Replace the AT fluid or don't? That's the odd question...

[Desmoquattro]

Ok, so I have a 91 Q45 that I recently picked up with 150 000 miles. The transmission shifts well, no hesitation, no single-gear problems. But it does slip a fair bit when starting in D (2nd gear start), and it occasionally slips on downshift (you get a vibration when it kicks down, but no clunking noise). My service records show it had a pan drop in 2004, but no mileage is marked. The fluid on the dipstick is pinkish-grey. I've been told, and also read in numerous sources, that after a certain point changing the transmission fluid will only create more problems, as removing the old fluid with the clutch material floating around in it will generate more slip (supposedly the material in the fluid acts as an abrasive that generates friction in the clutches). Basically it's a fatalistic view where you leave it alone until it breaks and then replace the transmission,

So my question for the experts here is, given my mileage and the symptoms, should I try doing a pan drop or leave it alone and start saving for another transmission? Anyone have experience with similar symptoms (and mileage) being "cured" by replacing the fluid and filter?

- Jason

[qship96]

Doesnt sound good either way...I would drop pan, inspect for amount of debris, change filter, refill with new fluid and see if it is ANY better-then make the assesment to replace transmission or throw another $100-130 at it doing a full fluid exchange

My gut says the grey fluid is due to extremely worn internals, which new fluid/filter wont cure and prepare to replace transmission

[Desmoquattro]

I'm thinking I'm willing to "risk" a fluid change considering it was done at least once in the last four years (if it hadn't been done since new it would have been a different story, then it's no way).

(By the way, fluid flushes are extremely bad and are not recommended by any manufacturers. You risk pushing sludge and debris into the valving and destroying the transmission in short order. I've heard plenty of horror stories about transmission going kaput only a few thousand miles after a fluid flush.)

[Q45tech]

Depends if it is an original 150k 91 AT or was replaced like the majority were under warranty bfore 70k?

[Desmoquattro]

Depends if it is an original 150k 91 AT or was replaced like the majority were under warranty bfore 70k?

I'll look through the records (I have the files going back to the original owner) but the problem is warranty-type work isn't recorded for the most part. For example, the person I bought it from had to haggle to get the proof of the timing chain guard being replaced in '97, it's a printout from the warranty department rather than a bill of any sort. That's pretty standard policy, when I worked for a certain motorcycle company we couldn't give any written proof of serious warranty work (as in, say, an engine rebuild) because the company preferred to stay tight lipped about any work that may or may not have been done on a newish vehicle.

EDITThe only record I could find that was unexplained was a 1000$ bill in 2001 with 80 000 miles for "A repair as per our estimate" with no part numbers or description listed.

I also found the mileage for the pan drop, it was done at 105 000 miles.
Modified by Desmoquattro at 7:21 PM 2/3/2008

[Desmoquattro]

Looks like I'm answering my own questions here, after doing some research on the site -

I don't think it's the replacement transmission, I can't see any drain plug on the underside of the pan. Mind you I don't have access to a jack at the moment so I could only get a quick glance with a flashlight.

Second, after looking through some other posts, I'm thinking maybe it isn't the transmission at all, it sounds more like the transmission mounts that have given out. That would explain why it shifts great and but still get low frequency vibration at certain points. If revving the motor in park or neutral, there is some vibration (almost as if a cylinder was misfiring above idle, but the motor runs perfectly). Putting it into reverse and slowly releasing the brake causes a mechanical crunch from the underside of the car (not from inside the transmission).

SO first order of business is having a look at those mounts, I guess.

[Skibane]

If the ATF is grayish-pink, it's probably still badly in need of replacement. The odor will tell you a lot...

Personally, I'd rather put in fresh fluid - along with a good ATF additive if the shift characteristics demand it - than watch old fluid get more sour every day.

[maxnix]

The fluid on the dipstick is pinkish-grey. I've been told, and also read in numerous sources, that after a certain point changing the transmission fluid will only create more problems, as removing the old fluid with the clutch material floating around in it will generate more slip (supposedly the material in the fluid acts as an abrasive that generates friction in the clutches).

My question to you is if the "experts" think that you should continue use the transmission with contaminated fluid, why isn't it delivered new with contaminated fluid?

There is no reasonable rationalization. You're dilemma is whether it is worth $235 to do a mechanical fluid exchange (or 2, given the color - no nonsense about drain and fill being effective enough here), pan drop, inspection, clean, then filter, gasket and one time use bolt replacement?

