rational explanation sought

[ATG]

My car eats fuel and ECU relays. How? Why? They were both replaced about 2 years ago and now one of them has filled up with a corrosive, greasy mess. Where the french connection did this stuff come from?? I've managed to temporarily repair the corroded one with a contact chopped out of one of the relays that blew two years ago (never throw anything away, it may come in handy) and this will get me to the motor factor to buy a new one, so I'm back in action, but I really don't understand how these things can be so unreliable.

[v8 racing]

It could possibly be water leaking in, we have had a couple of griffs that have leaked water in this area so could be worth checking

[ATG]

Could be. It absolutely pissed with rain lastnight and the carpet next to the ECU is damp this morning. Arse. Will have to go hunting for dribbles the next time it rains hard.

Couldn't get an exact match for the relay at the factors. They had one that fits the same connector, but (a) it has a plastic, sealed case rather than the crimped steel one (which sounds like a benefit if its the damp that's killing them) and (b) it doesn't have a diode in series with the coil. I guess that diode is needed to protect other circuits from the back EMF when the relay's coil is switched off, so I'll splice some diodes into the loom. I was quite surprised at the strength of the back EMF. When I was testing the relays last night, one of them gave me a bit of a jolt as I disconnected it.

[mongoose]

ATG said:

Could be. It absolutely pissed with rain lastnight and the carpet next to the ECU is damp this morning. Arse. Will have to go hunting for dribbles the next time it rains hard. Couldn't get an exact match for the relay at the factors. They had one that fits the same connector, but (a) it has a plastic, sealed case rather than the crimped steel one (which sounds like a benefit if its the damp that's killing them) and (b) it doesn't have a diode in series with the coil. I guess that diode is needed to protect other circuits from the back EMF when the relay's coil is switched off, so I'll splice some diodes into the loom. I was quite surprised at the strength of the back EMF. When I was testing the relays last night, one of them gave me a bit of a jolt as I disconnected it.

If you look up your nearest Bosch agent,you can buy the original item for £7-8 from memory,my nearest one mailed me the parts.Your spot on about the diode,it'll do the ecu no good at all to recieve that back emf,and we did have a guy posting on here once,who's ecu packed up from what appeared to be that very problem!I will only ever use the proper Bosch relay now,and at that price i carry a new spare

[ATG]

OEM would have been great but I need the car fixed by tomorrow afternoon else g/f will have a major sense of humur failure. I rang around a load of our local factors and a couple of Landy specialists and no one seemed to have the original, which surprised me. Given that I'm currently relying on a relay that is held together with my enthusiatic soldering, anything is better than the status quo!

[andy-w]

I used the black plastic relays as a temp measure until i got the original ones.
If you do not pull them when you turn the ignition off you get a flat battery!!!!

Think it does mention this in the bible...also my ECU was shot and i was getting approx 6mpg and that was taking it easy!!!
Different ECU and it was fine!

[tahiti450]

v8 racing said:

It could possibly be water leaking in, we have had a couple of griffs that have leaked water in this area so could be worth checking

Could also be a leak from the heater pipework / matrix as this all sits just above the electrics, worth checking?

[ATG]

I had a good nose around today while I was splicing the diodes into the loom. The heater matrix pipes all felt dry and the moisture doesn't appear to be coolant, so I think I'm OK on that front, thank God. It looks like the water may be getting in through the doorseal about level with the passenger's knee, then running down behind the carpet to the floor. If so, there wouldn't be any water flowing near the relays themselves, but they would be sitting in very humid air. Ho hum. Will wait for the next rain storm and go looking for drips of water with a torch.