head gasket change....

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mpr1956
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head gasket change....

Post by mpr1956 »

I sit here with bloodied hands and bruised arms having just finished a hg change... what a job.. I don't fancy doing it again soon, but I'm glad to say the car runs smoother. If anyone is tempted to scrap their xantia through a duff hg, then do what I did and give it a go (I finished the job in two days -in the drive) Once I figured out that removing the right hand engine mounting and then lowering the whole engine on the supporting jack lets the engine move forward allowing access to the turbo plastic pipes and inlet manifold etc, the job was fairly straightforward.
mpr1956
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Post by mpr1956 »

Sorry, forgot to say the car is a 93 td sx
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fastandfurryous
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Post by fastandfurryous »

Well, look on the positive side... the next time you have to do that job you'll know exactly what you're doing, and have it done in half the time! I've done so many of them now I can almost do them in my sleep!
It's all good fun though! and isn't it a lovely feeling to know that you did it yourself, and wern't ripped off to the tune of several hundered pounds by a "professional"
j_roc
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Post by j_roc »

Thanks for reminding me - I must get round to changing the HG on my Xantia.
citronut
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Post by citronut »

i hope you had head presure tested,then skimed,sunk valves to corect depth and used quality gasket regards malcolm
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Post by Peter.N. »

I take it that it is a 1.9, be thankful for small mercies, if it had been a 2.1 you would still be doing it (well if it was an XM you would).
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Post by ActivaV6uk »

I do wonder why the XM is so much harder, I’ve worked on both the 2.1 and the 1.9 out of the car and in and they were basically identical in procedure the only difference was that the ECU needs unplugging on the one engine and the tensioner and engine mount are diferent. is the XM bay really that badly designed? I thought it had a bigger bay surely that makes it easier (i had to unbolt the Activa spheres out of mine because I couldn’t move the engine at all with them in).
mpr1956
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Post by mpr1956 »

Hi Malcom, all I did was check the head for warping and obvious cracks and threw it back on after cleaning. What does worry me is that I could not see any obvious signs of hg failure ( my bx hg looked like it had rotted away in the corner), but on a car this age and mileage (93 + 180.000m) I didn't want to spend too much so just got decent gasket with 3 notches like the old one and new head bolts. Anyway the engine runs very much smoother and there are no bubbles in the coolant, so I'll claim a victory of sorts and hope for the best! The next step I suppose would be an engine transplant if problems return. regards, Martin
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Post by PeterMann »

This tends to confirm my suspicion that a significant proportion of headgasket failures are simply leakage past an undamaged gasket ; effectively due to the repeated extra compression on the gasket by the difference in thermal expansion between the alloy head and the steel bolts, so that the gasket gradually gets thinner, and eventually loses its sealing strength.
I have myself stopped a head gasket leak simply by backing off each headbolt in turn, oiling the thread, and torquing up to spec+5Nm. This was on an engine that had not got so hot as to warp the head.
It is my opinion that this epidemic of head gasket failures could be prevented by going back to the old procedure of retorquing the headbolts after running the engine for a few thousand miles. But what would I know .. I'm just an old mechanical engineer.
JohnT
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Post by JohnT »

I agree with PeterMann......if in doubt spend a little more and buy a metal head gasket. I fitted one to what seemed to be a straight head for a friend and it has done 63k since.
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Post by sooty »

I've recently changed a HG on a 1.9td with my son. His water was really chugging out of the rad, but when the gasket was checked there was no real signs of the blown gasket.
What you should look for is black carbon on the surface of the cylinder seal (metal ring folded around the cylinder sealing of the gasket edge), the black mark normally reaches towards a water passage and you also see black markings on the cylinder head and block.
Whether you see any warp or not, its false ecomony to refit the head without a skim, which costs about £25. As far as reseating the valves, providing the surface of the head is still above the wear steps on the edge of the head, which is approx 2.00 mm deep. Once this has been removed from all the reskims previous, then you'll need the valves to be remachined deeper into the head.
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