joelk

I do not usually drive my 2000 Vette when it is cold, but occasionally do.

Last winter(or perhaps prior winter) I started it to get it out of the unheated garage and let it run for a little bit before moving it.

I don't remember exactly how cold, but IIRC below 20F.

Found a small puddle or trans fluid under where the trans was parked and a small trail of fluid where I backed out of the garage. It was not a lot of fluid, but very obvious that it just leaked out of trans area directly under rear center of car. It stopped leaking after a very short period of time.

Each time since then I have kept looking for other signs of leaking and never found any other indications of it leaking again(have driven several thousand miles since original leak) until a couple days ago.

Same situation. Very cold, below 20F and I started the car to back out of garage. Left it idle for a minute or two then backed out. Small puddle and a trail where I backed out.

Under different circumstances, I would just avoid driving the Vette when it is below freezing, but my truck is out of commission while I had the engine out to repair it. I may need to drive the Vette a few more times in very cold temp before I get the truck operational.

What would cause the A4 transmission to push fluid out ONLY when it is VERY cold?

Where would it likely be coming from?

Is there a vent that might be frozen?

Is there a seal that might contract in the cold?

I have a lift, but the truck is on it. Once I have access to the lift is there a specific area I should look at?

Vetteman Jack

Moved to C5 Tech.

joelk

No one has encountered this, or heard of it happening?

SG Lou

Nope

joelk

Well I got the engine back in my truck so hopefully I won't have to drive the Vette again before it warms up.

Sure would be nice to know where to focus my attention and/or preorder parts before I put it on lift so...

runner140*

The answer is usually the same: get it off the ground, take a close look, clean all fluids off the entire area of the transmission and floor. Start it up and see where the leak is coming from.

I've got a 2000 A4 also but no leaks...BUT that is what I would do.

joelk

Thanks for the reply!!!

I'm curious, do you(or others) EVER drive your's if it is VERY cold(below 20) and car has been out in the cold overnight or longer?

It may be a more widespread issue than it seems, because I doubt that many C5s are driven when the weather is that cold. I'll bet the percentage is very low. It is a very rare event for me.

I will probably end up doing as you suggest, but one of my concerns is that it only seems to leak when VERY cold. My car is currently in an unheated bay beside the heated main bay of my garage where my lift is located. Temps are now above 20, higher where the car is as it gets some transferred heat from the main bay so it may not leak if started now.

My lift is in the heated part of the shop. Even if it gets very cold again driving it from unheated bay to heated bay is probably enough to stop it from leaking and if fully warmed up in heated bay I am pretty certain it won't leak.

I may be able to diagnose the source of the leak from where fluid is on the outside of the trans, but the first time it leaked(1-2 years ago) I put it on the lift on a warm day and could not tell where it came from.

runner140*

I live in Ft. Lauderdale and cold is 45. I guess cold weather would tend to shrink gaskets a little. Early C5's were a little like early Harley's...they leaked a bit.

tred99

This happened to me a few weeks ago when I had to move the car out of the garage to gain access to storage. My garage isn't heated and it was like 2 degrees outside. I didn't notice until I walked to the rear of the car to ensure clearance of the garage door that there was nice sized red puddle of fluid on the ground the size of a fifty cent peice. I then drove around the neighborhood to see if it would seal up. Another small puddle! My heart sunk to the bottom of my stomach! Today it was 50 degrees so I pulled it out and drove around the neighborhood and not a drop! I was very happy to see no fluid on the ground but then I noticed my oil pressure gage was pegged! looks like I will be changing the oil sending unit soon. Please let me know if you find anything out. I won't mess with it unless it leaks during the summer months. I don't drive it in the winter.

tred99

Yes this happened to me when the temp was below 10 degrees. once it warmed up no leak. I tried to reply a few days ago the pop ups on this forum make it almost unusable. Downloaded new browser and all good now.

Vettemaster1985

Being that it is winter I take it that it has been parked for a little bit, if so then it's leaking from the front of the trans pan , bad gasket. Mine does the same when it sits from weekend to weekend, but if driven the next day nothing. But of course put that baby up in the air and check it out, you can tell real quick..

tred99

You are correct the car is a garage queen during the winter. The dealer did trans fluid replacement about six months ago so I am wondering if that requires the pan to be dropped? I will have them check during the next oil change. also today when I put it in reverse while holding the brake i,heard some vibration. can't hear it while backing or driving. tranny or drive shaft? thanks for the reply

WetMountainMan

Well, I'll join in... I've had my 2002 C5 (less than 86K miles) only about 3.5 weeks, with the first 2 weeks fairly warm in CO (not freezing). It was driven on several trips of about 100 - 130 miles with no leaks. Then last week as the temps dropped I drove those same trips and afterward I had tranny leaks - from half dollar size to 2" to 3" size about 6" right of center below the tranny. on the days after the trips. Now after the last trip I also found engine oil leaks - two about half dollar size, about 6" to 9" right side of center, less than mid-engine from the front, I think.

I have no lift, so I'll probably end up taking it to a Chevy dealer 60 miles away (I live in the boonies on CO). Plus, I'm not a mechanic and have no experience with Vettes. I do have a powertrain warranty but not sure if it'll cover leaks....??? ... I'll have to check with the carrier.

But before I take it in I'd sure like to know what they might look for. The car resides in an unheated garage with the lowest temps seen in the last two weeks were 1 to 10 deg.F. at night and mid 30's to 50s during the days. My trips were to higher temp areas and home to lower temps where the leaks showed up.

joelk

Today, I pulled my C5 from unheated garage bay(probably about 30 degrees, but was colder overnight) into heated garage bay and onto my lift.

There was a very light drip trail of transmission fluid.

I put it up on the lift and was able to see where the fluid was coming from.

