Hello everyone, first of all I wanted to thank everyone for making this such a great resourceful community. This is my first post, but I have been lurking for some time and scouring for knowledge of my very first beloved Land Rover. I have a 99 Disco I and I have to tell you I love this thing more than any vehicle I have ever had. It has 109k on the clock currently.

When I first purchased the Disco I went to get it emmisions tested and it threw some 02 codes and a cylinder 7 misfire. I have since replaced all 4 o2 sensors, plugs and wires. I am still getting a P1193 code though

Now to the issue at hand. During one of the hotter days we have had here in the Chicagoland area I experienced a slight overheating. Since then I have had a knocking sound. I immediately changed the oil, the thermostat and replaced the coolant. This knocking is only present when the Disco warms up fully. It runs strong doesn't smoke or anything. I have attached the link to the video as well. Any help or direction is much appreciated. I am willing to put a little bit of money into this if needed.

video 2011 08 12 12 56 01 - YouTube

 

also, while wrenching on it today I did notice that there is a leak from the passenger side exhaust gasket that ties into the manifold. I'm sure it is unrelated but I wanted to give as much info as possible.

 

What oil do you use? Most people on here recommend a good diesel oil, like rotella 15w-40(or similar). Try running a heavier oil and see if it helps. You probably have a burnt bearing now from the overheating incident. Only way to cure that is to replace the problem bearings. It could be a rod knocking, or a main bearing.(disclaimer: I did not watch the video because I can't see youtube videos at work)

 

I went with the rotella 5w 30 and just switched to the heavier 15 w 40 with no quieting of the knock.

 

IMHO 5W oil is too thin for this beast except in the frozen north. The factory RAVE manual says you can run 20W50 in warm weather, might want to change to that el pronto. Others may suggest areas to check, but an old fashioned engine stethescope may help isolate the sound (valve train or bottom end). There have been posts about changing some of the lower end bearings with the engine still in the truck.

 

I have tried 3 different oil types, 5w30 10w40 20w50

 

Well, normally the overheating issue (from quantity of posts) causes head gasket failure, I guess because the heat is greater at the heads compared to the lower end. So perhaps some more poking around the valve covers. Old skool guys did not have a scanner or a stethoscope, they just placed a sawed off broom handle against the engine at spots and the other end to their ear. Actually works.

I saw the video. Your are correct to be most concerned. Perhaps one of the very experienced have heard this before and will comment. But I am not convinced it is a lower end noise, seems too rapid. Valve cover gaskets are cheap..... to inspect.

 

sounds like a valve train issue, remove the valve covers and see if you can pinpoint it closer from there, mine had a similar noise, turned out to be a bad rocker arm (or three), dont worry you wont make a oil mess by running it with the vlv covers off....let us know how it goes...........

 

Didn't listen to the video, but I can attest to the fact that an exhaust leak on these will making a tapping or slight knocking noise. Mine had a burnt y-pipe gasket. It made a big tappiung noise and you could feel the leak by placing your hand near the y-pipe junction.

Also changed to MaxLife oil and it made a world of difference as well. 5W30 is too light, but work your way thru it.

 

I hear both the tapping and the vacuum leak.
Mine tapped when there was a leak in the intake.
The tapping is not isolated... there is other noise like scraping: the water pump bearing comes to mind.
1- bring the engine to temp
2- turn it off
3- remove the belt after noting how it is routed (i've put it back the wrong way once)
4- spinn the alternator: any bearing/bushing noise?
5- wiggle the alternator pulley: any movement and it's to be replaced
6- tepeat 4 and 5 for the water pump, steering pump and might as well spin the A/C pulley as well.
7- turn the engine on and listen if the noise has changed. Dont run the engine more than 1 minute.
8- reinstall the belt (with the engine off, please)

Next you need to adress the vacuum leak: when was the last time you cleaned the oil separator? (If you don't know what i'm talking about... ask)Check the 1/2" hoses that run from the valve covers to the plenum for cracks.

Most of all don't despair or get angry... help allways come to those who ask.
I was saying that nothing was impossible, when a teen asked me to dribble a foot ball....

SD