discovery 300 tdi advice needed!!

hi all i have a query about my 95 300 tdi discovery hope someone can help me get to the bottom of my problem, travelling up the m54 it overheated and cut out,i got to destination (luckily 1/2 mile of the 54) and i took out the thermostat and topped up with water then i found out that the header tank had split from the pressure,i fibreglassed it up and filled up again and it started with no problems and ran perfect,until i got another 50 mile (outside my front door...they do say a landrover will always get you home!!) and it started to sound rattly, next day i took another look at but it wasnt as simple this time it started but with a knocking sound through the intercooler pipe which i could actually feel through the pipe,anyway changed headgasket and all valves,all pushrods looked fine,put back together proper torque settings and sequence (not the 1st one ive done) but it still sounds the same a knocking sound through the intercooler pipe,ive listened with a bar all over the engine but cannot hear any knocking within the engine itself,when its on a high rev it sounds like its pinking like the timings out but i didnt have to disturb the timing belt ??????????? any ideas at all anyone as its very frustrating,all the rocker arms are fine no broken or chipped ones all the bores and pistons seem fine and lying underneath it when running it sounds normal its coming through the inlet manifold and travelling down the intercooler hose please help me to eliminate this horrible knocking sound,many thanks in advance........keith

Turbo goosed??

Injector ?

Injector overfueling?

thanks for reply lads would a faulty injector cause a horrible knocking sound ???

Its surely would... A way to see if it is an injector knock.....is to start the vehicle in neutral of course or it runs over your feet lol. then crack open one at a time the diesel feed pipes to each injector and note the engine tone and amount of diesel spurted out of each.Do them 1 at a time, crack open nut and then retighten.

thanks for the tip wolfydave ill try that out 1st thing in the morning,...if it dosent change engine tone what else could it be,standing by the exhaust its defintly missing sounds like its running on 3 but under bonnet seems nice and even apart from the knocking sound,the knocking sound is consistent with the engine speed...stressing to the limit as no other car....oh and the wife drives it too!!!!!

You could always blame the wife for breaking it and score for some beer tokens lol.

If it is popping out of the exhault and sounds like it has a pot off, sounds to me like a duff injector.

If you put your location on your profile you might be able to get some local help.

hi thanks for replys and advice ,i have uploaded a video of the knocking sound on you tube........link is........... [nomedia="http://www.youtube.com/watch?v=zWcSzE4SoqI"]YouTube- discovery 300tdi need help[/nomedia] ...........thanks again any ideas on this noise please post back...many thanks in advance.

If it's injector knock you will feel which it is if you put your fingers on the top of each of them in turn.

It sounds more like one of your pistons starting to melt to me. Get a long handled screwdriver or a pry bar and position the tip of it against the block and next to each of the cylinders in turn. Press your ear to the handle. It will act as a stethescope and help you locate your knock.

thanks for reply ratty ive held a bar against all parts of engine and underneath on sump and cant hear it anywhere except through the intercooler pipe from the inlet manifold.

......when head was off all pistons looked fine and the bores were imaculate i could still see the original homing marks there was no scoring at all and it dosent smoke at all either.

mud_man said:

thanks for reply ratty ive held a bar against all parts of engine and underneath on sump and cant hear it anywhere except through the intercooler pipe from the inlet manifold.

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Have you tried taking the oil filler cap off and seeing if it's breathing heavy?

......yes ive done that and it seems ok no smoke or back pressure coming through the filler cap.

mud_man said:

......yes ive done that and it seems ok no smoke or back pressure coming through the filler cap.

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does the noise get any louder when you do it?

....no the noise isnt any louder with filler cap off the only time its louder is when i take the pipe off the intercooler.

mud_man said:

....no the noise isnt any louder with filler cap off the only time its louder is when i take the pipe off the intercooler.

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In that case it sounds most likely that it's top end. Whip the rocker cover off and check the camshaft is properly bolted down and that the rockers are all correctly adjusted and the c springs between the rockers are all intact.

.....ill do that in the morning thank you so much for your advice its been drivin me mad i just couldnt work out where this knocking was coming from...ill keep u posted and let you know if i sort it..cheers for help

mud_man said:

.....ill do that in the morning thank you so much for your advice its been drivin me mad i just couldnt work out where this knocking was coming from...ill keep u posted and let you know if i sort it..cheers for help

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no probs. It'll be interesting to find out what it is.

just a quick update , it maybe pointing to an internal crack in the head ???....looks like an engine change is on the cards