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Old 06-19-2017, 08:32 PM   #1
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Default Damage skeg and misfire 2100sc

Dear Owners Club!
I have been a fan for a year now thanks for all the information gleaned already!
Unfortunately time for me to have a problem!

I have had my 2100sc for a year. 5.0 Carb onboard with alpha drive.
I am in the uk and have only had a dozen outings so far.
The outing before last I hit the bottom of the river at low tide, so in my infinite wisdom?!? I decided to Wot to get me out of the mud. After about 30 seconds this worked. All seemed well.....
The boat is kept on a trailer and I noticed some scuffs on the prop but that was it.
Took out last night and noticed a lack of pic up and some water spraying up from behind the boat. I raised the leg and could see two chunks out of the skeg. One above the prop the other under. The upper was causing the water to spray up I guess? Ran the boat for about two hours, it needed almost near full throttle to make 35mph. I kept an eye on engine temp and all seemed ok but then it starded to misfire under load? If I dropped down to 1500rpm it seemed ok but any higher it missed and backfired???

Revs fine out of gear?

Please reprimand me for foolish behaviour, also any idea about misfire?
Could this be caused by skeg damage???
Could bearings have been damaged??
No noticible vibrations?
A little vague but as a novice any advice from someone who might have been in my situation would be welcome.

Many thanks in advance.
J
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Old 06-19-2017, 09:52 PM   #2
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Welcome to the joys of boating, happens to everyone at some time.

Skew is the vertical fin under the bullet (gear housing) of the drive. You can have it welded or if enough material remains install a skew guard.

The flat plate above the prop is the cavitation plate, a new piece can be welded on.

Remember thus is alumium so whoever is doing the repair must have the tool and knowledge to weld alumium.

Regarding not achieving proper rpm I bet the prop is damaged, either have it repaired or replace.

Reving an engine in neutral tells you nothing. A load on the engine is required to get any kind of data regarding an rpm above neutral. You may have fouled the spark plugs by running the engine this way. The shock of running aground may have knocked a spark plug wire lose.
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Old 06-20-2017, 01:47 PM   #3
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Moved from "Welcome Mat | New Member Introductions" to "General"

Welcome aboard "Woolnuts"!!! (I'm just scratching thinking about the name).

You might have a spun the prop hub slightly.

Also lookup 'SkegGuard' and 'Skeggard'. This is a slip on skeg replacement.
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Old 06-20-2017, 02:40 PM   #4
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I have the 2100SD with 5.0 MPI and also had a chunk removed from my skegg early on in my ownership. In my case, it was likely catching a rock when we ventured too close to shallows while skiing. At the time, we didnt notice anything...except loss of power.

The boat couldnt make any speed and I feared my 'new' boat had engine trouble. Once out of water, it was obvious. The prop had minor damage, but the efficiency was lost.
With a new prop and stainless Skegguard (sp?) hammered gently over the damaged skegg we were 'good as new'.

Good luck!
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Old 06-21-2017, 01:33 PM   #5
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Thanks for the replies, yes I have taken a big piece from the cav plate and a small chunk from the other. I have taken the boat to a local dealer and he says he will try and get it welded for me this weekend. I can see what looks like a hairline crack running up to the anode bolt hole? I hope that the welding will hold all this in place? The dealer mentioned a rubber unit inside the prop that should protect the drive from a shock, he then felt the play from the prop and said it seemed ok and that he would look into the misfire as a separate issue? I will update when I know more.......woolnuts.
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Old 06-21-2017, 03:24 PM   #6
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Quote:
Originally Posted by Woolnuts View Post
T The dealer mentioned a rubber unit inside the prop that should protect the drive from a shock...
That is the prop hub. Once the work is done, make sure you can still get up to a proper max rpm. I would consider replacing the hub. I have doubts as to whether this can be checked adequately by manually spinning the prop by hand with the engine in gear.
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Old 07-11-2017, 09:18 AM   #7
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Well....I have got the boat back with what looks like a fabulous repair to the cav plate. You would never know it had been broken! The boat had been taken out twice by the mechanic but the Misfire did not show its ugly head. I went out for two hours the other day, I checked the WOT as Shrew mentioned....only 4000 RPM and after 1.5 hours lo and behold the engine would not function under load. Once I limped back I took a novice look at the engine and pulled off the coil HT lead and it came apart in my hand leaving the interference fit end still inside the coil! So....I hope this may be the cause of the misfire and fingers crossed the low WOT rpm as this will be cheaper than a hub!
I will order a new set of leads and maybe some plugs for good measure and see how it goes!?!
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Old 07-11-2017, 11:26 AM   #8
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While I hope you are right it may actually be the coil. Since it took 1.5 hours this sounds like a thermal issue and common in coil failures.
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Old 07-13-2017, 08:37 PM   #9
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That does make sense mmwjr, I have added a coil (£40) to my shopping list.
Seems sensible to change it whilst I'm at it.
I hope to be able to do it in the next few weeks.
I will test and report findings.
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