Page 1 of 2 12 LastLast
Results 1 to 15 of 21

Thread: 3S 'blowby' mystery

  1. #1
    Forum Member
    Join Date
    Mar 2006
    Location
    Bangkok
    Posts
    3

    Default 3S 'blowby' mystery

    Hi,

    I've recently done a 3SGE conversion. The engine seems "clattery" at the top end, and when I pull out the dipstick, there is a significant amount of "blowby", in other words, smoke coming out of the dipstick. Now I would automatically assume this is worn rings, but the only thing puzzling me is in over 1000km there is absolutely zero oil consumption. The level on the dipstick has not moved, and the oil still looks brand new. There is no blue smoke out of the back end, just this chugging out of the dipstick. I think the noisy top end is valves, the question is could this be related to the blowby ? As far as I am aware, the 3S-GE has no potentially faulty PCV valve either.

    I'm struggling to understand if the crankcase is pressurising from worn/bad rings, why is there no smoke/oil consumption ? I don't know so much about these engines, also I live in Thailand, so things like compression tests may not be so easy. I'm trying to do my homework before going back to the garage tomorrow.

    Any advice greatly appreciated.


    INTJ.


    .

  2. #2
    Forum Member
    Join Date
    Jan 2006
    Location
    QLD
    Posts
    4

    Default Re: 3S 'blowby' mystery

    Hi INTJ

    Im pretty sure you arent supposed to pull out the dipstick when the engine is going. Oil will come out if the engine is going. Instead pull the engine oil fill cap off when the engine is going. If there are smokey fumes coming out it is likely to be worn rings.

    My old 3SGE had a rattle/knock at about 3000 RPM when not under load. We pulled it down and found out that the big end bearing were worn. THe knock sounded like it was in the head, but it was definately the big end bearings

    Ty

  3. #3
    Forum Member
    Join Date
    Mar 2006
    Location
    Bangkok
    Posts
    3

    Default Re: 3S 'blowby' mystery

    There is no oil coming out of the dipstick, just fumes. Also, if the rings are worn then why no oil consumption ?

    INTJ.

  4. #4
    Forum Member
    Join Date
    Jan 2006
    Location
    QLD
    Posts
    4

    Default Re: 3S 'blowby' mystery

    Back to my point, the dipstick should never be pulled out when the engine is running!

    Well it is likely to be the big end bearings then. What generation is the engine? I have been told that the gen 1 3sge has weak big end bearings.

  5. #5
    Junior Member Backyard Mechanic 3sgte's Avatar
    Join Date
    Jan 2006
    Location
    Canada
    Posts
    489

    Default Re: 3S 'blowby' mystery

    Gen 1 motors occasionally kill valve shims, wearing a huge dish in a shim. I have seen 2 motors do this.

    One was noisy, a new shim 'fixed' it (the cam lobe still had some damage, but the noise was gone).

    The other was a parts motor, not running. It had actually progressed to the point where it spit out the worn shim.

    As for weak big end bearings, they were never an issue in my experience, however I don't do track time.

    I have seen 3SG with toasted big end bearings, but in all those cases it was a lack of oil that killed the bearings.

    Is the crankcase vented properly?

    EDIT:

    Forgot to mention, I also saw more than a few 3SG, gen 1 where a TVIS plate screw would either come out, or the head would break off. If lucky, the screw would get spit out the exhaust without significant damage.
    It is possible that the screw would be embedded in either the piston or head though...
    That is a nasty noise!
    Last edited by 3sgte; 18-06-2006 at 01:10 PM. Reason: TVIS

  6. #6
    Junior Member Grease Monkey BigBadBenny's Avatar
    Join Date
    Oct 2005
    Location
    Sydney
    Posts
    50

