Hi Everyone ,can anyone suggest a direction to look on my 79 auto,
We were out yesterday and after 50 miles turned a tight hairpin corner and started to clime a steep slope ,after a short time and in second gear a loud irregular tinny rattle came from under the car ,much like the noise if you are dragging you exhaust ,so we stopped but could see no fault ,checked the dipstick and found the level about 1.5 inches above the full make :o . I am a bit fussy checking levels and often do it at the end of a journey so i know it was correct (bare in mind i'm new to corvettes though),the level had appeared on the low side a few weeks earlier so again after a journey i had topped it up and must have done around 200 miles since then without any problems . Anyway i set of again only to find the noise came back as soon as the car tried to change to 2nd,i stopped at a friends and i siphoned out some gearbox oil as it was still showing way to high and set of again but the problem was still there ,we drove the 50 odd miles home and the only way it would go into second was by manually changing and from there it would go into 3rd as normal ,if i left it in drive in 1st it would change up to third once i got to 30/35 mph,the noise the car made changing from 1st into second slowly lessened and by the time i got home it had stopped altogether . I rang a friend who has worked on Corvettes for 30 years as he has been a great help with a couple of things and he suggested to take the pan off and change the filter and oil as this is the cheapest fix/option to start with and i didnt know how long they had been in the box which makes a lot of sense to me ,also to leave it till the morning and try again from cold and see how long it took to engaged 1st ,i did this and it was as quick as normal ,so i took it up the road but the problem was still there but still with no rattle noise ,i came back and took a load more oil out as it still showed high and tried again but still no change but noticed that the oil level was now down to just below the add oil mark .
The high level seems odd ,i wonder if there could be a blockage so the oil is in the pan and not in the box were it should be causing a high oil level and the rattle noise was from something spinning in no oil .
i have this morning checked the metal pipe is attached from the modulator to the manifold but not yet sucked down it to see if there is a hole in it .
If any one has any idea's i'd be please to hear from you

 

Just took the car out with the idea to run the car up to normal temperature and then read the level,did about 5 miles and the car developed a misfire which got worse on my way back home ,the misfire was worse when accelerating,I live at the top a hill and a soon os i turned into my road and started up the hill the car died and would not start and had to be towed home so ,i presume it must be something to do with the auto box and the vacuum to the inlet manifold . I'm not having a good weekend

 

Morning all.
Went out to car this morning feeling down,cranked it over ...nothing ,looked at engine(as you do) pushed the brown cabled connector that goes into the bottom of the distributor as it seemed to be sticking out a little more than i remembered it ,tried her again and she burst into life ..............
Now all i need is the same luck with the box, yesterday when i drove her i got it down to that it wont change into or out of second automatically ,you have to do it manually it then behaves as it should until the next time it should change up or down into second.
If anyone could help i'd be really greatfull

 

If your transmission is the TH400, it may just be the detente or kickdown switch. There is a wire connected to a switch at the gas pedal that activates the detente inside the trans. The part is less than $20 and simple to change (drop the pan and it is right there).

 

Thanks Jim , i should have said its the TH350 box