Pretty much in the center of the rear of the transmission case there is a small "notch" perhaps 3/8" by 1/8". The notch is in rear face of the transmission case that bolts up to the differential.

The fluid appears to have been dripping out of the notch.

I cleaned the area and no more dripped out after waiting about 1/2 hour.

I then put a white paper towel under the area and started the car while it was still on the lift. I ran it long enough to get the engine up to operating temp(I forgot to look at trans temp) I ran it through the gears multiple times then shut it off and looked at the paper towel.

Not a single drop on it.

I suspect that this notch is connected to(or part of) the transmission vent. CAN ANYONE CONFIRM THIS?

Assuming it is a vent, does anyone know why fluid would be coming out?

I had planned to flush fluid, change filter and install Dexron VI, but will hold off on doing that.

**IF** I need to pull the trans I don't want to waste all of that new fluid.

How hard is it to pull the transmission on one of these? The car would be on 4 post lift and I have a transmission jack.

jfernandez98

Nothing wrong with the trans.
When it is cold the fluid is thicker. When you put it in reverse the line pressure builds and pushes some fluid out of the seal between the trans and differential.
Not a venting issue.
If you waited with it in park till the fluid temp rose and then put in reverse no issues.
Not related to old trans fluid.
You can change the fluid but make sure when filling to follow the correct procedure.
I would also not flush with any kind of solvent.
Just drop the pan, change filter and refill correctly.

joelk

Thanks for the reply/info.

Are you saying this is a common occurrence on C5s with A4?

If it was VERY cold out I would think I would need to wait a long time for the trans to warm up a significant amount.

When I flush, I will only be using new trans fluid. I will D&R pan and R&R filter then add new fluid to the pan. I will then pull transmission line near the front of the Torque Tube and run engine(adding fluid to pan as needed) until new fluid runs out of the line.

This should get the vast majority of old fluid out. I have done this type of flush on multiple vehicles with good results.

My Dexron VI is synthetic and lower viscosity so hopefully using it will make this leaking a non-issue in the future.

joelk

I changed the filter and fluid today.

The fluid and filter looked very good and there was a very minimal amount of "the gray stuff" on the magnet and in the pan.

I used a small electric pump that I bought for changing oil in my boat to pump fluid into the transmission fill plug. It worked very well.

I did the flush technique and it worked well, but it would have been a LOT easier if I would have had a second person there to assist. I had to get in and out of the car several times while it was on the lift.

In case anyone else may want to flush the way I did, the lower transmission line (at front of torque tube) is the one that comes FROM the transmission.

bogeygolf

I had the same leak last summer. They had to pull the Trans and replace an O ring on the shaft. Then they changed trans fluid and gear oil. Have had no leak since.

ukmac

This is what i found!
I had the very same issue on my 1999 31,000 miles C5. I may have an easy fix for you.
I noticed the same type of drip happening on my Vette the winter before last. When very cold I found a small drip on the garage floor. I did a lot of research and also did some trials of my own. It became apparent that it only happened...as far as I could tell....when putting the car in reverse when it was very cold.....effectively first start up.
Not knowing exactly where it was coming from....I removed the sump and replaced the gasket....and also the filter while I had the sump off. I even bought a small torque wrench to ensure it was tightened up correctly when refitting.
Even after doing this I still had the occasional drip when putting the car in reverse...on a cold morning. I even drove a 100 mile round trip to a Corvette specialist who could not find anything wrong......but then again if my theory is correct....he would not as the car was obviously warmed up by then.
In my opinion it was down to the seal in the auto trans gearbox.........not sure what it is called......but at the rear of the transmission their is a seal effectively between the trans and the rear differential. If I am correct the two seals are effectively in a void to avoid contamination from trans to differential should either fail. Just at the back of the sump is a small rectangular hole....it was from here that I beieve the fluid was dripping from. Eventually finding it's way onto the rear frame as shown in the photo.
I bought a Lucas product.....cannot remember the exact name.....someone will tell us I am sure........but when added to the trans fluid this product effectively rejuvinates seals. I used this product and...fingers crossed.....cured the drip totally.
Even to this day.....over 12 months on.......I try never to put my car in reverse when the weather is cold.....until I have warmed the car up.....just in case my theory is correct.......and the pressure within the transmission is greater...when put in reverse. Hope this helps you...it certainly did the trick for me.

ukmac

I wrote my original reply late last night so now have a little more time to explain further..........I live in the UK and my garage....like most others over here is very small and narrow. When parking my Vette I always used to reverse into the garage and then creep forward slightly to give me maximum space at the rear of the car where I have a storage cupboard. This meant that every time I came to get the Corvette out I had to reverse slightly before pulling forward. This is how I initially found out that the leak only occurred when putting the car in reverse. To check if my theory was correct....I put the car on 4 ramps........not easy in such a small garage......and over a period of a week started the car up each cold morning and put the car in and out of reverse a few times before getting underneath the car and checking. It was only after putting into reverse that the leak happened.......definately. Since putting the Lucas additive in the trans fluid I always garage the vette in such a position that allows me to not to have to put the car into reverse when pulling out of the garage, this means that generally the first time i have to engage reverse the car is suitably warmed up.
I periodically check for this leak using a small extending mirror and have never found any evidence of further fluid loss. Adding the Lucas additive is not particularly easy.......I had planned to pour It into the sump whilst I had the sump removed before refitting the sump.....but suprisingly to me there is not a great amount of space to do this. Instead, I added it through the fill/level hole during refilling. I was a little hesitant at first to put an additive into the trans fluid as a lot of members had voiced their concerns generally over using additives. But Lucas products...to me...were so well known that I thought it was worth a try. Now over 12 months on I have not found any reason to doubt the product. Good luck which ever way you go.