YACT: What happen when you overfill the transmission fluid?

luvya

Banned
Nov 19, 2001
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Well well, as usual, let me get the facts out first:

98 Honda Accord V6................................................automatic :|
85k miles on the car

So I just had the transmission rebuilt by Honda a couple weeks ago, it is certainly behaving better than the last one, but still I can feel hard shifting from time to time. So I went to NAPA and bought a bottle of trans-tune made by SeaFoam, I thought this couldn't hurt. I followed the instruction and added half pint to the transmission, lo and behold, I overfilled the damn thing! But now, the transmission is on its best behavior since god knows how long it was, and I really like this trans-tune stuff. Only problem is I overfill it...I don't want to bother draining it if it's not going hurt the transmission, plus, one of the reason Honda transmission keeps having problem is due to lack of lubrication...so I thought a bit overfilling is ok and actually helps the cause? Anyone?
 

Eli

Super Moderator | Elite Member
Oct 9, 1999
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Well..

First off, the logic behind "Well, since oil is good, if I put a little more in than I'm supposed to, it will be just that much better, right?!" is flawed. More is not better.

In the case of your transmission, it probably isn't going to hurt anything, but there is a "maximum" for a reason. How much over are we taling here?

That said, drain your transmission fluid and get that transmission fluid additive garbage out of there.

It's all garbage!!!! All it does is upset the chemical balance that the people who made your (in this case) transmission fluid have put so much R&D into.

If it was really that good, we would already be using it!

I'd look around on the Honda forums and see if there is anything you can really do to help extend the life of that transmission. I would be willing to bet that using a synthetic transmission fluid is 1000x better than any POS additive you can get.

That is my opinion, anyway.

Edit: IIRC, it was going to cost you something like 3,000$ for the rebuild. Is that what you went for?

So basically, your transmission is probably going to fail again in another 80,000 miles?
 

luvya

Banned
Nov 19, 2001
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Well...the $3200 was quoted from a local shop, Honda has been nice to me, they replaced with a newly rebuilt one at no cost to me. I sure hope it's not going to fail any time soon..that's why I am taking some preventive steps now.
 

luvya

Banned
Nov 19, 2001
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Btw, the fluid level is quite a bit over the max, but I only added half pint to it! Before I did that, the fluid level was actually a bit below the min.
 

gunblade

Golden Member
Nov 18, 2002
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Do you test it the way it should be?

with the engine running and shift from P to D and back then checking.
 

HiTek21

Diamond Member
Jul 4, 2002
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I wouldn't really put any additives into my Transmission, only genunie honda ATF Z1 AT Tranny Fluid.
 

Eli

Super Moderator | Elite Member
Oct 9, 1999
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Originally posted by: luvya
Well...the $3200 was quoted from a local shop, Honda has been nice to me, they replaced with a newly rebuilt one at no cost to me. I sure hope it's not going to fail any time soon..that's why I am taking some preventive steps now.
Ahh. That's awesome of them.

Transmission fluid additives are NOT preventative steps, unless there is something I don't know about some specific additives and this specific transmission.

They're snake oil, designed to produce peace of mind. You have no way of telling how the chemicals in the additive are going to react and affect the chemicals in your transmission fluid.

In some cases, they can be much, much worse than no additives at all. You just have no way to tell.
 

luvya

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Nov 19, 2001
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Anyway, I will have fluid change next month, after that, I hope Honda genuine transmission fluid can hold on their own. I am not betting on it though.
 

Eli

Super Moderator | Elite Member
Oct 9, 1999
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Originally posted by: luvya
Anyway, I will have fluid change next month, after that, I hope Honda genuine transmission fluid can hold on their own. I am not betting on it though.
What were you using in the old transmission?

I reiterate that you should check out some Honda forums, and see if people have had good luck extending the life of the transmission with any specific fluids or maintenance schedules or anything.
 

HiTek21

Diamond Member
Jul 4, 2002
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Originally posted by: luvya
Anyway, I will have fluid change next month, after that, I hope Honda genuine transmission fluid can hold on their own. I am not betting on it though.

As long as your fluid isn't overheating it should last, but they recommend it to be changed every 30k miles.
 

luvya

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Nov 19, 2001
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Originally posted by: HiTek21
Originally posted by: luvya
Anyway, I will have fluid change next month, after that, I hope Honda genuine transmission fluid can hold on their own. I am not betting on it though.

As long as your fluid isn't overheating it should last, but they recommend it to be changed every 30k miles.

You have no idea how bad this POS Honda transmission is, just head over to v6performance.net.....lots of complaints.
 

CrackRabbit

Lifer
Mar 30, 2001
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overfilling an automatic tranny can be very very very bad for it, you might want to get a siphon and suck the extra fluid out of there. Overfilling can cause the fluid to foam and air to become trapped in it, the air gets sucked into the valve bodies and can cause incorect shifting, slipping, and eventualy total transmission failure.
 

luvya

Banned
Nov 19, 2001
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Originally posted by: Eli
Originally posted by: luvya
Anyway, I will have fluid change next month, after that, I hope Honda genuine transmission fluid can hold on their own. I am not betting on it though.
What were you using in the old transmission?

I reiterate that you should check out some Honda forums, and see if people have had good luck extending the life of the transmission with any specific fluids or maintenance schedules or anything.[/]


I always go to dealership for maintenance, they only use genuine Honda fluid. That's why I am not counting on the Honda fluid. Maybe the transmission is just built so bad that nothing will prevent it from breaking.
 

bernse

Diamond Member
Aug 29, 2000
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Depending on how much overfull it is, you could blow gaskets/seals quite easily and it may foam.

Either way, not good.
 

KokomoGST

Diamond Member
Nov 13, 2001
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The reason why your tranny isnt quite the same is pretty friggin normal. Every single master tech including those that have been in the business for pretty much forever know that even the best tranny shops with come back with some differences in the transmissions. So it shifts at a different point or the feel is slightly different from before. That's perfectly NORMAL.

BTW. when are you reading your trans fluid levels. They should only be read with the car ON... you didn't tell us if you did that. Generally it's been proven that additives don't do jack squat except mebbe hurt. Besides, those Honda trannies are notorious for being crappy... there's nothing you can really do about it. There's no way you can amazingly reengineer the car with some "mystery fluid" that will fix your car.
 

HiTek21

Diamond Member
Jul 4, 2002
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It's just the accord transmission thats not built well. My Legends Tranny has 183K miles on it and it still runs great.
 

OS

Lifer
Oct 11, 1999
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heh, honda gives you a goodwill tranny and you're already dicking around with it. It doesn't sound like you know what you're doing so it won't surprise me if in another 6 months you bitch about your second dead tranny.

Aftermarket/3rd party additives are almost always a bad idea, except for gasoline. Overfilling is also a bad idea in autos.

If I were you, I would drain out and fill the tranny with honda ATF. Use the amount specified in manual for a drain/fill. Make sure the level is correct. Drive it around for a bit. Drain and fill again. That way you get out most of the crap additive you put in the tranny.

As for maintaining the new tranny, do an ATF drain and fill every 15k miles. When you are servicing the auto, make sure everything you use is clean. Honda autos don't have filters inside so particles floating around will cause problems.