Lose of Coolant...

[usamarshal]

I usually have to add coolant every month or so to my Tahoe. It has a Vortec 5.7, but I can't find the leak. Could I be burning off the antifreeze when driving? Is there a way to check for any leaks in or outside of the engine? Thanks for any help.

[MT-2500]

Originally Posted by usamarshal

I usually have to add coolant every month or so to my Tahoe. It has a Vortec 5.7, but I can't find the leak. Could I be burning off the antifreeze when driving? Is there a way to check for any leaks in or outside of the engine? Thanks for any help.

A good old rad pressure test pump helps.
It will pump system up to the full running pressure.
Always check cold and warm and hot.
On the 5.7 watch for leakage on the intake front and rear and hater hose connection.
Check under warter pump for seapage and also check the rad side tanks.

For the real hard to find leaks they make a leak test dye you can add to coolant and use a special light to find where it leaks.
MT

[usamarshal]

Is the rad pressure test safe though?

[glenncof]

My own experience over 100K miles on 1997 Tahoe is there is no loss (zero) of coolant in proper operation.

My first leak was bypass valve in the heater hoses that keeps hot coolant out of the cabin when heater not used. Right passenger side drip on shock.

Next water pump. Seepage out of drain hole on the front. Look for water tracks from the hole even if dry. There should be no sign of drainage from the hole.

Finally the notorious intake manifold leaks, various locations, but mine was driver side rear dripping down back of engine and looked like it was coming out of tranny drain hole.

[usamarshal]

Yeah, I'm going to make sure this pressure test is alright before I have my technician do it...don't want to do anything silly and have to replace the radiator or something.

[MT-2500]

Originally Posted by usamarshal

Is the rad pressure test safe though?

Well as long as you do not exceed what pressure your pressure cap is.
Usually 16-18 lbs.
Most pressure testers have a danger zone on them around 19-20 lbs.
MT

[usamarshal]

Yeah, I'll make sure to find that out before having the test performed.

[quote=MT-2500]Well as long as you do not exceed what pressure your pressure cap is.

[777stickman]

Another thing is to pull the spark plugs out and look at them. They should all be a light tan color with little or no crud on them. If you find one or?? that looks different from the rest you may have an intake or head gasket issue meaning the coolant is getting into the combustion chamber. Sure hope they all look the same............Steve

[Mr. Smith]

Originally Posted by usamarshal

I usually have to add coolant every month or so to my Tahoe. It has a Vortec 5.7, but I can't find the leak. Could I be burning off the antifreeze when driving? Is there a way to check for any leaks in or outside of the engine? Thanks for any help.

You intake gaskets are leaking. Get the GM gaskets when you repair them.

[Kizar_Sozay]

I had a similar problem and discovered the inlet valve on the front of the radiator was corroded. Easy fix but still had a leak. Later discovered there was a pinhole leak that just oozed at the gasket between the head and the intake manifold. As the repair was expensive, I just resolved to top up the coolant occasionally.

[LimitedTahoe00]

I Had A Similar Problem And It Turned Out The Cap Was Not Holding Pressure. Then Noticed Problem Came Back. Clean Off Your Reservor And Check If It Has Any Cracks In It. Mine Did.

[usamarshal]

Well, had my coolant system pressure tested and there wasn't any leaks. The only thing I can think of that may be the reason for the loss of coolant is the intakes. Guess I'll have to take care of that here in the near future. Can't wait......thanks again guys.