Horrible knocking, high rpm and lack of boost (td5)

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Maciej

Maciej

Member
Posts
39
Location
Poland
Hello!

I have a 2002 td5 Discovery II with 270k kms or 168k miles, and some time ago it lost its power, it felt like the turbo wasn't kicking kicking in, so i started looking for the problem. yesterday i removed intercooler to check it for leaks and clean it, and when I put it back on and tried starting the car, it just made horrible noise and died after a second or two. Today i tried again, and the engine started, but it imidietly started making knocking noise and the rpms started rising, so i turned it very quickly. I was driving the car yesterday before removing intercooler and everything was as usual.
here is the list of the things I checked and did recently:
intercooler is fine
pipes from the turbo to intercooler and inlet manifold are fine
replaced MAP sensor
checked MAF sensor with multimeter
cleaned oil from the ECU plug, and check if there is oil in the ECU, but it was clean
wastegate and wastegate actuator work as they should
turbocharger seems fine
air filer is clean
fuel filter is brand new
fuel pump is brand new
Fuel pressure regulator is new
bypassed the wastegate modulator
i tried checking the faults with diagnostic computer but the one i have requires engine to be running, so i have to wait for my friend and hope his computer is better.
Anyone has any ideas what could be wrong? i'm honestly lost.

Sorry for any mistakes, English is not my first language.
Cheers!!
 
i cleaned it with extraction gasoline (i hope that's the correct term) i let it dry for some time in the sun and i don't feel the smell of it, so i think it's not the problem, but i will disconnect the pipes again, so if there is anything in there, it should evaporate
 
The fan does full circle without any problems and I don't see anything that could catch on the belt or pulleys.
 
Maciej said:
i cleaned it with extraction gasoline (i hope that's the correct term) i let it dry for some time in the sun and i don't feel the smell of it, so i think it's not the problem, but i will disconnect the pipes again, so if there is anything in there, it should evaporate
Click to expand...
As said above, any combustible fluids/vapours present in the inlet air tract will cause havoc with a diesel, (like spraying Aerostart or similar into an already running engine), the revving up of the engine is due to uncontrolled fuelling from vapours or in the case of a worn out diesel engine, engine oil, commonly called "runaway" where the engine can self destruct. To make sure they are (vapours) all evaporated out, disconnect the turbo inlet and outlet pipes from the intercooler and hook up a stream of compressed air to one side, (even a vacuum cleaner on the "blow/exhaust" side would do). then leave the air stream blowing through the intcooler for sufficient time to remove any smell of the cleaning fluid from the outlet air stream.
The lack of boost issue, it isn't clear to me if this condition existed before or after your cleaning efforts, and I'm not familiar with the operation of the Td5 turbo.
 
Last edited:
Stands to reason if the only thing he did was clean the intercooler then that is where the problem is likely to be coming from.
Needs to be thoroughly "rinsed" out with something that'll draw the cleaner away. I've used white spirit before and never had a problem, but then I did rinse it out with water after that then drain it and dry it very thoroughly afterwards.
Vacuum cleaner reminds me of a guy building a Kit Car who very nearly burnt his house down.
He had cleaned out the donor car's petrol tank very thoroughly, but wanted to be sure to get out all the rust dust. So he used the vacuum cleaner. Only problem was that that turned the VC into a jet engine, as the electric motor ingnited the petrol fumes, it shot backwards and knocked over the buckets he had used to store the petrol in that he had drained from the tank. They then burst into flames and set the garage on fire. He lost his Kit, the donor vehicle in fact the whole garage!
So be carefull with vacuum cleaners and inflamable vapours!
 
Reminds me of the cautionary tale I was told when first learning to dive of the diver who placed a fully charged tank between the front seats of his Ford Fiesta. The sun beat down on the parked car and Boyle's Law being what it is, eventually the pressure built up beyond the tank's overpressure limit. The pillar valve fired out forwards through the instrument panel and bulkhead and was only stopped when it hit the block.

Personally I used Screwfix No Nonsense HD Degreaser the last time I cleaned out an intercooler. Slosh around for a minute or two, pour away the black muck, rinse and leave to dry.
 
Si Click said:
Reminds me of the cautionary tale I was told when first learning to dive of the diver who placed a fully charged tank between the front seats of his Ford Fiesta. The sun beat down on the parked car and Boyle's Law being what it is, eventually the pressure built up beyond the tank's overpressure limit. The pillar valve fired out forwards through the instrument panel and bulkhead and was only stopped when it hit the block.

