right mates head gasket has slightly gone , will it need skimming ?
keep hearing different things

thanks dan

 

97 impreza btw

 

You're probably hearing different things because some people will be relating their anecdotal experience - some head gasket failures, particularly those secondary to (or involving) overheating, will warp the surfaces. Other modes of failure don't have the consequences and thus the only necessary remedial action is scraping the surfaces clean.

None of us can tell you what the correct answer is without actually examining the engine in question.

 

well i had told him they may need skimming , but he is still using it and needs it as he cant be without a car , its just pressurising the cooling system and blowing water out the expansion tank

so the other option i put to him was getting a pair of heads all skimmed and ready and just put them on at the same time , but are heads interchangeable ?
96 sti on to 97 uk turbo ?

 

mine is doing the exact same thing. i have stripped mine and i cant even see any sign of the headgasket failure. and i thought the v3-v4 sti headgaskets were one of the best.

 

Get them blue blocked to see if they need doing

 

Dan,
Its not just the heads which can distort when the engine has overheated - chances are the deck faces of the block halfs will show signs of distortion too - all depends on the 'degree' of overheating suffered.
Just something to be aware of.

Mick

 

as above having nice skimmed heads onto a possible warped deck fack isn't good either...

 

Mick, when this happens, are the block halves only good for boat anchors, or can the mating faces also be skimmed (if the warping isn't too severe)?

 

All i do to determine if i need a skim head and block is put a straight edge across the length of the surface (i use a metal ruler) then i try and fit feeler guages inbetween to see how distorted the surface is if at all! System pressurising first call is obviously air lock but if overheated allways worth a pressure test to check to see if the head has cracked!

 

checked for air lock several times , with system full of water running on tick over it is fine as soon as u give it any throttle it emptys water out , then in turn gets hot , also had the top rad hose explode

 

Joz - providing the warp is not excessive, then the block halfs can be skimmed/decked to a maximum of 0.005" in most cases

Mick

 

That's good to know.

 

its just good practise to get the heads skimmed usually cheaper than you expect, 50 to 60 quid for both heads, as above check the block with a straight edge with feeler gauges or shine a torch next to the ruler to see if you can see light coming from under the ruler.

 

is an 8thou skim alot?

 

Have you checked the Thermostat is opening and closing. I had this issue on mine when I thought the HG was on its way out....