Head Gasket/Skimming
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Because advice is honestly and freely given in this technical section, much of it will be amateur experienced based, so any information is given in good faith and is not guaranteed as correct.
Not many rules really, this board being aimed at technical issues, it shouldn't fall foul (hopefully) of some of the more personal issues that can affect forums.
Rule 1 - Is that you need to think very carefully before posting anything technical or asking anything technical relating to the security system of the car - See 'Security Issues' sticky for more info.
Rule 2 - We (MGF Register) do not support copyright infringement and therefore references to CD ROM, PDF versions or paper copies of the workshop manual (for instance) should not be posted on the forum. We don't want to get into trouble and we'd rather sell you a genuine hard copy through our Regalia shop anyway!
Because advice is honestly and freely given in this technical section, much of it will be amateur experienced based, so any information is given in good faith and is not guaranteed as correct.
Head Gasket/Skimming
Hi guys, bet you get bored of questions about head gaskets but hope you can help here.
I bought a 02 MGTF 160 VVC at the end of June from an independant dealer and as part of the deal they replaced the head gasket because I knew these were particulary weak on this model of car.
Now, 1500 miles later the headgasket has failed which Im not too pleased about. It sounds me to me like the dealer never replaced it in the first place or it wasnt done properly for it to fail after such little mileage. Fortunatly the car is still covered by the dealer warranty.
Now the real Q, the dealer informed me that when the headgasket was supposedly replaced before the head would also have been skimmed, but then I have been informed from another source that heads on TF should never be skimmed. Could someone tell me which is the case?
Many Thanks.
I bought a 02 MGTF 160 VVC at the end of June from an independant dealer and as part of the deal they replaced the head gasket because I knew these were particulary weak on this model of car.
Now, 1500 miles later the headgasket has failed which Im not too pleased about. It sounds me to me like the dealer never replaced it in the first place or it wasnt done properly for it to fail after such little mileage. Fortunatly the car is still covered by the dealer warranty.
Now the real Q, the dealer informed me that when the headgasket was supposedly replaced before the head would also have been skimmed, but then I have been informed from another source that heads on TF should never be skimmed. Could someone tell me which is the case?
Many Thanks.
- Chris Tideswell
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Re: Head Gasket/Skimming
The head should only be skimmed if needed, i.e. if the head has warped, if the was found to have not warped then it should be left alone as skimming has it's own risks but the procedure can be used to save the head if needed. The problem is that the second time there may not be enough left to skim meaning a new head is needed.
- Stampy
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Re: Head Gasket/Skimming
As Chis said, the head only needs skimming if the gasket fails and allows the engine to overheat.
If the alloy head gets too hot it warps, so when it's put back together the mating face doesn't sit flush on the gasket and leads to further problems........as yours was "replaced" as a precautionary measure I'd be inclined to say they had no need to skim it
If the alloy head gets too hot it warps, so when it's put back together the mating face doesn't sit flush on the gasket and leads to further problems........as yours was "replaced" as a precautionary measure I'd be inclined to say they had no need to skim it
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Re: Head Gasket/Skimming
Just watch out the garage doesn't do a DIY skim with a rotary sander as happened to me!!
- mel123
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Re: Head Gasket/Skimming
Err.....no expert but i got told that it should be skimmed and pressure tested as a matter of course after hgf. It would depend on how much the head was skimmed the first time as to weather it will take another skim.
My 1997 mgf has had the head skimmed twice. The first time i,ve no idea by how much. The second time by six thou. I was reliably informed at the time that the mgf 1.8 k series head has been seen in good service after having up to a mil skimmed off.
If you want to look into it further i would suggest you type "dave andrews" into google who knows and modifies the k series head.
The condition and the hardnes of the head needs to be looked at aswell before a decession can be made on wether to skim it or not.
Also get the latest LR gasket.
Hope this helps
Mel
My 1997 mgf has had the head skimmed twice. The first time i,ve no idea by how much. The second time by six thou. I was reliably informed at the time that the mgf 1.8 k series head has been seen in good service after having up to a mil skimmed off.
If you want to look into it further i would suggest you type "dave andrews" into google who knows and modifies the k series head.
The condition and the hardnes of the head needs to be looked at aswell before a decession can be made on wether to skim it or not.
