1970 Chrysler 300 - Lack of power on hills

[Waggy]

My 300 has suddenly decided to get back at me for years of trouble free driving! Last week I went down to Blaine Washington for another gas run. Filled the 300 up and headed home, all seem great! I was driving down the highway about 60 mph, stopped at a light and the hit it to go up a long hill, as I got closer to the top, until I was worried that I would not make it to the top, as the car went slower and slower. I played with the gas petal, trying to boot it. I got to the top, pulled over and could not see a problem. I started the car and away I went. Hit the gas and I was up to 60 again. All was great for the next 5 flat miles, until I hit a long hill and the same thing happened. Had no problems the rest of the way home as there were only little hills. I put a cleaning additive in the gas, checked the ignition on a scope, replace the gas filter, put the best gas I could find in the car. Took the car down to Bellingham today, coming out of Blaine where I got the new gas it was sluggish, but fine the rest the way. When I got on I5 on the way home near Belus Fair the 300 started slowing down on the hill. Rest of the way home was fine and I was doing 60 to 70 until I got the that hill on Highway 15 just after the border (same spot as before) and I again had problem with losing power in the hill. Got it home, checked the firing order, the lead connections, the plugs and the gaps. All seem fine! The car is stock, so it has points and all that.

Any suggestions?

 

[Dobalovr]

Was it downshifting ok? What is the condition of the transmission?

 

[Waggy]

Was it downshifting ok? What is the condition of the transmission?

The fluid level is low, so I just added some. Will have to take the car out and see if that helps.

 

[saforwardlook]

I would suspect an issue with fuel delivery. It may be that your sending unit in the fuel tank may be clogging up with debris so when fuel is needed in greater amounts on hills, there isn't enough unrestricted flow to satisfy the demand. I would pull the sending unit and take a look. You might see rust on the unit and probably rust in the tank, especially if the car sits a lot without being driven regularly. Ethanol in the fuel these days wreaks havoc with fuel tanks and the rest of the system.

 

[Big_John]

Float level.

 

[Fury440]

This maybe way out in left field, but I had a IHC 4x4 that had the same symptoms, would go anywhere except up a long hill. The problem took a lot of head scratching, but ended up being a plugged fuel tank vent.
The fuel tank had two vents, one at the front and one at the rear of the tank. When running on flat ground, both vents were above the fuel and all was great. Going down a steep grade, the fuel shifts to the down side front of the tank, covers the front vent leaving the rear vent above the fuel and able to vent the tank. However, going up a steep grade, the fuel shifts to the rear and covers the rear vent so that the front vent above the fuel level provides tank venting. In my case, the front vent was full of mud so no venting. On a long up hill grade the fuel pump would suck out fuel until a vacuum was created in the now "ventless" fuel tank. After cleaning the vent lines, the problem went away.
Not saying this is your problem, but worth filing away in the back of your mind.
Try an up hill climb with a near empty fuel tank.

 

[Rwc]

I agree with the fuel delivery suggestion. Start with the easiest and least expensive stuff first. Check all your rubber lines, starting in the tank side of the fuel pump. If it's soft and collapsing there is your issue

 

[68Nwprt]

Could be as simple as a clogged fuel filter, and then there is that worn fuel pump rod people have experience problems with.

 

[78Brougham]

My 76 T&C had a similar problem. After buying a new carb, distributor and pulling my hair out, I discovered it was the exhaust! What goes in...must go out. I hated to do it but I was so pissed, out of pure frustration and no other course of action, I cut a perfectly good looking exhaust off, only to find it was the original, dual wall design, and the innermost wall had collapsed! It was almost shut off in spots. From the "y" pipe back i had a new exhaust put on and it runs like a dream. You can do a little test if you're suspicious of it. Have someone hold their hand by the tailpipe while you put the throttle to the floor... if they don't get an immediate response when the secondaries kick in I would suspect a clogged exhaust. Such a simple fix, but sooooo aggravating. As soon as I cut it off at home on the lift and punched it, I could tell that was it. I drove it without an exhaust to a good pipe bending/muffler shop and he told me they've seen it before.

 

[saforwardlook]

My 76 T&C had a similar problem. After buying a new carb, distributor and pulling my hair out, I discovered it was the exhaust! What goes in...must go out. I hated to do it but I was so pissed, out of pure frustration and no other course of action, I cut a perfectly good looking exhaust off, only to find it was the original, dual wall design, and the innermost wall had collapsed! It was almost shut off in spots. From the "y" pipe back i had a new exhaust put on and it runs like a dream. You can do a little test if you're suspicious of it. Have someone hold their hand by the tailpipe while you put the throttle to the floor... if they don't get an immediate response when the secondaries kick in I would suspect a clogged exhaust. Such a simple fix, but sooooo aggravating. As soon as I cut it off at home on the lift and punched it, I could tell that was it. I drove it without an exhaust to a good pipe bending/muffler shop and he told me they've seen it before.

I had the same issue on my 1973 Monaco with the 440-2 bbl engine in it. Drove me nuts until I pulled the Y pipe down to check it out. Almost totally collapsed inner wall. But I am doubtful a 300 would have that issue since I believe the factory dual wall Y pipe didn't start in production until 1973 when there was a big push to quiet the interiors on the C bodies and muffle the exhaust noise (and the 300 model ended with the 1971 model year). Some engineer didn't durability test that design though, as my car with only 36K on it failed as you found out. Damnable.

 

[celticwarlock]

My first car, a 1972 NY, did this very same thing. The air filter was clogged. My guess is that you have already checked this. I never knew about the dual wall pipes on other C-bodies. Wow, that sort of thing could take a while to chase down.