Engine Rattle

[Henry-b]

Hello Gents

I have a query regarding the 4.6 in my old P38..

Ever since I bought her she has always had from what I can gather a Valvetrain rattle, however I can't be sure..

Recently I did a video on it, and for the first time it was audible on camera, link here.



It sounds quite sinister to my ear however it does disappear after around a minute HOWEVER when she is hot another slight rattle seams to appear, it is audible at idle "just" however if the throttle is blipped quickly the noise disappears at above 1100rpm however once it goes back down to idle there is a almost "crescendo" of noise and then it tapers off to a very slight rattle if I listen for it!

I know I sound insane but that is the best explanation I can give..

I'm running a 10w60 with a bottle of Lucas and a Bosch filter, all of which has been in the V8 for around 4k..

Cheers H

[SuperV8]

Why are you using 10w60? are you in a hot part of the world?
standard oil for UK is 10w40 for the crank oil pump V8.

To my ear it sounds more tapping noise than valve train rattling? - like some one hitting your engine with a hammer?

Is your cooling system ok? not using coolant?

[ChrisJC]

Mmm, I notice your water level is down.

I strongly suspect you have a cracked block and a loose liner, and what you can hear is the liner moving up and down with the piston.

It doesn't sound like valvegear to me, more bottom end, so if not a loose liner, maybe a big end on it's way out.

Either way, some dismantling is required. I think I would take the sump off first and check the big ends, as that's fairly easy. If they look OK, then heads off!

Chris.

[SuperV8]

Agree,
First thought was liner issue but also thinking about your 60 weight oil! Is this to 'help' with low oil pressure issue? which could that be caused by worn out big ends?

[garrycol]

Why are you using 10w60? are you in a hot part of the world?
standard oil for UK is 10w40 for the crank oil pump V8.

Exactly why use that oil - is too thick and may be the cause of your valve noise. Here in Aust even in the middle of summer 100F and above on a good engine you only use 10w40 and if an old engine is starting to get a bit smokey - then go to 50. ^0 only if you are selling with a worn engine.

The noise sounds like valve/tappets - maybe exhaust pop from a exhaust gasket - but change that oil.

[Henry-b]

Hiya gents, the coolant is full and it doesn't use any, the reservoir has gone cloudy which makes it look empty..

I'm using 10w60 it was recommended by V8developments - RPI recommended Valvoline 20w50

She doesn't have OIl pressure issues oil pressure when hot at 2000rpm is 47psi.

I should also add that particular "KNOCK" disappears when hot only to be replaced by a very faint rattle, that gets aggravated by blipping the throttle.

she only knocks like first video on occasion it isn't a constant issue "should of mentioned that earlier"

Most of the times she sounds like this



would it be prudent to change to a 10w40 or 5w40?

[Henry-b]

Why are you using 10w60? are you in a hot part of the world?
standard oil for UK is 10w40 for the crank oil pump V8.

To my ear it sounds more tapping noise than valve train rattling? - like some one hitting your engine with a hammer?

Is your cooling system ok? not using coolant?

10w60 was recommended by V8developements when I queried, as there is quite a discussion on the LR forums about what oil is best and it can get confusing..

And no she doesn't use a drop of coolant, the rad pipes don't go rock hard and she runs at a consistent 87c

I live in the UK so no Death valley type temps

Any particular 10w40 I should put in?

H

[ChrisJC]

I put in Halfords 10W/40 and my motor has 189,000 miles on the clock.

Those Thor engines have a very high oil pressure anyway, much higher than the previous versions of that engine. I've never had cause to doubt 10W/40.

Chris.

[SuperV8]

I use a good quality fully synthetic 10w40 in my GEMS 4.6 with supercharger (mobile or whoever is the best price at the time). Works fine with good oil pressure. The only reason I would go to a 10w50 would be if I was seeing sustained & excessive oil temps above 110 - which i'm not.

My old, tired 3.5 used to prefer 10w50 vs 10w40, used to make it quieter.

She doesn't have OIl pressure issues oil pressure when hot at 2000rpm is 47psi.

I have a feeling my oil pressure was similar when hot - but the 10w40 oil i'm using is 70% thinner at 100 degrees - so maybe the thick oil is hiding an oil pressure issue?

Try using a stethoscope/long screwdriver to try to determine when the sound is coming from?

Tom.

[Henry-b]

Thanks Gents!

I'll change for a 10w40 and check the oil pressure