D5 won’t start when hot, sometimes
 

I am on holiday in the middle of France. Twice on this holiday the engine has refused to start. The first time the car also shuddered a lot. The engine seems to be turning over normally. There are no error messages. The first time the car was very hot, towing a small caravan in a hilly area. The fan ran on at max speed for several minutes after turning the ignition off. Two hours later, after the car was loaded onto a tow truck for recovery, a last attempt was made to start it, and this was successful.

A week passed and the car was faultless including many hot starts. Then again it happened. Again towing, a hot day but engine not so hot and no fan. Not so shuddery this time. An hour later and awaiting recovery the 28th attempt to start it (!) was successful. Once again car just fine again.

The car is 2011 MY XC70 with 79k miles and full main dealer service history including only about 1,000 miles ago. I phoned the dealer and they have no idea what the problem is.

I am using Total Excellium diesel all holiday.

A helpful stranger showed me how to reveal error codes. This revealed 040 which might not be helpful as it is to do with air recirculation.

Anyone have any ideas?

Alec

Alecm

My knowledge of the D5 is not vast but an issue that befalls many a car in hot weather/ high temp situations (like towing) can be a failing crank position sensor.

Locate yours and have something cold to hand to spray it with, brake cleaner, plumbers freeze spray, cold compressed air or similar (be mindful of where anything flammable is being sprayed). Your looking to instantly cool the sensor then quickly try to start the vehicle.

If this fails, locate the temp sensor and do the same.

After this you really need diagnostics

HTH

Good luck

It does sound like a fuelling issue. If it was petrol I would suggest fuel evaporation due to heat soak but don't know if diesel is affected the same way. It could be an electrical issue with heat causing some 'breakdown' but I would expect that to probably show a fault code. Also check the diesel fuel cap, I have heard that that can have an affect but not sure how.

When was your diesel filter changed last? I don't know if heat would affect the starting as much but I have had problems in a Toyota in the past where car suddenly went into 'limp home' mode ( max 80 kph on the motorway, even slower on the hills - very scary as the trucks were just coming out for the night while crossing into Belgium), but without throwing any error codes whatsoever. Changed diesel filter the next day ( a common problem on the Toyota forums) and car was immediately back to normal.

Thanks, but I’ve no idea how to find either of the sensors you mention!
Plan is to allow enough time to get it to the ferry and take it to a dealer next week.
Btw the second time it failed I opened the bonnet, took the plastic engine cover off, and it started in one hour rather than two. So it looks like a heat related issue.
Alec

OK, update on this.
It's not a heat related issue at all. That was a red herring.
A week later (car 100% in the interim) the car would'nt start at campsite on journey back to ferry port. Volvo Assistance called (for third time). Car taken to local Renault garage (not to Volvo garage!) on Friday afternoon. They took it to Volvo garage on Monday who refused to accept it.
After days of prevarication tried again to start the car at local garage, no go.
Car taken to a different Volvo garage who wouldn't look at it straight away. This garage kept putting back further and further the expected date to even look at the car, until the time was expressed in weeks, not days.
Drove to this garage and again tried to start the car.

All the while couldn't accept offer of having car and us repatriated because that left the caravan stuck in France, as it wasn't "attached to the car" when the car broke down - it was 6 feet away. Eventually Volvo Assistance agreed to repatriate caravan as well. We flew back 8 days after scheduled end of our holiday, car and caravan followed 10 days later.

Where are we now? Still no car, nearly 4 weeks after breaking down. Car in local Volvo garage. Car starts! in fact, the recovery driver DROVE the car onto and off the transporter!
I visited the car at the Volvo garage to take them the key I had been using, and car would not start - with either key. Now again they say the car is starting.
The Volvo garage has said it can't be a key issue or there would be fault codes, and there are none. So they think it is something to do with fuel pump and associated wiring and propose they drop the tank to pursue this. Looks like I have little choice other than to accept this. No idea how this tale of woe will end.

The starting point is doing this.

I have a fair deal of experience with Bosch common rail diesel problems, albeit on Honda vehicles.

On that common rail implementation this problem would be caused by either the fuel rail pressure relief valve leaking and so returning fuel to the tank, or an injector with excessive leak-back flow returning too much fuel to the tank... either of these conditions would prevent the rail pressure reaching the 200 bar minimum while cranking required by the ECU to initiate injector operation.

Diagnosis would be performed by temporarily re-routing the individual tank returns into transparent containers, cranking for 30 seconds then comparing the collected volumes... zero should come from the rail valve and all injector returns should be roughly equal.

Many thanks Zebster. I have passed this information on to the Volvo garage.
Alec

Problem now diagnosed by Volvo main dealer: Corrosion of terminals on Fuel pump which apparently sits on top of the fuel tank. Cost to repair is £375 for the diagnosis plus £740 for pump, wiring loom, strap to hold fuel pump, labour etc. Oh and half a tank of fuel lost. Over £1,100 to pay when I get the car back on Monday.

Ouch.

Gone are the days when diagnosis is what the mechanic did to enable him to do the repair for which he was being paid. Then it was look, touch and listen and the referencing of his memory and experience that enabled him to know what work he was going to undertake. Today they plug in VIDA/DiCE but why they feel that they should charge you for that I do not know. Since I own a VIDA/DiCE, I am of a mind, if my car throws a fault, to present my garage with a printout and just tell them to do any work that my machine tells them to do!