Another V6 tapping noise

[chubbygordito]

I picked up a cheap ZT 190 today which I'll be using while I fix my ZTT (no doubt end up keeping both of them on the road), and it has a tapping noise from the engine.

I automatically thought "death rattle", but I don't think it is.

At idle there is no tapping noise, idles smooth. Rev the engine while stationary, no noise....maybe on the odd occasion when revving it up high and letting off there is a very fast tapping noise for a split second.

Driving along it will suddenly start tapping in relation to engine speed, although more noticeable at higher rpm's.

It never taps when cruising along, or when off throttle, only when under load/acceleration....and even then not all the time.

And its not a "rattle", its definitely a tapping noise.....like someone dragging a stick along a wrought iron fence. As the revs increase, tapping increases, moment foot off the accelerator, it disappears.

There is plenty of power, smooth idle, acceleration kicks in around 3-3.5k rpm.

Has anybody had any experience with this?

Thanks for the help.

[Lord of Hog]

Possibly the purge valve. It might be audible as you go along depending on how much bonnet soundproofing you have. I believe the electrical connections sit just behind the throttle body. Try getting it to make the noise and then disconnect the electrical plug and see if it stops.It normally does it more when idling and apparently it's nothing to worry about but might be a weight off your mind.

[SD1too]

Originally Posted by chubbygordito

I picked up a cheap ZT 190 today ...

I'd start by draining the engine oil and using some Comma Flush Out. As the car was cheap, it may not have been serviced very diligently.

Simon

[chubbygordito]

Had a quick look this morning, and sound seems to be coming from the vis motor area.

Do the vis motors only start working above 3-3.5k rpm?

Its just I noticed on the way to work this morning, driving and accelerating at low revs (2-3k), nothing, but when I accelerated harder and above 3-3.5k, the tapping appeared.

At idle, the engine is quiet and silky smooth.

[KWIL]

VIS motors come in around 2900 (Balance) and 3750 (Power) and you should feel both.

[murphyv310]

What you describe is tapping on the over-run!
I'd agree an oil change is on the cards as I think it could be a bit of little end noise. These (as do big ends) make most noise when you ease off the throttle and they are lightly loaded.

[chubbygordito]

I'll do an oil and filter change this week.

Just had a quick look, and its got a Rover/MG genuine filter fitted, and it looks old.....I'm guessing it hasn't been changed in a while

[chubbygordito]

I took it out this afternoon, and it picked up around 2900.....but nothing at 3750.

Unplugged the front vis and drove it, no change.

Unplugged rear vis, got worse.

I took the front vis (power??) out and checked the arm, moves in/out smoothly with no play. However the vis itself was covered in oil.

I'm going to change the oil tomorrow, and order another power vis as well....then take the old one apart and see if its repairable.

[Salad-Dodger]

Hi. When you change the oil/filter, fill the new filter and pull the fuel relay. Crank the engine till the oil light goes out, plus a few more seconds. Replace the relay and start the engine.
Our V6s are getting on a bit now so I think its a good idea to make sure there's oil present at the bearings on start-up. Steve

[SD1too]

Originally Posted by chubbygordito

... and order another power vis as well...

Don't buy a new one from MGR! They are ridiculously expensive. The actuators are repairable. Contact club member Stocktake for refurbished and modified actuators. He is our expert in the VIS system.

Simon