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 muz
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| posted on December 13th, 2004 at 02:27 PM |
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loose head nuts
The head nuts on the left head of my 2 lt have loosened .Any idea what causes this ? I have checked and tightened the bottom 4 a couple of times .I
now have the engine out and with access to the top 4,I find they have loosened to between 10 and 15ftlb.hence the farting noise.and loss of power.On
reassembly can I put locktight or similar on the nuts to stop this?Or is there a better solution?Is this a common problem?The right hand side is ok.
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 Bizarre
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| posted on December 13th, 2004 at 02:47 PM |
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On a Type 1 it is to do with the studs pulling out of the case. Usually solved with case savers - but i thought Type 4 would come with these
already
Could also have something to do with the barrels cutting into the head mating surface.
Maybe something in the case barrel seating / barrels / head aint parralell and or flat
Locktight i dont think is the answer - I would suggest a trip to a machinist
Futue te ipsum!!!
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Andy
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| posted on December 13th, 2004 at 03:48 PM |
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Yep, as blue says.
Type 4 motors come from the factory with the head studs threaded straight into the case like a type 1, but with a fair bit more material, making
pulling the heads studs less likely than a type 1 motor but still possible.
Loctite not likely to be the solution. As Blue says look at getting the head machined to ensure everything has a good surface to bed into when
re-assembling, especially if the head has been leaking.
Another thing often over looked is CLEANED AND GREASED threads for the nuts to go onto. If they are dirty or dry, you can often have the head studs
twist without tightening properly and they will soon loose tension. Also the original washers are large in diameter and quite thick so so they dont
cut into the head.
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muz
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| posted on December 13th, 2004 at 05:22 PM |
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Thanks for the replies
.What should the studs be torqued to into the case .Some seem a bit loose(under 10ftlb) The head went to a machinist about 18mths ago for the same
problem(thru a vw mechanic).I've heard some heads can go soft ,or be soft. Is this true? and if so ,would the machinist pick it up?
most of the washers are about 2.5mm thick but 2 are thinner.all are the same diameter.
thanks again.
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stevosky
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| posted on December 13th, 2004 at 08:58 PM |
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yes some heads can be soft already. if they have been overheated. some machine shops will just machine a head flat instead of straightening it
first.speaking from experience. it wasn't a vw head though.
Steve
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Che Castro
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| posted on December 13th, 2004 at 10:32 PM |
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The head studs need to be torqued in a particular pattern in a certain procedure. You alternate between left and right heads etc. It is outlined in
the Bentley manual and Muir manual.
I didnt follow this when i first got my dub and learnt the hard way! Heads leaked exhaust everywhere and ran like dogs balls
Jon
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Andy
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| posted on December 21st, 2004 at 07:31 AM |
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A little late to reply, but the studs don't get torqued into the head. The threads run through the case and shouldn't be tight. Might be showing up
that you have damaged threads in the case.
I have heard about "soft heads" but not sure if it's true. It's usually in relation to dropping valve seats or recessing valve seats in heads that
have been rebuilt too many times, or over heated as stevosky said.
The thickness and hardness of the washer is just to stop the nut wearing into the aluminium.
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