[bobttroll]

Why does the cylinder need to be at TDC when replacing the head gaskets? I am just curious.

 

[achille]

I would imagine it has to do with the fact that the headbolts also secure the valve train.



@ TDC there will (should ) be equal and minimal tension on valve springs et c.

 

[bandit]

Why does the cylinder need to be at TDC when replacing the head gaskets? I am just curious.

you probably mean...the piston[not the cylinder]

i cant think of a good reason why it has to be.the head gasket can go on with the piston in any position.

.........other than saving anything from falling into the cylinder[foreign matter]and causing damage

edit,now educated,i always did it,just didnt know why,its just automatic

 

[Reg in Bristol]

I would imagine it has to do with the fact that the headbolts also secure the valve train.



@ TDC there will (should ) be equal and minimal tension on valve springs et c.

I Agree

Trying to get the valve gear to sit down not at TDC on the compression stroke would be a

chore and increase the chances of buggering something up.

Backing the tappet adjusters off prior to fitting valve gear makes it even easier and is probably good practise anyway

 

[achille]

you probably mean...the piston[not the cylinder]

i cant think of a good reason why it has to be.the head gasket can go on with the piston in any position.

.........other than saving anything from falling into the cylinder[foreign matter]and causing damage

edit,now educated,i always did it,just didnt know why,its just automatic

Good call on the 'cylinder' vs. piston bandit; I really missed that altogether.



But actually you are right; it dosen't HAVE to be @ TDC.



But one would have to be extremely careful in cinching down the head so as to not distort anything.



$.02

 

[bandit]

Good call on the 'cylinder' vs. piston bandit; I really missed that altogether.



But actually you are right; it dosen't HAVE to be @ TDC.



But one would have to be extremely careful in cinching down the head so as to not distort anything.



$.02

isnt that just normal,4 main head bolts gradually decending evenly in a cross pattern until the required torque is achieved.

i only put it to tdc so i can see the cylinder is clean

 

[achille]

isnt that just normal,4 main head bolts gradually decending evenly in a cross pattern until the required torque is achieved.

i only put it to tdc so i can see the cylinder is clean

Yes,precisely; you are absolutey correct.



Well put,the key being "decending evenly in a cross pattern"



Meaning like one 'round' per,bolt per 'round'.



Same basic situation as with any OHC auto engine for instance where obviously only one pistoni can be @ TDC



and some valvesprings will be compressed,regardless.

 

[achille]

Sorry , sticky fingers here I guess!

 

[achille]

 

[bobttroll]

I do thank everyone for the input. I ask only because I already put did this and was curious if I should undo it but it seems I am good.

 

[achille]

It would be interesting to see what the concensus* is on re- torquing head bolts,(if any)and SPECIFIC procedures.



It seems everyone has a slightly different method and whether it is even 'required'.

 

[bear351c]

As stated, it doesn't matter, if all you are doing is replacing the head gasket. It does matter if you are installing valve gear.



Also, if there is a lot of oil in the head bolt holes, (if they are blind holes) it pays to gently blow them out with compressed air. The oil can actually stop the bolt from reaching the required torque, giving a false indication of tension.



To avoid warping the head, I always do up my head bolts in 3 stages, criss/crossing as I go. Never do them up to final torque in one go.



My 2 cents, which in America would be about one and a half.

 

[bobttroll]

As stated, it doesn't matter, if all you are doing is replacing the head gasket. It does matter if you are installing valve gear.



Also, if there is a lot of oil in the head bolt holes, (if they are blind holes) it pays to gently blow them out with compressed air. The oil can actually stop the bolt from reaching the required torque, giving a false indication of tension.



To avoid warping the head, I always do up my head bolts in 3 stages, criss/crossing as I go. Never do them up to final torque in one go.



My 2 cents, which in America would be about one and a half.

I did blow each one out with air. I remember reading that the head bolts are supposed to be lubricated with oil. I used trans fluid because that all I had around at the time. Do you guys think thats ok? Wow I sound like a real polack. and by the way I am half polish. LOL. really.

 

[bear351c]

Lubricating is fine.