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Old 17 January 2021, 13:27   #1
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Honda BF20D impeller snapped bolts

Hi,

I've been a lurker since August and gleamed loads of info from Ribnet for my SIB, thanks! I have now a 4.2m sib on an old converted caravan trailer. Like many I started with the idea of inflating but it gets heavy quick.

I wonder if anyone has faced a similar issue on Honda BF20D 2007, I went to change the impeller and two of the impeller housing bolts have snapped off. see pic

I believe from Googling I need to:
  • soak in wd40
    Buy left hand drill bit for pilot hole in snapped bolt
    then use bolt extractor bit
    Buy 4x new Honda bolts (50mm x 5mm)
    I have new impeller, just need to buy gasket from somewhere

Has anybody come across this before? There was no grease anywhere, it was bone dry which must have corroded the bolts. It was all going so smoothly and would've been simple to change otherwise!

I would be very grateful if anyone has any tips for a keen amateur. OR let me know if there is an easier way to extract the snapped bolts.

Thanks.
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Old 17 January 2021, 14:00   #2
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Does the housing with the snapped off studs in not come off the lower part now you have removed the 2 central bolts?
Find a parts list and see if it shows it separates.
I dont have a Honda so be aware I am guessing.


housing.jpg I think it loos like this when apart, much easier to drill out then too.
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Old 17 January 2021, 14:39   #3
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Can't seem to shift it with a rubber mallet.
Thanks though it looks as if it can separate so that gives me a plan B if drilling doesn't work. Cheers for that.
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Old 17 January 2021, 15:10   #4
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The bottom of that lower housing will probably have the mainshaft bearing in it so it wont just tap off.
You need to look for a drawing to be sure what to do next.
You might struggle to get directly above and center to drill the broken studs with the main shaft in place anyway, the drill machine body may be too wide.
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Old 17 January 2021, 16:27   #5
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Here from 13 mins in shows a BF30 lower housing removal which I guess should be close to what you have there.

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Old 17 January 2021, 16:37   #6
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When was that lower leg dropped for an impeller change? That looks like a few years. Good practice to lightly coat the bolt threads with a marine grease and tighten down when doing an impeller change. They need to be nipped up not over tightened. On Tohatsu they are only 10mm heads.

First off, forget WD40, utter waste of time. Now I don't know Honda gearboxes, but I'd have thought that the waterpump housing isn't tapped. On a Tohatsu there's a flat head screwdriver aperture between the housing and the lower leg to prize it apart.

Soak it in Plus Gas, or diesel on a rag. Give it a couple of light taps with a hammer and see if there's any movement.

Assuming the waterpump housing comes off, go easy on the exposed bolt thread. What they need is a electro magnetic induction heater, not a blow torch or you'll cook the drive shaft bearing.

Patience. Hit the exposed bolt thread with a hammer to shock them and break any corrosion, soak in Plus Gas and rock the threads anti clockwise, then clockwise with claw grips. Don't be tempted to go for full turns until you feel movement.

If they break then this is a drill out job.
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Old 17 January 2021, 16:54   #7
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If Bob77 when you do get that lower housing off, it may just be the gasket holding it in place, if the broken bolt threads are proud of the casing It may be so much easier to remove them without damage to take the casing to a garage with a MIG welder and get a competent welder to mig weld nuts onto the protruding studs. This has the effect of heating the studs and if done right allows you to put a socket on the nut and with care and wd40 wind out the broken bits. So much easier than attempting to drill hard stainless broken bolts.
I used to use this method all the time to remove studs even those broken 5mm below the surface rather than attempt drilling which rarely goes as intended unless you have a specialist setup.
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Old 17 January 2021, 17:03   #8
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Excellent thanks oldman and spartacus.

I purchased in August as a honwave outfit and sold the boat and new to marine engines. The seller said "last year" for service and impeller but doesn't look like it,tsk tsk.

They are M6 x 50mm (look like galvanised steel) and spot on advice the thread of the bolt is longer than waterpump housing and must thread into the part below. I best order the other gasket and seals. Will pick up some marine grease (was going to use multi-purpose Lithium had lying around) and do as advised and drop leg regularly to grease.

I'm new to the hobby. Managed 7 outings inflating from car boot, then once on trailer so thought I would service ready this coming year....... at least I've discovered now. Cheers again for help.
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Old 17 January 2021, 17:27   #9
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Quote:
Originally Posted by Oldman2 View Post
If Bob77 when you do get that lower housing off, it may just be the gasket holding it in place, if the broken bolt threads are proud of the casing It may be so much easier to remove them without damage to take the casing to a garage with a MIG welder and get a competent welder to mig weld nuts onto the protruding studs. This has the effect of heating the studs and if done right allows you to put a socket on the nut and with care and wd40 wind out the broken bits. So much easier than attempting to drill hard stainless broken bolts.
I used to use this method all the time to remove studs even those broken 5mm below the surface rather than attempt drilling which rarely goes as intended unless you have a specialist setup.
Thanks that's really helpful . Looking at where they have snapped there could be 3mm or so poking out. I purchased a hobby MIG welder in the summer (ROHR 135a or similar) for the trailer, I got there eventually (but drilled and bolted after welding just in case) but I think I may take this to someone for a good weld as the hex bolts required a lot of force until they started undoing and after about 4 or 5 turns they snapped.
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Old 18 January 2021, 06:35   #10
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Strip as far as you can then find a local engineering company that can deal with the sheared bolts.

Last sheared bolt I had was on one of my RRC cylinder heads.
I have a lot of experience with mechanical things - incl sheared bolt removal - & tools but after a bit of thought took it to a local engine reconditioning specialist who I've had dealings with over many years.
Can't remember what they charged - not expensive - & they got it out by using an extractor. Not the screw like ones (which are usually useless & shear in the hole leaving an even bigger problem) but drilling the remains dead centre & using a fluted extractor. No damage to the head & I still have the removed remains as a souvenir!
For anyone in the Leicester area they are Neyta Motor Engineers in Leicester. No website but a google will get you their details.
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Old 20 January 2021, 06:45   #11
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Just weld a welding rod to it; it will get hot. Drill a hole, hit in a square thing and turn loose.
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Old 20 January 2021, 07:13   #12
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What's the latest update with this Bob?

Soak the waterpump in Plus Gas, especially around the gasket area. I think the only thing that's holding this down is the gasket, which will be corroded. Give the housing a light tap all the way around with a hammer. Don't be tempted to drive a flathead screwdriver into the housing area where it joins the gasket, unless you see the area that has a step on it specifically for this task. You could run a Stanley blade around here, but just watch to lightly score.

I'm sure the housing isn't threaded, so with a bit of perseverance you should be able to lever it off, then you can get to work on the snapped bolts.
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