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gtiburge

Compression / head skim

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gtiburge

 I  have just started my first head gasket on a standard 205 Xs ,I’m not sure if the head has been skimmed so is there a measurement on the head to find out??? ,   It will need another skim as there is pitting, I’m not sure the safe about that can be skimmed and what gasket to use after ? I have got a 1.25 mm payen on order , engine is standard no cam ect so will I run in to piston valve cleanse problems , or pinking when it’s back together ? Any help much appreciated 
Thanks 
Olly

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DamirGTI

111.2mm +/-0.08mm says so in the 205 Hanyes manual too .

 

Either way , it'll be the job for the machinist ... get the head checked by someone who does that , aside from skimming you might need new valve guides too and valve seats regrind depending on how far you want to go with the repair .

 

D

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gtiburge

So the head is back from skimming they skimmed 23 thow off, There is still some pitting left but none around the sealing rings I will measure it up with a friend tomorrow to try and find out how much has been taken off over the years ,Here is a pic of it as it stands let me no what you think thanks for the help :D

3AF96714-0D88-4131-B8A6-AD4989DD9FB9.jpeg

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welshpug

0.023" =  0.5842mm, so that's a good chunk off the head, I'd be inclined to use a repair gasket, modern fuels and ignition timing adjustments will take up the rest of the increase.

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gtiburge

What would a repair gasket be then as I have a payen 1.250mm on the way there is A elring 1.47mm gasket and payn 1.5mm option, I take it if I used the 1.25 it would pink it’s ares off ? No Benefit in having higher compression with the std engine ? Sorry it’s my first time doing anything major like this I do have a good Mecanic friend that will help with reassembly thank god! the other thing is the tightening I read that the 2nd stage is quite a jump 240 degree And some split it in Half ? It is ally after all is that Recommend ? Thank you for all the help it is much appreciated 

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calvinhorse

It should be pretty good, if it pinks run it on super unleaded, personally I’d run it on super anyway.

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calvinhorse

The 1.5mm will be closer to the correct compression tho so is the safer bet.

 

just as a comparison I ran an Xs head on a saxo VTR bottom end which had the flat top pistons, no idea what the compression was but compared to a Xs where the pistons don’t even come up to the top of the bore it must have been astronomically high! I ran that on an Xs dizzy/dizzy curve and used super unleaded only and it would only pink if I really laboured the engine

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DamirGTI

The higher the piston goes up the bore and is flush with the block deck the better ... it's called "squish clearance" , it promotes steady burn rate , cools the mixture and piston crown , reduces pinking and detonation occurrence . Engine performance will be better too .

 

Does this UK 205 Xs have distributor or it's an SPi version ? if it's mechanical distributor , can always tweak the timing a bit if it pinks , or run higher grade fuel as said .

 

Question mark is how much was taken off the head till now .. without measuring the head or the combustion chamber volume its really hard to tell .

 

Tightening specs , split the 240deg. in two , so like this :

 

1. 20 Nm

2. 120 deg.

3. 120 deg.

 

Oil the head bolt threads or grease them with moly grease , apply some on the area under the bolt heads too .. and clean up the bolt threads inside the block and blow out with compressed air . Best to clean the threads with an old head bolt with two grooves cut on the sides , as the tap just weakens the alu. threads .

 

 

If you want to use "solid" HG without the "Vitone" element , then pick one of these :

 

Elring : 117.831 (1.47mm)

Elring : 984.136 (1.27mm)

 

D

 

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gtiburge

Thank you :D I have measured the head today it’s 110mm so it’s had about 1 mm off in it’s life time it is a carbed Xs with old school distributor I will run it on good fuel anyway it sounds like the 1.47 mm eliring is the one to go for ? 

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DamirGTI

Yes , use thicker "repair" gasket then .. so 1.47/1.5mm .

 

 

D

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gtiburge

Finally got it back together today and running its all good :)  apart from the coolant light stays on it’s the one above the temp gauge (Xs dash)  system is all bled and running fine , is that a coolant temperature light or level light ? Any ideas what I could be ? I was going to start with just a new sensor ? 
thanks for the help :)

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DamirGTI

TU's are a bit dicky to bleed properly ... you might need to bleed them few times till done , 205 TU's certainly as they're the worse .

 

Written something about that here years ago :

 

 

 

The light is for the low coolant level in the radiator .. red light/symbol like frying pan ... either it's not yet bled completely or you need to clean up the coolant level sensor , meaning need to take it out from the radiator and clean up the insides so that the float can slide freely inside the sensor (if there was oil mix in the coolant)

 

D

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gtiburge

Ahhhh I will try that Bleeding method but it sounds like I’ve got the clean the sensor as I’m sure it’s bled fine I presume it’s the one with the big nut on top driver side under slam panel ? 

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DamirGTI

Yes , that's the one .. but do not open up the sensor , there's one hole on the side and one on the bottom , use those to wash out the crap from the insides ... prepare in the bucket degreaser solution with warm water and soak the sensor in , and shake it a bit from time to time .

 

Can also try , with the sensor out , leave it connected and with ignition ON flip it upside down and see if the "frying pan" light turns off ..

 

Check the coolant level in the radiator , as i'd hazard a guess you might need some more bleeding too if above doesn't work/makes no difference .

 

 

D

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gtiburge

All is good just cleaned the sensor up and it was fine :D she is now on the road again just got a handful of other niggles to sort out :lol:

 

thanks for the help 

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