Your call. If you have the funds on hand as you should, effect the replacement as soon as possible, add the auxiliary ATF cooler and replace the rear main seal and maybe the turbine sensor rather than use the old one. You don't wnat to pull the transmission twice in a very short period of time.
Modified by maxnix at 9:27 AM 2/4/2008

[Desmoquattro]

My question to your is if the "experts" think that you should continue use with contaminated fluid, why isn't it delivered with contaminated fluid?

There is no reasonable rationalization. You're dilemma is whether it is worth $235 to do a mechanical fluid exchange (or 2, given the color - no nonsense about drain and fill being effective enough here), pan drop, inspection, clean, then filter, gasket and one time use bolt replacement?

Your call. If you have the funds on hand as you should, effect the replacement as soon as possible, add the auxiliary ATF cooler and replace the rear main seal and maybe the turbine sensor rather than use the old one. You don't wnat to pull the transmission twice in a very short period of time.

The problem is there isn't really any consensus on the "point of no return" theory of transmission fluid. Search around and you'll see just as many people argue for it as for against it. Hence why I ask the question here to see if anyone has experience with it on the Q specifically; I agree that leaving contaminated oil is counterintuitive, and the first time I heard someone say that I felt like asking him if he had had his head examined recently. I like to look at all the sides, you'd be surprised at how little consensus there is in the mechanical world. I worked as a motorcycle mechanic for a while, I've seen a lot of disagreement on how things should or should not be done.

So all this to say,

I am planning on replacing the fluid given it was done 45 000 miles ago and given that my symptoms sound more like a transmission mount problem than internal issues (my fault in diagnosis). While I'm under there some new mounts go in and I check the driveshaft for sagging.

[Haitian_King]

I'm thinking I'm willing to "risk" a fluid change considering it was done at least once in the last four years (if it hadn't been done since new it would have been a different story, then it's no way).

(By the way, fluid flushes are extremely bad and are not recommended by any manufacturers. You risk pushing sludge and debris into the valving and destroying the transmission in short order. I've heard plenty of horror stories about transmission going kaput only a few thousand miles after a fluid flush.)

I got one and I haven't had any negative things happen. I had a BG shop do it. Took 2 hours and cost me $150. Then again, I just cracked 90k on my Q. I think that a flush is only bad when you have an abused transmission. If it's already pretty clean, cleaning it some more shouldn't hurt it.

[Haitian_King]

Looks like I'm answering my own questions here, after doing some research on the site -

I don't think it's the replacement transmission, I can't see any drain plug on the underside of the pan. Mind you I don't have access to a jack at the moment so I could only get a quick glance with a flashlight.

Second, after looking through some other posts, I'm thinking maybe it isn't the transmission at all, it sounds more like the transmission mounts that have given out. That would explain why it shifts great and but still get low frequency vibration at certain points. If revving the motor in park or neutral, there is some vibration (almost as if a cylinder was misfiring above idle, but the motor runs perfectly). Putting it into reverse and slowly releasing the brake causes a mechanical crunch from the underside of the car (not from inside the transmission).

SO first order of business is having a look at those mounts, I guess.

Did the records show a driveshaft replacement? I'm having somewhat the same issue and after searching on the board, I found that all Q's pre-1994 had an issue with the rubber thing on the driveshaft wearing out quickly. In 94 the piece was redesigned and is "beefier". I find that the driveshaft piece, transmission mounts (possibly motor mounts too.) and the exhaust hangers can give that vibration issue.

[maxnix]

1.) The problem is there isn't really any consensus on the "point of no return" theory of transmission fluid.

2.) Search around and you'll see just as many people argue for it as for against it.

1.) There is on this board. Change in color and smell is a direct indicator of the fluids degree of demise. New fluid is always best as knowledgeable automatic transmission engineers will always attest.

2.) One has to discriminate between the knowledgeable and the ill informed. If one is a slave to opinions without reasonable analysis, that person is continually confused.

[Desmoquattro]

I'm not disagreeing with you on those points, it certainly makes sense to replace the fluid regularly. My concern was more with making the transmission slip by removing the old fluid, which is a known problem on high mileage automatics. Regardless I'm biting the bullet and doing a pan drop and filter replacement.

I have a small exhaust leak I'm getting welded tomorrow, so I'll look at the hangers and mounts while I'm in the shop. I'm guessing they are more than likely overdue, there is nothing in the service records about them. Nothing about the driveshaft either, but like I said the warranty stuff isn't listed on the work orders. The car was serviced regularly at the dealer from new right up to 2004 so if any work needed doing it was probably done.

