Head bolt size?

[Dave Abrahamson]

Does anyone know the size tap I should use to clean up the threads in my block before putting the heads back on?
I did break one bolt taking the heads off and I can't get it to come out with PB blaster, heat and vice grips on the little bit of bolt that's left sticking out.
I'm going to have to drill that one out I guess.
If I have to helicoil it, I'm not sure of the size I should get regarding that either.

Thanks for all your help and Happy Thanksgiving!

Dave

 

[colbyt]

Re: Head bolt size?

Before I drilled it out like you mentioned, I would try a liberal application of your favorite penetrating oil over several days then I would drill it and try using an easy out bit like these 12 Piece Screw Extractor Set

Note that the drill bits in this kit are less than worthless. The back out part seems to be decent.

You may need to use a cutting disc to get a flat surface to drill. Don't get in a hurry and give the oil time to work its magic.

 

[Dave Abrahamson]

Re: Head bolt size?

Does 5/16-18 sound right?
Somebody has to know this.
I looked up the part online but it doesn't say the size of the thread.
My OEM manual doesn't seem to think it very important to mention either

 

[durban]

Re: Head bolt size?

5\16 bsw

 

[colbyt]

Re: Head bolt size?

Clean one up and take it to any hardware store. Even Lowes and HomeDepot have a test pad that you can match the size and threads to.

 

[HighTrim]

Re: Head bolt size?

Forget the Easy Outs, they arent so easy when they break. TRY drilling that puppy out of there! Soak it in penetrating oil like PB Blaster, heat it with a torch, and use the vice grips. Might try combinations of heating with the torch, the using a cold spray or compresed air can upside down to cool it.

Noting your location, Im assuming this is a salt water motor eh? I was going to say a left hand drill bit, but might not cut it if it is a salt water motor.

 

[boobie]

Re: Head bolt size?

I've also used the left hand drill bits and sometimes the broken bolt will pop right out.

 

[GeneH]

Re: Head bolt size?

I've never done this but a lot of people have success with welding a nut onto the broken bolt. The heat loosens the threads and you use a wrench to turn out the broken bolt. I guess you just find a nut of the correct size, place it over the broken piece and weld through the center of the nut. Do a little searching for the procedure

 

[1946Zephyr]

Re: Head bolt size?

Yea, typically head bolts are 1/4 20, 5/16 18, or 3/8 16. I don't think I've seen a head bolt any bigger than 3/8" on an outboard.

 

[durban]

Re: Head bolt size?

i drill a 2mm hole along the stud put nitric acid in & leave for a few hours then screw them out some times just using my fingers ,

 

[Dave Abrahamson]

Re: Head bolt size?

Forget the Easy Outs, they arent so easy when they break. TRY drilling that puppy out of there! Soak it in penetrating oil like PB Blaster, heat it with a torch, and use the vice grips. Might try combinations of heating with the torch, the using a cold spray or compresed air can upside down to cool it.

Noting your location, Im assuming this is a salt water motor eh? I was going to say a left hand drill bit, but might not cut it if it is a salt water motor.

It sounds like you've been looking over my shoulder...that's exactly what I've been doing. PB, torch and Vice grips.
Now I've succumbed to drilling it out.
Yeah..salt water motor.
Thanks for all the replies...I'll post back with my results.

Dave

 

[HighTrim]

Re: Head bolt size?

I feel for you salt water guys. Every time I THINK I am having trouble with a motor with stubborn bolts I remember it could be much worse.

 

[Dave Abrahamson]

Re: Head bolt size?

Success, I drilled it out and I'm now putting her back together.
One question, after applying gasket compound, and bolting the heads back on, how long should I wait before starting the motor?
I'm aware that I should re-torque the bolts after a couple of heat/cool cycles, but can I start her right up when done?

Thanks,

Dave

 

[Tim Frank]

Re: Head bolt size?

Success, I drilled it out and I'm now putting her back together.
One question, after applying gasket compound, and bolting the heads back on, how long should I wait before starting the motor?
I'm aware that I should re-torque the bolts after a couple of heat/cool cycles, but can I start her right up when done?

Thanks,

Dave

Check your manual.
Gasket compound usually is neither required NOR recommended.

 

[Dave Abrahamson]

Re: Head bolt size?

Check your manual.
Gasket compound usually is neither required NOR recommended.

Thanks for the reply Tim, I actually do have an OEM manual and it states "lightly coat both sides of new cylinder head gaskets with OMC gasket sealing compound".
I have the engine back together now...now I just want to know how long I should wait before firing her up.

Have a happy holiday weekend everybody.
Dave

 

[HighTrim]

Re: Head bolt size?

It likely wont hurt anything, but as stated, the new head gaskets you get come with the sealer already applied on them. That is why they are shiny. No extra sealer required.

Fire her up and let us know how it goes. Have you checked compression yet?

 

[Tim Frank]

Re: Head bolt size?

Thanks for the reply Tim, I actually do have an OEM manual and it states "lightly coat both sides of new cylinder head gaskets with OMC gasket sealing compound".
I have the engine back together now...now I just want to know how long I should wait before firing her up.

Have a happy holiday weekend everybody.
Dave

Note my cleverly ambiguous use of the word "usually"...
You never have told us what model and year we are discussing.

 

[1946Zephyr]

Re: Head bolt size?

From the time you get the motor buttoned back up to the time it takes you to reach for the key, is how long you need to wait to start it.

 

[Dave Abrahamson]

Re: Head bolt size?

You never have told us what model and year we are discussing.

You're right Tim..sorry, I know better.
1997 J115 SPL Crossflow 90 degree
XJ115HXEUA

 

[Tim Frank]

Re: Head bolt size?

Ahhhhh... for that model the OEM manual says....