Disco 2 Injector Harness TD5

Good evening,

There's been a lot of discussion about these and a lot of advice given, but I just wanted to know something in particular about these. The backstory is that I bought a Bearmach 'More durable than standard' wiring loom with a 3 year warranty and I filled the top of the pots and the plug with instant gasket, just to make sure! 2,000 miles later and there's oil in the red plug again and it's running like a bag of spanners. I'm puzzled by this.

I have since seen that Sierrafery recommends only a genuine part. I'm intrigued to know what it is about the construction of the genuine LR part that makes it superior to even the best copies. Does anyone know what it is, please?

BTW, Sierrafery, I've seen you apologise for your English and, I don't know where you're from but, your English is miles better than many people who speak English as their first language!

Happy New Year, folks!

You should consider the harness a serviceable part and replace annually, that is low milage I found them all to be pretty crap let's hope the warrenty is honoured . Which instant gasket did you use ?? And did you let it cure over night ?

biketeacherdave said:

You should consider the harness a serviceable part and replace annually, that is low milage I found them all to be pretty crap let's hope the warrenty is honoured . Which instant gasket did you use ?? And did you let it cure over night ?

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I used Loctite 5910 and let it cure for about 2 days. I'm not 100% sure that it is the best sealant to use. The warranty will have been invalidated by filling the pots!

RTV would have been better

Charlie Charles said:

Good evening,

There's been a lot of discussion about these and a lot of advice given, but I just wanted to know something in particular about these. The backstory is that I bought a Bearmach 'More durable than standard' wiring loom with a 3 year warranty and I filled the top of the pots and the plug with instant gasket, just to make sure! 2,000 miles later and there's oil in the red plug again and it's running like a bag of spanners. I'm puzzled by this.

I have since seen that Sierrafery recommends only a genuine part. I'm intrigued to know what it is about the construction of the genuine LR part that makes it superior to even the best copies. Does anyone know what it is, please?

BTW, Sierrafery, I've seen you apologise for your English and, I don't know where you're from but, your English is miles better than many people who speak English as their first language!

Happy New Year, folks!

Click to expand...

Hi, I replaced mine 2,000 miles ago & like yours I've noticed oil in the plug, eng. end & a small amount at the ecu red plug. I didn't think to try instant gasket but when I get a new loom I might try running super glue in it & gasket sealer so when I dig out the receipt I'll give the supplier a call to see where I stand. Luckily I've had no running issues. Happy New Year to all.

biketeacherdave said:

You should consider the harness a serviceable part and replace annually, that is low milage I found them all to be pretty crap let's hope the warrenty is honoured . Which instant gasket did you use ?? And did you let it cure over night ?

Click to expand...

Hi, have you found the genuine ones to be as bad as aftermarket?

biketeacherdave said:

serviceable part and replace annually,

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Ridiculous, replace when needed. Genuine will easily give 5 years + service.

Replaced mine x3 times during my ownership 1st was a genuine rest aftermarket.

I've just checked & I purchased mine on 04/07/21 & fitted at the end of that month, it had done about 1,000 miles when I first noticed oil at the red plug again but thought it was residue in the actual engine harness (despite using a can of contact cleaner on it) ! So I cleaned it again & checked it about 3 weeks ago & it still had oil in it. I've just done a 400 mile round trip so I'll have a look tomorrow if possible. Mine incidentally came with a 5 yr warranty !

Have you got excessive crankcase pressure in the cam cover?
That would probably push oil into the loom.
I've only changed the loom twice in more than 10 years of ownership - the 1st time 10 years ago due to oil in the red plug (no misfire). The 2nd time recently as preventative maintenance as I had to replace the cam cover seals.
Both times replaced with an OE loom.

Pawl said:

Have you got excessive crankcase pressure in the cam cover?
That would probably push oil into the loom.
I've only changed the loom twice in more than 10 years of ownership - the 1st time 10 years ago due to oil in the red plug (no misfire). The 2nd time recently as preventative maintenance as I had to replace the cam cover seals.
Both times replaced with an OE loom.