Quick question, the "rear engine mounts" that are sold on InfinitiPartsUSA, do they come in a kit of two or are they 120~ each?

[maxnix]

My concern was more with making the transmission slip by removing the old fluid, which is a known problem on high mileage automatics.

Quick question, the "rear engine mounts" that are sold on InfinitiPartsUSA, do they come in a kit of two or are they 120~ each?

My question to you, to whom is it a "known problem"? If the transmission is toast, it is toast. There is no evidence (zilch, none, zero, nada) that retaining worn fluid will extend a transmission's life, period. Quite the contrary. But a pan drop with no mechanical fluid exchange is like putting a butterfly band-aid on slashed femoral artery.

3rd motor mount is the transmission mount. I thought about $70.

[Haitian_King]

I'm not disagreeing with you on those points, it certainly makes sense to replace the fluid regularly. My concern was more with making the transmission slip by removing the old fluid, which is a known problem on high mileage automatics. Regardless I'm biting the bullet and doing a pan drop and filter replacement.

I have a small exhaust leak I'm getting welded tomorrow, so I'll look at the hangers and mounts while I'm in the shop. I'm guessing they are more than likely overdue, there is nothing in the service records about them. Nothing about the driveshaft either, but like I said the warranty stuff isn't listed on the work orders. The car was serviced regularly at the dealer from new right up to 2004 so if any work needed doing it was probably done.

Quick question, the "rear engine mounts" that are sold on InfinitiPartsUSA, do they come in a kit of two or are they 120~ each?

The site shows $120, but sometimes, the listed price is incorrect. It's a little messed up I think. What if the customer had no knowledge of NICO or knew to call Joe and just ordered from the site? They'd pay out the nose.

BTW, where do you get your Q serviced in Montreal? I've been wanting to take a drive out there. I'd never seen one in Montreal before. I was surprised to see the Infiniti dealership in Laval I think.

[Desmoquattro]

I don't bother with dealerships, I do my own work. But this car was serviced (quite well) at Meridien Infiniti on Jean Talon (on the island of MTL). There is another dealer on the south shore (Brossard) that isn't quite as good in my experience, that's where my father bought his G35.

If you come up, feel free to drop me a line.

[bullittandy]

I just saw your signature and laughed. I used to own a 95 900SS and even though I was prepared for the dry clutch sound-it still startled me when I first heard it. That bike was wonderful, crazy torque, sick sound and in my humble opinion is the most beautiful bike ever designed.

Also typically Italian, a frame weld broke on the top frame rail connected just below the bars!!

[AlabamaDan]

The site shows $120, but sometimes, the listed price is incorrect. It's a little messed up I think. What if the customer had no knowledge of NICO or knew to call Joe and just ordered from the site? They'd pay out the nose.

It's all perspective. What cost $100 from Scottsdale would cost me $175-$200 at the local stealership.

I've found the prices on the site to be right on with what I'm getting charged on the phone. Do you get further discounts from Joe? Infiniti did raise all their prices across the board last year.

BTW, IMHO a pan drop never hurts anything. It might not exchange all the fluid, but it gets alot and if you start doing it reguarly you'll get it all eventually. The mechanical fluid exchange might cause problems from what I've heard.

I had a BG Flush 45k/6 years ago. I haven't noticed any problems. I'm trying to decide if I should have one myself. Sometimes it's hard bring yourself to fix something that isn't broken - but that's the NICO way!

[Q45tech]

The very very very robust LS400 transmission survived with just a pan drain every 2 years or 30k which ever occurred first. It was and still is rare to replace 250k transmissions as long as the 2 year 1/3 rd ATF is has been replaced.

As long as you catch the discoloration early when the red starts to destaturate, otherwise you have to do a FULL fluid exchange to get the black/brown out.

The Toyota T4 ATF is a premium synthetic usually made by Mobil in US.

[Haitian_King]

It's all perspective. What cost $100 from Scottsdale would cost me $175-$200 at the local stealership.

I've found the prices on the site to be right on with what I'm getting charged on the phone. Do you get further discounts from Joe? Infiniti did raise all their prices across the board last year.

I've never ordered anything from there. But Maxnix states way lower prices for parts than what's shown on the site. When I thought I had to replace my transmission, he told me that I could get one for $2500 from Joe, but the website showed it at like $4500.

[AlabamaDan]

The Toyota T4 ATF is a premium synthetic usually made by Mobil in US.

Are you recommending we use Toyata T4 ATF? Is that what you use?

I've never ordered anything from there. But Maxnix states way lower prices for parts than what's shown on the site. When I thought I had to replace my transmission, he told me that I could get one for $2500 from Joe, but the website showed it at like $4500.

