190E 2.3-16 idler sprocket wear

190E 2.3-16, 190E 2.5-16, 190E Evolution 1 & 2 models
16v specific information.
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oz coz
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190E 2.3-16 idler sprocket wear

Post by oz coz » Mon 24 Oct, 2011 2:08 pm

Attached hopefully is a photo of the idler sprocket that recently was replaced and the new replacement idler sprocket.

The idler sprocket is part of the single row timing chain system and is located immediately below the inlet camshaft sprocket where it redirects the chain to the distributor drive sprocket. The whole timing chain system (chain, tensioner,guides, sprockets) has been replaced.

The cause of what came out however is still a bit of a mystery.

Sequentially, the crankshaft sprocket was perfect,
all the guides whilst old were intact and in reasonable shape, the exhaust camshaft sprocket was intact and could have been reused, the inlet camshaft sprocket showed signs of abnormal wear but could have been a borderline decision as to whether it needed replacing, the idler sprocket shows heavy abnormal wear, and the distributor drive sprocket shows heavy abnormal wear. The old chain was correct and could have been reused if necessary. It showed no signs of wear and had been joined correctly. The tensioner was OK and could have been reused if necessary.

The problem became evident with the noise of the chain making contact with something it shouldn't have which turned out to most likely be the oil pick-up pipe.

The car and motor have done only 110,000kms and has received over frequent oil and oil filter changes. The car is driven fairly gently as the pilot is a bit past his prime!

Any thoughts on this lot?
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oz coz

1986 190E 2.3-16 Blue-Black
1990 300TE Diamond Blue
1987 190E 2.6 Signal Red

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oz coz
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Re: 190E 2.3-16 idler sprocket wear

Post by oz coz » Tue 01 Nov, 2011 7:11 am

A bit of research indicates that the oil spray to the distributor drive on the SOHC M102 was initially deleted from the 16 valve version but was reinstalled in the very late 2.3-16 engines. Can only assume that the original intent may have been to have more oil to pump to the top of the engine to cater for the needs of the two camshafts. The emergence of this type of wear may have been the reason for the oil feed to have been reinstated in the late 2.3-16 and all 2.5-16 together with the latter's oil needs for the double row chain.
Can anyone verify this?
oz coz

1986 190E 2.3-16 Blue-Black
1990 300TE Diamond Blue
1987 190E 2.6 Signal Red

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AMG
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Re: 190E 2.3-16 idler sprocket wear

Post by AMG » Tue 01 Nov, 2011 8:37 pm

You're making me nervous.... :clock: timebomb ???
Current:
1987 560SL 4sp. auto Signalrot "Stella"
1987 190E 2.3-16 5sp. man. Blauschwarz "Hermann"
1992 300CE-24 6sp. man. Perlblau / Iceblau "Gretel"
1992 Range Rover Vogue SE 4sp auto Ardenne Green "Oswald"
2012 Renault Sport Megane RS265 Trophy 8:08 6 sp. man. Liquid Yellow "Jean Rédélé"
Previous:
1986 560SEL Anthracitgrau "Schultz" - In Mercedes Heaven
1987 190E 2.6 4sp. auto Signalrot "Sabine" - which now resides/owns Andrew M's Garage
1972 350SLC Astralsilber "Lurch" - now in the loving care of Craig B
1989 2.5-16 Blauschwarz 4sp. auto (parted) formerly owned by Derek/Hasan.

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oz coz
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Posts: 107
Joined: Wed 21 Mar, 2007 2:32 pm
Model you own: I own multiple different models
Location: Sydney, Australia.

Re: 190E 2.3-16 idler sprocket wear

Post by oz coz » Thu 03 Nov, 2011 10:45 am

Hi Joe,

No, I don't think that it is a a time bomb. I have seen quite a few high mileage 2.3-16's that would not have had the oil feed to the distributor drive and which have not shown wear in the timing chain area at such a low mileage as mine did. But one member of 190REV posted exactly the same problem with the sprockets in the timing case area with photos of similar damage.

It is a bit of a guess but it would appear to be a bit of a few things which when combined add up to a problem. It does seem to be a lack of lubrication on one side of the timing case area coupled with the meshing of metals of different strengths. In particular the chain and crankshaft sprocket are hardened steel whilst the idler sprocket and distributor drive sprockets are castings. What the latter are actually made of I don't know but they sure have had the daylights belted out of them by the chain!
oz coz

1986 190E 2.3-16 Blue-Black
1990 300TE Diamond Blue
1987 190E 2.6 Signal Red

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