hello,

i have recently brought a 1967 Olds 98 with a 425 big block, i have been driving it round locally and had no issues
however ive come to pull of the drive today and 'drive' engages but doesnt pull properly, reverse is working fine i have checked the tranny oil and it seems okay

is there any common issues with these that i should be aware of?
do they have issues with oil draining out of torque converters if parked on a slope?

any help would be great

thanks

 

James,

If still original to the car, your transmission is the variable pitch (some call it switch pitch) model THM400 only used in certain GM cars from 1965-1967. My understanding is yes, these transmissions may be prone to converter drain-back. Don't know if being on a slope exacerbates the problem but I know my 1967 Delta Custom does so simply if I don't drive it regularly. If you let it idle for a minute after start-up it should pump the oil back up into the converter and run fine. If not, then your problem may more serious. Check your dipstick after the car has been parked for a while - would register way high (or at least much higher than when running) if you have a significant converter drain-back issue. Mine is annoying because as the pan becomes over-full I get seepage where the dipstick tube mates up with the transmission.

Dave

 

When you checked the transmission fluid level, was the engine running and warmed up?

 

Yes check the fluid running, in park, on level ground and warm. Is there a brake stuck, is the Ebrake on or hung-up?

Good luck!!!

 

As another data point here, I owned a '67 Delta 88 with the 425 engine and I presume this same transmission from 2009 until I sold it in January. Never once had any kind of issue with the transmission. Never parked it on anything other than a level surface.

 

Is this a new issue, or has the delayed engagement been a problem that’s slowly gotten worse?

Try putting the trans in manual 2 or 1st gear, just to eliminate the possibility of a shifter being out of adjustment. If your positive the fluid is full, and the trans won’t go into drive after a few seconds, it’s time to dig deeper.

Drop the transmission pan. Hopefully you don’t find a bunch of crud. If so, the trans is on borrowed time. At this point, might as well put a new filter in and refill. if it moves, great It’s a roll of the dice as to how long it will continue to work. If nothing happens, it’s time to pull it out for repair.

 

Thanks for getting back to me everyone, the engine was warmed up, but couldn't run it through the gears properly when I checked the fluid level
This is a new thing,
but on a point of it perhaps being a selector, my reverse doesn't engage on 'R' its slightly before, so perhaps looking at setting the selected properly is worth giving a go as well
I'm hoping this is nothing serious as it drove perfectly up until now

 

Count the mechanical detents when shifting into gear, rather than watching the shift indicator on the dash, those are notoriously off. A TH400 should have 6 detents: P-R-N-D-2-1. So from Park, 3 clicks to the right for Drive.

 

I havent had the car long, only a couple of months, and only driven in locally due to having a couple of other issues, but hadnt noticed any problems with it, after driving it around (in reverse) for a bit i have checked the oil again, and topped it up as it was a pint down and still no drive in D 2 or 1, it will crawl forwards, but when i press the accelerator, it looses drive all together,

the oil in it looks very clean (almost too clean)

 

hello,

it looks as through the box is still original to the car, the dipstick does read massively high when stationary, however even when the oil is pumped back into the converter on start up, i still don't have drive in any of the forwards gears

works fine in reverse, but will only crawl on idle in forwards, and loses everything when i touch the throttle, is this something you have come across before?

thanks

 

hello,

it looks as through the box is still original to the car, the dipstick does read massively high when stationary, however even when the oil is pumped back into the converter on start up, i still don't have drive in any of the forwards gears

works fine in reverse, but will only crawl on idle in forwards, and loses everything when i touch the throttle, is this something you have come across before?

thanks