My 4L60 (non-E) in my 1992 coupe hiccupped and seemed to be slipping a little today. When driven normally everything seems fine, but when I went to drive it like a Corvette there were a few moments that scared me a little. Never had a single issue before.

Everything online says this is basically a bulletproof transmission not to worry about. I read through the original owner's service records and found that they never had the fluid and filter changed ever. So while my car has only ~74k miles, the ATF is 26 years old. Should a fluid/filter change be in order? Also approximately how much should one pay for that service?

I also plan on pouring in a bottle of Lucas Stop Slip tomorrow. Ive never used it in a Corvette (or any other RWD auto) but I have put plenty of the stuff in beater Hondas/Toyotas with 200k+ and was really impressed with the results. If the Lucas works should I just forgo the fluid and filter change until 100k like the manual says?

 

IMVHO:

1) It's not bulletproof. Not by a long shot.

2) There IS a chance of washing plaque loose and sticking the governor or other controls when doing a fluid change at an interval that long, but having said that.. I would do it anyway if it were mine. I can't imagine running 26 year old ATF and the moisture and nastiness that would have to be in it by now. But, be forewarned that there is a small chance it can cause problems.

3) I'm not a fan of fixes in a can. But, if you have to use one, Lucas seems to be one of the more benign ones. Appears to raise viscosity, but doesn't overtly attack the seals and attempt to swell them like other products I've seen. (And I've seen some very severe effects and damage arise from using these products.)

I dunno if it is even still down there, but somewhere in the storage room of the shop there is a tupperware container of Lucas mixed up with ATF, and there's a front seal floating in it. I stopped checking it for damage after a few years of constant immersion because I never noticed anything appreciable. So, there's that.

4) I would absolutely change the filter also.. Yes. Be sure you get the old seal out of the pump and make sure the new one fits well. The flexible pan gaskets are nice. Farpack works well too. If you end up with cork, drive it a few weeks and then snug the bolts to prevent leakage.

5) If you thought you felt a slip, take a look at the TV linkage real quick and make sure it hasn't backed off.. The adjuster is plastic and it's old plastic at this point.

Regards and good luck!

 

Bullet proof my a** You should definitely not ignore it. Everything works great......until it doesn't. Your at that point. You should start with looking at the fluid and smelling it. Wipe the dipstick off on a white rag or paper towel and you can see the fluid condition. If it's dirty and/or burnt a fluid/filter change might help. If it's clean and no burnt smell then it needs help before you burn it up.

 

It is clean and does not smell burnt. What exactly is this "help" that it needs?

 

It's been a while since I worked on one of these transmissions but as mentioned the TV cable adjustment can be problematic if something happened to it. There is a governor on the side that cause issues. There are a countless number of o rings, accumulators, valves and other do-dads in the valve body that can cause problems. The "help" is getting it to someone or yourself diagnosing what's going really on because it's almost certainly more than a hiccup.

When specifically was the slip? 1-2, 2-3....?

There is lots of info online to diagnose it yourself. That doesn't necessarily mean you can fix it.

 

Thank you, sir! Nice to see you all again.

 

I would drain and fill, rather than going to a place that power flushes them.

 

No sir, these autos are not bulletproof. Since my rebuild, I change the fluid and filter yearly. Some call it overkill, I call it me being paranoid.

 

PS: I have seen transmissions that sat unused for very long periods that had obvious microbiological activity going on inside.

I am not a microbiologist and I never plated a fluid sample, so I dunno if the stuff was growing in the ATF, or in the condensation riding on it? Or in the housing? I'm not sure..

But I know I would absolutely, without question, change out 26 year old fluid without so much as a second thought, and regardless.

Because it's a contaminant and it's totally gross.

 

Oh hell no, the very first thing I would do is a fluid flush, and filter change. all sorts of nasty things happen in used oil, and they become acidic, attacking all of those beautiful, pristine, machined surfaces on the shafts, bearings, etc.

It really is simple

D.

 

OK, here is my answer, please no flames as it will have 50 different opinions, and yes, I understand why.....here goes. I managed a national transmission store back in late 80's early 90's....people with transmission problems (this was in the electric shift solenoid age btw) would come in and want trans flush, fluid change etc - exception to this is Ford . Lincoln town cars, crown vics with torque converter shudder - fluids WAS fluid related), by the time you transmission shows signs of problems and it HAS NOT BEEN SERVICES REGULARLY OVER THE LIFE OF THE TRANSMISSION , which is at least one or two full trans services, the fluids and the thickness of old fluid - including the broken down clutch particles were the only only thing holding it together. I would recommend diagnostic and advise AGAINST a fluid/service but would do it if the customer insisted. The fluid change to new clean fluids would allow correct operation of the internals, close gap of the contact points, and the transmission would fail almost 50% of the time within the next month. So IMHO- if the trans fluid is of unknown age and service, leave it alone or have it looked at , DON't just change the fluid and filter. Again, everyone has their view on this. Also if your auto is fine and has over 100k miles on it, I still recommend just leaving it alone, best bet is following factory maint. schedule or more from day one, but I understand most people here have used C4's and can't control or don't really know the service history. My fluids have been changed regularly- this includes the differential fluids, power steering, brake, coolant, and even cleaning out the nasty window washer jug and coolant over flow jug. It just a few hours or less with a fluid extractor. (can be bought cheap at harbor freight for one or two time use). (don't forget the GM additives for coolant/rear end depending on your options-may or may not be needed manual/auto trans)