Tdi rough idle

**SiddersC** · 6th April 2010, 04:02 PM

HI all,

New to the world of diesels, and would like a bit of advice.

My 300TDi, has a vibration at idle that I think is excessive, it will make the transfer lever shake quite rapidly, and you can feel it through the whole car and in the drivers seat.

It does have a bit of blowby, so I am tossing up weather to remove the head and replace the gasket or not?, I am thinking it is blowing between cylinders and into an oil way?

How smooth are these motors normally?, and how much blowby is normal?, my oil filler cap just bounces around when removed, doesn't fly off or anything of that nature.

I am not too concerned about the gasket replacement as I have rebuilt many petrol motors and the 300TDi seems very simple after reading the rave manual, but would like to know if it is worth it, or will I be chasing my tail?.

It does not get hot, uses no oil or coolant, and drives really well apart from the rough idle, fuel filter and sedimenter have been serviced and the injection pump was rebuilt 20000K's ago.

Thanks in advance.

**SiddersC** · 6th April 2010, 04:04 PM

Forgot to mention that the timing belt was replaced 20000K's ago also, as it had some bottom end work done, so I am thinking that the head may have been torqued down wrong?

**loanrangie** · 6th April 2010, 06:32 PM

Originally Posted by SiddersC

Forgot to mention that the timing belt was replaced 20000K's ago also, as it had some bottom end work done, so I am thinking that the head may have been torqued down wrong?

Read the other post here about a rough tdi, it was loose tappets that was the cause.

**SiddersC** · 6th April 2010, 06:34 PM

I have just adjusted the tappets, it has made the vehicle much better in so many ways, but I still have the rough idle.

How smooth are they normally?, how much blowby is normal, just trying to work out weather to pull the head or not.

**Blknight.aus** · 6th April 2010, 08:06 PM

the cooling system will tell you if the head needs work.

you might have some dicey injectors. or low injection pressures.

**Discovering NZ** · 8th April 2010, 05:18 PM

Hi,I have a rebuilt 300tdi in good condition. It has quite a vibration at idle (so my wife says...) and I find that running 300ml of mineral 2 stroke oil per 75 liters diesel makes a significant difference to the smoothness of the idle and general running of the engine. Not sure about improving economy or power, but the smoothness is much improved. It keeps my wife happy... The subject of running 2T has been discussed a bit here on the form, some swear by it and others see no benefit. According to some sources, the 2T oil lubricates the injectors and pump. When diesel changed to low sulphur, the sulphur, while not a lubricant itself, reduced the lubriscosity of the fuel and some fuel pumps and injectors don't perform as well, plus wear out quicker with the newer fuel. Worth a try - could be a cheap fix.cheers and good luck

**AKW** · 8th April 2010, 09:02 PM

Check the engine mounts..Easy to replace.
2 stroke oil dose work my 200tdi is running at 31.5mpg
at 30ml/10l diesel.

Andrew

**brianwood** · 9th April 2010, 08:37 AM

It might seem obvious, but is the idle speed high enough?

**SiddersC** · 10th April 2010, 07:31 AM

Thanks for the replies,

Cooling system is fine, I think I need a new expansion cap because mine is not holding pressure, but it never gets hot and does't lose any coolant.

Engine mounts are O.K, near new, so can discount them.

It is idling at around 750 on the tach, but how acurate that is I don't know, sometimes the idle smooths out and then it can be rough again at the next stop.

I am running some injector cleaner through it at the minute, so will see how that goes, I will give the 2 stroke oil a go after that, can't hurt.

Cheers

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