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Rumble Strip Noise/Torque Converter/High Mileage Car Trans Flush Options

I’ve got a 2003 Auto trans Honda Civic with 195,000 miles. Took car to shop about a month ago for broken sway bar links and asked them about an intermittent rumble strip sound (lasts a second or two) when cruising along on flat surfaces over 30 mph. Mechanic test drove the car and couldn’t replicate the noise so couldn’t diagnose (this makes sense as it was only occurring sporadically). Now a month has passed and noise is occurring more often - once every ten miles or so and is becoming louder so I’m worried about safety issues/small problem turning into a bigger one. The sound still only lasts a second or two. Did a Google search that has me thinking it’s the torque converter. Turns out despite having maintenance records going back to day one when I bought the car 15 years ago, I may have missed getting a trans flush along the line. Don’t judge - I was stupid enough to take the car to the dealer for full maintenance check-ups for the first 8 years and paid top dollar until my financial situation changed beyond my control. So anyways I thought, great - I’ll get the trans flush done tomorrow and maybe that will solve the problem - but have since been told that since I may never have done a transmission flush before that could cause more serious transmission problems in a high mileage car. They’ll have to check the fluid first to see how dark it is.

So long story short - taking the car back to my mechanic Monday due to my growing anxiety about letting this problem go. In the event they can’t replicate the sound again (I really can’t predict when it will happen), should I consider the trans flush or not? I read that this high-mileage issue could be a myth related to the fact that people get them done more often than not when their transmissions are failing regardless. Or pan drop and filter? How would they otherwise diagnose a torque converter problem? Any other possibilities? I considered wheel bearings but this sound is sporadic. I’d test braking while the noise occurs but as it only lasts a second or two I doubt I could react quickly enough. Any other possibilities? I can also just ignore it, but only if it’s something that won’t lead to bigger problems over the next 6 months (or year in my dreams if I can make it to the end of the model year sales next October) - trying to get one last year out of the car and save for a decent new car as I just started a new job. Plan to have mechanic check front end suspension (not sure why they did not do this last time - but taking it back to the same shop as I believe a sway bar link may have already broke again - very subtle knocking when turning hard left again, has new axel).

** No check engine light, no other issues

There is no pan/filter on your transmission to service.

So you either drain and replace the fluid which is only about 50% of the old fluid. Or a flush is done to replace all the fluid.


Is one safer than the other for a high mileage car that has never had an ATF before?

Let me put it this way.

If It were engine oil, would you replace some of it?

Or all of it?


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I would replace all - but called around to a few shops that told me the built up sludge could kill the transmission and not to do it.

If you want to believe that?

Then don’t replace any of the fluid.


Seems odd that they would tell me that they don’t want my business…

I think they say that because they’re worried that your transmission is on its way out anyway, and if it happens to fail not long after the fluid was exchanged that you would come back after them for the transmission rebuild

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Because they don’t want you coming in a few weeks after the service claiming that their work caused your transmission to fail . Chances are it was going to anyway

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Okay thanks, so basically I should take the risk as I might not have anything to lose. Honestly the car has 195k miles on it - I expect it to die on me any day - but causes me anxiety not to do anything about it as well if there’s a chance I can stave off a problem - even if it buys me a few months I’d be grateful.

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I’d go for it if I were you

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Does anyone really have a story of their transmission failing immediately after a flush? And at what mileage?

I have known people whose transmission failed at 90k-110k miles, because they never bothered to service the trans. On the other hand, I change my trans fluid every 30k miles, and I have NEVER had a trans failure in the 60+ years that I have been driving.

IMHO, the OP is skating on very thin ice with this high-mileage, unmaintained transmission, but if I was in his situation, I would not hesitate to do a trans flush. It might give him a few more miles from his neglected transmission, but even if it doesn’t do that, I think that it is a good gamble.

I’m hoping it’s anything other than transmission - just want to be prepared for Monday as it sounds like classic torque converter issue. But even if it’s not, I’ll still be considering whether or not to take a chance with the ATF. I’m committed to replacing this car in the next year so that’s a factor for any decision - just hoping not to have to go car shopping until at least after the holidays. Just spent almost $600 in past month for coolant sensor, window mechanism, and sway link bars - not sure what my limit would be for another repair this month - probably not enough to deal with torque converter.

Depends on the flush method. Does a flush force fluid in under higher pressure than the transmission pump usually exerts? I’ve heard some do, others don’t, but I’m not sure. I wouldn’t want fluid forced in under high pressure, and I wouldn’t want additional flushing solvents used for fear of some of the built up gunk being forced somewhere it doesn’t need to go. I’d just want a fluid “exchange”. If it were me, I think I’d just drain and refill to save some money. If that helps, do it again.

A transmission flush machine connects between the transmission cooling line and the radiator.

The machine is filled with new transmission fluid, and the engine is started so the pump within the transmission pumps the old fluid out while new fluid is pumped back into the transmission.

On a Honda, the transmission must be in gear. Because the pump within the transmission doesn’t operate unless so.


I’d have no issue with that. Are there machines that transfer the fluid using a pump other than the transmission pump? If so, I’d be leery of that on a high mileage trans. Maybe those machines do not exist. They may be part of the “don’t change the fluid” wives tale.