engine coolant

[grits]

In December, after I'd get home from somewhere, I'd smell antifreeze.  I checked all around my '94 Silverado with the 305 engine, and couldn't find a leak.  One day, I noticed the engine temp was going high.  So, I took it into the dealership for repair.  Mechanic couldn't find any leaks.  They replaced the thermostat.  The other day, I thought I smelled antifreeze again.  Last night, I drove the 10 minutes city driving home.  I stopped to talk to  a guy.  As we both passed the truck, we both smelled antifreeze.  I looked again with a flashlight but couldn't see anything.  The coolant reservoir was at hot engine level.  Any ideas?

[grits]

The water pump is about 5 years old.  The head gasket was replaced a year ago, and they can't find leaks in the others.  It is definitely getting too hot for the coolant reservoir to go to hot that fast.  I mean 10 minutes city driving, and it goes to hot level? 

[grits]

I think it may have 36K on this water pump.  The radiator is about 3 years old.  They pressure tested it too.  I wonder if the fan comes on at the right time.  If it is running hot, and you turn on the heater, it will go back down to a cooler engine temp.  The  antifreeze is not a funky color.  It is just  crazy.  It baffles the mechanics too.  

[tskeeter]

grits, if you smell antifreeze, you have a coolant leak. 

I've had similar situations.  You can smell anitfreeze, but there are no drips on the garage floor.  What is going on is you have a leak that just seeps.  Very little leakage.  The antifreeze that leaks out probably evaporates on the hot radiator before it leaks enough to drip.

There are a couple of things I'd check further.  The first is the coolant recovery system.  If the coolant overflow tank is full, but the engine is running warm, it sounds like the coolant is not being pulled back into the radiator when it cools down.  This would cause the coolant level in the radiator to drop and the engine to run warm.  Since the coolant recovery system probably wasn't tested during the pressure check, I'd look for a crack in the hose between the coolant recovery tank and the radiator.  Since that hose generally runs across the top of the radiator, a crack could allow coolant to leak down onto the hot radiator and evaporate when the cooling system is pushing coolant into the recovery tank.  Or, an old hose could be seeping a where it attaches to the radiator.  Another possibility is that the coolant recovery tank has cracked so that coolant can't be pulled back into the radiator.  In this case, the coolant level in the recovery tank will not change with changes in the engine/coolant temperature.  Coolant recovery tanks most often fail at the seams, which can make the failure point hard to see while the tank is still installed in the truck and covered with dirt.

The second thing I'd look at is the condition of the lower portion of the front side of the radiator. If you live in an area where they use lots of salt to melt snow, the salty snow spalashing on the lower part of the aluminum radiator core can start to eat away the radiator in just a few years and cause it to seep.  (When we lived in Chicago, I used to have to replace radiators every three or four years.  Even though I washed the salt off cars at least once a week.  I apparently wasn't getting the salt washed off the part of the radiator that was behind the bumper and closest to the road slop.)

Another thought.  Have you replaced the radiator cap?  If the cap is bad, I suppose it could leak a bit.  Radiator caps aren't expensive, so it may be worth just replacing the cap, just in case, as your first step.

By the way, if this helps you figure out what is going on when the dealer guys couldn't, you might want to start taking the truck to a different mechanic.  A neighbor had been battling some emmissions problems and check engine lights on his car for three or four years.  Trip after trip to the dealer could not resolve the issue.  Finally his wife talked him into taking the car to an independent shop run by the husband of DW's coworker.  Some testing showed that a vacuum hose routed across the inside of a fender had cracked and was leaking.  Don't know if the dealer mechanics who had worked on the car weren't very capable or if they were too lazy to do a thorough job of testing and locate the source of the problem in an out of the way location.  



   

[grits]

I think the coolant smell is coming from the engine going from cold to 210 degrees in about 9 minutes.  Then, the thermostat kicks in, and the temp drops back to normal.  In the ten minutes time, the reservoir goes from cold level to the top of the hot.  I need to call mechanic next week.  They pressure tested everything, and there were no leaks.