300Tdi Disco - I'm Confussed

[rb199]

Well as the title says I'm a little confussed with my 300Tdi Disco. I have posted about its starting and power on 2 previous ocasions and am now back for more thoughts.

First off it has 121, 000 on the clock, is serviced regularly, uses no oil or coolant and there is no signs of oil in the coolant. Has no EGR valve and the intercooler has been cleaned. In addition it has had a slight pump tweak and had the CAM belt done (not by me) about 18 months ago after it snapped (just after I got it)! When the CAM belt was done a couple of rocker arms and push rods were replacedand the bores looked like new.

Now to my problems, firstly it is a funny starter and secondly I feel it is down on power. With respect to the starting, it seems to require more cranking on a cold (but not frosty) morning to start than my old 300Tdi D90. It also seems to be affected when left for a couple of days. I also feel that at high rev throttle settings it runs out of steam.

So my thoughts are that given its starting issues are not down to battery, glow plugs or earthing (all checked) both snags could be related. If they are related then I think its down to fueling problems or lack of compression?

If I'am barking up the right tree then my diagnosis route will be as follows:

1. Check timing

2. Check valve clearances

3. Check compression

4. Check sedimentor

5. Change lift pump

So why am I posting, well first off have I missed somthing obvious and secondly if the above does not fix it what are your thoughts.

Cheers in advance Stu

[JimAttrill]

Apart from the usual Tdi puff of black smoke, does it smoke when started from cold? If so, what colour is the smoke?

Is it an auto with one of those horrible EDC pumps? They are often almost impossible to start.

How do you intend to check the timing? Just with the pins in the injector and the flywheel? That's not very accurate.

I would also change the diesel filter or at least check that it isn't full of water.

[rb199]

It is a manual and there is only the usual puff of smoke at start up no white or blue. The only other time I get smoke is occasionly on overrun wich I have put down to worn valve stem oil seals. I was planing on checking the timing with pins, have you any other thoughts on how best to check? Thanks for the swift reply.

Stu

[JimAttrill]

We have a piezo sensor from Snap-on which bolts to the no 1 injector pipe and senses the pulse of the pump. That is connected to a standard petrol engine timing light. We turn the injector pump spindle until we get to 10 deg btdc. (there is a timing mark on the damper and another on the timing case). The standard setting are normally a bit retarded, somewhere around 4 deg. The trouble is that a tiny movement of the spindle makes a big difference so we often have to try it a few times. Sykes-Pickavant make a similar sensor, which may be a lot cheaper. If you could find a diesel specialist who has one they could maybe check your timing for you.

If you want to ádvance your ''igniton' without a light, turning the spindle clockwise relative to the sprocket will advance. If the engine has a hard knock you will have advanced it too far.

[Richard Mills]

Hi There,

On my 300tdi the sedimenter started to let a small ammount of air into the system, which didn't help much. Also the lift pump was a bit tired. After fixing both it revs better, starts well and tows much better. Good luck with it!

[Les Henson]

Lift pump failure will make it slightly more difficult to start and also reduce the revs. Partially blocked fuel filter will do much the same thing.

If your tappet gaps are too tight, then as the engine gets up to operating temperature - the gaps will become too tight (and possibly stay open a small amount). This will kill the higher revs as well.

Les.

[filthy]

Lift pump failure will make it slightly more difficult to start and also reduce the revs. Partially blocked fuel filter will do much the same thing.

If your tappet gaps are too tight, then as the engine gets up to operating temperature - the gaps will become too tight (and possibly stay open a small amount). This will kill the higher revs as well.

Les.

Re all the advice left on the above replies - all relavent, good advice - carp trap under tank, lift pump, tight valves etc

Valve clearences are 2mm. I do mine with a hot engine.

Re over run - this is disturbing.

Might I suggest that you disconnect the crank breather from the turbo air intake tube & see how heavilly the engine is blowing from this tube when hot.

if too much gas is blowing out here, then OIL can go with it & start filling your intercooler. The engine can over run & do partial run-aways on this oil. This excess oil in the intercooler & the coating of oil in intercooler will drastically reduce the coolers effeciency at mid/high revs.

You have a real risk of a total engine runaway if this is the case & the engine will destroy itself.

