Small Coolant Leak

[VanIsleSprint]

I am experiencing a small coolant leak which appears on the shoulder of the engine block
where the water pump is situated. I have changed the gasket on the thermostat so I don't
think that is the problem. All the bolts on the intake manifold, water pump and clamps
on the hoses to the heater H pipe are tight. I'm thinking possibly there is a failure on one
of the O rings on the bypass tube. There is no overheating indicated on the gauge.

[gmsclassics]

Over the years I've had small water leaks in that overall area from numerous sources:

- 'O' ring on the bypass tube - most frequent but usually only after refitting
- water pump gasket - at the back where it was difficult to detect
- from the inlet manifold underneath at the front where the coolant passes through
- head gasket
- thermostat housing
- one of the bolts holding the cover over the thermostat - it had been drilled into the water chamber

Best to find out exactly where it is coming from before trying to fix it, nothing more frustrating than fixing the wrong problem (speaking from experience!).

The most successful way I found to located it was using paper tissues, which absorb and make even the smallest amount of coolant visible, but best when the engine hasn't had time to warm up completely. A small leak will 'disappear' when the engine is hot as the coolant evaporates almost instantly.

Hope this helps - good luck

Geoff

[xvivalve]

The other problem you face is the fan tends to blow coolant from a leak anywhere else up onto that shoulder! I had a leak manifest itself as a puddle in one of the core plugs up there that eventually transpired to be the bottom hose connector onto the radiator requiring a further 1/4 turn!!