Honda 20HP Cam Pulley Failure

gerry11m · 31 July 2011, 21:36

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!

spartacus · 01 August 2011, 06:47

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?

Fenlander · 01 August 2011, 09:13

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.

gerry11m · 01 August 2011, 18:18

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

Turbodiesel · 01 August 2011, 19:10

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.

spartacus · 01 August 2011, 19:21

Quote:

Originally Posted by gerry11m

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.

gerry11m · 01 August 2011, 22:50

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

Turbodiesel · 02 August 2011, 19:08

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!?

gerry11m · 03 August 2011, 09:43

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

Andy C · 04 August 2011, 11:53

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?

gerry11m · 04 August 2011, 17:58

Andy, sure no problems.
-remove outboard cover.
-unplug wire going to temperature sensor? (above carb)
-move wires out of the way that go across rear plastic cover (top rear of engine)
-unplug rubber drain tubes either side
-remove rear plastic engine cover (held in place by two rubber grommets on rear of cover)
-check that cam belt is lined up with the pully. On its own the pulley can drop down towards cylinder head which allows the belt to ride up and flip off
-test camshaft pulley with slight hand pressure both sides pushing down (and look for cracks around metal hub)
-replace in reverse order

Andy C · 05 August 2011, 07:55

Just what I needed, much appreciated.

hector · 09 August 2011, 15:58

Is this fault happening in the mid ranged sized hondas aswell? Specifically the 50 and 60 hp models?

gerry11m · 09 August 2011, 23:18

Hector, no idea myself.

Are the pulleys made of a hard dark plastic? Is the inner hub (part of the pulley) made from metal)? If yes, I guess they could be prone to the same problem.

By the way, got the run around from Honda UK (in Swindon)

regards
G

fastlane · 24 March 2012, 20:44

I also have a Honda BF20 2008 in which has done 40 hours. Yesterday the cam gear broke 2 klm's offshore. It's a bad feeling

gerry11m · 29 March 2012, 22:08

Hi fastlane, what are Honda in Australia saying or offerring in way of a repair to prevent a reoccurence?

Regards
G

Turbodiesel · 30 March 2012, 19:30

We managed to get one repaired under warranty but we had to do alot of work to get Honda to pay out, the engine was under warranty just but they didnt want to pay out because the customer had not had it serviced on the dot each yeah. We argued that the pulley failure would have happened regardless of the servicing.

actions · 31 March 2012, 12:07

Anyone know if this is the same for the 2005 40hp model. Just thinking for the sake a few quid if it is i'll replace it.

Also is it this part??? Number 4 and 2??

fastlane · 09 April 2012, 09:13

The gear is completly different

Quote:

Originally Posted by actions

Anyone know if this is the same for the 2005 40hp model. Just thinking for the sake a few quid if it is i'll replace it.

Also is it this part??? Number 4 and 2??

fastlane · 09 April 2012, 09:23

The small dealership replaced the cam pulley and checked valve clearance for free. They did not know that it was problem with them. The motor did not have service history as i do it myself but had an hourmeter and looks as new. Their service was great