MK4 Golf - 1.9 TDi - oil filler cap ''dances'' from pressure ?

Discussion in 'Diesel' started by jords.fjords, Aug 10, 2021.

  1. jords.fjords New Member

    Joined:
    Aug 5, 2021
    Likes Received:
    0
    Hello folks!

    Basically when the engine is running and up to temperature - I unscrew the oil cap and put it back in blows it like it's dancing.

    Yes' I've tried to serch for this elsewhere on the internet but only found some videos and threads about this with a gasoline engine and someone suggested that the PCV valve is clogged but I know that a diesel has a CCV so I wonder if that could also be the case? I'm not super tehcnical but I know that PCV uses vacuum to positively let the blow by out and the CCV simply uses a vent to let the blow by out or something like that?

    And No, the cap isn't broken, it screws on tight. It only bounces when I take it off.

    I just want to know if it's something serious for a diesel engine? Maybe something clogged/worn/failed?

    P.s. I have problems with my turbo and always wonder if a bad turbo can cause the oil cap to dance?
    My turbo problem is that it goes in to "limp" mode sometimes when I accelerate too fast. Will have it checked when I have the time and money.

    P.s.s. Will make a video of the cap dancing when I have the chance.


    Car info: Yeah, it has a lot of mileage, almost 400k. It's normal in my country. When I bought the car I had serious coolant loss and got the head gasket replaced and the head resurfaced. It still is loosing coolant but much much LESS. Previously I used up 8L every during 4 months and topped it up every 1-2 weeks, but know maybe 1-2 months. Can't see any leaks, don't know where it goes?

    Sorry for so much text but I had huge oil loss problems too, but very recently I changed the oil drain screw and it made a huge change. Previously I had to top up 1L every 1-2 weeks. Now almost none. Never saw any oil spots on the ground/asphalt. (Still need to fix the thread for the oil drain screw in the future)
     
  2. Tristan Paid Member Paid Member

    Joined:
    Apr 25, 2006
    Likes Received:
    790
    Location:
    Southern IRELAND
    That's a bit mad that you didn't see the oil leaking, it must be smeared back along the underside?
     
  3. NateS2

    NateS2 Paid Member Paid Member

    Joined:
    May 1, 2019
    Likes Received:
    229
    They do have breathers yes and it is possible its blocked. If you remove the vent hose you should see/feel some pressure and oil vapour coming out. Its the hose that goes from the rocker cover to the air intake pipe. If nothing comes out the hose or vent on the rocker cover may be locked
     
    jords.fjords likes this.
  4. jords.fjords New Member

    Joined:
    Aug 5, 2021
    Likes Received:
    0
    Nothing like that. I think it slowly dripped away. When I bought the car and didn't understood anything about cars, what I noticed with the old drain bolt was that it was all smeared up with gasket maker to prevent oil leak. I did the same until recently I thought about changing the screw
     
  5. jords.fjords New Member

    Joined:
    Aug 5, 2021
    Likes Received:
    0
    Okay, thanks. I think I understand what I must check but just to be clear should unplug this hose and feel for air/vapour from this going to the left?

    [​IMG]
    free image hosting

    The image is from the web for reference.
     
  6. NateS2

    NateS2 Paid Member Paid Member

    Joined:
    May 1, 2019
    Likes Received:
    229
    Yes thats right! and you should be able to feel air being sucked into the hose you removed
     
    jords.fjords likes this.
  7. jords.fjords New Member

    Joined:
    Aug 5, 2021
    Likes Received:
    0
    Update: I made a video and to my surprise it happens even when the car is cold started. Maybe it's just worn engine bushings after all ??

    P.s. Haven't check the CCV valve yet.

     
  8. Adamss24 Forum Member

    Joined:
    Jun 21, 2021
    Likes Received:
    21
    If you don't get high oil consumption and blue smoke from exhaust then I wouldn't worry much, limp mode will be dirty vnt mechanism on the turbos hot side- common issue on old, high mileage cars. I would give the car the Italian tune, high revs and sudden acceleration/lift off in 2nd/3rd gear usually do the trick. If you can get to the turbos actuator with a mityvac vacuum pump or similar to help it move the rod from min to max a handful of times...usually frees it off...
     
  9. NateS2

    NateS2 Paid Member Paid Member

    Joined:
    May 1, 2019
    Likes Received:
    229
    Hmm can you feel air coming out of the oil filler hole when the cap is removed? It should be like a wind tunnel if its throwing the cap around that much
     
  10. jords.fjords New Member

    Joined:
    Aug 5, 2021
    Likes Received:
    0
    Thanks for helping my worries go away [:D] The oil consumption at the moment is acceptable and as far a I know there's no blue smoke.

    I have tried many times - while driving in 3rd gear I leave it in 3rd gear and try to go to 5 on the rev counter but I've never succeeded and usually I get barely past 3,5 - 4. And if I rev it too fast (pedal all the way) then it goes in to limp mode. And with sudden acceleration you mean what? Almost always when I accelerate by pressing the pedal all the way it goes in to limp mode. I've moved the actuator a while ago but no difference. And I have no way to get a vacuum pump like that.

    And I know this is not the best way to go , but couple months ago I even tried the ''oven cleaner technique" as I've seen in some youtube videos, read in comments that people say it works for some and some comments that it's dangerous. I thought about it for a while and figured out that I will try it.
    I took of the EGR and the metal pipe and fed down a rubber hose till I felt that it went in to the turbo, I sprayed the oven cleaner, left it for 10 min, moved the actuator rod with hand, rinse and repat for 2-3 hours and took for a midnight drive to rev it up and get that gunk out. At first I thought I got it freed up but then the next day it went back to being the same. Only there was a small but noticeable difference in how the car felt like driving - it felt 5% better [:D]

    I have a local mechanic that I trust and he offered me to clean the turbo and check it out as he said the same as you that usually it's gunked up with carbon.
    But that will have to wait maybe a month or two because he broke his leg in June and has "vacation" now.


    It was days ago when I checked but I think I could feel air coming out, but don't remember precise. Will check once more [:D]
     

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice