Volvo Repair: kdetermining milage from computer and Odometer gear, volvo tools, threshold bank


Question
QUESTION: Hi Roger....94 850 turbo wagon...how do go about replacing the odometer gear myself....also how can I determine the actual milage on the car from the computer..?  also could you tell me whether its likely that I could change the timing belt myself without special volvo tools..?  it appears a tight squeeze between eng and body...just bought the car from some shady type character so I know very little of it's history only its present cond. ...Thanks Roger any help would not go unappreciated...not to over burden you with this question BUT check eng light was on....nice guy checked codes for me 1)catalyst below threshold bank 1        2)system too rich bank 1  and
3) O2 sensor ckt slow response bank 1 sensor 1....
 he reset check eng light for me and suggested driving around for 50 miles or so with some injector cleaner in the gas and then taking it in for it's smog check and keeping my fingers crossed......would you have anything to add to that.....???  does it sound as tho I'll need a catalytic converter..?  the $ are threating to get out of hand here on my "budget volvo" thanks again

ANSWER: Ron, not sure of your mechanical abilities but the timing belt is a crucial thing to not mess up.  The odometer gear is also a challenge so please let me know your abilities and we can press on.  Roger

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QUESTION: yes Roger, I have actually sucessfully rebuilt a number of auto and motorcycle engines in my day.........I have tools that might be needed other than "special" volvo tools...wondering mostly about the working space between the eng front and the body...does one need to be a contortionist to get in and turn what must be turned ?
 also what do you think about the chances of it passing smog considering what I've already written..?  well thanks the car runs great has very nice leather int and nice paint with no dents at all and we paid only $1000. BUT now I find out that the odometer does not work and the supposed 147k miles is not correct, also it needs tires $400. maybe a catalitic converter $400 has $300. in back dmv fees and needs timing belt $300-$400 if i have someone else do it......so NOW I'm not sure if I should have just paid more and bought one with the work already done...well thanks in advance for any light you can shed on my delema..Ron Powell

Answer
Ron, doing the gear is easy but to know the true milage, you need a Volvo Scan tool to know what it is.  All you need is a 25 torx driver and patience getting the cluster out.  The timing belt is a challenge sometimes even for me and I have done hundreds of belts over the years.   If you have a book and some patience, its doable.  What is it that you want to know?  Detailed step by step would take too long on this site.   You may want to dish out the money to do both jobs but thats up to you.  I suggest a real Volvo shop with Volvo Masters.  Joe's garage has a tendency to mess stuff up.  Roger