MB
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| posted on 29/1/03 at 10:32 PM |
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head skimming
My locost building has been skuppered by my main car blowing is head gasket this evening...
Took it to a garage and decided to do the job my self as they were going to charge £500! One of the things they said they were going to do was to
skim the head. Is that necessary?
Its a 9 year old Astra 8v 1.4i. with about 85k on the clock (if that's useful information). The garage said as is was an alloy head is should
definately be skimmed. Were they taking me for a ride, or should I get it skimmed?
If it does need a skim, how much should I be paying?
Thanks!
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Viper
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| posted on 29/1/03 at 10:38 PM |
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99 times out of a 100 you will need to skim an alli head if you have done the head gasket..its not expensive, i think the last one i done was about
£35...
enjoy.
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MB
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| posted on 29/1/03 at 11:15 PM |
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Thanks,
I'll get it skimmed then... do they like you to remove the valves? I would imagine they would get in the may of the mill cutter as at least a couple
of valves will be lowered.
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Viper
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| posted on 29/1/03 at 11:34 PM |
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i don't know your head , but the will the valves be open with the cam removed?? i have left them in when i have had pinto heads done..
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theconrodkid
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| posted on 29/1/03 at 11:56 PM |
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when the cam box comes off all the valves will shut so no need to remove them,remember new head bolts and timing belt,dont use house hold silicone
sealer for cam box usu the right stuff or it will leak
who cares who wins
pass the pork pies
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jollygreengiant
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| posted on 30/1/03 at 06:58 AM |
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When you put the head back on, but before you fit the hydraulic lifters(/posts) take each one & with a piece of cloth at each end (ball with pin &
flat base) place carefully into vice and compress slowly so that the oil contained inside comes out of the little pin holes in the sides.
The shoulder below the ball will go almost flush with the retaining ring. Or if you've got a lot of time to spare you can take each one to pieces,
clean & reassemble. This will prevent the posibility of a valve locking down & twating a piston when you come to start it.
Also try to keep each finger with the lobe that it runs under.
Enjoy.
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david walker
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| posted on 30/1/03 at 09:02 PM |
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The head will need skimming. Whoever skims it will (or should) leave the valves in. Make sure it is cleaned thoroughly afterwards.
Be aware that old Vauxhall heads also corrode quite badly, to the point that skimming will either not remove all of the damage or if it does it will
go too low. Do not allow more than .030" to be removed - a reputable machine shop won't anyway. If the head is corroded badly it will need corrosion
grinding out and alooy welding. If it's welded, strip valves out and clean. Lap valves back onto seats.
I presume your garage is in Mayfair or similar. I run a fair sized engine shop and we charge £20 + vat for a straightforward skim, a typical Vauxhall
that requires weld and skim would be £35 + vat. Assuming your Astra is spi and not multipoint we would do the whole job for £170 + vat. Not touting
for business, just telling you what the costs are around here.
JJG - your'e right about the lifters, in respect of bleeding them out, but I don't know how someone in his garage at home is going to strip them
down?????
Dave Walker, Race Engine Services - 07957 454659 or 01636 671277
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johnston
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| posted on 31/1/03 at 01:44 PM |
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get it done for less than 150
get haynes mag
head gasket set
timin belt
oil/filt
and do it yourself
done my old 1300 (no head skim) in a hour but cut a lotta corners
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MB
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| posted on 31/1/03 at 11:01 PM |
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Good job you mentioned about the hydraulic lifters - that bit is not in the haynes manual!
Got the head skimmed (less than 30 thou removed). Just spent the evening grinding the valves - hopefully I'll have it back together tomorrow.
When you press the hydraulic lifters will they stay compressed and then open out when you start up? I'm assuming that they are to automatically
adjust the cam to valve gap. Will this mean that it will rattle for a few seconds until they have expanded?
Thanks for the advice - my next post should be locost related when I get this problem sorted!
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jollygreengiant
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| posted on 1/2/03 at 08:41 AM |
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quote:
Originally posted by MB
When you press the hydraulic lifters will they stay compressed
No they have springs inside them but when they have been used they are full of (thick, cold, old) oil as well and they extend once out of
restraint/compression from the cam & fingers. Press the oil out and this will mean that instead of having a hydrualicly locked piston you will have a
piston that moves so that when you reassemble the fingers will be able, with the valves closed for the most parts to allow the ball post pistons in
the hydraulic adjusters to set themselves to the right height for starting and once the engine is running and you have oil pressure then the piston (
springs & valves inside do all the work) adjusts its self to the right hieght automaticaly. Turn the engine of and after a very long while any valves
that are open would slowly lever against the camshaft and do what you are doing with a vice any way.
and then open out when you start up?
I'm assuming that they are to automatically adjust the cam to valve gap.
Answer in above.
Will this mean that it will rattle for a few seconds until they have expanded?
Not normally. Unless your engine is the Ford 8V twin cam 2.0litre. Then the answer is most definately yes and for anything up to 3-4hrs and they sound
like you've left something major loose in the engine and you have an overwhelming desire to turn it off. Ford actually recommend on this engine that
you take the engine revs up to 2500/3000 because this can help to reduce the rattle time to an hour. And those of you who HAVE heard one of those
engines started after having had the head off will know exactly what I mean about RATTLE.
Thanks for the advice - my next post should be locost related when I get this problem sorted!
Enjoy.
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Stu16v
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| posted on 1/2/03 at 02:43 PM |
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But to expand on what JJG has said it will sound like you have left a bag of spanners in the engine on first start up!
Most VX engines will quieten in seconds, but sometimes you will have a persistent one or two that will 'hang on' and rattle for a bit longer. A
quick run up the road usually sorts it.
HTH Stu.
Dont just build it.....make it!
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