Personally I used Screwfix No Nonsense HD Degreaser the last time I cleaned out an intercooler. Slosh around for a minute or two, pour away the black muck, rinse and leave to dry.
Click to expand...
Like the story! Not only dogs should not be kept in cars!
The Screwfix stuff sounds good to me. Jizer, etc all fine. To be completely honest, you could use petrol, it would dissolve the muck and rubble very well and get rid of it too if you used enough, that is not the problem! It is getting rid of the vapours afterwards, for which you could just use water, but then you have to drain it all out and let it dry. Do I hear anyone say "put it in the oven???!!!"
There is I am sure official LR stuff, but I bet it's a price!
 
thank you all for the replies!!
Fumes in the intercooler make sense and maybe they also cause the knocking noise since they probably completly mess up the fuel mix. Today i will try to remove any fumes with some compressed air and try again.

Gazbo said:
The lack of boost issue, it isn't clear to me if this condition existed before or after your cleaning efforts, and I'm not familiar with the operation of the Td5 turbo.
Click to expand...

yes, it existed before i messed things up. i read the faults yesterday, but the only one i got was the ambient air pressure sensor, i will try dissconnecting it/
 
yes it has, i checked mine with the multimeter and it seemed fine, but i will try disconnecting it to check if it makes a difference
 
As @Stanleysteamer said, you can't be sure about MAF unless you take a live OBD reading. A VOM meter will test the supply and the ground but anything of relevance to the ECU must be tested with engine running at different revs. You will be able to see voltage variations on the input line to the ECU but what's important here is how the ECU is interpreting the non linear signalling. Hence why an OBD scanner is crucial to diagnose the MAF. I had the same experience as Stanleysteamer, in the sense that once I changed from an After-Market to an OEM MAF, the vehicle was unrecognisable in terms of response and performance improvement. That said, the symptoms you describe are a bit too extreme to suggest a MAF failure but there's no harm in disconnecting it and see what happens.
 
NPG said:
As @Stanleysteamer said, you can't be sure about MAF unless you take a live OBD reading. A VOM meter will test the supply and the ground but anything of relevance to the ECU must be tested with engine running at different revs. You will be able to see voltage variations on the input line to the ECU but what's important here is how the ECU is interpreting the non linear signalling. Hence why an OBD scanner is crucial to diagnose the MAF. I had the same experience as Stanleysteamer, in the sense that once I changed from an After-Market to an OEM MAF, the vehicle was unrecognisable in terms of response and performance improvement. That said, the symptoms you describe are a bit too extreme to suggest a MAF failure but there's no harm in disconnecting it and see what happens.
Click to expand...

All valid points except that as this is a TD5 an OBD scanner will not work. Ideally you need a Nanocom as this records live data; a Hawkeye Total is cheaper, works on most LRs and shows live data, but it does not record it so you need someone else in the cab. The Foxwell NT 510 to 530 will also work apparently and are a much cheaper alternative.
 
Today I finally got enough courage to try and start the car. it was sitting for a couple days with disconnected intercooler and today I removed the rest of the fumes with vacuum cleaner, and the car started without high rpms and without weird noises (not from the engine at least). Huge thank you to everyone, i'm so happy!!
But it's not exactly problem free, i had to bleed the fuel system (by pressing gas pedal 5 times) and crank it for a couple seconds. When i was waiting for the system to bleed i did some reading and it turns out, that the fuel pump shouldn't be so loud. I had the car for over two years and i just thought it's supposed to be like that. i have a small leak between the fuel filter and water in filter sensor, could that be the reason? the filter is Mahle if that makes any difference.
 
Good to hear you're back in business. Air in the fuel rail can also result in the engine to run erratically and the fuel pump will go into purge mode every time you turn on the ignition. You can check the fuel pressure for signs that the pump might be on its way out (should read around 4 to 4.5 bar) but before you do that, you need to make sure that the fuel system is entirely sealed. There are 3 rubber seals on the fuel filter - 2 on top for the housing and 1 at the bottom for the water sensor. You might want to check that none of the old seals got stuck in there when you replaced the filter. This happens sometimes and you will need to remove them manually before you install the new one.
 
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