Valve thrown advice please

Discussion in 'Engine & Transmission' started by Winged, Sep 13, 2017.

  1. Winged

    Winged Member

    Messages:
    157
    Location:
    Huon Valley
    Hi after a knocking caused an end to our family day out, I pulled and stripped the engine finding cylinder 4 exhaust valve unseated and stuck. Knocking solved i guess but was the breakdown caused by something?. So i suppose im after advice on how to proceed.

    Something that might be worth mentioning is that prior to this i had been getting oil in my air filter. I put in an inline trap, of which i pulled out sludgy water/ oil (alot of) weekly. Same inside the rocker cover over the affected valve. Is this leaky rings? Lot of carbon crap in the cylinder too.
    Do i replace the pistons and the lot, what are my options?
    Thanks for any advice

    20170913_142152_resized.jpg 20170913_142202_resized.jpg 20170913_142227_resized.jpg 20170912_164044_resized.jpg
     
  2. Mordred

    Mordred Super Moderator Staff Member

    Messages:
    2,477
    Location:
    Penna, Hobart
    Sorry to hear you are out of action. I would say the valve guide has worn and was letting combustion gasses into the rocker cover and then to the crank case. I am not sure of the age and condition of your engine, but if you know the compression values to be still reasonably high you may get out of it replacing the head. Even though you haven't failed the other head I would be tempted to replace them both. One failing means the other has done the same amount of work and potentially may be on the way out as well.

    IMHO, if I had the money I would consider rebuilding the whole thing as top end rebuilds are a stop gap to save money and you are less likely to get the full service from the new parts If you have it out and dismantled you might as well get it put back together as a new engine, and it will give you a nice line in the sand as all of the components will wear together. May not be others idea of a plan, and it is the more expensive option. But I believe it comes down to how much use you are going to put it to, and how long you plan on keeping it. If it is a daily driver and or yoy are planning long trips to the mainland, spend the money, if it is on SI rego and you use it on short trips probably a better investment to do a basic repair.

    Adrian
     
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  3. Winged

    Winged Member

    Messages:
    157
    Location:
    Huon Valley
    Thanks Adrian you always take the time to give sound advice. Much appreciated.
    I don't like to dont things by halves but realistically a full rebuild is unchartered territory for me. Is it an overly difficult job?. I use my bus mainly as a part time family car for school drop offs and weekend trips, camping. But isnt a daily car especially in winter. Like most things will come down to $$.
    If replacing cylinders/ heads I assume they need to match and there seems to be a bit of choice. For example would this work?

    https://au.vwheritage.com/021101062ax-cylinder-head-1-8-&-2-0-8-73-7-78-compl-no-egr-39-3x33

    https://au.vwheritage.com/029198075-piston-&-barrel-set-2-0-t2-mahle

    PS What are the merits of dish top/ flat top pistons? After i purchase them do they need machining?
    Thanks again
     
  4. saabman

    saabman Well-Known Member

    Messages:
    4,640
    Location:
    Goulburn
    I took the plunge and did a full rebuild a few years back it took a few months a bit of struggle as the Kombi was my only motorized vehicle.

    It took a few reassemblies to get it right but all worked well in the end.

    My engine originally had domed pistons and I changed them to dished pistons to reduce the compression to allow the use of low octane unleaded fuel.

    Don't rush it and be prepared to have a couple of goes and be patient.

    I based my rebuild on a great book called something like rebuilding a air cooled VW by Tom Wilson (I'll look it up and get back to you on that one)
     
  5. andrew

    andrew Active Member

    Messages:
    348
    Location:
    Richmond
    Hi Winged - this is exactly what I had on cylinder 4 - mine was a sticking lifter. I have just about finished rebuilding the engine. the lifter damaged the cam and the valve not opening shot back up through the carbi to the air filter.
     
  6. Mordred

    Mordred Super Moderator Staff Member

    Messages:
    2,477
    Location:
    Penna, Hobart
    When it comes to full rebuilds there are so many things you need to take in to account. I have managed to avoid doing it so far and managed to get a rebuilt one that was for sale at a good price. I have rebuilt a number of other water cooled engines before, but not had to do one of my VW engines, apart from ancillaries and clutches. That book is very good, but finding and getting the parts and getting them together to do the rebuild in Tas is a big pain. Things like getting the case line bored and everything measured up and checked is important as regardless of how much of this work you are going to do yourself it is going to be reasonably expensive in time and money, and you don't want to have to do it again too quickly.

    If you have the time and patience it is a brilliant project, and that book is rather good too. I have a copy but I cant think off the top of my head if I have got it back when I last lent it out. That said it wasn't a lot of money (I think $30) and easily worth it to have a copy on hand.

