Reply
 
Thread Tools Search this Thread
 
Old 31 July 2011, 17:36   #1
Member
 
Country: UK - Scotland
Town: Aberdeen
Length: 5m +
Engine: Outboard Tohatsu
Join Date: Jul 2011
Posts: 20
Honda 20HP Cam Pulley Failure

Hi, a few days ago my Honda BF20D just stopped. Obvious that compression was not normal. Turned out that cambelt had jumped off and the cause of this was the cam pulley (hard plastic) had become loose on the metal hub part. Engine only 3 years old but 2nd hand so in truth don;t know how many hours run - but looks like new.
Anyone else had this problem? Other than replacing pulley, is there a more permanent fix so that it won't happen again. My faith in the reliability is seriously damaged!
__________________

__________________
gerry11m is offline   Reply With Quote
Old 01 August 2011, 02:47   #2
Member
 
spartacus's Avatar
 
Country: UK - Scotland
Town: Aberdeenshire
Boat name: Sula
Make: Ribcraft 4.8m
Length: 4m +
Engine: Tohatsu 60hp + aux
MMSI: 235087213
Join Date: Jun 2007
Posts: 3,267
RIBase
The only reason a belt should jump is through wear and tear. As suggested the pulley bearing could be shot, the belt itself was worn or it wasn't tensioned properly during installation. Not sure if there will be internal damage on the engine?
__________________

__________________
spartacus is offline   Reply With Quote
Old 01 August 2011, 05:13   #3
Member
 
Country: UK - England
Town: East Anglia
Boat name: Nimrod II
Make: Aerotec 380
Length: 3m +
Engine: Suzuki DF20 EFI
Join Date: Nov 2007
Posts: 3,275
Isn't this a plastic pulley that wears away on the shaft until it comes loose or falls right off? I've heard of it before. Pulley about 50 I think.
__________________
Fenlander is offline   Reply With Quote
Old 01 August 2011, 14:18   #4
Member
 
Country: UK - Scotland
Town: Aberdeen
Length: 5m +
Engine: Outboard Tohatsu
Join Date: Jul 2011
Posts: 20
Spartacus, pulley bearing is the camshaft bearing and is not worn. There is no provision for tensioning so lack of tension would have to be caused by a belt out of tolerance. Apparently there is no internal damage to engine (checked by Honda agent). Root cause as far as I can see was a faulty camshaft pulley with the plastic pulley becoming loose from the molded in metal hub part. Is this just a piece of crappy Honda design and/or manufacturing?

Also, I searched the net and came up with two identical failures on a Honda outboard forum.

Regards
__________________
gerry11m is offline   Reply With Quote
Old 01 August 2011, 15:10   #5
Member
 
Country: UK - England
Town: Looe
Make: Delta
Length: 4m +
Engine: Mercury
Join Date: Apr 2004
Posts: 1,335
I have seen loads of Honda's do this, the pulley breaks up and comes loose leaving the bolt in place. Cam belt comes off and most of the time the valves get bent. When i did a part number search the pulley is the same on there lawn mowers. We had 3 of these go last summer.
__________________
Black Dog Marine
www.blackdogmarine.com
Turbodiesel is offline   Reply With Quote
Old 01 August 2011, 15:21   #6
Member
 
spartacus's Avatar
 
Country: UK - Scotland
Town: Aberdeenshire
Boat name: Sula
Make: Ribcraft 4.8m
Length: 4m +
Engine: Tohatsu 60hp + aux
MMSI: 235087213
Join Date: Jun 2007
Posts: 3,267
RIBase
Quote:
Originally Posted by gerry11m View Post
Apparently there is no internal damage to engine (checked by Honda agent). Root cause as far as I can see was a faulty camshaft pulley with the plastic pulley becoming loose from the molded in metal hub part. Is this just a piece of crappy Honda design and/or manufacturing?
Good news.

Looks like it's a design error then. Can the new pulley be modified (in any way) to reduce the likelihood of it coming off again? See Turbodiesel's comments regards the same engine. Might be worth bringing it up with Honda UK to see what they advise.
__________________
spartacus is offline   Reply With Quote
Old 01 August 2011, 18:50   #7
Member
 
Country: UK - Scotland
Town: Aberdeen
Length: 5m +
Engine: Outboard Tohatsu
Join Date: Jul 2011
Posts: 20
Hi Turbodiesel, so no point in beating myself up for any part of causing this failure.

I would like to replace the pulley with an all metal part: don't care if it is not OEM.

Regards
__________________
gerry11m is offline   Reply With Quote
Old 02 August 2011, 15:08   #8
Member
 
Country: UK - England
Town: Looe
Make: Delta
Length: 4m +
Engine: Mercury
Join Date: Apr 2004
Posts: 1,335
Honda told us the new pulley's we have fitted are different and upgraded. When they arrived they looked pretty much the same!. But who knows!?
__________________
Black Dog Marine
www.blackdogmarine.com
Turbodiesel is offline   Reply With Quote
Old 03 August 2011, 05:43   #9
Member
 
Country: UK - Scotland
Town: Aberdeen
Length: 5m +
Engine: Outboard Tohatsu
Join Date: Jul 2011
Posts: 20
Hi, the replacement pulley seemed to me to be exactly the same as the original.

One option to prevent a recurrence would be a flat metal washer that goes over the metal pully hub and the plastic pulley together with a longer bolt to attach to the camshaft.

I'll post a photo and sketch to explain. This would stop the plastic pulley moving upwards independently of the molded in metal hub (and hence throwing the belt). If I look at the witness marks that the belt makes on the pulley, the belt had been riding high by say 1/4" for some time. I would urge all Honda 20HP owners to check the belt tracking on the timing pulley, say every time the oil level is checked.

By the way, the only markings on the hub are "honda" and >PP-G< which I think referes to Polypropylene and the grade
__________________
gerry11m is offline   Reply With Quote
Old 04 August 2011, 07:53   #10
RIBnet supporter
 
Country: UK - England
Town: Sheffield
Length: no boat
Join Date: Feb 2010
Posts: 26
Hi gerry11m, could you post a short idiots guide on how to check the belt tracking please? Can the timing pulley be easily accessed to be checked for wear?
__________________
Andy C is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 02:56.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.