Anyone have experience 1st hand?

[captainluigi]

Reji, this is off the topic of this thread but; infinitipartsusa.com(ISO) internet prices are the same as nico prices with maybe some personalized service added. recent example is my crank pulley/harmonic balancer. lists for $357. @ miami stealership. our price $222. now thats cool + 3day shipping. we NEVER get anything in 3 days here in the keys.

[Desmoquattro]

Had a look under the car today while it was on the lift. Good news is that it's a replacement transmission with the drain plug on the pan.

Good or bad news, depending on how you look at it, is that all the mounts are beyond shot. The exhaust mounts are both split and one has a broken stud. The transmission mount is looking sorry too, with loose rubber coming out the sides. So I have the new parts on order, I'll install them soon.

[Haitian_King]

Reji, this is off the topic of this thread but; infinitipartsusa.com(ISO) internet prices are the same as nico prices with maybe some personalized service added. recent example is my crank pulley/harmonic balancer. lists for $357. @ miami stealership. our price $222. now thats cool + 3day shipping. we NEVER get anything in 3 days here in the keys.

I guess that's what maxnix did then. It was in a thread from about 3-4 months ago.

[Haitian_King]

Had a look under the car today while it was on the lift. Good news is that it's a replacement transmission with the drain plug on the pan.

Good or bad news, depending on how you look at it, is that all the mounts are beyond shot. The exhaust mounts are both split and one has a broken stud. The transmission mount is looking sorry too, with loose rubber coming out the sides. So I have the new parts on order, I'll install them soon.

Good stuff. Would you mind posting pictures of the install? I've been studying the FSM, but I'm still not clear on it. I hear it's a very easy job, about an hour, but I don't like to work on things unless I'm absolutely clear.

[Desmoquattro]

I just saw your signature and laughed. I used to own a 95 900SS and even though I was prepared for the dry clutch sound-it still startled me when I first heard it. That bike was wonderful, crazy torque, sick sound and in my humble opinion is the most beautiful bike ever designed.

Also typically Italian, a frame weld broke on the top frame rail connected just below the bars!!

I like the mid 90s SS a lot too, it's a classic design.But as you found out, they have serious problems with the weld around the headstock. If I had nickle for ever one I've heard of... Amazingly some people still manage to get them replaced under "warranty" by Ducati. I had looked for one but came across a well-used 916 for a good price, so I snatched it. It's an astonishing machine, I adore it and I don't plan on ever getting anything else, except maybe an MV F4 if I can figure out a way to import one into Canada.

[lino]

Depends if it is an original 150k 91 AT or was replaced like the majority were under warranty before 70k?

How can one tell if the transmission was indeed replaced under warranty?

Here is a page of my service records. Take a look at the last line. One Infiniti representative told me that it means that my transmission was replaced, while another was not sure:

[Haitian_King]

How can one tell if the transmission was indeed replaced under warranty?

Here is a page of my service records. Take a look at the last line. One Infiniti representative told me that it means that my transmission was replaced, while another was not sure:

The guys on the board had me check my AT pan. If there's a drain plug, like the one on an oil pan, then it's most likely been dealer replaced under warranty. If there's no drain plug on the ATF pan, then most likely you still have your old factory one.

[Desmoquattro]

Good stuff. Would you mind posting pictures of the install? I've been studying the FSM, but I'm still not clear on it. I hear it's a very easy job, about an hour, but I don't like to work on things unless I'm absolutely clear.

It's so straightforward, you can see it at a glance. When you are under the car you'll see the transmission pan, and near the back of that close to the primary driveshaft there is a rectangular support attached to a crossmember that slings underneath the transmission. That's the transmission mount. Just behind it are the exhaust mounts, rubber-sandwich looking things connected to the crossmember in the centre and connected to two arms that support the exhaust pipes on either side.

[Haitian_King]

It's so straightforward, you can see it at a glance. When you are under the car you'll see the transmission pan, and near the back of that close to the primary driveshaft there is a rectangular support attached to a crossmember that slings underneath the transmission. That's the transmission mount. Just behind it are the exhaust mounts, rubber-sandwich looking things connected to the crossmember in the centre and connected to two arms that support the exhaust pipes on either side.

Alright then. I'll have to get underneath. I just made friends with a man who has a lift in his garage. He's an aircraft mechanic by night and an import technician by day. He's quite knowledgeable about Domestic, European (Primarily VW), and Japanese cars (Nissan and Mitsubishi). My lucky day eh?