Hey Guys, Well i have done the motor mounts, vacume hoses, oil change, filter, Mobil 1 syn 10w-40, seafoam , injector cleaner . Fixed all exhaust leaks and i still have this engine soft knock like its a TD5 Diesel. It is driving me up the wall. You can only here it on acceleration as it idels quiet , well it seems a bit robust than my daughters 2000 DII SE7. Her's is quiet as a mouse. I am ready to tear the top end apart as it's really driving me insane. Does anyone know the sound i am talking about? It's not a tick but a knock . i am at wits end. Chime in if you know what i am talking about. It has 120,000.00 miles on it and drives very smooth besides the frekin diesel sound. I am ready to take it to a engine shop to find out what the sound is.

Thanks Chris

 

Question
My 2004 Discovery has a engine knock under light to moderate acceleration under light load. It sounds like a wrist pin or a piston. It was present with no miles and now has 13K. The dealer and Rover say it is in the engine and have ordered a short block. This was 4 months ago and now they still can't get the part for the repair. I was informed that there are many other customers with the same problem. Are you aware of this and if so do you have any idea of the depth of the problem?

Answer


I am aware of a camshaft tappet problem that can be fixed (sort of) by installing a rubber button on Disco II's but I thought LR had fixed this by 2003. I think it was camshaft vibration against the front cover. Some owners complained that the fix only lasted 6 months to a year.

 

I was going to say have your oil pressure tested. Cold at idle and 2K, then warm at idle and 2K.

 

I have a 03 outside of the fatal vin range and it's had a slight soft knock on acceleration but is quiet at idle and can't be heard driving most of the time. Good oil pressure etc etc. I've just learned to live with it. The engine was extremely dirty inside when I got it.. I flushed it with a lot of diesel engine oil, engine flush, and now run rotella t6 synthetic 5w-40. I hardly ever hear it anymore. It was pretty loud for a while. I even went as far as to pull the valve covers and look at the rockers etc. Found nothing. My final opinion is that it was a very stubborn lifter that took a while to clean out enough to pump up and bleed air out. Remember.. It can take as much as 30 mins to get a clogged lifter pumped up enough to quieten down.. I would flush it and run some good oil for a few hundred miles before Id move on.

 

You probably already know, but:

I suggest strongly that you take it to the engine shop (not p-boys)

If you read repair or fault diag, in the rave manual, if it knocks louder or more consistantly under load, its a rod bearing.

A lifter does not knock, it clicks,

Those of us who have engine building experiance can hear a SUSPECTED rod knock coming down the street.

I'm not saving it is, but a decent shop will know quickly.

Having said that, they will, (you can), pull the oil pan, pull rod caps, if they can't see excessive wear, they'll put a micrometer on each crankshaft journal (or plasti-guage)
and check for wear.

Inspect the rod caps bearings for wear. (you'll probably see it)

In a perfect world the crank will be ok (it's harder than the bearings), you'll install a set of new bearings & the engine will be fine.

I'm confirming what you already know

That's what I would do.

This has nothing to do with any sec. air noises that may happen.

luck,greg

 

Has anyone thought about the knock sensors?

What grade and brand of gas are you using?

I had a Oldsmobile that I bought brand new with the 3.1 and it "knocked" like that from day one when hot and still did it when I sold it 120,000 miles later.

 

I havent checked that. I am running super and have run seafoam every other tankfull. It has had a little more than two tankfulls . Just about 700 miles. I think i am turning **** as having driven a p38 95 RR for 300,000,000 miles i am constantlly looking at the temp gauge every 2 minutes... Like you said buick never had a problem with the engine until land rover laid there hand on it. idiots...

Thanks Chris

 

I have a feeling you are the winner...i have a real hunch you are right. I will take next week when i can find a engine builder. Thanks for the reply, I really appreciate it. Thanks...

All the best Chris

 

Hey There, thanks for the info. So you can actually run this in a non diesel truck? Would i be hurting anything if i ran in my 2004 Discovery with 120,000 miles? At the very least i guess it could help clean out the engine.I am in florida and its always hot...and now that summer is here, very hot..

Thanks Chris

 

Any one with an internal engine noise needs to first do a oil pressure tested as posted earlier, that is a must before doing anything else.
If the pressure is good, then have the rocker shaft, arms, push rods and lifters inspected for wear. Any one of these will cause the problems and they are not a major issue.