Hi,
Even though I do not believe your problem is your turbo, if you or anyone else discovers your turbo has seen better days, then there are two sources to buy NEW turbos, and these are from the states:
http://www.powertechnologies-turbo.com/liquidation.html[/url]
If you look under:
89473158 RHB52TW Isuzu VI 78 Turbo $ 325.00
Our turbo is the VI77, the only difference between ours and this this one, is the angle of the compressor housing. By undoing the 6 bolts on the back of the housing it can be rotated to the correct angle. I have bought one of these, but please note it does not have an actuator. So just use your old one. $325 at the moment is £205 for a NEW turbo. A friend of mine brought it back for me.
The other alternative on ebay is a cartridge:
cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=110437357028&viewitem=&sspagename=STRK%3AMEWAX%3AITThis is also the correct part, but at $299 I would go with the first option as it is a complete turbo.
I would avoid buying second hand turbos on ebay, as alot of them are rubbish. I foolishly bought one, and despite my best efforts in asking all the right questions, i.e compressor condition and shaft play, his response was "it worked ok on the car", ALARM BELLS should have rung. The reality was a compressor wheel that had digested a sand storm and the shaft had a ridiculous amount of play. I managed to send it back eventually, but lost out on P&P.
All the best
Rob