A moving target that doesn't move!
Ifirmly believe we’re born with a sense of fair play – otherwise why would young kids say ‘it’s not fair’ so often? It’s a human instinct to play by the rules. This urge isn’t shared by old Merc coupés. Having learnt last month that the Canems ECU is innocent of causing the persistent misfire (a verdict it shares with the plugs, leads, coil packs and sensors) I refitted the ignition system, determined to get to the bottom of the fault. The 500 SEC had other ideas.
Before I refitted the ECU I modified it by adding a heatsink to help keep the ignition drivers cool. Chris Savage, the EX-BBC electronics engineer friend who’d tested the box for me, suggested this as a precautionary measure to ensure no excess heat build-up in it, and as an alloy heatsink was a fiver and an hour’s work to fit, I took his advice willingly.
Sadly, I got caught out by one of those ebay sellers who pretend they’re UK based, but actually sell from China. I have nothing against Chinese stuff – in fact I get slightly irritated by people saying ‘Cheap Chinese rubbish,’ or other similarly pejorative remarks. The Apple computer I’m writing this on was made in China, as is my iphone. The Chinese have a space programme, for goodness sake. They’re not daft. They even made Ming vases.
Anyway, it wasn’t the heatsink’s nationality I was worried about, it was the time it took to arrive from China when the ebay listing had indicated it was coming from London. This slowed progress on the car, and in the intervening 10 days I lost some of my impetus to nail the problem. Which is when the Merc joined forces with the duplicitous ebay seller to completely thwart my remaining enthusiasm.
With the heatsink fitted and the ECU back in its passenger footwell home, I turned the key and discovered I also have a parasitic battery drain. There wasn’t even enough power in it to make an ignition light dimly glow. I have one of those very clever modern battery chargers – it’s so clever it doesn’t even
have a positive and negative lead. You just connect it up any old hoo and it works things out for itself. Unless the battery’s completely discharged, in which case it has no way of working out which way round it’s connected, so it just says ‘Battery Fail,’ and switches off.
When I say it says that, it doesn’t, my aforementioned iphone does, because the charger relies on an app installed on a phone to function. It’s too clever by half in my view, and utterly useless in this instance. I had to borrow a charger from a friend to reenergise the Merc’s battery. All this from a thing that has the brass neck to call itself a Smart Charger. It’s not as clever as it thinks it is, which is a fairly common theme, I’ve found.
With a full charge the starter span the 5-litre V8 enthusiastically, but it wouldn’t fire. I checked all my reassembly work but couldn’t find the mistake I was sure I’d made, so I had another go and drained yet more charge from the battery while the engine did nothing but enjoy a free ride from the starter. And then, suddenly, it caught. I’d love to tell you the misfire had gone, or even that it was still there, but the overwhelming stench of leaking petrol meant I killed the ignition so quickly I didn’t have time to notice.
A huge puddle of unleaded was forming underneath the car, and the smell filled me with fear. I lost a classic car to a fire some years back so I’m a little over-sensitive in this regard. Petrol is famously pretty sensitive to sources of ignition, so it was with some trepidation that I quickly disconnected the battery, worried that the parasitic drain would cause a spark as I pulled off the negative lead and send the whole garage up. As it sits under our bedroom, this wouldn’t have gone down very well with my wife. As it is, the elderly cat who shares the garage with the Merc overnight wasn’t wildly impressed with the new fragrance.
When I’d finished mopping up what felt like gallons of petrol (isn’t it amazing how little fluid you need to spill to make a slick, yet how much you need to make a journey?) a crawl under car resulted in me also smelling like a jerry can, and still not entirely sure where the leak was, although I did pinpoint an area from which petrol was still dripping.
While I was at it I also noticed a selection of flexible fuel lines coming to and from the tank and pump unit that looked like their time had been up several year ago, so decided the only safe course of action was to replace the lot. I also remembered that in the distant past I’d replaced a section of steel fuel line that had rusted through with some rubber pipe as a stop gap measure. It was long past the time to make that repair permanent with some new solid pipe.
I thoroughly enjoyed the bits of flaking underseal falling into my eyes as I struggled to remove the twin fuel pumps along with the large canister filter and pressure accumulator, but the dripping petrol helped wash them out of my eyes, so I was grateful for small mercies. Once off, the assembly presented a pretty grim picture. All the rubber hoses were shot, and I knew I’d never trust the steel ones again either. However, my idea of replacing all of them soon foundered on the rocks of financial reality, as the prospective bill edged over £500. Time for a rethink then. And I don’t care what anyone says, it just isn’t fair.