Engine Cut-out and Burning Smell

[Lionhead]

Hi all

I was nearing the end of a 200 mile journey today and all was well, but then I stopped at some traffic-lights and the engine suddenly cut-out without any warning. I could also smell a faint burning smell. I immediately tried to restart the engine and it started no problem and all was well for the rest of the journey.

I plugged in the OBD fault reader and there are no fault codes stored, so all seems well.

Any ideas of anything to check? Assume it's needle-in-a-haystack time without more information?

Cheers

[LTP]

An idea of the model, the engine, year, and possibly the transmission might help.

[Lionhead]

It's a 2008 V8 Vantage Coupe with Sports Shift Transmission.

[Calinours]

What is meant by ‘burning smell’? Assuming you know what clutch, brakes, tyres smell like when they get hot?

Assuming you can rule out the smell of burning rubber..

Were you really caning it? - suspect the brakes
Were you in a lot of stop start traffic ? - suspect the clutch. Ditto if you ride the clutch or get hard on the gas before the clutch is fully engaged (high bite point).

If oil is the smell, look for evidence of drips of oil landing on the exhaust manifolds.

[Lionhead]

Calinours said:

What is meant by ‘burning smell’? Assuming you know what clutch, brakes, tyres smell like when they get hot?

Assuming you can rule out the smell of burning rubber..

Were you really caning it? - suspect the brakes
Were you in a lot of stop start traffic ? - suspect the clutch. Ditto if you ride the clutch or get hard on the gas before the clutch is fully engaged (high bite point).

If oil is the smell, look for evidence of drips of oil landing on the exhaust manifolds.

Not sure I’d know the different smells other than rubber, and it didn’t smell like that. I wasn’t really caning it, was above 5k a few times just before but not by much. It had been mostly a gentle motorway journey and then ten mins of short stretches of dual carriageway. No riding of clutch because it’s SportsShift, and I’m adept at using SS these days. Brakes could make sense but that wouldn’t explain the engine cut-out. Will check for oil on the manifolds but again, wouldn’t explain the cut-out?

I ran over a sheet of plastic which I couldn’t avoid on the motorway outside Barcelona a couple of years ago which melted onto the underside of the car. I had to pull over and rip it off quickly on the excuse for a hard shoulder and when I got home took it to Bamford Rose who found various traces of plastic (it was a big sheet) and removed them. I wonder if there is still a bit stuck somewhere, although fells unlikely 7k miles later.

It’s the sudden cut-out that has concerned me more than the burning smell, rightly or wrongly.

[Calinours]

It may be that the two are related, maybe not. You don’t recognise if the smell was the same smell as before? - yes there may still be something lurking somewhere that has made its way into something hot.

Sportshift clutches can still get hot and burn, it’s actually more likely than a normal manual because sometimes the driver doesn’t realise that the car is continuously slipping the clutch, it happens in slow stop start traffic (especially if also uphill) and when reversing. Reversing uphill on full lock is the worst.

If the clutch was getting hot, you’d normally get a warning saying ‘clutch overheat, stop or pull away’ before the second stage of clutch overheat which from memory is either to disable gear selection or stop the engine. Again there would be a warning message. It may be that the temperature sensor, either a thermocouple or thermistor has failed, though I suspect that itself would generate an error message or a fault code.

It’s also likely that the engine stop could just be random and entirely unrelated to whatever is creating the smell. I’d advise to check all the fuses and relays for heat damage, then get the car up in the air and do a visual inspection of as much as possible focussing on the exhaust run from the cylinder head, and checking all fuel, oil, coolant and transmission lines and heat exchangers and other hydraulic fluid (brakes/sportshift/steering) lines for leaks. If nothing turns up all you can do is just keep driving to see if it happens again. The principle source of heat is the engine, and the hottest bits on the car are the exhaust manifolds. Look closely at these, and what is around and close to them. Check that the heat shield is still there on the LHS manifold. After that look at the catalysts, check for cable runs (like the O2 sensor lead) not coming in contact with any part of the exhaust. If you can get underneath, and get the under trays off, and get in with a torch, if something is there, you will see it. This is what a garage would do if you took the car to one and asked them to investigate.

If you do ever smell a slight burning again stop the car on a cleanish concrete surface and get out, lift the bonnet, look under the car for any leaks, touch (carefully) each wheel and tyre to determine if any tyre issue or brake binding or developing wheel bearing issue.

Plastic burning will have a distinctive smell.