1996 Discovery SE - 180,400 miles.

It seems to come more from underneath the car.

I was hoping it might be an exhaust leak, but I am afraid it is something more internal. It kind of seems like it is more pronounced when the engine is under more of a load.

It doesn't make this noise on a cold engine, but once it is warmed up it is pretty noisy - like when going down the road.

Thanks - Paul

 

Only thing i can think of that produces that noise when hot is a slipped liner or head gasket failure.

 

Dang, that's what I was afraid of. How does one positively diagnose that? What is involved in the fix if that is what the problem is (slipped cylinder liner/sleeve)?

 

Slipped liner requires a block pressure test. The fix is to pin them using set screws to hold them in place. Normally you'd remove the heads and then feel the difference between the deck and sleeve, should be none but a slipped liner will grab a finger nail. I'd have the oil pan off looking at shells and mic'ing journals....... kinda sounds like rod knock to me. You have a bunch of miles on the motor and I doubt it's been taken care of.

 

What's rod-knock and how is it fixed?

 

Go to youtube, search for "rod knock" and tell me if it sounds the same as yours. The world wide net is loaded with information about it. The bearings on your motor have 180k on em, they're tin coated copper, once through the tin coating they wear faster. You'll have to take a peek, just one will be enough to make you decide how much you like your Rover. I replaced the entire crank's worth at 120k. It's a common practice for us wrenches to replace to stall a complete rebuild until it's a must do.

 

can you do that by just taking the oil pan off?

I'll check out the videos on youtube and let you know if that's what it sounds like.

 

Yep, you can do it with the pan dropped, it's that easy. Best to have a caliper to measure your conrod journals with.

 

ok, not having good luck finding any sound bites of rod knock. I did find some good diagnosis articles though. Going to try shorting the sparkplugs one by one to see if I can identify any change in sound per cylinder. Also going to hook a timing light up and see if the noise is at engine rpm or half engine rpm. I think it is at engine rpm though.


I see a set of connecting rod bearings on ebay for $30 shipped - that's about all I want to stick into this thing at the moment...

 

Youtube had some pretty good clips of the sound. Con rod is a start, you can do the crank up to the rear main which would require you to disconnect the trans. I did em all except rear main. It helps to increase oil pressure by changing as many as possible.