George

User avatar
Bilge Rat
Posts: 226
Joined: Thu Jul 16, 2015 4:02 pm

Re: Removal of a broken engine plate drive screw

Post by Bilge Rat » Fri Apr 13, 2018 10:10 am

That's what I did to reattach the engine data plate on my Graymarine 327, however, it is attached to the forward engine mounting frame and not the exhaust manifold. I will have a similar data plate reattachment on a Chris Craft MCL exhaust manifold soon and would rather tap instead of using those drive rivets.
1966 Lyman Cruisette 25 foot "Serenity Now!"
1953 Chris Craft Sportsman 22 foot "Summerwind"

Post Reply