Last week I noticed my truck had started leaking some anti freeze. After watching it for a few days I can confirm that the leak is when I get home and engine has cooled off. I am running Zerex extended life which is red and easy to spot. The leak is on the left front of the engine. At first I thought it was the bottom radiator hose but it seems dry. Would the water pump leak be on this side. After looking for about 45 minutes I cannot find the leak. Besides a pressure test what else should I do?

 

A water pump would leak in the center right below the water pump shaft. It could be where the bottom hose leaves the water pump or possibly the seal on the radiator itself, the system pressure is the highest after shutting the engine down because the coolant stops circulating and giving up heat and the block and heads are still hot. You may try topping it off ( do not fill above the min line in the degas bottle as this is the new high level ) running it and get it up to temp then shut her down and start watching for leaks.

 

I had an upper radiator hose leak at the thermostat. Would puddle after truck shut down. Hose looked and felt fine, but leaked.

I am running Ford Gold so it was a little difficult to see. Your red should be easier to spot.

I recall folks also mentioning the plastic Y under the degas and a coolant hose that can catch the corner of the FICM.

Edit: you did say front of engine so YMMV with above suggestions

 

Might also be the doughnut between the intake manifold/front cover

 

Follow the hose out the bottom of degas tank to the block. Mine started leaking there once. I was able to just tighten the clamp.

 

So I found my coolant leak. It was the thermostat housing. The little rubber ring had gotten brittle. A lot of stuff to remove to remove to get at it. This does not seem to be an effective way to seal the housing after installing a thermostat. Wouldn't a gasket be better. What does everyone else do for sealing it?

 

Nothing but clean the surfaces, a little Vaseline on the NEW oring, install the ring in the groove, re-assemble. Finished. Never had one leak.