Broken bolts on water pump housing.

Old 06-29-2020, 03:51 PM
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Default Broken bolts on water pump housing.

I have a 100hp Yamaha 4 stroke. It has spent most of its life in salt water. 2000 motor I bought as part of a whaler restoration project.

As part of the project I and replacing the water pump and redoing the lower unit.

Two of the water pump housing bolts broke when I was disassembling was the water pump. I have soaked the two broken bolts with PB blaster.

I tried screw extractors yesterday but the bolts won’t budge. It appears the lower housing unit (which I am replacing) does not have threads to hold the bolts. The threads appear to be below the lower housing unit which is corroded and appears to be corroded to the lower unit as well.

my next plan of attack is to use heat to try and loosen up both the bolts and the lower unit housing and then try to extract the bolts.

if that doesn’t work I will try to drill out the bolts.

Any other options? Trying my best to keep the lower casing functional so I don’t have to replace it. Thanks for any thoughts.

Old 06-29-2020, 05:02 PM
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If things dont workout, an automotive machine shop / engine rebuilders in your area deal with that sort of stuff on the regular basis....
Old 07-02-2020, 08:34 PM
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Make you a mixture of 50/50 acetone and ATF. I keep a mixed bottle of this in my shop and have yet to find a bolt this won’t penetrate
Old 07-03-2020, 12:24 AM
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im not sure if you can get a pair of channelocks on the bolt.

That 50/50 is a good one. heat and candle wax. Get a quarter turn or more. Then reapply. Works wonders. Heat, heat and more heat.

if you can’t get out, helicoils are a good option or call a machine shop and have them try to remove #1 or put a threadsert in for you matching the thread pitch so you can have oem parts.

good luck been there done that on a 98 2 stroke.
Old 07-03-2020, 04:36 AM
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Left handed drill bits every time for the win. Let your broken bolts soak in penetrating oil for a few days, spray every 4-hours or so. Give it plenty of time to work. Start with a very small and sharp drill bit for a centering hole. Get you some left handed drill bits, start small work your way up in sizes. The opposite direction drill bit will jar them loose and spin them out.
Old 07-03-2020, 07:05 AM
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I just took out a snapped water pump bolt deep in the LU using the Irwin extractor. I didn’t have a left hand drill bit but got the job done using a normal bit. The key is, I think, to start with a punch and a very small bit. Put ur drill on its lowest speed and take ur time. After you’ve spent what seems like forever making zero progress, it will eventually make its way through. You need to keep the bit as straight up as possible and in the center of the bolt. Once you get that small bit thru the bolt, put the extractor in there and slowly drill it until it stops/won’t go any further. At that point I used an adjustable wrench and turned the whole thing out. Oh, and be prepared, the extractor will be a real bear to get the busted bolt off, lol. Ask me how I know.
Old 07-03-2020, 07:37 AM
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I had this same thing happen on my F90 to one of my WP housing bolts. I tried an extractor many years ago and will never use one again. They are hardened steel and if one snaps drilling one out is a monumental task. They wedge the shank outward and it just doesn’t work for me. I’ve had to remove about 6 or so bolts in my life.

I drill them out after soaking in PB or whatever your choice of penetrating oil. I start with a 1/16 or 1/8 inch bit and drill in an 1/8 or 1/4 inch Attempt to get dead center first time, but if you miss just adjust as needed with the next size bit by angling the drill and walking the drill back vertical as the bit gets on center. I keep the hole shallow until I’m good with being on center. Once on center I will drill to depth. I then just go through every next size bit in my case until I get gut wrenching close to the holes threads. As I get closer to the thread wall I will reverse the drill every so often and I have had them back out, other times when what’s left is thin enough I’m able to get them out with varying types of picks.

But I’ve worked with my hands most my life and I’m like a surgeon with most tools..........................
Old 07-06-2020, 12:24 PM
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soak in PB blaster and if you have room, use a small pipe wrench to get the bolt to turn. It may take several soakings and alot of patience but it will eventually start to turn.

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