News:

Due to a technical issue, some recently uploaded pictures have been lost. We are investigating why this happened but the issue has been resolved so that future uploads should be safe.  You can also Modify your post (MORE...) and re-upload the pictures in your post.

Main Menu

My Caddy "Pukes"

Started by DanishEldoradoFan, October 27, 2016, 05:12:38 AM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

DanishEldoradoFan

Hi - when i come home, and park the Caddy, and shut off the engine, the motor continues for 2-4 seconds, and them make a coughing sound, and then it smells bad ... as if there is unburned gasoline.

What could be my problem?
Niels, Denmark

The Tassie Devil(le)

Sounds like the idling speed is too high, and the carby could be running rich, and or, the solenoid that allows the throttle plates to close shut when the ignition is turned off isn't correctly adjusted.

What is happening is the engine is "dieseling" and if you keep the gas pedal down when turning the engine off, you could get it to run on and on, because the combustion chambers are still hot, and igniting the incoming air and petrol.

One way to stop the engine is to leave the transmission in gear whilst turning off the ignition.   This keeps the revs low.   Then, put the gear selector in Park.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

wbdeford

What year is your car? My 71 had the correct idle speed, but still ran on like that (called "dieseling") except when I shut the car off with the transmission still in Drive, as Bruce mentioned.  My problem was a non-functioning anti-dieseling solenoid, which holds the throttle slightly more open when the engine is running, but lets it close a little more when you turn the engine off.

One way to know if your anti-dieseling solenoid is functioning is to restart the car (while hot) without touching the accelerator.  If the solenoid is working, the engine should be running at a lower speed (about 400 rpms).  Then, if you briefly open the throttle and release, the engine should return to its normal idle speed (about 600 rpms).  This happens because the anti-dieseling solenoid is, by design, not strong enough to *force* the throttle open; it is only strong enough to *hold* it open. 

If the anti-dieseling solenoid is not working, someone may have tuned the car to the normal idle speed of 600 using the idle screws, which leaves the throttle too far open to shut down properly.
1958 Sedan de Ville

Past:
1956 Fleetwood 75 Sedan
1957 Fleetwood 60 Special
1958 Miller-Meteor Futura Landau Duplex
1960 Coupe de Ville
1966 De Ville Convertible
1970 De Ville Convertible
1971 Eldorado Convertible
1979 Sedan de Ville
1980 Seville

Scot Minesinger

Bruce is right, that is probably the problem.  There is an "anti-diesel solenoid" that when car is in park lowers idle so it will not do that.  Problem is idle is hard to adjust so it runs fast enough in D to power climate control without being too fast in park, hence the solenoid.  Many do not know what this is for and adjustments reflect this - read shop manual.

In the mean time the easy answer is to just shut it off in drive, then put gear selector in park.  If that does not do it slow idle down.  If that does not do it, you need some engine work (could be minor tune up or otherwise).

Dieseling is bad because engine is essentially running backwards, drawing air in from exhaust (instead of air cleaner housing) and exhaust out thru carb.  In a boat it is real bad because it sucks water into engine.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

David Greenburg

If the timing is advanced too far, that could also be contributing to the problem.
David Greenburg
'60 Eldorado Seville
'61 Fleetwood Sixty Special

The Tassie Devil(le)

Quote from: Scot Minesinger on October 27, 2016, 08:48:43 AM
Dieseling is bad because engine is essentially running backwards, drawing air in from exhaust (instead of air cleaner housing) and exhaust out thru carb.  In a boat it is real bad because it sucks water into engine. 
Sorry Scott, but dieseling is when the engine is running on, with the ignition is turned off.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

DanishEldoradoFan

Hmm, my anti-dieseling solenoid is completely missing :o)

Trying to find a replacement. Tanks for all the advices :o)
Niels, Denmark