Date: Mon, 31 Jan 2005 19:03:14 -0800
Reply-To: Mike Miller <mwmiller@CWNET.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Mike Miller <mwmiller@CWNET.COM>
Subject: Re: wrist pins Boston bob
In-Reply-To: <2ada01c507fd$910bd800$6601a8c0@yoursz6x6sefxo>
Content-type: text/plain; charset="US-ASCII"
Many thanks to the engine meister. Once again sense prevails. OK not
everywhere but my friend will be happy. I hope.
If this noise is the result of not align boring the case how long does the
engine have before another rebuild?
Thanks again, Bob.
Mike
On 1/31/05 5:27 PM, "ROBERT DONALDS" <donalds1@verizon.net> wrote:
> Mike, Jimt and fellow vanagon types
>
> The wrist pin noise is not what it sounds like pun intended The term wrist
> pin noise is a piston slap unless the bushing comes loose in the rod and the
> piston rattles around then its just called engine failure
> Wrist pin noise or piston slap is heard when the piston does not transition
> from one side (skirt) to the other just before the piston reaches
> TDC..Pistons are made with an offset wrist pin hole the offset is in the WBX
> piston is 1MM with this offset the piston gently transitions the piston
> unless of course you install the piston backwards. Other things that can
> cause a piston to not transaction are damaged pistons or tight fitting rod
> bushings . Most con rods also have an offset top to bottom the top sits a
> little
> to the left or right depending on what side of the engine we are talking
> about. When the rod is installed backwards it can touch the wrist pin boss
> of the piston and hold a little side pressure on the piston and this
> prevents the piston from transitioning and you can hear that for sure. I had
> one fellow bring in an WBX engine that he had taking apart more than once
> tiring to find the rapping noise with no luck I was brought in for the
> autopsy it was the rods on backwards
> The air cooled bug engines can have a wrist pin noise if the rod bushing is
> worn but its minor AND WOULD LAST FOR EVER most water cooled engine may
> have as much noises but the water jacket is a great noise damper
> One other thought about wrist pins is that if the bushing is damaged when
> the piston pin is installed then the bushing can come loose over time the
> signs of bushing damage is that the piston does not float on the con rod
> after it installed this is hard to check when the cylinder and piston go
> onto the rod at the same time with little room to wiggle the piston on the
> pin.
> I think that the chances are that its not a wrist pin noise but more likely
> a lifter, rocker or crank rattling around in the case. Loose main bearings
> are common in the 1.9 enignes at about 20 to 30Kwhen the block is not align
> bored at the time of the rebuilding or reassembling. If you suspect the
> main bearings are loose in the case check for exsessive crankshaft endplay
> its a dead giveaway for loose mains
>
> yes I ramble what's your point
>
>
> going faster miles an hour with the heat on
> I remain
> Bob Donalds
> Boston Engine
> http://www.bostonengine.com
>
>
> ----- Original Message -----
> From: "Mike Miller" <mwmiller@CWNET.COM>
> To: <vanagon@GERRY.VANAGON.COM>
> Sent: Saturday, January 29, 2005 2:58 PM
> Subject: Wrist pins
>
>
>> Volks, especially engine volks,
>>
>> A friend has a 85 van with less than 30k on a rebuilt engine. Mechanic
>> says
>> that the new noise in it is wrist pins, dump it.
>>
>> What are the chances it is wrist pins with that many miles?
>>
>> Is that an engine killer with van engines, or like piston slap in the
>> early
>> Audi 5 cylinders, let them slap?
>>
>> TIA
>>
>>
>> Mike
>>
>
>
>
>
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