Head Gasket Gone Help

CITROEN-SUCKER · Post by **CITROEN-SUCKER** » 13 Jan 2004, 19:51

Hi my nice new 1.9td vsx with 125k on the clock. Died this weekend after overheating with no sings of leaks done all the checks seems to be head gasket.[xx(] I'm happy to do the work but have no idea what it will cost to get the head re-skimed and where i can get it done (I live near Edinburgh) also once it is re-skimed how do i know what notch gasket to use as to be honest i don't have any special tool as described in the manual?
please help[?]
thanks
J.J.

mbunting · Post by **mbunting** » 13 Jan 2004, 20:28

Usually the thickest gasket is used, there is a guide in the Haynes manual.
Skimming should cost you no more than £50 from a local engineering firm or engine specialist.

James.UK · Post by **James.UK** » 13 Jan 2004, 23:41

Logicaly the engineer who skims the head will first run a clock guage over it to (a) make sure its parallel to the machine head and (b) to see how much he needs to take off to get it flat again, he will then take off the minimum amount necessary. But he will know *exactly* how much material he has removed and I imagine he will tell you if you ask. Add that amount to the thickness of your old gasket and you will know exactly how thick the new gasket should be..
Alternatively you could buy the "next size up" gasket and ask the engineer to remove that amount of material.. I doubt the head will have distorted more than a few 0.001 of an inch..

Dave Burns · Post by **Dave Burns** » 14 Jan 2004, 00:11

The thickness of gasket fitted is dependant solely on piston crown protrusion above the block face, it has nothing to do with metal removed while skimming the head, fit a gasket with the same number of notches that is on at the moment wether the head gets skimmed or not.
Dave

edd001 · Post by **edd001** » 14 Jan 2004, 00:43

i agrre with all above but make shure you have not craked the head.
you must look closely as sometimes it can be very difficault to see the crack (normaly between the valves).

James.UK · Post by **James.UK** » 14 Jan 2004, 00:53

Hi Dave. If that is true why do they make gaskets of diff thicknesses? Surely crown protrusion wont vary in manufacture? The distance the crown protrudes is fixed, unless you either skim the block, shorten the con rods, Or, even more unlikely, by altering the throw on the crankshaft, none of which is applicable in this case..
I think its either:- to maintain the distance between something on the head, and something on the block, possibly clearance between the top of pistons and valves? or:- as it also effects the compresion, i.e. the more you skim off the head, the smaller the chamber becomes, you compensate for this by adding a thicker gasket?

acrowot · Post by **acrowot** » 14 Jan 2004, 01:07

You will find that the piston protrusion does vary in manufacture, if you check the protrusion on any given engine you will find them different to one another, you have to choose the one with the biggest protrusion and use that to decide on the gasket.

James.UK · Post by **James.UK** » 14 Jan 2004, 02:18

Having served a 7 year apprenticeship in machine shop engineering (pumps and compressors) and many more years working in other company's workshops and tool rooms I am amazed!! [:0] In every mass produced engine-pump-compressor shop I have ever worked in, all the items were held in jigs whilst being machined, in order to make them all identical to extremely fine limits.
How Citroen can get their components to work if they all vary to the extent that piston crown to block measurement, varies so much that they need different sized gaskets from new, I simply dont understand. Makes one wonder what else varies *inside* the engines huh [:I]. Still...they are French... [:o)]
However, skimming the head will still effect the two items mentioned.. Valve clearence and compression. Oh and possibly fuel distribution pattern within the compression chamber itself to a certain extent? Depends how critical chamber size, shape, and ratio are. I've never worked on a diesel engine so I dont know.. [:I] But based on the fact they seem to run on anything and everything its prob not too important. [:D]

acrowot · Post by **acrowot** » 14 Jan 2004, 02:31

The head on these engines is flat (ie no combustion chamber) when it is skimmed it is still flat, it has made no differance to the compression as there is no combustion chamber in the head, the only differance being that the valves are marginally lower in the bores (possibly increasing compression very very slightly). If the valves are also lapped in then there will be no noticable increase in compression at all. The valve clearances will not be affected (providing the shims are relaced in the original places)unless the valves are lapped in.

CITROEN-SUCKER · Post by **CITROEN-SUCKER** » 14 Jan 2004, 03:55

Thanks for the help but what is the real thing with the gasket then ... do I go 1 size up or do I get the biggest?

acrowot · Post by **acrowot** » 14 Jan 2004, 04:14

You should not go a size up, as Dave Burns said use the same gasket thickness as the one you removed (ie count the notches on the old gasket,if they are there on the old one, on the last one I did the old gasket did not have any notches on it). If there are no notches on the old one and you want to do a "proper job" you will have to measure piston protusion and then determine the correct gasket.

wheeler · Post by **wheeler** » 14 Jan 2004, 05:18

I agree with Dave Burns & Acrowot on this one,the same size should be used & to do it properly you have to measure the highest protruding piston crown then refer to the chart.

Dave Burns · Post by **Dave Burns** » 14 Jan 2004, 05:58

<font color="blue">However, skimming the head will still effect the two items mentioned.. Valve clearence and compression. Oh and possibly fuel distribution pattern within the compression chamber itself to a certain extent?</font id="blue">
No, machining wont affect any of those, excepts compression ratio maybe, and then the difference would hardly be measurable in a diesel of this nature.
It wont alter valve clearances either, how could it.
Fuel distribution, no not at possible, combustion chamber, also called swirl chamber or pre chamber is deep within the head and is unaffected.
Some of what you say James will affect a petrol engine, compression ratio could be significantly raised plus squish area's could be reduced or removed completely on some engines reducing cylinder turbulence.
Dave

James.UK · Post by **James.UK** » 14 Jan 2004, 06:46

hmmm. So no valves in the head at all? bit like a side valve petrol engine? and the "swirl chamber is deep in the head? So does the pistol actually go up into the head to compress the air? I think I need to see some drawings of diesel engines, all sounds micky mouse me? lol...
Interesting though.

DoubleChevron · Post by **DoubleChevron** » 14 Jan 2004, 08:33

There's gotta be valves in the head ??
As it's an overhead camshaft, you valves won't go out of adjustment (as it would with pushrod operated valves). However if you skimmed to much off I imagine the valve would open deeper into the bore... There could be a possibility in extreme cases that it would touch the piston (though I think there is a cuttout in the pistons so the valves won't touch when fully opened.
The cambelt may also need re-tensioning in extreme cases as the head sits lower on the block ??
So what do I get ?? a 'D+' or an 'F-' [:o)]
seeya,
Shane L.