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Old 22 May 2017, 04:49   #1
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Sucked up mud!

First post here so sorry to be starting off asking for help!

I'm Ed, I bought a Bombard Explorer 5.5m with a 50HP Honda, 4 stroke about 6 weeks ago to use as a general safety boat while the kids are sailing and for a bit of fun.

When we took the boat out the first time we realised there were a few issues, mainly the engine was working on two cylinders, there wasn't any water coming from the tell tail and it seems to accumulate some water in the hull.

I took it to the boat yard and gave the ncie chap a cheque to get it all running well. He sorted out the engine nicely with new carbs, a full service and new impeller. The old one has 3 of it's 6 vanes broken.

We've been out in it a few times and we're happy. I took it out last night but while not paying enough attention we went through some mud as the tide was quite low. The engine was pumping out water beautifully before with a good strong tell tail, it's now a bit of a trickle which increases in strength as the revs rise.

I suspect maybe I've just sucked up mud, but I wonder if I could have damaged the new impeller?

What can I do? the boat is currently on it's mooring and I'm keen to try and solve this myself if I can. I've just read advice about putting strimmer wire up the tell tail to see if there is a blockage, is it worth trying? Or do I really need to take the lower unit off to get at the impeller? Could it just be that a few of the vanes are full of mud so it's only pumping on two?


Oh, and in the mud there must have been a stone as one of the prop blades is badly bent, looking around i see adds for BF90 props? Is this what I need of the engine?
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Old 22 May 2017, 05:50   #2
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If you have good reason to think you've pulled up enough mud to reduce the water flow prodding the tell tale is not the end you need to be concerned with in my opinion. Given that water flow is crucial to an engine I'd be looking first at the intake filter grids on the lower unit. If they look clear then nuisance that it is I'd just have to drop the lower unit to check what's going on with the impellor.

I don't know the cross compatibility between BF50 & BF90 props but obviously getting the pitch you want is important. What do you have at the moment and might a change improve the performance at all??

Other alternative is having it repaired. The prop repair guys are amazing at bringing back a prop from the dead.

Steel developments have given me good service in the past...

Propeller Repair Service
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Old 22 May 2017, 06:17   #3
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Quote:
Originally Posted by Fenlander View Post
If you have good reason to think you've pulled up enough mud to reduce the water flow prodding the tell tale is not the end you need to be concerned with in my opinion. Given that water flow is crucial to an engine I'd be looking first at the intake filter grids on the lower unit. If they look clear then nuisance that it is I'd just have to drop the lower unit to check what's going on with the impellor.

I don't know the cross compatibility between BF50 & BF90 props but obviously getting the pitch you want is important. What do you have at the moment and might a change improve the performance at all??

Other alternative is having it repaired. The prop repair guys are amazing at bring back a prop from the dead.

Steel developments have given me good service in the past...

Propeller Repair Service

The grills look clear when I raised the engine, maybe I just have to take it apart, or take it to the boat yard as I've got to fix my car this week thanks to the suspension collapsing this morning.

Excuse my ignorance but what is the difference between a BF50 and a BF90 prop? I only mentioned the BF90 as they is what I saw online. Should the engine have a BF50 - does the 50 indicate the power rating? Also, do all props fit or are they customer specific? I'm keen to just buy a good used on.
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Old 22 May 2017, 06:27   #4
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If you look at this prop chart it seems you need a 13 spline and the BF90 is a 15 spline... when you click on the detail seems too the BF90 has a larger dia gearcase.

Honda Prop Style Charts by Model | Solas Propellers
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Old 22 May 2017, 07:09   #5
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Thank you Fenlander.
Very helpful indeed.

First off I'm going to have to sort out the water issue by taking a look at the impeller and see if there is a blockage somewhere.
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Old 22 May 2017, 07:37   #6
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did they find the old vanes? if not has the thicker water [mud] dislodged them sealing off the water way?
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Old 22 May 2017, 07:59   #7
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I don't see any harm in poking strimmer wire up the tell tale... if the cooling flow might be poor (rather than non-existant) then I'd run at tick over only...
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Old 22 May 2017, 08:57   #8
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Does the engine have a flushing point to attach a hose pipe, iirc the Hondas do. See if you can back flush the engine
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Old 22 May 2017, 10:08   #9
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Thanks chaps, to confirm:
1. It does allow some water to come out at idle, just a trickle.
2. When you increase the revs, a faster flow comes out.
3. It does have a engine flush points.
4. When the impeller was replaced, all the vanes were still attached, just flattened to one side making it useless.

as the boat is "on the water", it makes accessing it that bit more tricky, I think I'll just have to get it on it's trailer and take a good look.

I suspect, given it pumping a bit and the flow gets better when the revs increase that I've managed to break some vanes on the new impeller already when it sucked in the mud.

If I get the engine out the water, it's only 4 bolts (from memory) to get the lower part (skegg???) off and from then accessing the impeller is just a few more bolts. If I do it at the boat yard I can plead for help if needed and buy a new impeller from them also if needed. I just need some time.
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Old 22 May 2017, 12:06   #10
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The hard part of dropping the lower leg is usually disconnecting and reconnecting the gear shift rod. Personally since it's afloat and you are going to drive it to the trailer I'd have a go at clearing the tell tale first.
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