Tranny is bad. Pump pressures are boosted in Reverse and Low range. If it pulls good and accelerates in Low range but not in Drive, low pressure from pump will let the Drive clutch slip under power/acceleration. It will try to pull under light throttle. Other possibility IF pressure is in range is the Drive clutch piston seal is bypassing. Either way, rebuild is required and pressure test before removing trans is prudent to identify problem. Dynaflows have 2 pumps, the front pump operates off converter and is always running with engine. The rear pump operates off the output shaft and only contributes at speeds above appx 30 mph to complement front pump. *If the car will engage Drive clutch and accelerate normally above 30-40 mph, that would indicate rear pump has taken over for the failed front pump.
Will the pump makes noise if it's bad? Even in park? Sounds like I'll be pressure testing this weekend
Ok guys little update after fixing my dad's Impala... I was having a hard time biting the bullet and jumping right to a trans problem which might still be the issue but here is some more info and a question. Instead of a trans pressure test I decided to check the exhaust first. sprayed everything with PB Blaster and let if soak. Dropped the exhaust at the connection right after both manifold come together. Towards the engine side both sides look clear. down the mid pipe (between header connection and muffler inlet looks clear until bend that I can see). Started engine and it races like it should all way from idle to full throttle. Reconnected it. Disconnected connection at muffler inlet to mid pipe. Start engine its like it gets stopped at a certain point and wont accel past the point. Looked up stream towards engine and it looks almost like an inner pipe collapsed and is blocking the exhaust. In return creating a blockage and possibly my whining like a piece of grass between your thumbs and blowing magnified. I assume that exhaust should be "hollow" or open all the way to the muffler correct? With exhaust unhooked at manifold meeting pipe its to loud to tell if still whining.
Take it for a ride with the pipes dis-connected from the manifolds. If the power is back you now KNOW you have a restriction in the exhaust.
Not what I would expect to see as a heat riser. Looks almost like a melted inner pipe for some reason. Tried to take a picture but doesn't look anything like what I see...
I think I finally found the problem. Thanks for the guys who said exhaust restriction... time for a new exhaust pipe.
Notice how thin the collapsed section of that double-wall exhaust pipe is ? Probably had a hole rust thru up stream on the thin inner pipe and then the hot exhaust gasses got in-between and collapsed the the thin section........which looked like it was in the upper part of the pipe. I remember cutting a bunch of double walled y-pipes off of 63-64 single exhaust big Buick. This is what V-8 Buick is all about.....helping each other with our Buicks! Peace WildBill
Also......that aftermarket carb might be running the motor lean and hotter......i'd check the plugs to see.But it was probably just a bad section of pipe...... Peace WildBill
Late timing (or restriction, esp. together) puts A LOT more heat into the pipes than a lean carb. Constant heavy throttle would also abuse the pipes much more than reasonable cruising. The exhaust temp drops at some point the leaner it gets. I wonder what other conditions might have been noticed prior, besides the restriction? Does the pipe show any other heat related indications?
Working at a Buick dealer in the early 80's - we checked for that alot, and found quite a few. Saw it in late 60's Rivs and Electra's as I recall. I'd never heard of it before I worked there....
Plugs don't look that bad. Car came out of new Mexico and I'm only the second owner. I don't have all the records but pipe could be original from what I'm seeing... but not positive.
If it's a double wall pipe it is definitely original unless the dealer replaced it when the car was fairly new, within 5 yrs???, when the OEM parts were still available.
Hello My 1964 Wildcat seems to have this issue. The exhaust system looks so good hard to believe it's original Was the entire pipe double wall ? I'm pretty excited & believe this is going to wake my Wildcat up. Thanks for your help Hope to see some Buick owners down the road
