G4 Owners Club

DII Nasty Tappet Like Rattle on Cold Start?

https://forum.g4ownersclub.com/Topic3112.aspx

By DarrenG - 21 Aug 2007

This started recently and sounds bad but may not be (fingers crossed!) When left overnight, upon starting their is a loud tapping sound that increases with revs but disappears quickly (within 10 secs) as the engine warms up.



Any ideas? I've only just returned from hols but will see if I can pin down the location of the rattle today. IST that loose exhaust manifold studs could be a possible cause?
By CraigS-L - 21 Aug 2007

I know it is a relatively old tech engine, but have you got hydraulic tappets (or something else in that mechanism)? A friend had an old Mazda MX-6 V6 that made an awful racket on starting, for about 5 secs, until the oil pressure filled the tappets, but was fine other than that.

Other problems (if it is oil draining down from where it shouldn't) are sometimes caused by the wrong oil filter being used, or the non return valve in the filter being broken - have you had it serviced recently?

By 110gary - 21 Aug 2007

Having a stab in the dark with the information you have given and not being able to hear it for myself id agree.  A hydraulic tappet could well be the cause but really without hearing it I wouldnt be sure. Your car does have hydraulic tappets but unfortunately even this is not a cheap job as its so labour intensive, plus quite a few parts are required in the way of gaskets etc. If i remember rightly book time is around 4 hours for the later Bosch injection system. The tappets/cam followers can wear over greater millage but this tends to be ticking noise all the time rather than dissapearing when it gets warm. Its more likely that its a faulty follower as these will be noisey untill the oil works it way inside. Best to leave it with your local specialist overnight so they can have a listen when its cold.
By g4mudman - 22 Aug 2007

Hi Darren,

Sounds like a hydraullic tappet, but I had a similar noise from my engine although it was there all the time, it went back to Keith Gott's for repair and it turned out to be a rocker sticking/seizing on the rocker shaft. Perhaps a call to KG may help.

Regards

Alan

By DarrenG - 22 Aug 2007

Cheers all, I did try to identify it yesterday but typically it didn't make the sound :crazy:
By General Lee - 22 Aug 2007

Darren,

If your Discovery has been stood for a few weeks , the oil will drain back and on first start up you will get the rattle. Now you are using it daily  no rattle ??

By DarrenG - 22 Aug 2007

It was happening before I left the car all alone whilst I went on my travels, I'm going to book it in with Keith Gott for a service when I get back from Dubai and have it looked at, I'll hopefully have a nice new performance exhaust from TD5Alive for them to fit as well, check out the V8 sound clip on their website :)