I have a 1970 Jeep DJ5a. The engine is a Chevy 153 CI. The transmission is a 2 speed power glide. This is the way these came from the factory in 1969 & 1970. Here is my weird problem. When I make a left turn and am moving faster then 5 - 10 mph, the car will suddenly accelerate as if I had pushed the gas pedal to the floor. The pedal itself doesn’t move. Once I come out of the turn, sometimes it will stop trying to speed up, sometimes I have to twitch the wheel a bit to the right to make it stop. (This of course is not a very good thing being a jeep and prone to rollovers) There are no electronic controls on this car, and I cannot see anything that would catch the linkage and cause this under the hood. Anyone have any ideas?
Is the throttle cable firmly attached to the engine? How are the engine mounts and throttle return spring?
Inspect the engine mounts, especially the left one (driver’s side). If the left one is broken, the engine will lift to the right pulling away from the throttle linkage causing the sudden acceleration.
It’s funny that you both mention the motor mounts as that was my initial thought as well, Turned out that the right mount was broken and the left mount was missing the nut holding it to the frame. Both these items were corrected but the problem remains. I just double checked the mounts (Big A$$ cheater bar under the engine and pry up), the motor seems to be pretty well attached to the frame.I checked the throttle cable and the return spring and as far as I can tell they are fine. By the way, I should mention that the car is a right hand drive, it has a rod that runs from the gas pedal across the front of the firewall to the left side of the engine where the carb is. I have looked to see if there any way it could be binding up, but that wouldnt explain the acceleration, it would just stick. Any one know if the carb could be the culprit? any way to tell if it is?
Thanks for any help you can give.
Still having this issue, Anyone have any ideas?
Have someone watch the engine with the hood open while you put the transmission in gear and with your foot FIRMLY on the brake step on the gas. Give it as much gas as it’ll take for a second or two and see if the engine moves on its mounts. Then find out why it moves.
Have you checked the transmission mount?
You have really got a head scratcher here. If you ever find out the cause of this, please reply back and tell us what it was. I can’t think of anything else that would be actively accelerating the engine.
I had this same problem with a 1968 DJ-5A several years back. There were 2 seperate causes to this problem that occured on different occasions. One cause was the faulty MOTOR MOUNTS others have mentioned. The other issue was a SAGGING and UNSECURE BODY. Inspect your body to frame bolts for missing or loose hardware. Also look for cracks or bends to the crossmembers where they meet the frame. Check the sheet metal floors in front of and under the seats for front to back cracking too. I replaced all of my body to frame hardware. I also reinfroced my crossmembers between the body and frame with 3/8" thick steel bars plus welded new sheet metal to the inside of the floor pan. You may not need to do all that I did, but stabilizing the body from excessive side to side rocking should eliminate the binding of the linkage.
Best of Luck
Throttle shafts have been known to corrode too, especially a day after it rains. Penetrating oil helps when you have that problem. Is the throttle return spring OK? Some of them were one spring inside another. Maybe one is off or broken.
Hello again, it has been a LONG time since I posted this original question but I have only just discovered the answer so here it is.
I just had the motor rebuilt on the jeep and the mechanic discovered a crack in the weld for the right side motor mount adapter plate, (My jeep came from the factory with a GM 4 cyclinder engine, there is an adapter plate welded to the frame that the motor mounts are bolted to) he said that when turning left, the weight of the engine along with g-force and torque could have caused the motor to slip enough to cause the acceleration. He aligned and re-welded the adapter plate before putting the engine back in and I have been driving it for about two weeks now with no more crazy accelerations YEAY!