Also get the latest LR gasket.
Hope this helps
Mel
1997 BRG MGF
- sniperpenguin
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Re: Head Gasket/Skimming
Both are wrong. You pressure test the head - if it fails, you skim it then test again. If it fails, the head is usually knackered.Now the real Q, the dealer informed me that when the headgasket was supposedly replaced before the head would also have been skimmed, but then I have been informed from another source that heads on TF should never be skimmed. Could someone tell me which is the case?
Replacing the gasket on an 02 car is pointless unless you are changing it for a better gasket (e.g. the Land Rover one), since the fault lies with the head itself You want to completely remove the "2002 curse"? change the head for a new one / non-2002 reconditioned one.
Hope this helps.
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Re: Head Gasket/Skimming
The head is Pressure Tested to check for porosity. No amount of machining can remove this.
Geoff F.
Geoff F.
- mel123
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Re: Head Gasket/Skimming
Geoff how does this pressure test work then to check for porosity .Geoff.F wrote:The head is Pressure Tested to check for porosity. No amount of machining can remove this.
Geoff F.
I thought the pressure test was to see if it was machined flat after/before the skimming.
Would just like to learn abit more
Mel
1997 BRG MGF
- mgtfnut
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Re: Head Gasket/Skimming
Absolutely right. Skimming is only "necessary" if the head is warped after severe overheating. It may not need skimming at all.Geoff.F wrote:The head is Pressure Tested to check for porosity. No amount of machining can remove this.
Geoff F.
Worse still is the softening of the alloy which may lead to liner marking/sealing problems of the head, no matter how many times you skim it. This is sometimes over looked. A hardness test should be made on the cylinder head surface.
Porosity is something completely different, and may have been there since day one. A chance skim may remove it - unlikely, and the LR gasket might possibly do something to help here. Normal porosity means a new head.
A pressure test is just that, a pressure test to see if the combustion chamber and passages hold up when pressurised. If porous, leakage will provide evidence the head is probably scrap.
Jerry
MG TF 135 - 100k
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MG TF 135 - 100k
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- mel123
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Re: Head Gasket/Skimming
Cheers for that
The reason why i,m asking is that a mate of mine got his HG done at a VERY well known garage and they said that skimming should be done as a matter of course as the head may not resume it,s original position /trueness when re fitted,so they always skim the head after a hgf.
I will check the above next week .
What i,m thinking is that i,ve had my hg done last year and the previous owner had it done 4 years earlier. I got the pressure test and skim (all ok)and the lr gasket, so my head would probably not take another skim. If it went again......what would you do providing the pressure test was ok,just re fit a new gasket??
Just want to arm myself with the right choice now if i can.
Cheers guys
The reason why i,m asking is that a mate of mine got his HG done at a VERY well known garage and they said that skimming should be done as a matter of course as the head may not resume it,s original position /trueness when re fitted,so they always skim the head after a hgf.
I will check the above next week .
What i,m thinking is that i,ve had my hg done last year and the previous owner had it done 4 years earlier. I got the pressure test and skim (all ok)and the lr gasket, so my head would probably not take another skim. If it went again......what would you do providing the pressure test was ok,just re fit a new gasket??
Just want to arm myself with the right choice now if i can.
Cheers guys
1997 BRG MGF
- Debs
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Re: Head Gasket/Skimming
Bah!
Most garages will insist on skimming.
Why?
Because they know DAMN ALL about the K Series!
The Ally that the K Series is made from is case hardened via quenching - is why the engine is so light - overheat it and you destroy the case hardening.
Now, if you skim the head you remove the case hardening.
SO...
UNLESS you use a multi shim gasket after this, then you are highly likely to get gasket failure again.
Most garages will insist on skimming.
Why?
Because they know DAMN ALL about the K Series!
The Ally that the K Series is made from is case hardened via quenching - is why the engine is so light - overheat it and you destroy the case hardening.
Now, if you skim the head you remove the case hardening.
SO...
UNLESS you use a multi shim gasket after this, then you are highly likely to get gasket failure again.
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- MGsteveT
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Re: Head Gasket/Skimming
Debs has got it spot on!
I could'nt have written it better myself.
I could'nt have written it better myself.
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