Diagnosis ? Lean Burn Computer Dying or another problem?

[Bruce85FifthAve]

My 1985 Chrysler Fifth Ave. recently has been my wife's transportation to work. It developed a slow coolant leak that I have been nursing along, the leak seems to be on the right rear of the motor, but not from the lower freeze plugs. It still has the Lean Burn computer that had leveled out and was working good. Yesterday, my wife started on her trip to work and the motor started running rough so, she headed back to the house and it died before our driveway. I got it started later and it seemed to be very flooded. This morning she again started to work and it died again!
I wonder if the lean burn computer completely died or is there a cracked head gasket? I haven't noticed any water or coolant in the oil before, but I guess I need to check again!
Any advice, thoughts or opinions would be appreciated!

Thanks,
Bruce

 

[Jack Meoff]

As far as I've ever known lean burn computers either work or don't.
There doesn't seem to be an in between. As far as the coolant leak I can only hazard a guess at head gasket?? But not being an expert myself it's just a guess going by where you say it's leaking.....I'd definitely be checking the oil.
Gas flooding.....if it's the Holley 6280 feedback carb...I've heard they can be problematic.

Sorry....that's about the best this driveway mechanic can offer.
Hopefully someone with more expertise will chime in.

 

[Bruce85FifthAve]

Thanks Capt. Caravelle,
As far as I know, I think it is a Carter carb. with the electronic input from the lean burn computer. That brings up another question; I've seen mixed opinions as to if this same carb would work with the conversion to the old mopar electronic ignition set-up. It seems to get a rebuilt Carter carb for a 1970s 318 cost about $250?
Any more ideas/opinions?

 

[MiradaMegacab]

Could be a head gasket, freeze plug (block or head) intake manifold gasket. May even be seeping out the exhaust manifold bolt.
Partially open the radiator cap and see how it runs, there wont be any pressure build up.
Can you see any white smoke out the exhaust or smell coolant?

 

[Jack Meoff]

Thanks Capt. Caravelle,
As far as I know, I think it is a Carter carb. with the electronic input from the lean burn computer. That brings up another question; I've seen mixed opinions as to if this same carb would work with the conversion to the old mopar electronic ignition set-up. It seems to get a rebuilt Carter carb for a 1970s 318 cost about $250?
Any more ideas/opinions?

If it's an 85 Fifth I'd say it's the Holley.
2280 was non feedback and 6280 was feedback.
The Carter was earlier if memory serves....

As far as if that carb would work with a conversion....that I don't know but I'd think non feedback.....maybe....6280.....don't think so.

 

[Mopar_Gods]

If you still have the lean burn ignition system, it has probably gone bad. Chrysler used to sell a kit that included a new distributor and module to fix this problem and get rid of the lean burn system I do believe. It has been a long time since I have tinkered with a 5th maybe others can offer you a better and more accurate opinion. Good Luck.

 

[Jack Meoff]

The problem with internet diagnosis is lack of being there.
How did it die. How was it running when it died?
As said....never known a computer to slowly fizzle.
Usually something pops and then you have a no start.
Driveability could be anything from a cracked distributor cap to a vacuum leak to a bad plug wire to a stripped dizzy gear to.........

Internet diagnosis is difficult without the correct info....

 

[Mopar_Gods]

I agree completely. It has been a long time since I have owned a 5th Ave. But I am sure it has many sensors. I never did care to much for the over rated sensors and computers myself to me they seemed to be more of a pain in the azz then anything. Just curious how many electrical sensors are in a 5th anyways?. I remember once I had a 5th ave and I couldn't figure out why it was over heating all the time. A visual inspection I could not see anything that was leaking as in antifreeze ect but I kept seeing moisture in my front lower dash windshield it ended up being a cracked block and if I recall correctly I scrapped the car all together. Was to much of a headache to mess with think I gave $300 for vehicle back in the day Lol.

 

[Jack Meoff]

They're actually not that bad to troubleshoot with the Factory Service Manual.
Compared the computer nightmares in new cars....the prehistoric workings of a Fifth are relatively tame.

That being said.....I hate doing electrical.

