1.9 head leak

[dieselsmoke]

My friend has a new 1.9 td AAZ engine that was rebuilt by a shop and he got a new head for the rebuild and a 1 hole metal head gasket. Ran great for the first 1200km but now we noticed that there is antifreeze seeping around the head of the engine coming from the headgasket area. When it is just idleing it is a really slow seep but when you rev it up it drips a bit. I know that the shop installed it but didn't do a re-tourque. Should we warm it up and give it an extra 1/4 turn to see if it stops leaking?? I have heard that the metal head gaskets can be a pain sometimes to get them to seal properly.

[8v-of-fury]

are you using Head Studs? or Bolts?

[dieselsmoke]

I am using the head bolts.

[rallydiesel]

Kind of difficult now. You could snap a head bolt easily. That's why I always go to non-TTY bolts when I get a chance.

[8v-of-fury]

what about replacing them one by one with head studs.. and re torquing?

[rallydiesel]

Yeah, I have heard of people doing that successfully.

[dieselsmoke]

I read in the bently manual that it says to retourque with a warm engine 1/4 turn. Is it safe to say that the bolts should be able to do that since the book says for it to be done?? How much are the arp head studs and where can I get them?? I don't want to leave this go for too long and risk damaging the engine.

[8v-of-fury]

well does the Bentley have a km interval when the re torque is meant to be done? 1200km+ is a fair distance.. Like said you could snap one off below the deck of the block.. that would be a real PITA.

[Vincent Waldon]

I read in the bently manual that it says to retourque with a warm engine 1/4 turn.

If memory serves, and it sometimes doesn't, that instruction doesn't apply to the metal gasket used on the 1.9 AAZ engine.  No where near my manuals at the moment or I'd check.

[dieselsmoke]

one book says retourque after 1000km and the other is right away after the engine has been warmed up. Both say tighten 1/4 of a turn. I have another set of new head bolts, if retourquing dosen't solve the leak can I take one bolt out at a time (in sequence) and put these new bolts in one at a time and tighten each one to spec as I go???

[dieselsmoke]

If you retourque with a metal head gasket will that damage it? or why would you not retourque on a metal head gasket??

[Vincent Waldon]

why would you not retourque on a metal head gasket??

They don't squish down with temperature like the older fibre gaskets do.

I think what's confusing folks here is the "additional 1/4 turn" vs "additional 1/4 turn after the engine has been run up to operating temp", and "additional 1/4 after 1000 miles".

Just grabbed my A3 Bentley... here's what it says on page 15a-13:

"On AAZ diesel engines, if the old-style composition head gasket is used, run the engine until it reaches normal operating temperature and then retorque the headbolts in the proper sequence an additional 1/4 turn.  AAZ, AHU, and 1Z diesel engines that use the newer style metal gasket DO NO require this step.  Retorquing after the first 1000 miles is NOT needed for either style of head gasket."

A bit above this paragraph it says:

Tightening torque:  40 NM, 60 NM, additional quarter turn, additional quarter turn.

A bit later it says:

AAZ with composition head gasket only: additional quarter turn.  

[dieselsmoke]

Interesting. I just looked in my red 1993-1996 bently manual and on page 15a-11 and 15a-12 it gives the process of torquing the head down and it says to do the extra 1/4 turn for diesel engines but dosen't mention anywhere about the metal head gasket.

Since I have a small leak, would it damage the head gasket to give it an extra 1/8 - 1/4 turn for each head bolt? or can I remove one head bolt at a time and install the new head bolts I have and tighten them to spec one bolt at a time?? or would that wreck something??