    Personally, as I don't have the time or the good workshop space to do it, I reckon if I start having problems I will be getting one rebuilt at least to long block stage on the mainland and organised a weekend trip to bring it home. Going to cost me extra but at least I will be able to spend more time enjoying it.

    Adrian
     
  7. Mordred

    Mordred Super Moderator Staff Member

    Messages:
    2,477
    Location:
    Penna, Hobart
    I found the book if you would like to borrow it.

    Let me know.

    Adrian
     
  8. Winged

    Winged Member

    Messages:
    157
    Location:
    Huon Valley
    Hi, I think on the balance of things a full rebuild isnt going to happen at this stage. After reading Bentley and Muir i might even get someone to put the piston Cylinders on for me. Then do the heads -on myself. i would love it done right for the bucks i will be shelling out.
    Thanks for the sage advice, i have some piston/ pot questions but i will start a new thread. Ps thanks Adrian turns out a mate has that book, cheers
     
  9. Mordred

    Mordred Super Moderator Staff Member

    Messages:
    2,477
    Location:
    Penna, Hobart
    Glad you have access to the book. Lots of good info there, but at least some of it out of date as far as getting parts.

    Hope it isnt too long till we see you back on the road.

    Adrian
     
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  10. Winged

    Winged Member

    Messages:
    157
    Location:
    Huon Valley
    Turns out the stud closest to the blown valve was a loose. I'll need to get it time sert, helocoil or whatever.
    Question is this a symptom ( milky white oil and unseated valve) of my problem or the cause of it?
     
  11. Luckyphil

    Luckyphil Well-Known Member

    Messages:
    5,039
    Location:
    Gosford
    So is this van air or water cooled.
     
  12. Winged

    Winged Member

    Messages:
    157
    Location:
    Huon Valley
    Sorry. Air/ type 4. 1976 2lt bus.
     
  13. Mordred

    Mordred Super Moderator Staff Member

    Messages:
    2,477
    Location:
    Penna, Hobart
    I doubt the moly white oil has anything to do with the valve. Normally water in the oil but air cooled so no water. Must be from somewhere else, or air may be mixing in the oil. Take a sample and let it settle out over a few days in a glass. If it was a loose head stud you may have had an air leak causing it to run lean.

    That's what I get from that info.

    Adrian
     
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  14. cbus

    cbus Well-Known Member

    Messages:
    10,206
    Location:
    sunshine coast
    Tassie in winter, short runs.
    Oil not getting hot enough to drive out moisture.
    Not unusual.
    Would be deposited on inside of oil filter cap as well
    Should be no signs in oil itself.

    I would guess a wipe of existing deposits and few hot runs should sort the issue normaly.
    An oil change should accelerate improvement.

    My expectation is 2 separate issues.
    Adrian has covered options.

    A real rough option could be repair damaged head.
    Pull lifter on damaged valve to check for damage to lifter or push rod.
    Fix anything obvious ( damaged lifter to cam surfaces or side damage would mean engine strip)
    Reassemble and bench run or install and check for noises etc.
    Might ?? be lucky.
     
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  15. Barry

    Barry Well-Known Member

    Messages:
    1,687
    Location:
    Abbotsford NSW
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  16. Grantus

    Grantus Well-Known Member

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    13,061
    Location:
    Southern ACT
  17. David H

    David H Well-Known Member

    Messages:
    1,900
    Location:
    newcastle
    "oil Filler cap"
    One of the most overlooked & underrated places to get info from... for what's happening in your sump:).
    Cheers
     
    Last edited: Oct 11, 2017
  18. andrew

    andrew Active Member

    Messages:
    348
    Location:
    Richmond
    I looked at new heads and opted to have my heads done up with slightly larger better quality valves. Crankshaft Rebuilders in Blackburn took their time but did an excellent result.

    On the piston front I went with flat tops and bought them from Rod Penrose. Rod was good to deal with despite not being a fan of the t4 engine he was helpful with advice on the replacement cam etc.

    Fitting the pistons and barrels is a straight forward job and goes hand in hand with the heads - if you prefer video's - YouTube has some great step by step reference videos.

    I strongly recommend an engine stand as it makes this job a lot easier to do.

    Good luck.
     
  19. Winged

    Winged Member

    Messages:
    157
    Location:
    Huon Valley
    You can see my lifter (exhaust cyl 4) is full of pits but no acute damage. The corresponding toe doesnt look as bad as cyl 1 which has the rectangular wear pattern on the toe of the cam.
     

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  20. Winged

    Winged Member

    Messages:
    157
    Location:
    Huon Valley
     

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