Click to expand...

Hi, that's a good question, I'm going to fit a new depression valve as there's some misting around it & in case it's faulty inside, otherwise it doesn't smoke/use oil.

Guys, I think I've found the problem. I took the harness out and the RTV, that I'd sealed the connectors and the plug with, is intact and I'm pretty sure that oil is not leaking through the wiring from the harness itself. I put an earbud into the male connector and it's dry. The oil is leaking around the o-rings on the male plug and into the female connections, then travelling up the wiring to the ECU. The o-rings look quite flat, which is surprising considering the limited mileage I've done since fitting the harness. I've ordered a couple of genuine o-rings (£11 with postage!) and hope that will fix it for a good while!

biketeacherdave said:

You should consider the harness a serviceable part and replace annually...

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Start of rant>

I spent the last 35 years of my working life designing electronics used in harsh environments, the last 15 years in the oil and gas industry where temperatures can reach 200C and pressures 10,000psi and more, often in a corrosive environment as well. We never had a connector leak, I never had a component or soldered joint fail and only the battery packs were considered service items.

It is beyond me to understand how or why the injector loom still causes problems with a temperature range rarely up to 100C and virtually zero differential pressure.

It's just a matter of choosing your components and materials appropriate to the environment that they are used in.

Rant over, thank you for listening.

PopPops said:

Start of rant>

I spent the last 35 years of my working life designing electronics used in harsh environments, the last 15 years in the oil and gas industry where temperatures can reach 200C and pressures 10,000psi and more, often in a corrosive environment as well. We never had a connector leak, I never had a component or soldered joint fail and only the battery packs were considered service items.

It is beyond me to understand how or why the injector loom still causes problems with a temperature range rarely up to 100C and virtually zero differential pressure.

It's just a matter of choosing your components and materials appropriate to the environment that they are used in.

Rant over, thank you for listening.

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You're right, it's a very poor design. I'm surprised at the number of counterintuitive component designs I've seen on cars, even BMWs and Mercs. I sometimes wonder what people are thinking!

Charlie Charles said:

Guys, I think I've found the problem. I took the harness out and the RTV, that I'd sealed the connectors and the plug with, is intact and I'm pretty sure that oil is not leaking through the wiring from the harness itself. I put an earbud into the male connector and it's dry. The oil is leaking around the o-rings on the male plug and into the female connections, then travelling up the wiring to the ECU. The o-rings look quite flat, which is surprising considering the limited mileage I've done since fitting the harness. I've ordered a couple of genuine o-rings (£11 with postage!) and hope that will fix it for a good while!

Click to expand...

You can split the ecu casing and check for oil ingress there to and clean as required.

Thanks, I already checked it and, thankfully, it's ok

On my D2 I had the mis fire. Replaced the loom and it was still there. Found it was a loose connection, there was oil in the ecu.

Could a lot of the problems with oil in injector harness plug be the cam cover pressurising due to the oil separation steel wadding , a faulty or blocked breather valve or collapsed breather hose

Hi, I suppose you could check for 'pressure' straight from the valve cover where the breather pipe goes on & then after the breather valve to see if there's a difference but how you judge whats ok I wouldn't know, I have seen mentioned just resting the oil filler cap on it's opening with the eng. running & it should barely move it ?
According to the parts list the valve cover up to eng. no. 1A736339 has the part no ERR6859, for eng no's after that it's LDR500210 until the end of production & there are two different part no's for the valve covers gaskets, does this mean you can't interchange the valve covers & were the later covers meant as a cure for oil in the harness due to excess pressure in the early ones, who knows ? (if that is the cause) but as far as I can tell all versions of the TD5 engines inj. harnesses suffer (or were the later ones better)?
For the 'early 10P' engines (not sure if they only went up to 1A736339) you can also buy the oil separator gasket so it looks like you could check the gauze (not sure how it's held to the underside of the valve cover or if it's removable on the later engines maybe others can let us know).
At the end of the day it's a PITA & like others have said should have been cured pre- production.
HNY

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