    Default Re: 3S 'blowby' mystery

    Intj,
    From the sounds of it, you may have worn bearings or quiet possibly some piston slap.
    If it is piston slap, this would answer your blowby concerns.
    Oh, and you CAN remove the dipstick when the engine is running, but it is better to remove the cap so you can see it better.
    And.....I've never seen oil come out of a dipstick tube, but I sure as hell have seen it come out of the filler hole if some one has left the cap off.
    I recommend to take your car to a reputable mechanic for a proper diagnosis.
    Regards
    Ben

  7. #7
    is the most useless Backyard Mechanic jonchai's Avatar
    Join Date
    Oct 2005
    Location
    South Australia
    Posts
    413

    Default Re: 3S 'blowby' mystery

    I had the same problem....you need to drill a hole into the sump....have a pipe leading into it....bend up to clear the oil sump level, to release the sump pressure. this will lead to the catch can to filter before being plumbed back into throttle body.
    i had the same problem except the pressure in the sump was so high it was preventing oil from draining back down from the head...the oil built up and would shoot throught the standard breather pipe and spit oil thorugh the throttle body leading to huge (and i mean huge) puffs of smoke at suspended high revs.

    i have pictures of the set-up on my car if you want!
    Performance Through Technical Supremacy
    (\__/)
    (='.'=) This is Bunny. Copy and paste bunny into your
    (")_(") signature to help him gain world domination.

    hehe

  8. #8
    Forum Sponsor Grease Monkey
    Join Date
    Dec 2005
    Location
    nsw
    Posts
    197

    Default Re: 3S 'blowby' mystery

    Quote Originally Posted by jonchai
    I had the same problem....you need to drill a hole into the sump....have a pipe leading into it....bend up to clear the oil sump level, to release the sump pressure. this will lead to the catch can to filter before being plumbed back into throttle body.
    i had the same problem except the pressure in the sump was so high it was preventing oil from draining back down from the head...the oil built up and would shoot throught the standard breather pipe and spit oil thorugh the throttle body leading to huge (and i mean huge) puffs of smoke at suspended high revs.

    i have pictures of the set-up on my car if you want!
    isn't that basically what the PCV valve is for? are you sure you had one that worked?

  9. #9
    is the most useless Backyard Mechanic jonchai's Avatar
    Join Date
    Oct 2005
    Location
    South Australia
    Posts
    413

    Default Re: 3S 'blowby' mystery

    yeah...but the PCV only works if the pressure works its way to the head....the pressure that i am talking about (and i presume INTJ aswell) is coming from the sump, but cannot be released to the head
    Performance Through Technical Supremacy
    (\__/)
    (='.'=) This is Bunny. Copy and paste bunny into your
    (")_(") signature to help him gain world domination.

    hehe

  10. #10
    Junior Member Backyard Mechanic 3sgte's Avatar
    Join Date
    Jan 2006
    Location
    Canada
    Posts
    489

    Default Re: 3S 'blowby' mystery

    Quote Originally Posted by jonchai
    yeah...but the PCV only works if the pressure works its way to the head....the pressure that i am talking about (and i presume INTJ aswell) is coming from the sump, but cannot be released to the head
    On a properly functioning engine there should be no need to drill holes in the block to relieve crankcase pressure.

    Having said that, Toyota did release a rear main seal update for the 3SGTE to address the potential of crankcase pressure pushing the seal out... (note: the area of the seal exposed to crankcase pressure was reduced, the flywheel flange of the crankshaft was made larger to allow this, requiring a different seal. Seal O/D was the same, seal I/D was larger for the updated seal)
    I remembered seeing a TSB to this effect, but that was many moons ago...
    Last edited by 3sgte; 18-06-2006 at 08:32 PM. Reason: Clarity (added "of the crankshaft")

  11. #11
    Junior Member Grease Monkey BigBadBenny's Avatar
    Join Date
    Oct 2005
    Location
    Sydney
    Posts
    50

    Default Re: 3S 'blowby' mystery

    if you need to drill a hole into the sump to release pressure, then I think you need to buy some oil flushing additive when you do your services,
    How many Km's do you do between services?
    Ben

  12. #12
    Forum Member
    Join Date
    Mar 2006
    Location
    Bangkok
    Posts
    3

    Default Re: 3S 'blowby' mystery

    "On a properly functioning engine there should be no need to drill holes in the block to relieve crankcase pressure."

