Content / V12 Engine / The Timing Chest - S3 E-Type

S3 E-Type

The Timing Chest
Tensioner & oil pump

by Administrator

Some quick views of these components on strip-down


The Crank pulley/damper is fitted to this conical piece which is in turn located on the front of the crank. Woodruff keys ensure alignment for balance/TDC positioning. Oil seal runs against a spacer on the crank, separating the cone from the timing sprocket.

timing_gear_12-26-2005_03.JPG

Here's the [upside-down] timing chest after removal of the sump. The bolt with the dowel seen on upper left of the pic is a guide for the cast oil gallery, already removed.
timing_gear_12-26-2005_02.JPG
Removing the front cover allows the chain to be seen, and the famous tensioner. The tensioner works by the spring tension forcing the plastic piece into an arced shape. The chain runs against the plastic effectively & "balancing" the spring tension.
timing_gear_12-26-2005_04.JPG
To release the tension in the device its possible to pull on one end to "flatten it out" allowing the  black rod parallel to the spring [and with a reduced diameter at its top end] to engage with the catch device which has a screwdriver-shaped oval hole in one side. This allows the tension to reapplied using a screwdriver thru a hole in the timing cover when the engine is built-up. [picture inverted, so tensioner appears 'correct' way up as it would in the car]
timing_gear_12-26-2005_05.JPG
The oil pump comes off as a complete unit.These generally don't wear very much, so there's normally no need to open it up unless a specific oil pressure problem was noted.
timing_gear_12-26-2005_08.JPG
It's driven by this gear directly off the crank:
timing_gear_12-26-2005_10.JPG

The timing chain guides are supposedly very carefully positioned. Because i dont have access to the tools needed to re-position these guides i chose to leave them in-place to avoid problems.
Comments
The Timing ChestGasman59|12 Mar : 20:34
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Did you replace the tensioner during your rebuild? This is one item that scares me a bit.

Re: The Timing ChestAdministrator |13 May : 11:00
Comments: 13


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Yes! I think a new tensioner is a must if you are in there anyway. I don't know how prone to failure they really are... it would appear that chronic long-term overheating of the engine combined with turning the engine backwards (which forces the tensioner 'flat') are probably required to make it break... but still, replacing a 30+ year old piece of Nylon seems prudent...

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