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Discussion Starter · #1 ·
I've just recently (last week) got this car. The name is pretty long, so I think in future I'll just go with NYFA to save keystrokes.

This is my second-ever Mopar, having sold a '66 Coronet 440 in 1975. (Both were 318s--it must be synchronicity.)

I'll be posting in this thread as I uncover all of the car's quirks and features. (Where have I heard that phrase? :) )

Undoubtedly I'll have some questions for the members here too. Looking forward to getting into it!

Wheel Car Tire Land vehicle Vehicle
 

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1966 Crown Coupe, 2016 200 S AWD, 1962 Lark Daytona V8.
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A 40 year-old car will always need something. ;)
 

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They are nice, comfortable cars. Here are the weak spots.
1) nylon coated timing chain gears.
2) possible 7.25” rear axle with terrible 2.2 gears
3) lockup torque converter, though they were around 5 years by then and not as problematic as earlier.
4) Lean Burn (also called Electronic Spark Control) will get blamed for every performance issue, and people will tell you to rip it out. But the performance problems are more likely to be carburetor related than ignition.
 

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1966 Crown Coupe, 2016 200 S AWD, 1962 Lark Daytona V8.
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5) Replace 4 headlamps. Something wrong with Rt. hi-beam aim?
6) Drain & refresh all fluids. Still use the amber P/S fluid. Use ATF+4 in trans. If the differential is quiet, use a synthetic 75W-140 hypoid.
 

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Why ATF+4? I've been having a harder and harder time finding Dexron 2D (which is called for in the manual), but am afraid to switch to any of the ATF's in my 3 speed as I lost a transmission shortly after switching to ATF +3 in the early 00's.
 

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Why ATF+4? I've been having a harder and harder time finding Dexron 2D (which is called for in the manual), but am afraid to switch to any of the ATF's in my 3 speed as I lost a transmission shortly after switching to ATF +3 in the early 00's.
ATF+(3 or 4) is much better than Dexron for anything with a lockup torque converter, which most 3 speeds got in the late 1970s. The lockup is smoother.
 
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And ATF+4 is the Chrysler-recommended fluid to replace ATF+3 and earlier fluids.
 
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Why ATF+4? I've been having a harder and harder time finding Dexron 2D (which is called for in the manual), but am afraid to switch to any of the ATF's in my 3 speed as I lost a transmission shortly after switching to ATF +3 in the early 00's.
The switch to +3 certainly wouldn't have been the cause or your transmission failure. It was obviously close to failing when you went to the +3. Most common causes if failure in the legacy transmissions was incorrect in kickdown adjustment, followed by incorrect fluid level.
 

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Definitely go through the fuel system. Clean or replace the tank and sending unit. Blow out the supply and return lines, test the supply line for leaks. One little trick I used to do was take a length of fuel hose, slice it down the middle, and slide it over the fuel supply line as insulation. These cars like to vaporlock.

Change the secondary filter near the pump, use the correct 3-nipple filter, orientated properly. If the pump works, great. If not, replace it with a Carter pump. Buy a spare. I would normally say go through the carb, but if it looks rough, you'd be better off finding a good 6280 out of an '85 or newer M body to rebuild. It will bolt right in and work the same as the BBD.

Champion plugs, Echlin cap/rotor/wires (or replace the whole dizzy with a new (not used) unit. Test the SCC and set the timing per FSM, but be aware of timing chain slop or worn harmonic balancer.

Last thought - these cars, 2bbl and 4bbl, were all flat hydraulic lifters through 1984. The very best lube today, in the 2bbl car up through '84, would be a Rotella 10W30. I wouldn't use anything heavier, nor would I bother with a synthetic. Just run a regular oil like the Rotella or the Pennzoil high mileage is fine, too. Definitely also clean or replace the PCV and breather, as well.
 

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Nice cars. Too bad they feel so heavy. And the delayed reverse engagement is just nuts on fast idle.
 