If you have a lot of gas blowing from the breather, simply duct it under the vehicle & plug the intake hole where once fitted - make damned sure that the plug cannot get sucked in or you will instantly destroy the turbo.

Remove intercooler & flush with petrol, then thoroughly flush with water. Allow to drain dry for hour or so & replace.

NOTE - under no circumstances refit a cooler that has any traces of petrol/vapour in it or engine will run-away & be destroyed & absolutely will not stop until it has smashed itself to bits.

The engine in my current Disco is on it's last legs & suffers from excessive crank pressure/breathing & has the above symptoms.

Good Luck

Filthy

[rb199]

Sorry for the delay in replying guys and thanks for the advice so far. What it has confirmed is that my thoughts on fuel issues could well be the cause so I'm going to look down that line first rather than the timing. I have also been told that the fuel return pipes can cause problems be letting air in so they are also going to get looked at.

Filthy, thanks for the reply, my post re smoke on over run was not that clear. It only smokes if it has been left for 8hrs plus and only the first couple of times on over run and never after. These are the same symptoms the old mini A series gave when the vlv stem oil seals were worn so I suspect thats all it is, that said I am going to look at the crank case breather.

Cheers fur noo

Stu

[TheRecklessEngineer]

Sounds very much like fuel to me.

Another vote for checking lift pump, filter and sedimenter.

[orangemach5]

I had a 200Tdi that had the same symptoms, it turned out to be the pump timing. Is it blue or white smoke on overrun, white smoke is unburnt diesel which could also point to the timing being out.

[rb199]

I had a 200Tdi that had the same symptoms, it turned out to be the pump timing. Is it blue or white smoke on overrun, white smoke is unburnt diesel which could also point to the timing being out.

Blue smoke on over run. As I had said above I did think about pump timing, so it may well get looked at too. That said it also started fine on Sun afternoon after sitting for 48hrs in the snow and wind!!! Do'nt you just love the green oval!

[TheRecklessEngineer]

Blue smoke tends to be oil - that is a little more concerning...I think filthy said everything I would in his post above.

[rb199]

Blue smoke tends to be oil - that is a little more concerning...I think filthy said everything I would in his post above.

Aye I'm not to fussed as it uses no oil and it only happens from cold once or twice then will not reoccur until the engine is cold and has stood for at least 8hrs. My understanding is that it is the rubber valve stem oil seals wearing and letting a little oil run down the valve stem when the engine is on overrun. My old mini did the same for ages until I had the time to take the head off and replace the seals.

I have checked the lift pump by cracking the bleed nut on top of the fuel filter and operating the lift pump lever, and I get fuel out. However is it posible the pump is still not great?

[TheRecklessEngineer]

Yes, check it with the engine running.

[George1]

We have a piezo sensor from Snap-on which bolts to the no 1 injector pipe and senses the pulse of the pump. That is connected to a standard petrol engine timing light. We turn the injector pump spindle until we get to 10 deg btdc. (there is a timing mark on the damper and another on the timing case). The standard setting are normally a bit retarded, somewhere around 4 deg. The trouble is that a tiny movement of the spindle makes a big difference so we often have to try it a few times. Sykes-Pickavant make a similar sensor, which may be a lot cheaper. If you could find a diesel specialist who has one they could maybe check your timing for you.

If you want to ádvance your ''igniton' without a light, turning the spindle clockwise relative to the sprocket will advance. If the engine has a hard knock you will have advanced it too far.

Hi guys

Regarding the comments of setting pump timing without the proper instruments, DON'T TRY IT!!!! or you will destroy the cylinder head if too much advanced, alternatively you will get bore erosion from unburnt diesel (overfuelling)this can also happen when the pump feed is set correctly but the start of injection is set too late.

I ground my teeth on a Golf 1 Diesel (1600), which has the same injection pump in principle but with pre-chamber and which I drove to over 1'000'000 million kilometres. In the beginning after I got it it went through 2 cylinder heads over 8000km, because the garage that fixed it set the pump timing without the proper tools. I then got myself the proper lift gauge and adapter and after that changed a cyl head after a further 580'000km, because it was just worn out.

The idea with the Snap-on piezo sensor is brilliant, because it allows an accurate timing on the running engine and is also much much quicker.

George1