VT coolant leak at top of motor from water jacket

[Lanza]

Before doing a coolant change on my VT ecotec. I placed a pressure tester on the radiator to test the cooling system. I took the pressure up to 120 kPa, first I had to tighten the top radiator hose and then I noticed a small leak coming from a bolt that appears to be in the water jacket? next to the rocker cover. The system pressure drops to 105 kPa after 5 minutes.
What are these small 3/8" bolts head for? Thought I would ask before loosening one.

 

[Lex]

They are lim bolts (lim = lower intake manifold). Appears they could be loose? If so, possible lim gasket may need replacing?

I'd take one out at a time, put some RTV sealant around the bolt, put it back in. dont over tighten it. IOnce you've done them all, torque it down. I think its about 13 nm? Not a lot.

If you have sludge under the radiator & oil cap, l'd just replace the lim gasket first.
If no sludge, then try sealing the lim bolts first.

 

[Fachoo]

yep agree with Lex, seems your gasket coolant port seal is leaking into bolt hole of manifold. Using any sealant is only a temp fix and coolant could/will leak into other areas once pressure is higher with fix.

 

[vxcalais_01]

Use a threat sealant or as most Holden owners you should have a tub of No.2 Permatex or Aviation Sealant. Makes the best thread sealant apart from the real stuff. Silicon based stuff is not resigned for threads. Seems you will need to fix the LIM one day or use some type of stop leak if its water to air/oil only.

But don't be tempted to overtighten this bolt as you will further damage the gasket.