QD-15, need help with broken exhaust cover screw

[mixin]

When my exhaust manifold/cover started leaking I thought I was doing the right thing by replacing the gaskets, but of course one of the screws snapped even though I was being very careful. Judging by the size of the remaining screw that did come out, I was able to get several revolutions on it as it was coming out before it snapped.

I would like to get the rest of the screw out and leave the factory threads in if possible. So far all I have done since these pictures is dig around the screw with a pick tool to get some old sealant out and then squirt it with PB Blaster. I also wanted to change my head gasket since it looked original, but judging by the condition of the head bolts in the picture - I'm very scared to. Since there is no paint on the port side of the head, I'm thinking that this motor was overheated at some point in it's life. The exhaust manifold screws closest to the head were in the worst shape as well. The others all came out reasonably well.

If there is anyone who has been in this spot before with a broken exhaust cover screw could lend some sage advice, I'd be very grateful. If I'm lucky, I think I'll get one shot to get this thing out so I want to do it right! Thanks all!!!

Mike

 

[Cofe]

Re: QD-15, need help with broken exhaust cover screw

Get a left twist drill bit at a local auto parts store. Center punch the broke off bolt stud and start drilling. The left twist drill bit will sometimes grab while drilling and unscrew the broke bolt. Use pb and some light heat helps. If you drill all the way through the stud, use a easy out, pb and heat.

Remember to set your drill to reverse when using a left twist drill bit.

 

[jonesg]

Re: QD-15, need help with broken exhaust cover screw

EZ outs snap all too ez.
Unless its a new bolt that broke, the old frozen bolts will snap an ezout , then you're up the creak and need a EDM eroder.

A machine shop trick is mig weld a nut to the flush broken bolt. Then just wrench it out.
http://www.youtube.com/watch?v=4BFUfGKU_ts&feature=related
If you don't have a mig just give it to a machine shop, its a quick cheap job.

 

[Cofe]

Re: QD-15, need help with broken exhaust cover screw

Instead of using "brittle" ez outs. A old mechanic trick is to grind 4 flat surfaces on a old center punch. Drive the punch in, and a wrench fits the shank. A center punch is good hard steel.

 

[HighTrim]

Re: QD-15, need help with broken exhaust cover screw

My wife always knows when Im removing an exhaust cover by the language, I hate how they used slotted screws, even with an impact driver can be a bear to get out. Lots of cut up knuckles. Wish they were socket style.

 

[1946Zephyr]

Re: QD-15, need help with broken exhaust cover screw

Did you invent some words Chris? I've done that a time or two.

 

[mixin]

Re: QD-15, need help with broken exhaust cover screw

Update:

I have been soaking the broken off screw for the last few days with Liquid Wrench. Then tonight I marked the center of the screw with a small centerpunch and started to apply heat to the screw's boss inside the exhaust cavity. After a min or two I noticed some liquid bubbling out of the bottom exhaust port of the bottom piston - it was fuel mix. I got a little leery of a fire, so I shut the propane off and got the drill out. The screw has a 3/16" stud, so i used a 1/8" left-hand drill bit and proceeded to drill all the way through the screw quite easily. I tried, but could not coax the screw to grab the bit as I drilled.

Now I am just soaking the drilled out screw in Liquid Wrench again. Although the bottom of the tapped hole must be connected to the coolant passage or something, cause when I squirted the LW in the hole, it just kept going in the hole and not squirting back out.

I guess at this point I should try more heat and the squared off center punch to try to get the rest of the screw to back out. If the screw proves too small for the center punch method, I might try the easy out too (very carefully). I'll just have to somehow isolate that fuel mix that is bubbling out from the flame this time!

Any further advice would be greatly appreciated. Thanks again all - I am truly grateful for all of the responses!

Mike

 

[bktheking]

Re: QD-15, need help with broken exhaust cover screw

Don't use the ez out, trust me, they are junk, they break and are impossible to drill out. drill out the broken bolt then tap it out to the next size and be done with it.

 

[1946Zephyr]

Re: QD-15, need help with broken exhaust cover screw

I just drilled out a head bolt on my old HD-20 and I got real lucky on keeping the drill centered.

 

[mixin]

Re: QD-15, need help with broken exhaust cover screw

Alright, I fiddled with trying to dig the rest of the screw out and just decided to "just be done with it"! I drilled out the screw with a 11/64 and tapped it to a 12-24 - the tap only threaded 3/4 of the hole (like from 9 o'clock to 6 o'clock), but I think it will be ok. That success inspired me to try to remove the head since I've always wanted to put a fresh head gasket on. One of the bolts (in the pic) was so bad, I had to tap a 10mm socket onto it with a hammer to get it out. I heated the boss and bolt for awhile and then tapped it with a 2lb hammer and started working it back and forth, gradually more and more. Once I got it a 1/2 turn loose, it let me back it all the way out without indication that it was going to snap. (A trick I learned here!)

At this point I have all the gasket surfaces cleaned up and am going to the OMC store to get some replacements for the screws and bolts that are too far gone. Thanks to all who guided me through this process I am very thankful!!!

Also, check out my new snazzy prop I got on fleabay for $18!!! I'm not sure if it makes the motor look better or calls attention to how bad it the rest of it looks!!! HAHAHA!

http://claspics.com/941/701497