2.0L BKD - difficult to start hot

[mechanic]

Bought an 08 TDi Golf a few months ago. After I bought it I found it would crank for 10 seconds before starting, or not start at all when hot! Tested the battery under crank and found it dropping to 9.5V. Replaced battery with Varta original.

Now, it starts almost instantly when cold, but seems to crank for 3 or 4 seconds when hot and starts with a jerk. It's never let me down since the new battery, but it still isn't quite right.

It drives and operates flawlessy otherwise - a great car.


Has anyone else had this problem and/or solution?

[stickshift3000]

Hot start issues are fairly common with the bkd engine.

have you had it scanned for any fault codes?

[mechanic]

yeah, it's the first thing I did. No fault codes.

[Umai Naa!!]

What's the state of the intake flap and EGR valve like?

[mechanic]

intake flap operates normally, and there are no EGR DTCs. I'm pretty sure the EGR would log a DTC if it didn't operate normally.
Intake manifold inner walls are thinly covered with the normal carbon buildup.

I've read on other forums (USA) that the starter motors wear internally and this reduces the cranking speed. The engine code is different over there. Is this starter fault a problem in Australia too?

[mechanic]

intake flap operates normally, and there are no EGR DTCs. I'm pretty sure the EGR would log a DTC if it didn't operate normally.
Intake manifold inner walls are thinly covered with the normal carbon buildup.

I've read on other forums (USA) that the starter motors wear internally and this reduces the cranking speed. The engine code is different over there. Is this starter fault a problem in Australia too?

[Umai Naa!!]

There are starter motor-related issues, as well.

Basically, the injectors won't inject if the starter motor can't turn the engine any faster than 280rpm.

[poyta]

Are you waiting at least a 2-3 seconds for the glow plugs to warm up before turning the key?

[mechanic]

Yep, tried combinations of not waiting for glow plugs, waiting until lights extinguish, and reheating 2 or 3 times before cranking. It doesn't seem to make a difference to the hot start problem.
In any case, it only happens when the engine is at operating temperature. This fault can occur literally seconds after I switch it off after a good drive.
I could understand if it struggled to start when cold, but this goes against everything i've ever learned. The battery should be slightly above normal charge and cylinder compression will be at its highest. If it also struggled to start when cold, I would have a better chance of finding the problem... but I'm stumped!

280RPM huh? Do you have any more info on this?

[Umai Naa!!]

If you have a way of measuring the cranking speed, you'll be able to confirm this.

Basically, the technical bulletin went on to say; if the battery is good, but the cranking speed is less than 280rpm, replace the starter motor.

[ian]

I find I have starting problems when the engine is cold and has stood for a week, I find that if I turn the key and wait till the Glow plug light goes out and turn the ignition key again and wait for the glow pugs light to go out again it will start no problem
Before ive had to crank the engine for quite a while before it would start .

[mechanic]

I've got a handheld tacho that reflects a laser off a piece of reflective tape that I can attach to the crank pulley.
I'll check this weekend.

If cranking speed is below 280 RPM, why wouldn't it also be hard to start when cold? Do the glow plugs glow during a hot crank?
I wonder if the engine management system is programmed to not glow above a certain coolant temp...

[nutttr]

2.0L BKD - difficult to start hot

Same problem with mine... Problem hasn't gotten better or worse in the last 20,000k's, so oh well... On mine it is because it can't crank fast enough when hot.

The engine is a bit tighter presumably when hot and this probably causes a slightly lower cranking speed which means no start till it gets a bit more lubed?! Annoying... Sometimes it takes up to 5s to start, after waiting for glow plugs... I find it much better to start it straight away without waiting for glow plugs when it is hot and it starts better (presumably the battery has a little more power and makes it start a touch easier!)...

(edit - my reasons above are because the ecu doesn't let the engine get fuel until the magical rpm figure.... No idea... But I believe the glow plugs do work on a hot start....)

[Steve879]

Hello, just bought a 2007 TDi jetta and have so far been very happy with the car except for a small hot start issue, the car is just a little hard to start and then only sometimes! You can crank it and it will cough, stall, then crank and it starts, no problem with it once started, heaps of grunt and starts perfect when cold. I have read through this thread and a few others and that it may be a slowly cranking starter motor or a temp sensor? Has a brand new battery and has had a new injector pump in the last 20k. Bit of a shame as the rest of the new car experience has been great. Loving the fuel economy!

[glidn]

I had a 2.0 BKD golf TDI briefly I might add, less than 5 months.

I too had the hard starting issues, thankfully this was a condition of sale repair. the Battery was replaced but problem persisted.
Ended up being a Injector seal causing the problems. Once hot with expansion it was gapping air.

All 4 injectors seals where replaced and re-calibrated. Started first time every time after that.
They replaced the power Cable from the Battery to alternator as well.

I think I would still have owned it till today 4 years later, if it's fuel consumption (only 650km's per tank) was not on par to my MK5 GTI I had owned till last year.
Additionally, replacing the Mechatronics unit 5 times from collection till return. Lost all my hope in owning that car.