Thanks Guys I found that the tacho flicker was caused by the feed wire on the back of the alternator !! Wasn't loose but the wire was silver soldered to a terminal connector & the joint wasn't good , a bit like a dry soldered joint with ordinary solder any way its fixed now thanks for all your advice . I took the alternator right out while I was doing the P gasket & pump replacement . Its worth mentioning that I did a quik fix on the P gasket leak 3 months ago with a product called RISLONE Bloody expensive stuff but it worked , they claim permanent water fix on block & head gaskets & you dont have to drain coolant or anti freeze . I better get back to the beast am now fitting a boost guage . Cheers Chris L