The V8 Owners Forum -

The RH bank of my 3.9 Rover V8 (ex-'95 Range Rover) has developed a clacking noise that initially appeared to exhibit no pattern but has now settled to a routine. No matter how warm the engine, after 5 - 10 mins of 4th/5th gear 50mph or more driving, a loud clacking noise (matching the revs) starts. The noise will stop after 5 - 10 mins of 1st-3rd gear sub-30mph driving. I've searched the forum for symptoms similar to mine and have discovered several possibilities. I tightened all the exhaust manifold bolts (cylinder 2 was 8th turn loose) and removed all the spark plugs to no effect.
Can anyone advise me what steps to take next?
Many thanks in advance,
Tim.

Cracked manifold?

Chris.

cracked manifold, or blowing manifold to head gasket

Many thanks for your replies Ian and Chris, I'm very grateful. I've little mechanical knowledge so I'll have to get a professional to look into this so any help or advice is invaluable. I had a look at the area the noise appears to emanate from and saw this dirt around no.2 (I think -front driver's side) cylinder exhaust :



Compared with its neighbour :



Could this be a symptom of the problem ie-gasket?
Am I best just getting the head and exhaust gaskets replaced on the offending side at the same time as having the manifold checked?

Many thanks again,
Tim.

I think I would remove the manifold where that staining is, and see what's going on with that gasket. Bear in mind that those gaskets can be fitted incorrectly, so you need to check that as you remove the manifold as once they've fallen on the floor, you'll never know!

Also give the manifold a good inspection.

Chris.

You will need to check the flanges for straightness and make sure all is good there to ensure correct seating once it all gets tightened up.

Hi Tim,
Before you dismantle, get a length of hose (3 Ft garden hose) and put one end to your ear and the other to the suspected exhaust leak.
You will hear clearly if you have any leaks.

Denis

Thank-you Denis, Chris and John for your advice. Most appreciated. I've not had a chance to give the manifold a proper visual examination but I carried a length of hose around and managed to stop and listen while the noise was there but I didn't hear any differences between the exhaust ports. The noise appears to come from inside the rocker cover or below.
Please forgive my ignorance but I thought I could assume that the noise had a mechanical origin due to no change in noise intensity with the systematic individual removal of the spark plug leads? I mention this as the clacking noise is very similar to the clattering in the first 2 - 3 seconds after ignition before the oil flows. I fear this may be sign that there's more than one fault...
Don't get me wrong - I'm going to follow up the manifold leak as far as I can. I will have to take the car to a garage so I'd like to supply them any gaskets and bolts they may need to replace.
Would it be advisable to clean up the manifold faces and replace the gaskets in order to eliminate them from the possible cause list?
Thanks again in advance,
Tim.

(after I've fixed this maybe I can discover why tick-over rate increases with engine temperature or when I pump the brakes......)

Meatus wrote: (after I've fixed this maybe I can discover why tick-over rate increases with engine temperature or when I pump the brakes......)

Air leak somewhere - try plugging the feed to the brake servo and see if it still does it.

Chris.

ChrisJC wrote:

Meatus wrote: (after I've fixed this maybe I can discover why tick-over rate increases with engine temperature or when I pump the brakes......)

Air leak somewhere - try plugging the feed to the brake servo and see if it still does it.

Chris.

Tim,
It's quite normal for the engime speed to rise when the brakes are pumped. This it due to extra air getting to the engine via the servo vacuum valve.

If you have eliminated the exhaust leak then the clacking noise may be one of the cam lifters bleeding down at steady low revs.
You say that when you put the car into the lower gears the noise dissapears. This is probably due to the lifter pumping up again as the oil pressure increases with revs.

Denis

I've revived this thread in the hope my symptoms may ring a bell with someone or my RV8 troubles may help someone else in future.
After Denis (Devonman)'s mention of oil pressure I thought it best I get a digital gauge and new sender to get an idea of the actual pressure in the engine. I was miffed as the gauge seemed knackered. It showed about 20psi for a short while before suddenly dropping off to zero and then intermittently spiking up to 5psi at random. The car went into the garage today and apparently the pressure showed the same sypmtoms. 20-odd psi at tickover dropping off to zero when warm.
Can I assume there's a blockage somewhere and a re-build is on the cards?
All advice gratefully received.
Cheers,
Tim.

I suppose you might have a blockage on the pickup side, maybe the screen in the sump is clogged.

I fear some substantial investigation is in order whatever happens!

I think I'd pull the sump and have a look.

Clearly there is enough oil of the correct grade in there?

Chris.

ChrisJC wrote:I suppose you might have a blockage on the pickup side, maybe the screen in the sump is clogged.

I fear some substantial investigation is in order whatever happens!

I think I'd pull the sump and have a look.

Clearly there is enough oil of the correct grade in there?

Chris.

<This or possibly even a loose oil pick up pipe, wouldn't be the 1st time

Is the oil pressure warning light working and does it come on at a hot idle? If not, all those gauges could simply not read accurately at very low pressure. And low pressure at idle when hot on an RV8 is perfectly normal.

Thank-you Chris, Simon and Dave - I'll have a chat with my mechanic friend about investigating the sump but not before we've checked the oil pressure light (probably best to check the pressure relief valve too I assume) - the light's never come on so I've not worried about it. I've got a lot to learn...
Thanks again - I'll update on progress.
Cheers,
Tim.

p.s. the oil's a 'classic' 20w/50