Clapping Tappets

Engines and Engine Systems
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Michael
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Clapping Tappets

Post by Michael » 10 Feb 2017 14:08

So here is one for the guys doing maintenance on their own vehicles.

I am sure everyone that have adjusted their Patrols tappets before have always found this one tappet that just doesn't want to stop clapping hands. No matter how hard you try to get the clearance perfect, it just sounds like one is set incorrectly.

Well....I might have found the problem to this.

While building a TD42 engine I did a close inspection on the rocker shaft and the individual rockers and found that the area that presses on the valve itself, has a very shiny dent in. This is very slight on most of them and you could barely feel it, but on two of them, the dent was quite deep and very noticeable.

Now the problem comes in when setting the valve clearance with a feeler gauge. the blade is as broad as the rocker and the area that is dented is about 6/7mm. This means that if you set your air gap to 0.30mm and the dent is another 0.2mm deep you end up with a 0.5mm tappet clearance.

The fix was very simple, I used a flappy disc on my angle grinder, and very carefully polished every rocker until the dented area was flat again like it should be. It is really not a big job to remove the whole rocker shaft when the tappet cover is off and anyone that has a little bit of DIY skill can pull it off.
Attachments
rocker_dent.jpg
visible dent in rocker
rocker_dent.jpg (172.56 KiB) Viewed 715 times
rocker_fixed.jpg
The end result
rocker_fixed.jpg (200.94 KiB) Viewed 715 times
"The Just shall live by Faith" Rom1:17

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Peter Connan
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Re: Clapping Tappets

Post by Peter Connan » 10 Feb 2017 17:02

That makes sense, but be very careful with the grinding. If you make that face skew, you could cause all sorts of issues.

Wonder if it wouldn't be easier to buy a second set of feeler gauges and grind the applicable blades down to something narrower than the valve stem?
Mag ons ons kenniskry met lekkerkry aanhoukry.

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Michael
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Re: Clapping Tappets

Post by Michael » 10 Feb 2017 17:50

Look I think the safest option will be to take it to an engineering shop to do, but you really only polish the surface with a flap disc and I dont see any major risk in this.

Besides the valve will make a new mark on the rocker face and start creating a new "dent" within time.
"The Just shall live by Faith" Rom1:17

Check out my build here My Patrol
And my engine rebuild here mostly engine related stuff

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Peter Connan
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Re: Clapping Tappets

Post by Peter Connan » 06 Mar 2017 05:22

I serviced my car yesterday, setting the tappets with my newly-modified narrower feeler gauges.

Wow! for the first time ever, my Patrol doesn't clap hands all the time.

Thanks Michael!
Mag ons ons kenniskry met lekkerkry aanhoukry.

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offroadbiker
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Re: Clapping Tappets

Post by offroadbiker » 06 Mar 2017 08:01

The only "clapping" tappet in my vehicle is the one behind the steering wheel :surprised: Any assistance their Michael???
Dirk
1996 Nissan Patrol 4.2 ST

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ricster
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Re: Clapping Tappets

Post by ricster » 06 Mar 2017 08:56

Dirk ...... :rolling: :rolling: you are beyond needing a flappy paddle ..... :rolling: :rolling: :rolling:
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Michael
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Re: Clapping Tappets

Post by Michael » 06 Mar 2017 09:54

Peter, its just a pleasure. Glad to see someone could benefit from my finding.

Dirk...... jys op jou eie ou maat :lol:
"The Just shall live by Faith" Rom1:17

Check out my build here My Patrol
And my engine rebuild here mostly engine related stuff

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