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Fond memories of the 1984 Diplomat SE my wife and I ordered back in late winter 1984 and received late April. We kept that for 13 years. I do remember test driving one on a lot, and was NOT impressed with the handling, and it sounded/felt like a front tire was rubbing somewhere as I was in a tight corner and suspension bottomed out, so I did special order ours with HD suspension. If I could have ordered it with the Police Package - 318 - 4bl, with the better 360 heads, and an 8 1/4" rear with 2.94 gears and a Sure-Grip, I would have! As mentioned above, the 2.2 gears were pathetic as far as acceleration, but you could cruise high speeds all day. Never had any issues with the Lean Burn system or lockup convertor. Same with the nylon gears. I imagine that unless they are very old, or have very high mileage, the "whopping" 140 HP motors really don't have enough power or torque to tear up much of anything...
 

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Fond memories of the 1984 Diplomat SE my wife and I ordered back in late winter 1984 and received late April. We kept that for 13 years. I do remember test driving one on a lot, and was NOT impressed with the handling, and it sounded/felt like a front tire was rubbing somewhere as I was in a tight corner and suspension bottomed out, so I did special order ours with HD suspension. If I could have ordered it with the Police Package - 318 - 4bl, with the better 360 heads, and an 8 1/4" rear with 2.94 gears and a Sure-Grip, I would have! As mentioned above, the 2.2 gears were pathetic as far as acceleration, but you could cruise high speeds all day. Never had any issues with the Lean Burn system or lockup convertor. Same with the nylon gears. I imagine that unless they are very old, or have very high mileage, the "whopping" 140 HP motors really don't have enough power or torque to tear up much of anything...
Rather than the police engine, you’d have been better served to wait on the updated 1985 318 roller engine with higher compression, a Holley carb, and the swirl heads.!Still the terrible rear gear ratio, but a better tuned engine.
 
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Fond memories of the 1984 Diplomat SE my wife and I ordered back in late winter 1984 and received late April. We kept that for 13 years. I do remember test driving one on a lot, and was NOT impressed with the handling, and it sounded/felt like a front tire was rubbing somewhere as I was in a tight corner and suspension bottomed out, so I did special order ours with HD suspension. If I could have ordered it with the Police Package - 318 - 4bl, with the better 360 heads, and an 8 1/4" rear with 2.94 gears and a Sure-Grip, I would have! As mentioned above, the 2.2 gears were pathetic as far as acceleration, but you could cruise high speeds all day. Never had any issues with the Lean Burn system or lockup convertor. Same with the nylon gears. I imagine that unless they are very old, or have very high mileage, the "whopping" 140 HP motors really don't have enough power or torque to tear up much of anything...
April of '85 delivery was well into the 1985 model year.

If the ride height and camber weren't carefully watched, they'd scrub the inside of the front tires in a sharper turn. It was usually the right side that would run out of positive camber adjustment, which required a couple of shim in-between the subframe rails and upper control arm bracket. That became a factory field modification in 1986. They all did it, but it was the '86 and early '88 models that had the most trouble. Those things were squirrely until they were fixed. By May of 1988, they had changed the engine cradle in a few areas that seemed to eliminate the problem. I restored an '86 Plymouth squad that had received an entire new k-frame, along with the green poly biscuits. Both that, and an '89 5th Ave that I had, would hold their alignment and ride height with no trouble. An '86 Diplomat SE that I had would sag if you looked at it the wrong way. So I do believe the resolved the problem, but only 7 months until they shut down production.
 

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Discussion Starter · #17 ·
Beautiful ride Imperialfan! What's your favorite feature on it?
Ah, gosh, dm5thAvenue--I'm so new with it, it's hard to pick. But I think I have to say the color--that's basically why I bought it. Is the car in your avatar yours?

And thanks to everyone for all the maintenance tips! I need to have a talk with my mechanic soon, and I'll bring all this up.
 

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Discussion Starter · #18 ·
Can anybody confirm or deny that this is a factory radio? It matches the dash so well, it sure looks like it, but I can't find a picture anywhere of another car with the same unit. And when I cleaned the dash, I noticed it was a little bit loose--factory units are normally solidly mounted.

Vehicle Car Plant Steering wheel Vehicle audio
 
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