CJ1 Posted June 11, 2013 Share Posted June 11, 2013 For the last week my engine has been making a sort of irregular knocking/popping sort of sound which seems to be coming from the top right hand pulley area of my fan belt. I have had the belt replaced and the tensioner is fine. This noise speed doesn't seem to change much if at all with speed of the car or engine revs. You can feel it in the cabin too especially at lower end revs and under load. Any idea's please? Any advice would be greatly appreciated as I am really enjoying owning this Discovery. Cheers. Quote Link to comment Share on other sites More sharing options...
Tetsu0san Posted June 11, 2013 Share Posted June 11, 2013 Could it be valve clearances? Have you checked these recently? Problems can occur by the rocker shaft breaking/coming loose, the caps on the valves wearing through or just general wear and tear. When they are out if can cause a soft of booming/knocking sound which comes from the exhaust and inlet side of the engine because the combustion is being pushed back into the inlet. Run the engine up and take off the air filter box cover and see if it gets louder. Other than that could it be an alternator bearing or water pump problem? Quote Link to comment Share on other sites More sharing options...
CJ1 Posted June 11, 2013 Author Share Posted June 11, 2013 Air box cover removed and the noise gets louder. But no sound out of the exhaust at the back. Quote Link to comment Share on other sites More sharing options...
Tetsu0san Posted June 11, 2013 Share Posted June 11, 2013 You won't get the noise out of the back because that is where the noise is meant to go. Anyway, sounds like you found your problem. Take off the rocker cover and have a look. Might be just the clearances that need setting, but check it all including the rocker shaft itself. Quote Link to comment Share on other sites More sharing options...
CJ1 Posted June 11, 2013 Author Share Posted June 11, 2013 Thank you. I will get the rocker cover off tomorrow and will update what I find. Quote Link to comment Share on other sites More sharing options...
Marten Posted June 14, 2013 Share Posted June 14, 2013 I had the identical problem a while back and it was excessive clearance on an inlet valve tappet. In my case a new cam follower roller was soft and wearing rapidly. If you find one tappet with excessive clearance, but the adjuster screw and locknut are still tight, then you may feel inclined to investigate further, either by removing a side plate or taking the head off. It could just be a cam follower problem. Can you see all 8 heads of the bolts (injector side of the engine) that locate the tappet slide guides in the block? make sure they are all tight. Is the push-rod in good condition? Are the valve spring and collets correctly located? Is the cap that sits on top of the valve stem in place? You can't really see anything else with the head on. Quote Link to comment Share on other sites More sharing options...
reb78 Posted June 14, 2013 Share Posted June 14, 2013 or taking the head off. You can't really see anything else with the head on. Uh oh... Quote Link to comment Share on other sites More sharing options...
CJ1 Posted June 15, 2013 Author Share Posted June 15, 2013 The noise doesn't happen all the time, and I am not panicking about it. But will hopefully get round to getting the rocker off on Sunday. Quote Link to comment Share on other sites More sharing options...
black5f Posted August 2, 2013 Share Posted August 2, 2013 Hi. Mine has little caps on the top of the valve stems, one broke in half once, no idea where it went but suddenly a much bigger valve clearance so suddenly a much louder noise? That was 100k miles ago so clearly no damage, very easy to fix. Also, I had a bolt run loose on the little clamp that holds the injectors in. This made more of a puffing / wheezy noise but something very simple to check... bolt loose and you can feel the air blowing by the injector, fix, just tighten up the bolt. Hope this helps. Tom Quote Link to comment Share on other sites More sharing options...
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