Hi everybody .

 

first sorry for my english (i'm french and many persons know me here as Mark Derby).

 

Last week i've change all my head gasket in my 300zx ( it was smooking ).

 

One of head cylinder has been surfacing with 4/10 mm then we are surfacing the other head cylinder with the same value.

 

now , my engine is smooking again in the right side and the pipes are very hard ( air in pipes) then we have again a problem with the right head cylinder or with the new gasket ( all gasket has been changed)...

 

I've two question :

 

1) is it a problem with this value 4/10 surfacing ( too much for the head cylinder) ?

 

2) could i change again my head gasket cylinder with a special quote gasket for 4/10 mm surfacing ?

 

the other side with the same surfacing value doesn't' smoke.....

 

 

 

i hope that you understand me with my poor english.

 

somebody could help me ?

 

regards .

Do you know the stock thick for a 300zx head cylinder gasket : 1.02 mm ?

max. limit for resurfacing the heads (and block) is 0.1mm.

 

If I understand correctly you skimmed the heads 0.4mm ? ..which is far outside the limit and if the head needed to be resurfaced that much, it was very distorted and it would have been better you replaced it.

 

the smoking can be caused by many things..

Does it burn oil or coolant ?

Does it smoke from cold or does it take a while ?

 

also what do you mean by " the pipes are very hard ( air in pipes)" ?...or do you mean the coolant hoses ?

thank you Lymon . Yes coolant hoses are very hard ;)

 

I think the same thing as you , i have to change my heads cylinder !!! :(

 

It's smoke a lot after 5 mns running ...oil i think

 

Thank you again for your answer and this information about 0.1mm .

the coolant pipes getting very hard can just be trapped air, which is common after a large coolant refill.

Try leaving both radiator cap and bleed screw off, start the engine and let it gradually get up to operating temperature while slowly filling the radiator with coolant

Once the radiator won't take anymore coolant, put back bleed screw and rad.cap

 

I presume the warping of the head(s) occured after overheating the engine ?

If the heads were distorted that much, the engine must have been extremely hot and it may have glazed some of the bores.

(But this could/should have been inspected before putting the skimmed heads back on.)

I prefere change my head cylinders ( the 0.4mm is too important).

Now i'm going to search theses parts ( in great condition i hope) .

I'll check again my engine before reinstall head cylinders but it seems to be in great condition .

 

Thank you to think about me if you see theses parts to sell :)

Hi there .. the Heads can take up to 14tho of skimming before its determent to the Compression and Clearance Issues

How ever up to 7tho on Stock gaskets will be fine ..

 

Have you done a Compression test on the engine ?