Spark plug threads twisted off in head

LarryNMO

Member
Hi guys, I know this is a tractor site, but maybe I can get some help with this problem. I've got a 150hp outboard mercury engine that has the spark plug threads twisted (broken off) in the head. It was being installed to specs (torque) when it broke off. Is there a better way other than an easy out, haven't attempted that yet but just looking for other options. Thanks Larry
 
Is it recessed and how much do you have to work with? Was it a new plug you were putting in? A photo would help. What is the head made of.
 
If you use an ease out be sure to use a square tapered one and not a spiral one. The spiral ones will just swell the part you are trying to remove and make it harder to get out.

Zane
 
Popgun, Yes the broken threads are recessed and about 75% of the threads is in the head. The plugs were older but not ran that much and I was trying to winterize it when it twisted off. My options for photos are not good. I think the head may be aluminum but not pos., will check with magnet tomorrow. The engine is a 1985. Thanks Larry
 
Depending on how a GOOD easy out may work. I have good ones but bet your not close enough to be able to use them.
 
Thanks Old, I'm not to close to you, I'm in the Wentzville area. I think you are around the lake ozark area. I think I may have one of the good ones, may try it and see what happens.
 
Ya figured you where not close to me. Yep down here at the lake. The good easy outs are less then 1.5 inches long and cost a good bit. This set I have cost me $75 and that was more then 10 years ago and I have only broken one of them in all that time
 
By the way what engine is that?? I have a Older Johnson 75 that is a parts engine
 
Warming the aluminum head up a BIT will help with the extraction process. A LITTLE heat will make the aluminum expand and let go of the remains of the plug... too MUCH heat will encourage the aluminum to continue to stick to the remains of the plug and tear off of the head/attach itself even tighter to the remains of the sparkplug.
 
(quoted from post at 06:00:28 02/17/14) Hi guys, I know this is a tractor site, but maybe I can get some help with this problem. I've got a 150hp outboard mercury engine that has the spark plug threads twisted (broken off) in the head. It was being installed to specs (torque) when it broke off. Is there a better way other than an easy out, haven't attempted that yet but just looking for other options. Thanks Larry

Worst case there's nuttin to removing the head.. It would be a good time to replace all those rubber oil lines that run everywhere...
 
To be fair. most broken ez outs I see are when a person uses one too small. ie. the don't open the hole up sufficiently to use the largest ex out possible, with only a thin shell of the original stuck part in place.

on the flip side.. i also look at the original problem. if it was stuck bad enough that the original whole diameter fastener broke? why gripe if something with a smaller cross section breaks? kinda expected ain't it. ;) ?
 
LarryNMO,This style of eazy out will get it out and not have to worry about breaking it off in the head.
REX114A.jpg
 
A outboard engine is a different animal than what most are accustom to... I would not want any foreign de-bre floating around in a cylinder on one BTDT broke a reed valve... Heads coming off If I am working on it.... There's nuttin to it the head is nuttin but a cover over the cylinders just like a N.... Piece of cake...

While you are tinkering wake that Black Max UP :!:

https://www.boyesen.com/
 
Thanks again to everyone for all the great tips. Haven't had the time to work on it yet, but the weather is getting great for a few days so hopefully I can get on it. I need a fishing trip too for some fresh CRAPPIE. lARRY
 
(quoted from post at 05:54:26 02/19/14) Thanks again to everyone for all the great tips. Haven't had the time to work on it yet, but the weather is getting great for a few days so hopefully I can get on it. I need a fishing trip too for some fresh CRAPPIE. lARRY

This is my baby,,, Its a 1984 black max that's been on two boats its on a 1990 Winner I brought new now... I have blew it up twice :oops: The first time it broke a reed plate and damaged a cylinder,,, the second time a oil feed hose broke going to the upper main crank bearing...

boat1.jpg
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boat4.jpg
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(quoted from post at 21:54:26 02/18/14) Thanks again to everyone for all the great tips. Haven't had the time to work on it yet, but the weather is getting great for a few days so hopefully I can get on it. I need a fishing trip too for some fresh CRAPPIE. lARRY

I caught 15 crappie on Saturday - no boat required. Just walk on out and drill a hole where you want to fish.
 
Hobo ,that is a good looking bass boat. Looks about the same as my Ranger and the same motor. Didn't have it in the water last year at all, too busy!!!!!!! I need to stop working so much and play a little more.
 
(quoted from post at 07:40:02 02/19/14) by the way, what is a reed plate

https://www.boyesen.com/power-reeds-pwc

The original are SS (metal) and fracture over time when they do it gets swallowed into the cylinder and wrecks the pston and cylinder :cry: When I built it the fist time I installed OEM reed plates when I went into it the second time I went with these it really wakes up and it pops out of the hole fast... You do have to re-jet the carbs (maybe) I had to re-jet 5. You leave the carb cover off and blip the throttle in daylight if you see a flame behind the throttle plate you go up in jet size till its gone... Nuttin to it....

I was turning it around 6300 RPM I spec that's what broke a reed it runs out best around 5900 at 63MPH so I don't push it above that anymore... I had that engine on a 84 Winner and it would run a dangerous unstable 70 MPH like it was on ice,,, the difference is the 90 weighs 400 lbs more and stable (safe) 8)
 
Hobo, where are the reeds located and are they easy to replace? I'm not sure if I really need them, I've really slowed down on the water unless a thunderstorm is chasing me back to the ramp. Last time I was in my friends (he was 83 years old) 22ft bullet bass bt. with a 250hp on the rear he decided to kick it in the a$$. I think we were hitting about 75 and we were dancing all over the place and we hit a small wake and that really got things rocking and rolling. That was enough for me. My top speed is about 35 now
 
(quoted from post at 21:54:26 02/18/14) Thanks again to everyone for all the great tips. Haven't had the time to work on it yet, but the weather is getting great for a few days so hopefully I can get on it. I need a fishing trip too for some fresh CRAPPIE. lARRY

Forget about those scale fish and hook up to slime!!!! Lots more fun on the rod and reel!!!! LOL
mvphoto3750.jpg
 
Not yet Jerry, too much going on. Wife had surgery on one eye and can't see too good out of the other one, will keep you posted. Thanks
 

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