JB750 Posted October 23, 2012 Share Posted October 23, 2012 Hi all. I have a wierd fault just appeared on the Disco. She is a 300Tdi auto (but I have replaced the EDC pump and throttle with mechanical). Truck has been running fine since last summer when I did the modification, but yesterday when I started it up after a week of not driving, there was a horrible knocking noise from somewhere in the engine area. A neighbour had a peek and suggested we take the belt off to check that it wasn't one of the aux illiary bits. removed the belt and hey presto! the noise dissappeared. Put the belt back on and it seemed to have gone still, but after a few minutes it came back but more intermittent. So I assumed that we had disturbed something and it was to do with either the water pump, power steering pump or alternator. I would not expect a water pump to make a noise that loud so started thinking that the steering pump or alternator were at fault. However, when I took the belt off again to check for play in the components, the noise is still there It seems to come and go but more often than not it happens on the overrun. It is a really loud knock and sound pretty expensive!! I was going to try and replace the injectors with some spare ones I have to see if maybe one of them is at fault but not really sure if that would be the cause? Any help or ideas would be great as I am worried now that it may be something more terminal :( I just tried uploading a .wav file I recorded but the site won't let me! John Quote Link to comment Share on other sites More sharing options...
PaulN Posted October 23, 2012 Share Posted October 23, 2012 Starters...until a grown up comes along I'd say it's worth a look at the crank pulley to see if it is slightly buckled on the inside edge and knocking on the block. There is very little clearance and it is hard to see the back edge rim of pulley (from underneath) but easily bent - especially if there is a bit of play....? Quote Link to comment Share on other sites More sharing options...
JB750 Posted October 23, 2012 Author Share Posted October 23, 2012 Nope, just checked that but it's waaaay too heavy for that! I've managed to record it: Most obvious around 10 to 20 secs then 1:10 to 1:40 Quote Link to comment Share on other sites More sharing options...
PaulN Posted October 23, 2012 Share Posted October 23, 2012 See what you mean!! Seems to catch up after the throttle is released and then something catches up or gets knocked out of he way - untill the end of the clip where it appears athe offending item isn't out of the way and continues to knock. Doesn't seem to effect engine running, reving or performance when it occurs though... Until I replayed the vid thought it might be the crank pulley wobbling when the belt goes slck again after engine back to idle? They do crack away - as you say it was different when aux belt was off... Appreciate it is quite a heavy sound... Sounds almost ancilliary though... Can you pinpoint the area coming from? Gawd - got a few more thoughts but I'd be guessing - hope someone can help identify it for you soon ATB, Paul. Quote Link to comment Share on other sites More sharing options...
JB750 Posted November 5, 2012 Author Share Posted November 5, 2012 Bump! Any ideas fellas? I'm stumped here Don't want to start stripping stuff down unecessarily 'cos I ain't got the time or the money! I can try and make another recording if that will help, but not sure about how long to run it in case it's Uber expensive! Quote Link to comment Share on other sites More sharing options...
jad Posted November 5, 2012 Share Posted November 5, 2012 Where are you from? you may have friendly neighborhood forumer that would come and have a listen. Jad Quote Link to comment Share on other sites More sharing options...
JB750 Posted November 6, 2012 Author Share Posted November 6, 2012 I'm in Burton, not far from Castle Combe, Chippenham in Wiltshire. JB Quote Link to comment Share on other sites More sharing options...
mdsmark Posted February 3, 2013 Share Posted February 3, 2013 hey mate im from australia, i was wondering if you managed to find what was causing the noise on your 300 tdi? mine is making the exact same sound. Quote Link to comment Share on other sites More sharing options...
Boydie Posted February 3, 2013 Share Posted February 3, 2013 My guess is your noise is coming from the vac pump, mine has the same noise and the pump is a new unit, the cam shaft only has a single lobe to operate the pump so it gives out a distinctive knock-knock-knock sound. An easy way to prove this is to remove the vac pump off the block cover the exposed camshaft with a wad of rag so prevent oil from splashing out and run the engine, with my 300TDi it was instant silence. If I'm right and the knocking is the vac pump I guess the only solution if you need a super quiet engine is to fit an electrtic vac pump and fit a blanking plate on the engine Quote Link to comment Share on other sites More sharing options...
mdsmark Posted February 3, 2013 Share Posted February 3, 2013 thanks ill have a go a testing it that way. originally thought it might be the big end, pulled the sump off, big ends had some wear but nothing extreme. checked main bearings 1-4 (the ones i could get to and they were fine) cylinder bores were fine as well no scoring or damage. car runs fine, no loss of power and doesn't blow any smoke. still makes the noise with all the belts removed and its not the harmonic balancer either. i did pull the vacuum pump off and the spring and everything internal seemed intact. pulled off the rocker cover as well, one of the valve caps was starting to get hammered flat, but everything else such as pushrods and valve springs etc are all fine. just waiting on a set of big end bearings and valve caps to arrive and ill put it back together to a stage where i can get it running and ill try the vac pump again. will keep you posted Quote Link to comment Share on other sites More sharing options...
mdsmark Posted March 3, 2013 Share Posted March 3, 2013 turns out it was the flex plate on the flywheel, know this now cos it finally let go on the highway. pulled out the engine and found it had sheared the whole way around. Quote Link to comment Share on other sites More sharing options...
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