1985 4+3 transmission.....48 k odometer

So, Im new to the vette thing. I love the car. Love the transmission. Hate the issues. So what if it leaks. So what if the 4+3 has a mind of its own. But I just cant stand its latest surprise trick its pulling.

For some reason it makes a horrible rattle when its cold and rolling. It sounds like a bolt is bouncing around in the transmission or in the clutch area. It is independent of the rpms, and does it when the engine is off and simply rolling. When on and accelerating the the frequency does not change. Occurs whether the clutch is engaged or not. It sounds like a bolt bouncing around in a thick walled can or maybe the unused gear in the transmission are touching each other while those engaged are doing their jobs appropriately. I can feel it in the shift stick as well. I fear for the life of the car.

The weird thing is.....it goes away once it warms up and the oil temp shows on the dash.

Had the fluids changes everywhere. All were in terrible condition. When they were changed the tech said the std tranny had a fluid level he couldnt touch when he stuck his finger in the drain plug hole. When he pulled the plug out of the overdrive, he said, fluid shot out sideways as if over full or under pressure.

BTW... I changed all of the fluids because it over heated to 300 degrees. Thanks to a mechanic that didnt tighten the radiator cap that extra 1/4 turn. And yes, the engine clattered by the time I got home. It only took a couple of miles to do that by the time I noticed the temp hit 212 degrees. I thought I had more time. Yes, im an idiot. Ill admit it.

So, now the questions...justa couple.

1. What do you think causes the noise? Remember, its independent of rpms and occurs when cold and coasting with engine off as well, until warmed up.
2. Is there supposed to be THAT much fluid in the OD?
3. If not, how could it have been that full? If so, where is the fill spot for it?

That's it for now. I cant decide on whether to let it sit for the winter or stomp on it until it blows up.

 

Couldn't tell you without driving it but it could be a lot of things. I imagine others will have similar replies.

 

You are welcome to drop by and drive it. Just take a turn south at Denver, CO and stop in Castle Rock. Cant be more than 3000 miles away from anywhere USA. You may wanna wait until the snow melts. The 4wd isnt working on the vette either.

 

Did the rattle occur before you overheated the engine? Just curious as it may have some bearing on the issue. As Daniel stated it will be difficult to diagnose without actually being there to hear it. Since you can feel it thru the shifter I would start there. There is a seal between the 4 speed and the overdrive portion so the 4 speed parts fluid may be leaking into the OD. I dont know about "shooting" out tho, that seems odd. Check the OD fluid again for water intrusion as it flows thru the radiator just like an auto tranny. It will turn milky pink with water in it. Hopefully he put 90wt back in the 4 speed and ATF in the OD.

A lot of things happen when the car goes into closed loop after it heats up and something there may be the culprit. Maybe its the cat converter. They can make a rattling sound but usually do it continually.

hopefully someone will have more useful input. I have an '85 and severely overheated mine but have not experienced any rattling. All I have to say is thank God for iron heads cuz both of us woulda been screwed.

 

It was long after the overheating AND after the fluid change. Ill check the ticket to see what he put in there.

Im wondering if he doesnt have enough ATF in the OD. It would seem to me that if the ATF flows through the radiator, then he may have unwittingly drained the fluid out, thinking that it should be filled like a standard transmission or a rear end; only up to the side plug.

I'm thinking that the fluid pouring out like that is normal as maybe the OD should be full as well as the radiator.

Does the OD have a fill tube in the engine compartment, like an automatic transmission? If so, where? If so, does it have a dipstick? If so, ill check its level and add if necessary to see if thats it.

 

Check your catalytic convertor.

 

Assuming the noise only happens while your rolling, and assuming it does not change in frequency or amplitude with engine RPM, then I would guess it's related with the transmissions final drive, or the drive shaft it-self..

just a guess..

 

thinking heat shield too.