Thread: Disco ! V8 top end rattle

Originally Posted by nigelbuilding1984

Hi I just noticed my V8 disco 3.9 that has only done 165000 KMS 5000k oil changes developed a ticking noise from the top end from startup to about 2000 rpm on accelaration and then makes a light metalic rattle on de acelaration and i dont belive it to be an exauhst leak any help would be appreciated thanks oh it only sounds like one cylinder doing it too

Stop the car when it's doing it, open bonnet, put hand (careful its warm!) on top of plenum chamber, rev engine. If you feel knocking under your hand it's probably the intake trumpets loose under the plenum. A resonably quick fix, undo the six 6mm allen bolts, lift off cover, you need loctite retaining compound and maybe a hammer and anvil to slightly expand the trumpet bottom ends.

Originally Posted by nigelbuilding1984

Hi I just noticed my V8 disco 3.9 that has only done 165000 KMS 5000k oil changes developed a ticking noise from the top end from startup to about 2000 rpm on accelaration and then makes a light metalic rattle on de acelaration and i dont belive it to be an exauhst leak any help would be appreciated thanks oh it only sounds like one cylinder doing it too

I would say from my experience that at that many K's the engine is shot and will need major surgery!!! Ticking will be lifter(s) starved of oil possibly due to a shot oil pump or blocked pick up, Worn cam and timing chain could also be additng to the woes.

Originally Posted by bee utey

Stop the car when it's doing it, open bonnet, put hand (careful its warm!) on top of plenum chamber, rev engine. If you feel knocking under your hand it's probably the intake trumpets loose under the plenum. A resonably quick fix, undo the six 6mm allen bolts, lift off cover, you need loctite retaining compound and maybe a hammer and anvil to slightly expand the trumpet bottom ends.

I had a listen today and The noise didnt come from the plenum but with the screw driver used as a stethiscope i couldnt find the knock from anywhere this is starting to make me belive it may be a somthing as silly as a manifold leak i tightend it up and its a little queiter i think i warped the manifold a little pressure cleaning the other day i will try new exauhst gaskets first before anything more serious cheers

Originally Posted by INter674

I would say from my experience that at that many K's the engine is shot and will need major surgery!!! Ticking will be lifter(s) starved of oil possibly due to a shot oil pump or blocked pick up, Worn cam and timing chain could also be additng to the woes.

That many Km's? Thats not a lot of K's and although you could be right in what yoou are saying, many of these donks are still going strong at twice that.

turns out i was looking in the wrong place it wasnt the manifold leaking it was the flange gasket but the noise is really wierd for an exahust leak thats what made me think it was somthing more sinister thank you for your input.

Originally Posted by INter674

I would say from my experience that at that many K's the engine is shot and will need major surgery!!! .....

I tend to disagree with 5K/6 month oil changes and only 165K. Expect to see a tuned 3.9 with 250K still getting 85KW at the wheels and only using <0.5 litre oil per 5K.

My 3.9 V8 manual D1 (not gas) is now up-to 235K with 10K oil changes for the last 75K. I get a little bit of lifter noise when cold but other than some minor oozes (I would not call them leaks) all is well. Could probably do with a fuel system clean up (never touched the injectors). Currently uses about1 litre of oil every 5K (of which I think most is lost on the oozing)
Other than a water pump replaced and one cracked exhaust manifold all is well which is quite annoying because I really want to replace with a 4.6 but just can not seem to kill my 3.9. Hope to replace either motor or vehicle at 250K but if all is still going well then who am I to argue

I used to have a Discovery 3.5V8i I purchased it in Australia. It did about 250,000 Kms. I then shipped it to England and changed the body. It then did a further 50,000 Miles before I decided to rebuild it with a better Cam and some ported heads. I was not religious about the servicing but did change the oil fairly often. It still ran really well with no strange noises before I had it rebuilt. The only reason I had it rebuilt was that I wanted more power (got about 200bhp in the end). So it did around 300,000 Kms before I rebuilt it.
So the OP's engine at 165,00 Kms it's just about run in

Ivan