Poorly Disco 300tdi

Good evening boys and girls, are you sitting comfortably, then I shall begin.

My 1998 300tdi disco is loosing power but not all the time.

It can be fine for weeks then it will rev to 3500 rpm in first and about 2500 rpm in all other gears and looses power so i have to back off to stop it smoking. It never smokes at all no matter how much I rev it. When the problem happens it smokes grey at first and then black.

I was thinking Turbo but I would think that wouldn't be intermittent?
I was also thinking injector possibly?

It starts fine all the time, runs spot on when the problem buggers off, not using water or any more oil that usual.

Any ideas before I pull it apart would be much appreciated

How many miles has it done?

Have you changed the lift pump at all?

tetsu0san said:

How many miles has it done?

Have you changed the lift pump at all?

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It's got 174000 on the clock but not convinced it's the original engine because I think I remember the last owner (member on here) mentioning a replacement, lift pump not changed in the 7 months I have had it.

Thanks for the reply

fuel filter? Or is it possible that there is something restricting air intake?

markav8r said:

fuel filter? Or is it possible that there is something restricting air intake?

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Not long had a service including filter but for what it cost I will swap it anyway. The bit that gets me is it being intermittent. I had a evo that done it every time it got to boost and that was a pipe collapsing.

Thanks for your reply

lpoolalan said:

Not long had a service including filter but for what it cost I will swap it anyway. The bit that gets me is it being intermittent. I had a evo that done it every time it got to boost and that was a pipe collapsing.

Thanks for your reply

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with black smoke thats what id be looking at

Might be worth testing/changing the lift pump as this is relatively cheap. And check the fuel lines for blockages. This can be done by blowing down them with a compressor.

And as markav8r said it could be a restriction. Intake pipes can delaminate before the turbo which could restrict air flow and could cause performance issues.

Brilliant thanks guys. I have a lift pump in my garage I can put on and maybe a filter aswel, I will give the fuel lines a blow through while I am at it and check the pipes from the air filter to the turbo.

I will post the solution after some messing tomorrow

Thanks again

Quick update.

Lift pump changed.
Fuel filter changed.
Fuel lines blew through.
Loads of messing with turbo hoses.

I think I will try swapping injectors and see if that helps.

Thanks again for the help

It doesn't sound like an injector problem to me. But I could be wrong.

Change the pipe from the fuel filter to the injector pump for a clear pipe, then look for air bubbles.

Just had a thought though. It could be a sticky wastegate or a sticky/stuck EGR. Remove the actuator arm from the wastegate and see if it moves freely. If not, try some penetrating oil or similar and keep moving it until it is very free. Also, have you blocked off the EGR at all? Might be worth doing if you haven't.

Me again. Does it rev OK when stationary? Does it only have this problem when driving? Either the wastegate or the EGR will cause problems more when driving that when stationary. Also a faulty EGR will usually give a lot of smoke if it's stuck open. If it's stuck shut then you usually only see an increase in performance and fuel economy!

tetsu0san said:

It doesn't sound like an injector problem to me. But I could be wrong.

Change the pipe from the fuel filter to the injector pump for a clear pipe, then look for air bubbles.

Just had a thought though. It could be a sticky wastegate or a sticky/stuck EGR. Remove the actuator arm from the wastegate and see if it moves freely. If not, try some penetrating oil or similar and keep moving it until it is very free. Also, have you blocked off the EGR at all? Might be worth doing if you haven't.

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EGR blocked off but I have just noticed a lot of carbon/sut around the blank so will have a fiddle with that.

Got a few meters of clear fuel resistant pipe here so will give that a go thanks, I was going to change the injectors anyway because I have 4 nice shinny new ones sat doing nothing.

As for the waste gate I will get the penetrating oil out and give it a go.

Thanks for your help, much appreciated

tetsu0san said:

Me again. Does it rev OK when stationary? Does it only have this problem when driving? Either the wastegate or the EGR will cause problems more when driving that when stationary. Also a faulty EGR will usually give a lot of smoke if it's stuck open. If it's stuck shut then you usually only see an increase in performance and fuel economy!

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When stationery it is fine and in first gear it's not to bad, as soon as I get above 2500 rpm in higher gears it just refuses to rev any further. I have noticed it's using more fuel than normal but that may be because I have changed my driving style to compensate. I give it the beans in first to get going then from there I am in 5th at 30 mph to stop it bogging down.

Thanks very much for your help I will continue to poke and prod around

Alan

Black smoke would indicate overfuelling which is probably due to a boost leak. I would pressure test the system and see if it holds 15psi. You will need to make up a kit, basically take the hoses off the compressor of the turbo and the intake manifold. Block one end and then you need something to block the other thats also got a tyre valve fitted. Pump it up and see if it holds pressure.

Tuskenraider said:

Black smoke would indicate overfuelling which is probably due to a boost leak. I would pressure test the system and see if it holds 15psi. You will need to make up a kit, basically take the hoses off the compressor of the turbo and the intake manifold. Block one end and then you need something to block the other thats also got a tyre valve fitted. Pump it up and see if it holds pressure.

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I am sure I could make something up then use my airline with tyre gauge.

Probably blow the thing to bits in the process lol.

I am leaning more towards boost because I have had similar on petrol cars but that was pipes collapsing on boost.

Thanks

Alan

(SOLVED)

After messing about for ages and finding intake and boost pipes full of oil I thought the worst.

The whole problem was caused by a bloody air filter, it had a cleanable one that must of been past its best.

Long story short the filter was clogged and causing a vacuum so it was pulling oil back up from the sump, I can't belive a filter can cause so much difference.

New high quality filter fitted and all is well.

Thank you all for your help.

Alan