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crcked head?
- Thread starter ben_p
- Start date
220 50 50 220
that the compression i have now.. have a major misfire!. i think the gasket has gone between the 2-3 cylinder.. there is no over heat in cycle.. or oil water mix.. so im guesing the oil and water jackets have not been mixed through the fail.
stripping the block in the morning and having the head skimmed and tested but have a feeling its cracked..
also the the new gasket is .9mm thicker.. now im only looking really to skim 4mm off the head leaving 5mm extra.. how will this effect the compression on stock internals?
this is on a gti/vts .. saxosports are usless..
BenR help!
ive alos been offered a high flow head for £120 should i just take this and be done with it?
that the compression i have now.. have a major misfire!. i think the gasket has gone between the 2-3 cylinder.. there is no over heat in cycle.. or oil water mix.. so im guesing the oil and water jackets have not been mixed through the fail.
stripping the block in the morning and having the head skimmed and tested but have a feeling its cracked..
also the the new gasket is .9mm thicker.. now im only looking really to skim 4mm off the head leaving 5mm extra.. how will this effect the compression on stock internals?
this is on a gti/vts .. saxosports are usless..
BenR help!
ive alos been offered a high flow head for £120 should i just take this and be done with it?
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50psi?
Yep its well and truly broken.
I'm note sure if you could see a crack you should be able to there two ways to findout out
1) NDT testing (expensive)
2) Using your eyes.
4mm off the head is a lot though why so much? a 0.9mm thicker gasget (assuming its stays that thich when you torque the head will up the CR a lot mycbe to much.
£120 for a "ported" head seems very cheap
I cannot find the CR etc for a normal engine but a race VTS has an 85mm stroke (I think) and a 10 to 1 CR so the space at the top of the head was 8.5mm your cuting 3mm off or so so your CR will be massive 15.5 to 1 which is way to high unless you've other huge bits. BenR was on about a person in Japna who had a 16 to 1 CR Golf GTi which didn't last long.
Yep its well and truly broken.
I'm note sure if you could see a crack you should be able to there two ways to findout out
1) NDT testing (expensive)
2) Using your eyes.
4mm off the head is a lot though why so much? a 0.9mm thicker gasget (assuming its stays that thich when you torque the head will up the CR a lot mycbe to much.
£120 for a "ported" head seems very cheap
I cannot find the CR etc for a normal engine but a race VTS has an 85mm stroke (I think) and a 10 to 1 CR so the space at the top of the head was 8.5mm your cuting 3mm off or so so your CR will be massive 15.5 to 1 which is way to high unless you've other huge bits. BenR was on about a person in Japna who had a 16 to 1 CR Golf GTi which didn't last long.
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thats what im thinking.. just gettin hold of one in the morning.. lol theres a lad next door has a 02 plate vts.. hes gone away for 2 weeks! do u reckon u could remove the engine from under the car then fit a new one without the bonnet open? think ill need brucy baby for this one
Could always lift next doors car over the engine and then just drop it ontop of yours, no need to fit it for him, when he comes back if your lucky will just presume his engine 'fell out' maybe.....maybe not....
...on a serious note mate you have a PM
Good luck
edit : its a bit pricey but its delivered to your door
...on a serious note mate you have a PM
Good luck
edit : its a bit pricey but its delivered to your door
Ben, you cannot check for cracks by compression testing in situ.
To locate the problem you must do a combination of compression and leakdown testing to isolate an area.
Whip the head off and inspect the gasket since your compression values are out of whack anyway. But a leakdown test will isolate if its inlet or exhuast valves, or leakage between cylinders, into the coolant system, past the rings or oil system.
With the head of go get it pressure testing, this is basically using compressed air in a tank of water to check for leaks. You cannot magnaflux a non ferrous metarial like alluminium.
DO NOT buy a cheap modified cylinder head with no history and no documented gains/details, reciepts from a specilist in that cylinder head. More than likely you will end up with something that flows less than std.
Why fit a thicker gasket? Whats wrong with an OE one?
Skim the head as little as possible if your not doing anything for any good reason, it should only be a thou or 2 to clean it up if its straight.
To locate the problem you must do a combination of compression and leakdown testing to isolate an area.
Whip the head off and inspect the gasket since your compression values are out of whack anyway. But a leakdown test will isolate if its inlet or exhuast valves, or leakage between cylinders, into the coolant system, past the rings or oil system.
With the head of go get it pressure testing, this is basically using compressed air in a tank of water to check for leaks. You cannot magnaflux a non ferrous metarial like alluminium.
DO NOT buy a cheap modified cylinder head with no history and no documented gains/details, reciepts from a specilist in that cylinder head. More than likely you will end up with something that flows less than std.
Why fit a thicker gasket? Whats wrong with an OE one?
Skim the head as little as possible if your not doing anything for any good reason, it should only be a thou or 2 to clean it up if its straight.
BenR said:
hi ben!
im gettig the head off in the morning..
im not convinced its the valves. the coolent.. holds its temp, and it hasent moved down, the oil is clean and gold.. the OE gasket is paper and is the cause of most of the failers.. the other alt is a 3ply steel.
will a visual inspection of the head show and damge even the slightest?
if the HG is blown then a visual inspection will show the fault.
I doubt its a cracked head, but you cannot diagnose a cracked head without a pressure test, if you can see one, its going to be pretty big.
A leakdown test would of told you if its the valves or where the gasket it blowing as you can listen through the inlet, exhuast for respective valve leakage, you can listen to other cylinders for cylinder to cylinder leakage, or listen through the breather pipe for a blow into the oil galley/crankcase. Hence why i say a leakdown test is much better at diagnosing the problem, where a comp test just tells you there is a problem.
The thicker your head gasket, the larger you make the quench clearance, which induces det and makes it a much easier and common problem. 1mm thicker is massive, the most i run in TOTAL quench clearance is 40-45 thou (1mm) itself, not an additional 1mm ontop of the original gasket thickness.
If you want to bring the CR back upto std you will need to skim it by more than the gasket thickness increase itself, since you have quench pads which reduce cross sectional area and thus volume. So over 40 thou skimming.........not a good idea.
I doubt its a cracked head, but you cannot diagnose a cracked head without a pressure test, if you can see one, its going to be pretty big.
A leakdown test would of told you if its the valves or where the gasket it blowing as you can listen through the inlet, exhuast for respective valve leakage, you can listen to other cylinders for cylinder to cylinder leakage, or listen through the breather pipe for a blow into the oil galley/crankcase. Hence why i say a leakdown test is much better at diagnosing the problem, where a comp test just tells you there is a problem.
The thicker your head gasket, the larger you make the quench clearance, which induces det and makes it a much easier and common problem. 1mm thicker is massive, the most i run in TOTAL quench clearance is 40-45 thou (1mm) itself, not an additional 1mm ontop of the original gasket thickness.
If you want to bring the CR back upto std you will need to skim it by more than the gasket thickness increase itself, since you have quench pads which reduce cross sectional area and thus volume. So over 40 thou skimming.........not a good idea.
Seat Leon Cupra 290
saw you been posting on 106rallye.co.uk ben, good site
