I've owned my 1990 Volvo 240 DL for about 3 years. It currently has 170k miles on it. When I first got it it had a really bad transmission leak where all the fluid drained out(At least none showed on the dip stick). So I had the gaskets replaced.

I want to keep my car healthy, so I was going to use some of my tax return to have a transmission flush($200). But I heard of stories where that can make the Transmission go bad if it has never had a flush before(don't know since I haven't had the car my whole life). Is it safe to have a transmission flush done on it(my Volvo repair shop), or am I taking a risk?

 

Let me preface my response by making sure you understand any response you receive, including mine, is merely an opinion. I know of no documented study concerning the subject. What you'll get from me and anyone else weighing in is anecdotal in nature at best. That having been said, I generally tell customers if the car or transmission is new, service it regularly or has been serviced regularly, then by all means do a flush. If the transmission shows no symptoms, the fluid isn't burned but it either hasn't been serviced regularly or the history is unknown...leave it alone. Yes, we've had a few customers insist on a service and had their transmissions fail. Is it connected? Would they have failed anyway? I have no idea. But it's enough for me to not push the service except on cars that are being maintained regularly. By the way, $200 to flush a tranny and replace the filter seems a bit steep. I hope that's a power flush rather than just drain the 3-4 quarts in the pan when they do the filter. If it were me...I wouldn't recommend it if you are having no issues currently. No doubt you will get any number of contrary responses...issues with no documented positive answers always seem to get the most hotly contested responses.

 

Change your tranny fluid but don't flush it... these tannys just pump it out while you are putting it in. Remove the radiator top tranny cooling line, attach a hose leading into a bucket, put a funnel into the fill tube, start the car and the fluid will pump out. Make sure you or a helper is pouring in new fluid as the old pumps out... Also make sure that you don't overfill it... About 12 quarts takes care of it.

 

We have 308K on our 89 and I change the transmission fluid every 50-60K miles. I have done this from new and basically use the method described above. Because it has been done on a normal schedule I don't feel that it is a problem. In your case I would be a little concerned in doing a power flush. If anything I'd look at the fluid and see if it is discolored or burnt. If so then I would just drain it and replace the filter and fill it up. If it looks OK then I would leave it alone. My 2 cents here.

 

The reason power flushing is supposed to be risky is because they force a lot of fresh fluid into the system, which can stir up sediment in the trans oil pan and knock crud out of the trans filter.
I've never been a fan of trans flushing that disconnects cooler lines (be it power flush or hoses into buckets). Hoses into buckets more often than not starves the trans pump of fluid if done by first timers.
The best way is to drain sump, change filter and gasket, refill, run for 5 mins, then drain and refill.
Then drain and refill at service intervals.

Regards, Andrew.