1970 CDV suddenly started revving high. What's up?
Cadillac
 

Cadillac Forums | Help Us Help You | Advertise | Cadillac Parts | Cadillac News | Cadillac Classifieds / (Old System)

Cadillac Technical Archive | Cadillac Dealers | Cadillac Reviews | Cadillac Dealer Reviews | Cadillac Vendors

CadillacForums.com is the premier Cadillac Forum on the internet. Registered Users do not see the above ads.
+ Reply to Thread
Results 1 to 9 of 9
The Classic Cadillac Forum Discussion, 1970 CDV suddenly started revving high. What's up? in Past Cadillac Vehicle Discussion; Today when I started up my 1970 CDV the engine was revving high as if the gas pedal was stuck. ...
  1. #1
    IanW is offline Cadillac Owners Member
    Join Date
    Sep 2004
    Location
    Honolulu
    Age
    70
    Posts
    8

    1970 CDV suddenly started revving high. What's up?

    Today when I started up my 1970 CDV the engine was revving high as if the gas pedal was stuck. The pedal was in fact not depressed at all.

    Now I have to keep my foot very hard on the brake when stopped in Drive.

    In Neutral and Park the high rate of revs is very apparent.

    When driving, you can take your foot off the gas pedal and the car keeps going at about 30mph.

    Is this likely to be some linkage or cable that's stuck? Or maybe an engine/transmission problem?

    I'd be very grateful for some tips on what to look for.

    Thank you.

  2. Remove Advertisements
    CadillacForums.com
    Advertisements
     

  3. #2
    carnut is offline Cadillac Owners Master
    Automobile(s): 1988 Allante' (sold), 1984 Eldorado, 84 Sedan DeVille
    Join Date
    Feb 2003
    Location
    california
    Age
    67
    Posts
    5,767

    Re: 1970 CDV suddenly started revving high. What's up?

    Look for a mechanic and have it towed!

  4. #3
    CADforce69 is offline Cadillac Owners Connoisseur
    Automobile(s): Cadillac Sedan de Ville 1969, Dodge 3700GT '73, Audi A3 1.8T
    Join Date
    Oct 2010
    Location
    Madrid (Spain)
    Age
    47
    Posts
    1,586

    Re: 1970 CDV suddenly started revving high. What's up?

    Check the accelerator cable. Possibly itīs stuck at some point. If cable is ok, it must be the carb. Maybe itīs the choke which is jammed. If choke is ok, you may check idle adjustment. As carnut says itīs not advisable driving the car until the problem is fixed as transmission could be damaged.

  5. #4
    klinebau is offline Cadillac Owners Member
    Automobile(s): 1970 Deville Convertible Red
    Join Date
    Jul 2012
    Posts
    75

    Re: 1970 CDV suddenly started revving high. What's up?

    I also had this problem with my '70 and I am not 100% sure of the cause yet. I have been doing a lot of work to get mine into shape. I have two theories as to the cause. My problem started after I replaced the hoses and thermostat which required a coolant change. I believe that there may have been an air bubble in the cooling system which caused the thermal switch to activate giving me more advance timing from the intake manifold. The next time it happens I am going to look at the timing to confirm.

    The only other possible cause I could think of is a vacuum leak in the intake manifold that seals itself after the engine warms up. I already have an oil leak there, so I know for sure that there is some sort of sealing problem.

  6. #5
    carnut is offline Cadillac Owners Master
    Automobile(s): 1988 Allante' (sold), 1984 Eldorado, 84 Sedan DeVille
    Join Date
    Feb 2003
    Location
    california
    Age
    67
    Posts
    5,767

    Re: 1970 CDV suddenly started revving high. What's up?

    A vacuum leak will NOT cause a higher idle on a carb'd car.

  7. #6
    P.Katson is offline Cadillac Owners Member
    Automobile(s): 1966 Eldorado
    Join Date
    Oct 2007
    Location
    San Diego
    Posts
    53

    Re: 1970 CDV suddenly started revving high. What's up?

    Quote Originally Posted by carnut View Post
    A vacuum leak will NOT cause a higher idle on a carb'd car.
    Why? More air is entering the intake which is similar to opening the throttle.

    ----------

    Sounds like the choke may be stuck on the fast idle cam. With the engine off, open the throttle and try to move the choke flap. Clean the carb linkage with carb cleaner and then lightly lubricate it with WD-40 or similar.

  8. #7
    bigm57ict's Avatar
    bigm57ict is offline Cadillac Owners Connoisseur
    Automobile(s): 1995 Sedan DeVille, 1979 Coupe deVille
    Join Date
    Aug 2011
    Location
    Wichita Kansas
    Age
    42
    Posts
    1,290

    Re: 1970 CDV suddenly started revving high. What's up?

    How does a vacuum leak allow more air to enter? Isn't that controlled only by the throttle plate?

  9. #8
    carnut is offline Cadillac Owners Master
    Automobile(s): 1988 Allante' (sold), 1984 Eldorado, 84 Sedan DeVille
    Join Date
    Feb 2003
    Location
    california
    Age
    67
    Posts
    5,767

    Re: 1970 CDV suddenly started revving high. What's up?

    I wont dignify the P.Katson post with a discussion. And never use lubricant on carb linkage. Lubricants attact dirt and cause sticky linkage issues.

  10. #9
    P.Katson is offline Cadillac Owners Member
    Automobile(s): 1966 Eldorado
    Join Date
    Oct 2007
    Location
    San Diego
    Posts
    53

    Re: 1970 CDV suddenly started revving high. What's up?

    No need to be rude CarNut, we are all here to learn.

    You are correct. As a rule, carb linkage should not be lubed, however, many are worn, corroded and can benefit from LIGHT oiling if new linkage or parts cannnot be found or afforded. The problem is most people over lubricate and it becomes a greasy and sticky mess.

    Back to the vacuum topic: If you take off a vacuum hose and the vacuum source is below the throttle plates the engine speed will rise. Maybe not as much as a fuel injected engine and it varies depending on the engine and the size of the vacuum hose, but it will increase. Send me a PM if you do not want to discuss here, we both may learn something.

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.
If you do not want to register, fill this field only and the name will be used as user name for your post.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Bookmarks

Cadillac Posting Rules

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
Read about Lincoln | Buick | Kia Forte Forum
Need products for your Cadillac? Check out your options at the links below:

custom floor mats | Cadillac Chrome and Black Chrome Wheels | window tinting