The day after I bought my 99 Disco the engine started ticking. The tick is always at Idle, athough I have a hard time telling if it is there when stone cold, as it also has a bit of an exhaust leak the masks some of the noise. The truck currently has 67k on it. I switched to Rotella T 15-W40 soon after I got it, and am running the larger K&N oil filter, which hasn't really helped too much with the tick. Just put in a 180 thermostat and switched to green coolant yesterday, which also had no impact on the tick, as some have reported. I have unfortunately not tested the oil pressure yet.

Today I was poking around under the Rover and had my friend rev the engine to see if the tick would go away at high RPMs, indicating a slipped liner. He accidentally revved up to about 4500, but I noticed the tick went away completely for about 15 seconds when it came back down to idle. I decided to try it again and this time held the engine at 3k for 20 seconds, and the tick goes away about 2 seconds after it's back at idle, and stays gone for about a minute or two. I've tried this about five different times, after idling and after driving, and it makes the tick go away every time.

Does anyone have any thoughts on what this could be? Possibly increased oil pressure at higher RPM getting to parts (probably lifter?) that aren't getting lubed at idle? Would switching to the synthetic Rotella help with this? Thanks for the help.

 

You need to back up and for now pretend it is not a dropped sleeve.
First, if you pull the oil fill cap and look at it on the inside, how dirty is it?
The first thing you need to rule out is low oil pressure, do you know how to do an oil pressure test? Needs to be tested cold at idle and 2000 RPM and again hot at idle and 2000 RPM's. Get those 4 numbers and get back to us.

 

I can see some deposits in the oil fill cap, but it's not completely covered. I was planning on picking up one of the oil pressure test gauges at Auto Zone, and tapping the port that I understand is on the front cover by the OEM pressure sender. I'll let you know as soon as I get the results. Thanks!

 

No, don't tap the front cover. Unscrew the oil PSI switch and screw in your test gauge.

As for slipped sleeve going away at speed, the liner can't reverse as fast as the piston, so eventually the up/down motion is reduced to the point it does not tap against the fire ring of the gasket. It is still moving, just not as much amplitude. Or it heats up and seats for a while. Some have drilled holes and bolted the liners in place, posted about it on here.

Equally could be oil PSI at high rev finally gets PSI it needs to be, then drops back down and valve tick returns. You can listen to valve covers thru a yardstick.

Once you remove the valve covers you have reached the world of enchantment. Might be a lot more sludge than you expected, can't see it thru oil filler because of the VC baffles.

 

.....

 

Ok, it's been a busy week, but I finally installed a pressure gauge under the hood until I can take the time to route one into the cabin. Went for the regular gauge so I don't have to keep hooking and unhooking a tester gauge during the course of my wild tick chase.

I'm waiting on the engine to cool down now, but hot idle is about 23-24 PSI, hot @ 2000 RPM is about 56 PSI. Both of these are higher than normal, but that's about all I know. Any thoughts? Also, when revving to 3000 RPM which still can make the tick go away, the oil pressure hits 62 PSI.

 

Got the cold readings, so:

Cold Idle : 60 PSI
Cold @ 2000: 62 PSI

Hot Idle : 24 PSI
Hot @ 2000: 56 PSI

 

Your gauge is readying a little high but the overall numbers look good.
As for the noise going away, any upper valve train or sleeve noise will go away when reved up.
If you want some help with this, PM me your number and I'll call you back.

 

Just got the intake manifold off, looks like the previous owner wasn't very fond of oil changes. I'm taking a break for a bit and haven't pulled the lifters to inspect yet, but I think I saw some signs of wear on the cam. I'll post some more pictures when I pull the lifters.

 

The operative word is "pull" lifters. Once valve train is released with four bolts, you may find lifters won't pull up, due to mushrooming. They will drop out the other way, when you change the cam. Your cam looks nice in the photos.