Change trans fluid on '84 Riv?

[Guest 84riviera]

My 1984 Riviera has about 40,000 miles. I was thinking of changing the trans fluid because it's probably original, and it "clunks" into gear from park. It leaks trans fluid, about a drop a day, so the gaskets must be going, right?

If I replace the gaskets, do I need to pull the engine?

Should I even mess with it?

[63 Rivi]

Clean around the trans to determine where the leak is coming from, it is usually the pan gasket. If it is the front seal (you would have to loosen the inspection cover to see it) then I would try some trans sealer. It is not worth the aggravation and cost to remove the trans to fix such a small leak.

I would recommend putting a new filter and gasket, and reusing about half of the old fluid that drained out. At this point, putting in all new fluid and completely flushing the trans is asking for trouble. The bands inside the trans will not like all the fresh strong detergent in the oil. Use a small bead of silicone on the pan gasket, torque all the bolts to 10 lbs, let it set up for an hour or two and then refill. Let it warm up and check the fluid level while running and parked on a flat surface to ensure you fill it to the proper level.

The "clunking" sound could be something as simple as the idle being too high. Check to make sure it is set to the specs on the underhood label.

[sosuzguy]

Sounds like he could have a line pressure problem too. They shouldn't chunk or slam into gear.

[RivNut]

The last time I had a car that "clunked" when I put it in gear had a cracked flexplate.

[Lapham3]

Agree with Darrell, excepting the need to reuse some of the drained oil. ATF is a lube and friction modifier, but has no detergent qualities. Also, there will be plenty of undrained ATF left in the convertor so the 'shock' of complete ATF r+r is not there as with the flush proceedure. Nice to service that 29-30 year old transmission-good luck Dan Mpls. Mn.

[TexasJohn55]

It is the nature of the forums, everyone has an opinion or perspective on things and they sometimes agree, sometimes disagree.

Experience has taught me to NOT use a sealer on cork gaskets. A contact adhesive is sometimes used when necessary that will not allow movement. Silicone on a cork gasket will allow the gasket to slip and "squeeze out" causing distortion and loss of seal. For a cork gasket to seal effectively, it must be clamped without movement.

If fluid is burnt, contaminated or otherwise unfit for re-use I don't understand the logic of wanting to use half of it back. The better choice would be to drain the converter also. My 55 has 2 plugs in the converter to allow venting and draining, I don't know about your 84 Riv. I don't believe in "band shock" from new fluid. If new fluid fails the transmission, it was doomed to begin with.

A clunk when put in gear could be several things: flexplate as mentioned, idle speed as mentioned, loose or worn mounts, loose ujoints or loose differential.

As already mentioned, if you have a leak, you must clean it up and locate root cause. It might just be a shifter shaft seal leaking and running down onto the pan.

Good luck...........

[63 Rivi]

It is the nature of the forums, everyone has an opinion or perspective on things and they sometimes agree, sometimes disagree.

Experience has taught me to NOT use a sealer on cork gaskets. A contact adhesive is sometimes used when necessary that will not allow movement. Silicone on a cork gasket will allow the gasket to slip and "squeeze out" causing distortion and loss of seal. For a cork gasket to seal effectively, it must be clamped without movement.

If fluid is burnt, contaminated or otherwise unfit for re-use I don't understand the logic of wanting to use half of it back. The better choice would be to drain the converter also. My 55 has 2 plugs in the converter to allow venting and draining, I don't know about your 84 Riv. I don't believe in "band shock" from new fluid. If new fluid fails the transmission, it was doomed to begin with.

...........

I have no problem with someone disagreeing with me, like you said, it is the way forums are.

I worked in a garage and had done many gaskets on engines and including transmission pan gaskets. I have always used a small bead of silicone and never had an issue when used with cork gaskets. The only time I saw this is when someone was overly aggressive in tightening down the mounting bolts.

The advice I gave on this model is from my intimate knowledge of its weaknesses. The initial design of the 325 was a non-overdrive 3 speed model. They held up very well but when it was converted to the 4 speed overdrive, they suffered from durability issues with many failing before 100k. (The clutches and brake bands were the weak points - they would not hold up well when exposed to excessive heat) If the car was not driven hard and the trans fluid was changed every 25k, they would last. I got 167k out of an 85 I had just by changing the fluid at the right intervals.

84 Riviera did not state his transmission fluid was burnt or dark red. If it was, then I too would advise that it should be drained out and we'll just hope for the best at this point. The newer dexron type IV fluid has more additives in it than the original formulation his car came with. While it is backwards compatible, you run the risk of loosening up contaminants in the trans. (I meant to say additives and not detergents in my last post, sorry)

There are two schools of thought on changing fluid in an older trans that still looks and functions well; change out some of it and avoid "shock" or do a fluid change - either by changing out all the fluid that comes out when you drop the pan or by a fluid flush. With most transmissions, it would be advised to do a fluid change but the overdrive 325's need to be treated more carefully. My friend has owned a transmission shop for over 20 years and has rebuilt and serviced dozens of these. In his experience, he learned early on about the issues with this model and has had good success by erring on the side of caution. In 84 Riviera's case, he can do either type of fluid change but one runs more risk than the other. Regardless, the filter should be changed and the pan cleaned of contaminants.

Also, another source of clunking when going into gear could be a bad transmission mount. The rubber inside the mounts can fail, especially after almost 30 years.

Edited November 12, 2013 by 63 Rivi (see edit history)

[Guest 84riviera]

Thanks for your input, guys. I have some Dexron-IIE in my garage that I compared with; should I use it?

