leeh795

Hi everyone,

Well the other week, i had my dad drive me early to school because i got up late and didn't want to find parking.

Anyway when he drove i noticed a loud thud when he accelerates to about 40mph. The sound happens just once and i'm assuming it is when the auto trans gets into 3rd gear? Anyway the sound consistently makes this noise at around 40mph when he accelerates from a speed lower than 20mph (or from a stop).

My dad's solution to this problem was to let go of the gas before 40mph and if he does this he can avoid the loud thud i've been talking about. He's a bit worried about spending too much to fix the car so he never took it to a mechanic. It probably has been happening for a month now and i'm worried the car might get worse.

Anyone got any ideas what could be wrong? I just replaced his window regulator today and felt like i should do something about that engine problem.

thanks in advance!

ekb16a

add tanny fluid migth be low on it mines makes noise ttooo n feeels like is being force

leeh795

Thanks, i'll update when i check tomorrow; and is honda oem auto trans fluid the best to get? I know they are about $2-3 each bottle but are there any local autoshop brands that can be good substitutes?

Vindicator9000

Yes, on Honda automatics, a ton of problems are caused by tranny fluid either being too low, too high, or wrong type. Honda OEM is the only kind to go with. I'm sure others will probably work okay, but Honda is the only kind that I KNOW will work.

To make sure none of that is causing the problem, I'd recommend doing a drain and fill. Completely drain the fluid and refill it with oem Honda. Make sure that you don't overfill. When I bought my CRV, the guy thought that it had a bad transmission because it was shifting really hard... turns out that it was just a quart overfilled with non-Honda fluid. Removing the excess helped the problem, but it didn't go away until I completely drained it and replaced with Honda oem fluid.

I also highly recommend NOT doing a transmission fluid flush on a Honda automatic. Honda has released service bulletins on several models saying not to, and that it's been known to cause premature automatic transmission failure. If you want to flush it, just do a multiple drain and fill instead.

Not saying this will fix it, but in my experience, it's always the best place to start when you have auto transmission problems. Furthermore, I recommend changing the fluid completely every year.

leeh795

So i checked the car, looks like the engine oil is near the "max" - and the trans oil is also near the "max". So i'll try flushing the auto tranny since he does do reg. oil change. hope his engine doesn't get worse before the oil comes home.

leeh795

UPDATE:

Since the auto has gears 2-3-4 to choose from besides the usual "D" i gave that a try. Nothing happens when on 2, but shifting to 3 and 4 i have that same sudden knock/thud - it just happens right from the start and ends.

leeh795

car transmission was out, the new fluid didn't solve the problem... had to replace the transmission. thanks for help though guys - looks like my dad learned his lesson... he'll be changing his trans fluid every 20k-40k miles or so

NOFX

So what exactly was wrong with it?

Maybe someone else can be helped later if they find this thread.

leeh795

Yeh so what happened was my dad didn't keep up with changing his automatic transmission fluid, he thought he should only change if the oil was low. And because of his assumption he hasn't changed the oil for over 100k miles and the transmission got damaged.

But really, you should be changing the transmission oil for any car after 40-50k miles periodically -- or whatever it says in your car manual.

I went to a recommended auto-repair shop for Hondas nearby (DNR Performance, Hayward) and asked more about this while he serviced the car. He said that the transmission oil's viscosity decreases every time the engine is being used and it is to be changed periodically. He further explained that if the oil is really thin, the metals inside the engine will start making contact and that is the cause of some odd engine noises and leads to transmission damage.

Thanks for the reply NOFX, i hope sharing this experience / information prevents problems for people in the future. Well, at least in the end i found a GOOD honda mechanic .

NOFX

Thanks for replying back about what the problem really was.