Head gasket leaking

[kachel 5]

Hi all, I have rebuild my D6b engine in 2016. Now I have a small leak of coolant on the back corner of the ignition side on the head gasket. It might have always been there but I didn't notice because I drove only like 500km per year. This year it is a lot more km :-) But it only leaks a bit when the engine is cold. When it is hot there is no more leaking visible. My question is, is it an option to give the headbolts a little extra twist? Because it seems the leaking stops when the engine is hot, the head gasket is more compressed. 

Or is it a no go to do? 

[mmt 15]

Bite the bullit. :-) 

[DamirGTI 342]

Yes , can always try .. but undo them first by 1/4 of a turn then tight back a little bit more .

 

Only issue might be , during the years from rebuild , that the grease/oil has dried off the head bolt threads thus it'll be a bit hard to torque them up precisely/evenly  .. when the bolt threads lack lubrication they tend to be "snappy" grabbing on the block threads while torquing them up so you'll skip some Nm/deg. during the tightening making some of them more/less up the specs. , thus uneven across the head/block base .

 

If they feel "springy"/snappy" while turning/torquing , I'd reconsider taking the bolts out completely one by one , re-grease the threads and then tighten them back up . 

 

I've done that in the past on a few engines , and it worked ...

 

D

Edited September 5, 2020 by DamirGTI

[kachel 5]

Damir, thanks for the clear information and thinking along in all the steps of the probable solution! Cheers mate! 

[zak 0]

Hey guys,

 

I also have a leaky gasket with my XU9JAZ.

Years ago I installed a reinforced Spesso gasket and after the first dyno run this year to setup the ECU (Haltech), a little bit coolant ran out when the engine was warm (and still do so).

The engine has a higher compression around 12:1. Could that higher compression cause a little bit of head lift?

 

Before I asseble the head again I'm a bit unsure if I should use new standard head bolts or use studs & nuts.

 

What do you think?

Studs are much more expensive and I would like to save the money when they aren't necessary.

 

Thanks a lot for your help :-)

[DamirGTI 342]

No need , diesels run on + 20:1 CR with std. head bolts and head gaskets thus yours should be fine at 12.1 CR .

 

Alu. blocks tend to distort after all the years of heating/cooling cycles , so the block base ends up uneven kinda oval shape .. i've certainly found more than one XU block which needed block base resurfacing , and had just the same problem on one of mine high CR engines too ( was also around 12.3) .

 

Try to loosen and re-torque the head bolts , and see what happens ...

If still no good dismantle the head and check/measure the block base and liner protrusion , if in doubt take the block to the machine shop and let them do the measuring and resurfacing , head also .

 

 

D

Edited September 25, 2020 by DamirGTI