URGENT - re-tension headbolts

[AE101LEV]

I have noticed a VERY VERY small leak in the corner of my head gasket on Cyl 1.. on 4agze

I am guessing because since the rebuild I have not re-tensioned the headbolts which was 2400km's ago

I have the cams out and im ready to do so but because the way you tension them up is in three stages

Torque to 25nm then 2 stages of 90 degree turns, in order to retension them i will need to loosen them off in which i am NOT going to do.

so could I just nip up the bolts slightly? (they are toyota genuine bolts) and wasnt sure wether if it is those bolts that after a certain torque they just start stretching.

Cheers

[merc-blue]

find a total torque figure, eg 60ft lb or whatever it is and torque them at that

where they dont up with a proper angle measuring (forgot the name you know the thing you put over the socket with the probe etc) or by eye?

[Bananaman]

find a total torque figure, eg 60ft lb or whatever it is and torque them at that

where they dont up with a proper angle measuring (forgot the name you know the thing you put over the socket with the probe etc) or by eye?

torque wrench?

[Enchanter]

I didnt think you needed to retorque the TTY bolts??

What kind of leak are you talking about ?

If using a MHG did you machine the head ?

Edit: did you lube the bolts before you torqued them down ?

did you make sure the bolt holes in the block were clean and not filled with oil ?

[roadsailing]

head bolts are not torque to yield, workshop manual shows head bolts as a reusable part.

also, manual says 29 N.m then 90 and 90. (4age manual, ZE could be different, but dont really think so)

did you oil the bolts before you torqued them?

i'd put a new head gasket on and retorque it properly, relatively cheap insurance - a mate had to do this when he put the first one on upside down.

[1200det]

My 4AGZE Engine manual is certainly TTY head bolts so no set torque.


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[roadsailing]

hmm, interesting.

1200DET, can you scan in that bit of the manual?

[AE101LEV]

I honestly cant remember if the headbolts were oiled before they went in , the block and head were faced.

I gave them a little nip anyway, a very small nip but was weird cos some felt looser than others so I will see how I go.

[1200det]

hmm, interesting.

1200DET, can you scan in that bit of the manual?

In the next few days i will scan it and upload and link to it no problems


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[terryo]

the early 4AG bolts were re-uesable subject to not being stretched beyond a certain length. manul includes lengths. later ones are torque to yield and are throw-aways. most modern gasket manufacturers put a warranty clause that requires new bolts to be used. loose bolts are a sign of either a soft head (that will not old the tensions) or over tightened/re-used, , torque to yield bolts. the smallest error in angles when tensioning torque-to-yield bolts can cause them to be wrong. if the instructions say "oil" use only that, and make sure you use the correct grade.

[love ke70]

i would nip them up and see what happens (Which you have done)
if it doesnt solve the problem then pull the head off and see whats goin on

[Ben Wilson]

hmm, interesting.

1200DET, can you scan in that bit of the manual?

This is from a 4AG manual, but the ZE is the same.

[roadsailing]

ben, i think thats the same as the manual i was looking at (from the toymods tech reference)



this part of the manual (and your pictures in a way) pretty much state that the head bolts are reusable.

i'm trying to work out when the change to toraue to yield bolts was made, the manual i got the above picture from was a bigport manual, my engine is a smallport so it could concievable have TTY bolts in it.

if it isnt too expensive, i want to change over to head studs and nuts anyway, so it might be an acedemic question.

BTW, the lenghts specified in ben's picture are just so you know which side the short bolts go, and which side the long bolts go.

[Ben Wilson]

Bear in mind that if you go to studs, apparently you'll have clearance issues with the back of the distributor drive and you will definitely have to re-torque them..

[allencr]

Hasn't the torque-to-yield(TTY) bolt design been written up before, because it still seems that everyone that mentions the torque-angle bolt tightening method is showing that they wouldn't know a TTY bolt if it bit'em!!

one is a tightening method that is independent of the bolt design.
one is a bolt design that is independent of the tightening method.
Toyota 4AG's have one and only one bolt type that is NOT TTY, & not throw away/non-reusable, and has two tightening methods for it, one of which is better then the other.

I think ALL aluminum heads should be retorqued, one bolt at a time, after loosening enough to get oil under the washer & bolt head, and also to give you a feel for the bolts condition - thread & stretcheness wise.