2004 Discovery Tap Passenger Side

rosl8m · Oct 23, 2014

Hello everyone,

New to landroverworld! I've acquired a tap under the passenger side valve cover! I know there are many post about this tap, but I wanted someone with knowledge to help me out. On a cold start, the vehicle does not tap, but once it warms up, it starts tapping! Low rpms it taps, past 1000-1500 rpms it stops. I ran seafoam and changed the oil with rotela t6 5w-40. I believe i need a rocker shaft assembly, but I don't know. Please help! Thanks

grumpy_bottom · Oct 29, 2014

Likely a deflated lifter. Drain one or two quarts oil, replace with equal amount atf, run to operating temp, once temp is reached, rev to 3-4k for 3-5 minutes (essentially until tapping goes away). Drain oil and filter, replace with quality 10-40 synth. If it gets better bit doesn't go away, lather, rinse, repeat. If it doesn't improve at all, problem is almost certainly not a lifter, but from your description, this should work great.

Disco Mike · Oct 30, 2014

Whatever you do, do not ever rev an engine with ant amount of ATF. I have done and always recommended the use of ATF, but only as described by the manufactures over 20 years ago. Drain all oil, leave the old filter and install 5 to 6 quarts of ATF, turn off your A/C, keep the hood down and let the engine idle for 20 to 30 minutes watching the engine temp every 5 to 10 minutes.
Once done drain the fluid, replace the filter ith a Mobil 1-301 of a K&H 3001 both having a much larger capacity. Usually around 1000 miles changes it again to catch all the residual carbon and sludge.

grumpy_bottom · Oct 30, 2014

I've been told by Porsche, Ferrari, and BMW techs to rev, its necessary to get the oil pressure up enough to get the atf through the clogged passageways. I've done this on Z8s, Testarossas, and other higher performance cars, but never with 5-6 quarts...1-2 has always been plenty

Disco Mike · Oct 30, 2014

Doesn't mean it is right,
I have nearly 30 years managing dealers shops that suggested others don't do this unless it is done properly. Atf does not have a high enough vescosity to to prevent putting bearings under that sort of a load.

grumpy_bottom · Oct 30, 2014

I would counter that thirty years of not doing it doesn't make it wrong, nor does it in any way invalidate fourteen years of actual, empirical evidence showing that it works, and that its safe for engines that are subjected to far higher stresses than ours.

Disco Mike · Oct 31, 2014

Grumpy, go back and read the original statement, no noise till the engine warms up, lifters won't cause that. Also any good engine man will tell you, you never run a noisy engine at 4000 RPM's, with no load for a steady 3 or 4 minutes, unless your plans are to sell him a new engine.
Also, show us all the TSB's from your above mentioned manufactures recommending what you have described.

grumpy_bottom · Oct 31, 2014

I read it. Running 5w 40. 5w is getting through passages cold that 40w isn't when hot, at idle, when oil pressure is low. Rev, build pressure, lifter regains hydraulic pressure. I stand by my diagnosis. And tsbs? Are you serous? Some of the best mechanical diagnostics I've been around come from independent mechanics trying to fix the mechanical mistakes that manufacturers make and will never issue tsbs for because they don't want to admit liability or culpability

Disco Mike · Oct 31, 2014

By the way, most of the manufactures you quoted, don't run hydralics. I would stick with playing with others engines and not giving out bad advise on the forum.

grumpy_bottom · Oct 31, 2014

Disco Mike said:
By the way, most of the manufactures you quoted, don't run hydralics. I would stick with playing with others engines and not giving out bad advise on the forum.

Bmw m5...hydraulic lifters
Porsche 944 & 928..hydraulic lifters
Ferrari 355 (i misremembered that it was a Testrossa issue initially)...hydraulic lifters
Not to mention chevy small blocks i in spades, 283 & 327s galore in old Corvettes where this has worked as well

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2004 Discovery Tap Passenger Side

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