I have a 1995 Disco with the 3.9l v8i motor. The engine runs great and the truck drives normal and has plenty of power and idles and runs smooth, until the truck reaches operating temp and it starts knocking but the engine still runs perfect. It almost sounds like a rod knock but it doesnt have the same symptons. Also as you increase rpms the knock gets quieter and if you romp on the throttle when the rpms drop it sounds like a rattle but at idle its consistent with rpms. Any ideas on where to start looking for this? THe guy I bough it off of said he thought it was a loose piston sleeve, is that possible? Any help is greatly appreciated, thanks.

 

First, stop driving it cause most likely your oil pump is failing and if you continue to drive it like that you will loose an engine.
How mechanical are you, or do you have a good mechanic that can check the oil pressure both cold at idle and 2000 RPM's and when warm at idle and 2000 RPM's.
Don't let anyone try and sell or fix anything till you get back to us with those 4 pressure readings.

 

Piston slap generally occurs at cold idle and goes away when hot.
First remove the fan belt and then run the engine in the driveway, is the noise still there?
With the truck cold tap on the catalytic converters and see if they rattle, then the guts fall apart it will rattle and can telescope up the exhaust and sound like rod knock.
Have you changed the oil? What oil and weight did you use?
What grade of gas are you using? How about the previous owner?

 

First off I am a mechanic at toyota and used to work at an independent land rover/jaguar shop, I do have less than two years experience but my dad was a gm tech for 30 years. I am currently not driving it, I drove it home from the guy I bought it from and parked it and it hasnt been registered for awhile so no one has been driving it. Any work that needs to be done will be done by me so I wont be having any work done by a shop. Im sure my dad has an oil pressure guage but where is the location of the port to hook it up?

 

I havent changed the oil yet, im using mid grade but I bought the truck with this problem and only drove it home and then parked it. I dont know what the previous owner was runing but he only had it parked as well, it was given to him with this problem. It makes no knocking noise when its cold it only starts knocking after it warms up. What oil and weight and filter do you recommend using? Ill try removing the belt and listening to it then.

 

I use and recommend 15w-40 and NAPA, Wix or Purolator oil filters, Fram is crap.
If you live in the snow belt then switch to 5w-40 for the winter.
If the wrong grade of gas (I know you bought it as a project and I am not yelling at you just trying to give you info to work with since you are a tech) is used for prolonged periods in these trucks the oil will bake in the heads and sludge them up, it will sludge up the valves and oil passages.
It is not uncommon for the oil to not drain back to the sump fast enough to keep the pump in adequate supply of oil and you can starve the engine.
There is no EGR on these and regular gas runs hotter than premium.
Look inside the oil fill hole and have a look.
If you cant find out what the noise is externally then flush the engine a couple of times and then drop the oil pan (pretty easy on these) and clean the oil pick up tube.
The oil PSI switch is right above the oil filter, and that is a common leak point, the PSI sending unit is porcelain and it cracks and leaks, $15 at AutoZone when I bought mine.

 

OK I need help again, I bought this oil pressure gauge http://www.harborfreight.com/engine-...kit-98949.html and there doesnt seem to be an adapter that is the right size, there is one the is close and will tighten up but as soon as you start the vehicle and pressure builds it starts leaking badly, any one know what the land rover adapter looks like and where I can get one?

 

There is a oil pressure sending unit thing that sandwiches between the oil filter and the filter mount and then you run your oil PSI gauge off of that, it will work on any car or truck.
I forget what it is called but several guys on here have bought one and there is a link somewhere on the forum.
I will see if I can find it unless you find it first.

 

My 97 was acting pretty much like that. Is it basically the same as you describe for the 3.9?

I was considering removing the valve covers just to take a look inside and see how badly sludges it may be. Is that advisable? Any precautions or specifics to look for?

All input greatly appreciated. I did pick up a deep well 8 mm socket to tighten the valve cover bolts with. but I kinda want to go ahead and pukk them and see what it looks like in there.

 

Yes.
Rover used the same V8 from the first RRC in '72? until the '04 model year.
Very minor changes.
For ~$1500 I could put a distributor and a 4BBL carb on my truck if I wanted too.

A flat tappet engine is a flat tappet engine is a flat tappet engine is a ...
The oil has to work harder because it not only lubes and cools the engine it also works the lifters because they are hydraulic and hydraulics work by PSI, when oil gets hot it gets thin, to thin and then you loose PSI and lifters get weak and valves dont open all the way and things get noisy.

On a OHC engine the oil just lubes and cools.