The V8 Owners Forum -

Hi,

I was wondering if anyone here with Rover V8 knowledge might have had a similar experience and so know what might be causing an intermittent tap within my 4.6 v8 (Gems ignition)

I have supplied as much info as I can below but the summary is, there is an intermittent tapping when warm that changes in note and frequency depending on it's mood and a motorway journey cures the problem for several weeks afterwards. Does this sound familiar to anyone?

Engine : 4.6 V8 Standard factory engine.
Year : 1996
Mileage : 150,000
Oil basically changed every 4,000 miles for it's whole life.
Still on original cylinder head gasket.

History of issues since new:
130,000 miles - intermittent tapping when warm. - Rocker arm replaced. sorted.
Water pump failure - Caught before lost too much coolant and never got hot.

New camshaft and follower kit from RPI


Current issue which having searched the web for a month or so on and off, I cannot find a match for the issue we are having so wondered if anyone on here had had this and so might point me in the right direction in case there is something to try before stripping down the whole engine.

Emissions are good. Runs and idles very smoothy. Starts instantly cold and warm. When cold sounds sweet with no noises or issues. However,

when warm there is an intermittent tapping that changes in note sometimes there are two taps sometimes one. Only occurs when warm. Sometimes it is in sync with engine revs sometimes it is not. It can be one tap sound every 30 seconds with engine idling.

The odd thing about this is that after a good spirited motorway journey the knocking goes away for a few weeks both hot and cold and slowly returns over time.

It was suggested in places that it would be a slipped liner but from what I understand once they come loose that is it and they do not re-seat themselves. So it cant be that given the weeks of it going away.

No coolant loss at all. No overheating. Pulls like a train still. No smoke of any kind through exhaust.

Hoping someone might be able to shed some light through experience on what this might be before I consent to bleeding from the wallet for a strip down and rebuild.

Cheers and many thanks. Ben.

Being out of sync with engine speed is weird. Are you sure it's coming from the engine?

Chris.

Its odd in that it sounds like it is coming from everywhere, wherever you listen, that is where the sound seems to come from. It does not seem to be exhaust leak, mate put professional electronic nose all over the engine bay and no exhaust gases what so ever. R you thinking flex plate or something else?
I have a sound file for it but not sure I can upload it here.

Cheers, Ben.

I've seen (heard) this caused by nothing more than a worn belt.

Cheers Rossco,

Do you mean the serpentine belt that drives the water pump and auxilleries?

cheers Ben.

Yup

No guarantee its whats causing yours but always worth a look.

ok, many thanks, it could do with a change anyways. I will give it a go. I have found out today that no preload aspects where checked when the new cam and followers where fitted, they were just installed and bedded in so thinking that might also be a problem! There was no measurements taken or consideration given to whether shims were needed etc.

benrr46v8 wrote:ok, many thanks, it could do with a change anyways. I will give it a go. I have found out today that no preload aspects where checked when the new cam and followers where fitted, they were just installed and bedded in so thinking that might also be a problem! There was no measurements taken or consideration given to whether shims were needed etc.

No need with a standard cam and followers unless the heads have been machined. The tappets are designed to self adjust over quite a wide range.

I agree with Dave - I have just got my 4.6 running - aftermarket cam, skimmed heads and block - I have standard lifters etc and went together no issues - nothing special.

To your original question where there are a range of contributions - with a RV8 the first place to look for noise you is - loose exhaust manifold bolt/ blown gasket, OR sticky lifters OR a slipped liner.

If none of those then look elsewhere like has been discussed.

Garry

many thanks, will do. thanks for all your help and advice. Will post if it is ever resolved!