 

[Mopar_Gods]

Yes me too. I would rather do anything else on a vehicle then any of the electrical. Seems the older you get you seem to forget more. I do anyways. Electrical has always to me been a pain in the butt to do.

 

[Jack Meoff]

Yes me too. I would rather do anything else on a vehicle then any of the electrical. Seems the older you get you seem to forget more. I do anyways. Electrical has always to me been a pain in the butt to do.

I'd rather have dental work done then do electrical...

 

[MiradaMegacab]

Inspect the spark plug on the cylinder that is leaking(7 or 8)
Maybe the flooding condition was hydrolock from a head gasket that "pushed out"?

 

[Bruce85FifthAve]

I was away from my computer on the weekend. Thank you to Captain Caravelle, Mopar_Gods, and Mirada Megacab for your replys and info. It seems that I have two separate problems: I found the usual culprit - the water pump has a very small & slow leak from the weep hole that was hard to see. But the rough running and flooding effect - I still don't have a solution for. I guess I will pull the plugs and inspect them. I'm also replacing the EGR valve that was totally blocked and stuck, but I don't think that's the problem.
There doesn't seem to be any other coolant leak or vacuum leak that I can detect. I might have to give-in and take it to a garage, if it will run long enough to get it there! I don't want to start the conversion to the older mopar ignition system without really knowing if that is the true problem.

Thanks again - still puzzled.
Bruce

 

[Monkeyed]

I was away from my computer on the weekend. Thank you to Captain Caravelle, Mopar_Gods, and Mirada Megacab for your replys and info. It seems that I have two separate problems: I found the usual culprit - the water pump has a very small & slow leak from the weep hole that was hard to see. But the rough running and flooding effect - I still don't have a solution for. I guess I will pull the plugs and inspect them. I'm also replacing the EGR valve that was totally blocked and stuck, but I don't think that's the problem.
There doesn't seem to be any other coolant leak or vacuum leak that I can detect. I might have to give-in and take it to a garage, if it will run long enough to get it there! I don't want to start the conversion to the older mopar ignition system without really knowing if that is the true problem.

Thanks again - still puzzled.
Bruce

the egr is probably just one piece of the problem. If what I ran into with mine is typical, it's usually many parts gradually wearing/getting fouled/etc.. but still within the parameters that the ancient computer can work with. then one thing goes out of range, which creates conditions that takes several others out with it..

don't kow if that helps, but I don't think you'll find one magic bullet that will set everything right. you will save a ton on labor costs and chasing it's own tail if you can take it on yourself..

 

[Monkeyed]

just a quick thought, if it's flooding, you might want to check the floats. those old style foam type plastic ones are notorious for absorbing fuel and sinking as they age. I think you can still order replacement ones for less than $20..

 

[Monkeyed]

I spent less than $200 on parts for mine, and maybe a good 20-30 hours total working on it. even considering that it takes me twice as long as the rated time to do things, at $100+ an hour at a shop, for a car I bought for $600... it's the difference between a hell of a deal, and bend over and hope they brought vaseline..

 

[Jack Meoff]

These are all driveway mechanic hunches.
I am no expert but I do own one of these beasts.
The flooding condition could be a result of things being gummed up over time by the evil that is ethanol....stuck float and or choke?
Also.....when is the last time it had a full tune up.

The water pump leaking from the weep hole is actually not a bad scenario.
At least you know you just need a new pump.

 

[Jack Meoff]

just a quick thought, if it's flooding, you might want to check the floats. those old style foam type plastic ones are notorious for absorbing fuel and sinking as they age. I think you can still order replacement ones for less than $20..

Ha...you beat me to it.

 

[jasperjacko]

Your problem sounds like two possible things that I've experienced. One, the egr valve stuck open, Two, the run pickup in the distributor. Your dist. has a start, and a run pickup. If the run goes bad, the car goes into limp mode and runs on the start pickup. It will run VERY poorly. I took a car to the 5 star dodge dealer to have the "EXPERTS" figure it out. Nope. I spent 5 mins in a Chiltons and got the answer. The part is cheap also. Good luck.

 

[Jack Meoff]

That's a good call too Jasper....
I was trying to figure out the flooding issue also....