P38A Range Rover question about engine knocking

Bexer · Oct 26, 2016

Hi all

There is a problem with P38 4.0 gems engine - knocks from right side of engine, which worn off after ~1500 rpm. Also I can't hear any knocks from left side, so I suppose that it is one of hydraulic valve lifters, but may be it is something else, which is located on the right side and generate knocks like that? Thanks in advance

ironhorse · Oct 26, 2016

Sounds to me like a cam follower warn, it will tap louder when cold, start to clear as engine oil pressure rises and engine heats up. Cure is engine strip and investigation. if the engine is high mileage I would be more inclined to put a couple of tins of ametech in the oil should help used many times before, won't cure but had good results with old warn engines.

Bexer · Oct 27, 2016

I hold investigation and found two things:

First, I found that on cold engine this knocking is quiter, than on hot engine

Second, I found strange voice of gas leakage in tact with this knocking while I stopped engine - this is normal sound or may be it is connected with knocking, which means gas leakage from valve or exhaust manifold?

Moron · Oct 27, 2016

Exhaust manifold gasket blowing

Grrrrrr · Oct 27, 2016

Moron said:
Exhaust manifold gasket blowing

Yep, could be or maybe the head gasket blown. Could try a strip of bog paper on a stick to see where blowing from.

Saint.V8 · Oct 27, 2016

exhaust gaskets blowing can sound like a tappet knocking...I had this on a 3.9 Classic.....(same engine!)

ironhorse · Oct 28, 2016

I think this could be head gasket, that doesn’t sound like a knock to me, it sounds like pressure escaping.

It’s always going to be difficult to diagnose for definite from internet, but you can get a fairly good idea.

Get a used kitchen antibacterial bottle or similar wash it out, and fill it with a good squirt of washing up liquid and water, then start the engine and spray the water around the head aria you will probably see bubbles wear the gasket is leaking.

martynv8 · Oct 28, 2016

+1 sounds like HG.
Have a look from under the engine with it running & look between the head & block. Also remove oil filler whilst engine running, is it sucking air or blowing?

Bexer · Oct 28, 2016

I checked - no noise or sucking air from oil filler cap.

I am going to check exhaust manifold gasket first - It's easier to check. And also engine works normally - I suppose, that if head gasket is broken engine should works bad - like misfires

Grrrrrr · Oct 29, 2016

Bexer said:
I checked - no noise or sucking air from oil filler cap.

I am going to check exhaust manifold gasket first - It's easier to check. And also engine works normally - I suppose, that if head gasket is broken engine should works bad - like misfires

You'd be amazed, these engines run with all sorts of abuse. Often there is no symptom at all. You can put UV dye in the expansion tank and then check the dipstick with a UV torch after a few days. Any mixing must be the gasket gone.

P38A Range Rover question about engine knocking

Bexer

Member

ironhorse

Active Member

Bexer

Member

Moron

Well-Known Member

Grrrrrr

Technician, Bodgit & Scarper Ltd

Saint.V8

Dyed-in-the-wool 100% RR Junkie

ironhorse

Active Member

martynv8

Well-Known Member

Bexer

Member

Grrrrrr

Technician, Bodgit & Scarper Ltd

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