Lumpy idle when cold

[Snail921]

My 2.5 diesel has a very lumpy idle when cold. Starts first turn of the key but then coughs and splutters,and sometimes cuts out, until working temp is reached.
Runs like silk once warm.
I'm using 40% veg but it was doing this
on all diesel
Any advice would be appreciated
Brian

[Gasy]

I'd start with glo plugs / relay
Fuel filter / banjo filter( little one in top of fuel pump )

[Snail921]

Thanks,Gasy. It's in for service and mot next week so I'll give them a heads up
Regards
Brian

[francophile1947]

Glow plugs for me

[roosmith]

Looks like a set of glow plugs for me too, exactly the same symptoms. It is definitely worse when running a higher percentage veg oil. I'd rather change the plugs than dilute the veg oil

How easy are plugs to do yourself? I've never had a diesel that needs them before.

[Diplomat]

How easy are plugs to do yourself? I've never had a diesel that needs them before.

A doddle the second time around! Not too difficult the first time, just takes an hour instead of half an hour.

Make sure you have deep enough box spanner type sockets to fit over the top of the glow plugs and don't drop any of the nuts and washers down into the under tray.

With the bus bar disconnected you can test them individually in situ and if any don't come out easily just leave them alone and deal with them another time rather than messing them up. Mine only has real difficulty starting with them all blown. One or two gone and you might not even notice it in summer, even on veg oil. Winter is the big test.


Frank

[teenmal]

Sounds very much like...Too much Cooking Oil ,or its not mixing properly.

[roosmith]

Thanks for the advice Frank. How do you test them?

Teenmal, too much veg oil is possible. With the ambient temperature being as high as it is and my rapeseed oil resembling water type viscosity I have been pushing it a bit I will admit On a long run at the weekend, after the engine had warmed up I topped up and was probably running a 90% mix but I did top up with another 30 litres diesel about 10 miles from the end, to give it enough time to mix up ready for the cold (ish) start the next morning. I repeated the procedure on the way back.

The only thorn in the side of that argument, that the mix is too high, is the lumpy start is evident on near 100% diesel and it has got worse of my 2 years of ownership.

I'll get the plugs changed at some point, after other more essential maintenance issues are addressed

[teenmal]

Thanks for the advice Frank. How do you test them?

Teenmal, too much veg oil is possible. With the ambient temperature being as high as it is and my rapeseed oil resembling water type viscosity I have been pushing it a bit I will admit On a long run at the weekend, after the engine had warmed up I topped up and was probably running a 90% mix but I did top up with another 30 litres diesel about 10 miles from the end, to give it enough time to mix up ready for the cold (ish) start the next morning. I repeated the procedure on the way back.

The only thorn in the side of that argument, that the mix is too high, is the lumpy start is evident on near 100% diesel and it has got worse of my 2 years of ownership.

I'll get the plugs changed at some point, after other more essential maintenance issues are addressed

In the 2 years you vehicles engine will probably(more than likely) have lost a bit of compression, the compression of A Diesel engine is vital to performance .

[roosmith]

And that is one of things top of my list, so that's interesting you should point that out. I have a slight chuffing from near side front corner which I can't diagnose with the naked eye, so that's top of the list to give to someone to investigate and while it was in, I was intending on getting the compression tested.

Are there any particular areas to look at if compression is found to be down?

[Diplomat]

Thanks for the advice Frank. How do you test them?

Make sure that nothing else is connected to each glow plug (for instance, all the others via the bus bar metal strip). Then, without removing them, either use a multimeter on the resistance range (or, if the meter has one, the continuity buzzer) or use a test lamp.

To test with a lamp, connect one side of a 12 volt test lamp to a known live 12 volt source in the wiring and the other side to the glow plug terminal. If good the lamp will light because the glow plug will behave electrically just like a solid wire to earth.

The resistance of each plug is very low so it is difficult with most cheap test meters to get a meaningful reading if you just test from the bus bar, with all plugs connected, to earth unless all the plugs have failed.


Frank

[teenmal]

You don't even need to go near the glow/heater plugs to check if they are working, this can be done in 5 minutes by checking the draw on the battery.

[The Great Pretender]

Lumpy startup, lets explore that. It is unburnt fuel. And running a mix allows unburnt veg to get onto the bores and then into the piston ring grooves, this can then gum up piston rings reducing their efficiency or worse. Running veg as a mix is ok as long as the engine is running fine, personally I would run 100% diesel until it was sorted.

[Diplomat]

You don't even need to go near the glow/heater plugs to check if they are working, this can be done in 5 minutes by checking the draw on the battery.

That is very true.

I have got a clip on (centre zero)ammeter which reads DC current in any wire without breaking into the circuit. I should have noted the total current drawn by a set of 4 good plugs and kept it for reference. For all I know, my plugs fitted over a year ago could already be failing, one by one.

When diagnosing possible battery/glow plug faults, bear in mind that a reasonably high battery reading at glow plug switch on might not be indicative of a good battery but, instead, failed glow plugs.


Frank

[mikeonb4c]

Lumpy startup, lets explore that. It is unburnt fuel. And running a mix allows unburnt veg to get onto the bores and then into the piston ring grooves, this can then gum up piston rings reducing their efficiency or worse. Running veg as a mix is ok as long as the engine is running fine, personally I would run 100% diesel until it was sorted.

That was always my concern about running with veg oil on a standard Bongo. I remember the days of Castrol R and two strokes: some may not!