flush or not to flush

They might not generate "sludge" but they do generate "varnish." Every time a clutch or band engages, a minute about of fluid is "cooked." Some of this ends up coating the walls of the fluid passages and the walls of the actuators. I don't know that a flush will remove this stuff, so I have my doubts about the usefulness of a flush.

I agree with this. My Frontier has a drain plug on the pan. I figure if I change part of the fluid (around 5 quarts come out if you pull the plug) every 25k miles, I'll be OK. Interestingly the Frontier shop manual describes taking off the oil cooler line with the truck running as a way to do a fluid exchange. You allow the fluid to be pumped out of the cooler line into a bucket while at the same time adding fluid to the pan via the fill tube. I have read of others doing this but I'd never seen it in a factory service manual until now.

Ed

Reply to
C. E. White
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If "new" means "since 1978," then yes. :-)

Seriously- giving the transmission a few hours to drain instead of a few minutes will get 2/3 of the fluid out of the convertor, leaving only about a quart or 2 of old fluid. Maybe that's a problem on some foreign transmissions that only use 3 quarts of ATF, but not a problem on a transmission with a pan and sump that holds 8 quarts.

Reply to
Steve

I have opened up a fair number of transmissions, and have never seen varnish in the actuators and fluid passages, even in transmissions where the fluid had been overheated to the point it looked like molasses. ATF is pretty rugged stuff and has very good anti-deposit additives. Yes, it can "cook" but it seems to do so *ON* the clutch disks when they're abused, and the varnish accumulates there as a glaze. It doesn't seem to precipitate out elsewhere in the transmission.

Just my observations...

Reply to
Steve

Any decent additives for cleaning some of the gunk out, either for general use or to add just before a change?

Reply to
clifto

Thanks for all the good info on that! I have learnt a lot. I have decided not to do flush at all. I was hesitant about dropping the pan and replacing the filter. There are a couple of posts that made me believe that draining only will do good.

  1. It is not that east to replace the filter as somebody already experienced on this group:

"Changing the fluid would not be a problem since there is a drain plug but to anyone considering changing the filter - DON'T do it it's a trick. Let me clarify that this is the 4-sp auto tranny paired with the 1.6L engine. You see, Nissan decided to make an otherwise simple job into a nightmare. One of the bolts that holds the filter threads through a washer into a nut on the top of the valve body. When you remove the bolt, the washer and nut get lost in there...." It goes on and on ..guy might not be skilful enough to do that ... neither am I !!!

  1. This is what some Nissan mechanic got to say :

"have done allot of services on Maximas and have never changed the filter on one. Two reasons the valvle body of the transaxle has to be removed to remove one of the bolts holding on the filter. Aswell the filter is a fine metal mesh unlike the American cars which are paper and require replacement. I DO NOT sugest removeing the valve body unless you are realy sure you want to possily damage the transaxle the smallest peice of lint of dirt could and will stick or damage a valve causeinf a poor shift and an overhaul." ..kinda follows up on the unlucky guy's experience

  1. Owner's manual says nothing about pan dropping let alone filter replacement... drain/refill is all they mention

  1. Some 12-15 rotten screws hold the pan. I do not have any wrench (nor ever used one) that would tell me how many pounds I need to apply to screw the pan in order not to damage gasket and not to make the whole thing leaky... As automatic transmission is a freaking precise mechanism I better not touch what's inside

So drain/refill is all that is left on the table. Two things that can happen are : overfill, drain screw will leak (rotten again) Do you think I should buy this thing and apply it to the screw (bottom of pan).

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Perhaps there are some good sealants that can be applies to prevent the leak ? Again thanks a lot for you input !

Reply to
Altima

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