E320 coupe wiring loom

uk174 · 12-02-2009, 04:46 PM

Help,can any of you learned chaps please tell me how to check if the wiring loom on my e320 has been changed or is in need of a change.

Druk · 12-02-2009, 06:11 PM

You need to remove the cover from along the top of the injector rail and the top cover from the rocker box. Identify that part of the loom that runs from the main loom into the rocker cover that feeds to the three HT coils. With a scalpel very carefully slit the cloth insulation at the neck where the loom passes through the narrow gap and before it becomes encased in the rubber sheath. IIRC there are four wires in there, one large red(?) one which is the +VE feed and three smaller ones which are the trigger wires from the ECU to each coil pack. This place is where the wiring loom is likely to 'go' first. The inner coloured insulation should be intact with no sign of cracking or flaking. If it is then it's a new loom. It's the disturbing of this area when the plugs are changed at a service that causes all the grief.

imadoofus · 12-02-2009, 07:26 PM

At the NSF of the engine, there are a couple of plugs which are much easier to get to than the above.

Here's a picture of mine before it was replaced. Everything under the cover alongside the plug cover looked perfect.

dino645 · 12-02-2009, 08:01 PM

When I cut mine the wires inside had just disintegrated into fragments of wire - there was no insulation left at all. As I cut it tiny pieces of wire just fell out.

andy_k · 12-02-2009, 11:17 PM

if it has gone and needs replacing we managed to get a discount off MB Eastbourne for replacements - still expensive but cheaper than anywhere else.

If you need one, PM me for details

12-02-2009, 04:46 PM	#1
uk174 New Member Join Date: Oct 2008 Location: West midlands Car: E320 ,190cosworth,420 sl,e220 Est Posts: 26	E320 coupe wiring loom Help,can any of you learned chaps please tell me how to check if the wiring loom on my e320 has been changed or is in need of a change.

12-02-2009, 07:26 PM	#3
imadoofus Hardcore MB Enthusiast Join Date: May 2005 Car: This and that. Posts: 3,311	At the NSF of the engine, there are a couple of plugs which are much easier to get to than the above. Here's a picture of mine before it was replaced. Everything under the cover alongside the plug cover looked perfect. __________________

12-02-2009, 11:17 PM	#5
andy_k Events Committee Member Join Date: Apr 2003 Location: Bexhill, East sussex Car: E55 AMG Posts: 5,703	if it has gone and needs replacing we managed to get a discount off MB Eastbourne for replacements - still expensive but cheaper than anywhere else. If you need one, PM me for details __________________ <insert smart sounding witty comment here>

12-02-2009, 06:11 PM	#2
Druk Hardcore MB Enthusiast Join Date: May 2004 Location: Bathgate Car: w211 320 CDi Estate. 1981 280 R107 SL. 2007 Burstner Trecento 525TS. 1900 Gaff Cutter. 20ft. Posts: 943	You need to remove the cover from along the top of the injector rail and the top cover from the rocker box. Identify that part of the loom that runs from the main loom into the rocker cover that feeds to the three HT coils. With a scalpel very carefully slit the cloth insulation at the neck where the loom passes through the narrow gap and before it becomes encased in the rubber sheath. IIRC there are four wires in there, one large red(?) one which is the +VE feed and three smaller ones which are the trigger wires from the ECU to each coil pack. This place is where the wiring loom is likely to 'go' first. The inner coloured insulation should be intact with no sign of cracking or flaking. If it is then it's a new loom. It's the disturbing of this area when the plugs are changed at a service that causes all the grief.

12-02-2009, 08:01 PM	#4
dino645 Hardcore MB Enthusiast Join Date: Oct 2007 Location: Warwickshire Car: Mercedes E320 CE/ML270 Posts: 177	When I cut mine the wires inside had just disintegrated into fragments of wire - there was no insulation left at all. As I cut it tiny pieces of wire just fell out.

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