    My sentiments exactly. I want to find exactly what needs repairing in this engine, then sort it out *properly* without any homegrown modifications.

    I'm still struggling to work out how pressure can be blowing past the rings into the crankcase but the engine not be burning a drop of oil. Are there any other potential causes of blowby other than rings ? Could valves be causing this, as to me the noise seems to be coming from the top of the motor ?


    INTJ.



    .

  13. #13
    Junior Member Grease Monkey BigBadBenny's Avatar
    Join Date
    Oct 2005
    Location
    Sydney
    Posts
    50

    Default Re: 3S 'blowby' mystery

    to answer your question, yes.
    You could have worn valve stem seals, but I've never seen worn seals causing such a corncern as you are descibing.
    Ben

  14. #14
    Junior Member Domestic Engineer urantia's Avatar
    Join Date
    Oct 2005
    Location
    WA
    Posts
    711

    Default Re: 3S 'blowby' mystery

    i've dealt with this more then a few times, i can say from experience these motors have a little blowby no matter what. They do not have a PCV valve, they do have a fixed orifice (pipe from head to throttle body).

    The sump relieves pressure thru the oil return's from the head and out that fixed orifice pipe.

    With a new set of rings the blowby is reduced but there is always pulsating pressure with this motor, if your not burning oil you shouldnt worry.

    Yeah they do tend to have noisy valvetrains, doing the valve clearances can solve this as can making sure your getting correct fuel flow/pressure most toyota motors seem to get quite noisy/tappety when there is insufficent fuel flow (strange but true). There could be a hundred different reasons -
    98 3rz-fe Hilux 4x4
    97 Hiace AWD Super Custom 1kz turbo diesel (sold)
    87 MA70 w/ 1JZ-GTE Manual Conversion GT (moss growing on roof deteriorating away but open to offers)

  15. #15
    is the most useless Backyard Mechanic jonchai's Avatar
    Join Date
    Oct 2005
    Location
    South Australia
    Posts
    413

    Default Re: 3S 'blowby' mystery

    I have rebuilt my engine and i change my oil whenever i need to...since i've had it, i've put on about 12,000km's and changed oil about 4 times.
    There is no "real" solution to this problem as it is techinically, a design fault (mine is a Gen 1 3sge) and the Gen 2 no longer had this problem with a different head design. The need to drill a hole through the sump is not a backyard solution as such, but it is a solution and it has fixed the problem. If it has fixed the problem (permanently) why isnt that a good thing, as it was relatively cheap, do-able, and fixes the problem.
    The system consist of a pipe from the sump, a pipe from the head (the one that is aready on there, just connected to the catch can), another pipe to lead back to throttle body (or can be left out of want to) and another to drain back into the sump. the systm is perfect, in the sense that the problem is solved, oil is filtered out, the oil that is filtered is drained back into the sump, and the remaining fumes are burnt off as per normal. the system is fully enclosed and hence no problem with the law, and the car therefore blows no smoke whatsoever
    Performance Through Technical Supremacy
    (\__/)
    (='.'=) This is Bunny. Copy and paste bunny into your
    (")_(") signature to help him gain world domination.

    hehe

Similar Threads

  1. 5S FE to 3S GE
    By adam golder in forum Tech and Conversions
    Replies: 19
    Last Post: 05-10-2007, 09:47 PM
  2. 2S -> 3S Conversion
    By 81rolla in forum Tech and Conversions
    Replies: 3
    Last Post: 22-02-2006, 01:08 PM
  3. oils an't oils what to use in a 3s gte?????
    By sirbabblealot in forum Tech and Conversions
    Replies: 34
    Last Post: 14-02-2006, 09:26 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •