Engine: D5244: Rattle on acceleration (injectors?)

[LankyTim]

Hi all,

I've got a 2002 V70 D5 with 230k on the clock. The engine runs fine except there's a distinct rattle on acceleration, between 1500 and 3000 rpm where the noise suddenly stops.

I'm fairly sure its an injector noise, maybe one isn't injecting enough fuel, or is injecting it at the wrong time. There's no smoke from the exhaust at all and a leak off test showed all injectors were well within the necessary parameters. The engine starts first time without fail and has a nice quiet idle.

One of the injectors (number 4) had a pronounced "thud" compared to the others while the engine was running, I could feel it by holding he top of the injector with the engine idling, I swapped it for another injector from my spares stash (which may or may not have been in the first flush of youth) and the rattle under acceleration virtually disappeared. The new injector didn't have the "thud" that the old one had and the engine felt much more powerful on acceleration. I also ran a can of "Liqui Moly diesel purge" on a closed circuit through the injector pump, as per instructions on youtube. Nothing nasty seemed to get cleared out although the engine did become quieter seemed to have better throttle response.

Overall, very pleased, the rattle had 90% vanished.

Fast forward a couple of weeks and after some long journeys the rattle is back, almost as bad as before, although the MPG seems to have improved.

Has anybody fixed this issue? My old 2002 V70 had exactly the same issue and I can see many other forum members have suffered similar symptoms with their D5 engines, many at fairly low mileages. Most don't seem to have found a cure though and some just accept the noise and slight lack of power. It doesn't seem to cause damage to the engine, just annoyance to the driver.

Would VIDA provide a live read out of the behavior of individual injectors while on the move? Maybe one or two of the injectors can deliver fuel into the cylinders at low engine speeds but lean out when there's a high demand for fuel, i.e when under acceleration.

Any advice or words of wisdom for this desperate Volvo driver?

[cheshired5]

Short answer, low ash mineral 2 stroke oil added to the fuel tank at a 1:200 dilution so for a full (70 litre) tank of fuel, add 350ml of 2 stroke.

Dirt cheap, very effective for the symptoms you have and doesn't need to be every single tank of fuel.

[LankyTim]

Thanks, I'll give it a go.

What does the 2 stroke oil do?

[cheshired5]

Originally Posted by LankyTim

What does the 2 stroke oil do?

It makes the diesel a little more "slippier" and lubricates the pump and injector mechanism.

[V70Zig]

Have a look here - https://www.ebay.co.uk/itm/5-Litre-2...sAAOSw7FRWUiaf

I buy it in the 5 litre as it's cost effective, fill a bottle with the correct amount and add to the tank as I fill up on the forecourt.

[MarvinMitt]

It benefits for the lubrication properties of low sulfur diesel.
However the Zinc content in 2 stroke oil causes minor injector fouling so it's like taking painkillers to go running with a twisted ankle.
In reality it might not foul the injectors that much to have a drastic effect, I don't know and I'm not using it, just a thing to consider before using 2 stroke oil in diesel.

[V70Zig]

I think that's why cheshired5 posted "low ash mineral" in his post above.
I used it in my old P1 for more than 100,000 miles with good effect and no problems. My current D5 gets a dose once a month....60k on and it's still running fine.

[LankyTim]

I usually run on bio diesel but recently have been running on pump diesel, i'm not sure if bio will make a difference one way or another in the long run. On other cars it usually has the effect of making the pump and injectors quieter.

[ASt85]

Originally Posted by MarvinMitt

It benefits for the lubrication properties of low sulfur diesel.
However the Zinc content in 2 stroke oil causes minor injector fouling so it's like taking painkillers to go running with a twisted ankle.
In reality it might not foul the injectors that much to have a drastic effect, I don't know and I'm not using it, just a thing to consider before using 2 stroke oil in diesel.

It may not be relevant to modern diesel engines, but my grandfather used to put paraffin in the bus fleet tanks to keep the diesel injectors clean.

The rate of dilution he used was around 1 gallon of paraffin to 250 gallons of diesel so in a V70 tank around 280ml ie just over half a pint, it also acts to reduce the gel point of diesel in winter.

[V70Zig]

Can't comment on the bio diesel as I've always used the pumps......