Jim Henderson
Dedicated LVC Member
Found an interesting unusual leak for the LS V8. Long story so skip to bottom for short version.
For a few months I have been losing maybe a quart of water every week or so and figured I would need to replace the degas bottle sooner or later. Last week I parked the car on a hill, face downhill and saw maybe a cup of water dribble out under the radiator area. Uh oh bad radiator I thought. I had seen this dribble a few times before but assumed it was AC runoff.
Yesterday I lost enough water to overheat during an all day drive in 100+ heat, stop and go and idling type driving. PITA, figured I waited too long.
Couldn't really see the leak without tearing into the engine bay. But I did see water spots on the front area of the engine on the air intake sound baffle and on the Engine shroud or top cover. Hmmm, radtiator or leaky hoses, I think. But still could not find the leak even with the engine very hot and hissing sounds from somewhere. Even removed the engine shroud, very easy, 2 plastic button/screws.
Today, I was messing with it while a friend was watching. Still no visible leak even though I lost a quart on my drive in to work. Arrr.
At lunch I removed the "Radiator Cap" on the thermostat housing, top front of engine. Poured in maybe a cup of water but noticed some small puddles of water on top of the throttle body. Hmmm, must be close. Started luke warm engine and finally noticed tiny water droplets spraying off of the top pulley, guessing waterpump but the LS doesn't always have stuff where you think. So capped the tstat and was talking with a guy but noticed no more water spray. Hmmm, removed the cap and again water spray, hmmm. Then noticed water dribbling out from the underside of the lip of the filler neck where the cap screws in, NOT from the fill opening itself.
It is the seam of the filler neck that is leaking. I need to remove the tstat housing to inspect by I bet money it is a crack in the neck where you can't see it from above. I am guessing why I never could catch it in the act is that the system did not leak until it was fully pressurized while at freeway speed and full of water. Then the pressure forced the "radiator cap" Spring loaded "plunger" to lift enough in the neck of the tstat housing to expose the crack to water under pressure and you know the rest. When The water was down or the engine slightly cooled and under less pressure the plunger resealed the neck crack so no evidence of where the leak was other than some water drops here and there.
The water was puddling on the plastic splash shield under the front of the engine and radiator but did not spill out all at once unless you parked on a hill or had enough puddle. The water dripping mislead me as to where the leak was.
So Long Story SHORT... If you have a strange leak but can't find it when the engine is running or stopped and it is from the front of the engine(water spots)... It might be a cracked Thermostat housing filler neck.
I never did feel right about plastic components on an engine. This just reinforces my thoughts on it.
I am ordering the housing from Rock Auto and should have it replaced shortly after.
The LS seems to give me problems I have never seen in over 1 million miles of driving and almost 40 years of tinkering. What a PITA.
Jim Henderson
For a few months I have been losing maybe a quart of water every week or so and figured I would need to replace the degas bottle sooner or later. Last week I parked the car on a hill, face downhill and saw maybe a cup of water dribble out under the radiator area. Uh oh bad radiator I thought. I had seen this dribble a few times before but assumed it was AC runoff.
Yesterday I lost enough water to overheat during an all day drive in 100+ heat, stop and go and idling type driving. PITA, figured I waited too long.
Couldn't really see the leak without tearing into the engine bay. But I did see water spots on the front area of the engine on the air intake sound baffle and on the Engine shroud or top cover. Hmmm, radtiator or leaky hoses, I think. But still could not find the leak even with the engine very hot and hissing sounds from somewhere. Even removed the engine shroud, very easy, 2 plastic button/screws.
Today, I was messing with it while a friend was watching. Still no visible leak even though I lost a quart on my drive in to work. Arrr.
At lunch I removed the "Radiator Cap" on the thermostat housing, top front of engine. Poured in maybe a cup of water but noticed some small puddles of water on top of the throttle body. Hmmm, must be close. Started luke warm engine and finally noticed tiny water droplets spraying off of the top pulley, guessing waterpump but the LS doesn't always have stuff where you think. So capped the tstat and was talking with a guy but noticed no more water spray. Hmmm, removed the cap and again water spray, hmmm. Then noticed water dribbling out from the underside of the lip of the filler neck where the cap screws in, NOT from the fill opening itself.
It is the seam of the filler neck that is leaking. I need to remove the tstat housing to inspect by I bet money it is a crack in the neck where you can't see it from above. I am guessing why I never could catch it in the act is that the system did not leak until it was fully pressurized while at freeway speed and full of water. Then the pressure forced the "radiator cap" Spring loaded "plunger" to lift enough in the neck of the tstat housing to expose the crack to water under pressure and you know the rest. When The water was down or the engine slightly cooled and under less pressure the plunger resealed the neck crack so no evidence of where the leak was other than some water drops here and there.
The water was puddling on the plastic splash shield under the front of the engine and radiator but did not spill out all at once unless you parked on a hill or had enough puddle. The water dripping mislead me as to where the leak was.
So Long Story SHORT... If you have a strange leak but can't find it when the engine is running or stopped and it is from the front of the engine(water spots)... It might be a cracked Thermostat housing filler neck.
I never did feel right about plastic components on an engine. This just reinforces my thoughts on it.
I am ordering the housing from Rock Auto and should have it replaced shortly after.
The LS seems to give me problems I have never seen in over 1 million miles of driving and almost 40 years of tinkering. What a PITA.
Jim Henderson
