Water leak cylinder head outer screw

Spider1175

Spider1175

New Member
Im struggling with a water leak on my P6
The water is leaking through the outer screw. What confuses me is that there is no water channel behind. The engine is a 3,5l with SD1 heads with a Composite gasket.

Any ideas before I completely dismantle it.

Thanks
Peter
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The thread holes in the block are in pockets surrounded by coolant. If there is a crack in the hole then you will get coolant getting out past the bolt head. If the car is not overheating and the only issue is the water leak you could withdraw the bolt and put copious amounts of thread sealer on the bolt and see how you go. You have nothing to lose IMHO. Re torque the two rows of bolts under the rocker cover to 65lb ft and the outer row to 45 lb ft.
 
Hi Cobraboy, thanks. I’ll try that tomorrow. The outer row I always hard torqued to 10 ft pd which was recommended from Paul from V8tuner for the SD1 heads. I’ll report about the status.
peter
 
No problem. If you feel happier with a lower torque setting on the outer row then go with it. There seems to be many recommended figures for the outer row, you can take your pick. IIRC I did mine to 45lb ft, on the two engines I have in use now, with no issues.

It would be nice if the leak stopped and you avoided a strip down, particularly as an issue with a threaded hole is not going to be an easy fix.
Of course the water could be tracking along a flaw in the gasket and finding its way out. If the cooling system is not being pressurised by combustion gasses then it is worth trying a low tech fix.
 
You can get tests for exhaust in the coolant, so you could exclude that possibility.
 
Spider1175 said:
Hi Cobraboy, thanks. I’ll try that tomorrow. The outer row I always hard torqued to 10 ft pd which was recommended from Paul from V8tuner for the SD1 heads. I’ll report about the status.
peter
Click to expand...
One last thought on this.
Before you refit the bolt blow out the hole with an airline, if there is coolant in the hole and you put the bolt in there is a possibility the bolt will hydraulic and damage the block, which may have happened to cause your problem originally.
 
@cobraboy Thanks for the hint. I realized when pulling out the screw that the threat was dry and also used an endoscope also no water in the hole... the search continuou.
 
possibly porosity or Fine crack? allowing coolant to creep out under heat and pressure. have we noted how much level drops? not easy to seal though I would be tempted to try thread sealer and a 'dowry'? seal/washer for size of bolt.
 
classicalgreen said:
possibly porosity or Fine crack? allowing coolant to creep out under heat and pressure. have we noted how much level drops? not easy to seal though I would be tempted to try thread sealer and a 'dowry'? seal/washer for size of bolt.
Click to expand...
A quick fix is a thin diameter O-ring a size or two smaller than the bolt/stud. Roll it down, then fit the washer and torque it up, and it should expand the same as a Dowty washer would.
 
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