A couple of tips for preventing headaches.
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  1. #1
    Moderator Alan S's Avatar
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    A couple of tips for preventing headaches.

    As a couple on here know, amongst other various dramas at present, we are in the process of doing a rebuild on a couple of 16 valve motors one of which turned sour after it was put through the Pittsworth Sprints. The engine had around 120K miles on the clock (private import) & what was initially thought to be a valve stem seal job turned out to be a "re-ring, re-sleeve & anything else we could see" rebuild. As these motors seem to be shrouded in a certain amount of fear & mystery when it comes to working on them, I thought I'd pass on a few things we have discovered & will continue to do so up until completion so those who may have need to redo one can benefit from our experiences & info we've been told. Some of this I've seen first hand whilst other stuff has come second hand from my son so I suppose "E & OE" should apply

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    Point #1: Common habit amongst engine rebuilders is to "blast" a head to remove carbon & varnish build ups.
    Problem it creates: These heads have "blind" oil gallies which given circumstances as I will describe below, can lead to the "beads" becoming lodged in these gallies and impossible to remove causing the potential for oil starvation.
    Point #2: When the engine starts to use oil, the common response is usually to increase the thickness of oil being used. (ie) If using say 10W-40, this will be increased to 20W-50 or higher.
    Problem it creates: Being a modern multi valve engine, the oil is required to travel through a maze of oil passageways, to hydraulic lifters, spray inside pistons etc so on intial start up tends to take longer before the oil finds its way through the entire system & hence causes increased wear. The thicker oil also tends to stick to the internals of the blind gallies almost like a coating, increasing the "varnish" or scum build up capacity. When the bead blasting then occurs, the beads coated in this build up then tend to jam inside these blind gallies.
    Solution (we hope): The head has had 3 hot baths and still the varnish coated beads will not totally remove. Drill out the ends of the blind gallies so as to flush through and tap & set new plugs into ends.
    Problem #3 - A trap for young players. The hydraulic lifters have a smaller "piston" (for the want of a description) in the centre of them. When removed, they can drain their contents and when the head is refitted, the "piston" then has air trapped under it. The result is that when an attempt to start the car is made, it will either not start, show symptoms of no compression, only run on a couple of cylinders or knock loudly.
    Solution: Before reassembly, remove centre "pistons" from within the lifter and wash out & refit. The ones operating OK will feel quite smooth & springy whereas the ones likely to cause problems will feel rock hard. As a precaution all should be removed, cleaned & refitted; effectively "burped."
    Be warned though, it's a bugger of a job. cry spanner

    Hope those pointers are worth something to somebody as they have the potential to turn a straightforward job into a pile of headaches. As I say, some we've seen first hand whilst others are warnings from specialists in this field.

    Alan S wink
    If it ain't broke, use a 12" shifter.....that usually does the trick!!

  2. #2
    Budding Architect ???? pugrambo's Avatar
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    if the lifters aren't "burped" or make a little noise what then ?
    say for arguements sake you have had a head taken off and put back on and the lifters were making noise and you put cleanser through to "clear" as much sludge as possible and they calm down to almost normal again ?
    will they over time return to normal or is it a head off job again ?
    if they make a little noise but nothing major what then ?
    i'm very curious about this with these newer engines
    3 x '78 604 SL

    1 x '98 306 GTi6

    1 x secret project

    1 x '98 406 STDT troop carrier and i don't care if it stinks, i don't sniff it's arse Death by wank tank

    1 x '99 406SV 5spd wagon, time to burn more fuel

    1 x 1994 605 SV3.0


    WTD long range fuel tank for 605

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