It does smell a bit burnt. Am I SOL?

[RivNut]

Thanks for your input, guys. I have some Dexron-IIE in my garage that I compared with; should I use it?

It does smell a bit burnt. Am I SOL?

[ATTACH=CONFIG]222393[/ATTACH][ATTACH=CONFIG]222394[/ATTACH]

A guy, Bud Miller from southern Missouri, in the old MO/KS region drove an '85 Riv over 500K. He had the trans overhauled at around 225K and engine rebuilt at 375K. I think you're probably good to go for at least another 40K. The body on his car got so rust eaten that he needed to scrap it. The rebuilt motor and trans were still going strong at the 500K mark.

Get the car on a lift and have a professional figure out what the clunk is. Pick the most logical advice, compare it to what the factory calls for, and hope for the best. Unless you severely damaged the trans, I don't think you can go wrong.

You haven't had to replace the TCC solenoid yet have you? That's one thing I had to do to some of my 79 - 85's at around 80K.

Edited November 12, 2013 by RivNut (see edit history)

[RivNut]

Also, another source of clunking when going into gear could be a bad transmission mount. The rubber inside the mounts can fail, especially after almost 30 years.

An easy diagnosis for this is to put the car in gear. Left foot hard on the brake, right foot on the accelerator. Rev up the engine and see if it lifts on the right side. If it does, the right motor mount is busted. Put the car in reverse. Same scenerio but look to see if the left side of the engine lifts; if so, busted left motor mount. Don't rev it up so hard that you bust them, just enough to see if the engine lifts. Is there an inspection cover for the flex plate / torque converter? If so, pull it and check the tightness of all of the bolts, and take a look at the flex plate. Check the other mounts while you're under the car.

[Guest 84riviera]

I don't have access to a lift, although I'll try your test, RivNut. I have not touched the TCC solenoid.

[RivNut]

When/if the TCC (Torque Converter Clutch) solenoid does go bad it's an easy, relatively inexpensive fix. As you slow to car down to a stop, you'll notice that the engine will start to bog down as if you were driving a manual transmission and tried to bring the car to a stop without disengaging the clutch. That's exactly what's happening inside the trans, the clutch on the lock-up torque converter is not disengaging.

It does not make the car undrivable. When you need to slow down or make a stop, you simply shift into neutral. That will manually disengage the clutch. When you put it back in gear, it's like starting over again. To change out the solenoid, it's only a matter of dropping the transmission pan to get to it.

Ed

[63 Rivi]

Thanks for your input, guys. I have some Dexron-IIE in my garage that I compared with; should I use it?

It does smell a bit burnt. Am I SOL?

[ATTACH=CONFIG]222393[/ATTACH][ATTACH=CONFIG]222394[/ATTACH]

No, I don't think you are SOL if the trans is still behaving properly. Knowing now that your fluid is burnt, I would drop the pan and replace whatever fluid drains out. Keep in mind that you will only get out about 1/3 of the total in there. If you decide to really roll the dice, (not my recommendation), you can bring it to a shop that can do a complete fluid flush. Just make sure they do not use a high pressure machine to do it. That can release contaminents and could clog up some of the really small passages which can effect the way it operates.

Like Jayson said a few posts earlier, it could be an internal issue that is causing the "clunk" that you are experiencing. However I would explore all of the external factors first, as well as making sure that your idle is not set too high.

[Barney Eaton]

Automatic transmissions are like hydraulic systems. Any farmer know that hydraulic systems do not like dirty fluid. If it looks dirty it is.....maybe no big chunks of crud but dirty. If you have a car that is a keeper..... change the fluid, it takes very little time and is cheap.

[sosuzguy]

I will tell you from my experience with 5 of these cars ranging from '83-'85 models, if your transmission is performing as it should just change the fluid & filter and go on. Drive your car in town in Drive, not over drive, use that for highway driving. TCC can go bad and you can have line pressure problems that will make it slam hard into gear. Also trans mounts/engine mounts... Otherwise if much else is wrong with these transmissions you will have a difficult time finding someone who will be able to rebuild them correctly. Next thing is if you need hard parts for the rebuild, you better keep your fingers crossed.

Just .02 from someone who's messed with a bunch of them.

[Guest 84riviera]

Should I use Dex VI, Dex/Merc, Multi-vehicle, high-mileage (for leaks?)? Can I mix Dex IIE with the recommended oil?

Which brand do you guys prefer? Can I go with store-brand?

[63 Rivi]

Dex IV and yes it is backwards compatible with earlier Dex. Don't really think there are any differences between the brands.

[Guest merrillcrosbie]

I have an 83 that I bought new and have 130K miles on it. It also goes into gear very hard, but it always has. Mine also leaks tranny fluid from the pan gasket, and I have put stop leak in with no significant results. So, I just keep a pan under the car. I have changed the transmission fluid twice in 30 years. I do a complete change where the fluid was pumped out from above repeatedly until the color is bright red. It had gone rather brown. The fluid changes have always made it drive much better. I have taken it on several long trips (2000k+ miles each) since the most recent fluid change and the transmission has performed flawlessly...except it does go into gear rather hard, especially reverse, and leaks a bit. I guess my point is, just maintain it and drive it. It will probably outlive you.

Oh, I also had a TCC failure at about 80K miles. As mentioned, it was an easy and relatively inexpensive fix once I found someone who knew what to fix. But, it didn't affect the hard shift. It only caused the car to stall when stopping.

Edited November 15, 2013 by merrillcrosbie
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