Disappearing coolant

[jfruauff]

Hey guys I got a 1999 tahoe with the vortech v8. I been having a problem with diappearing coolant. No visual leaks but can smell it. I was thinking crap bad head gasket. But then I though it was weird daily city driving it will burn a lot over 300 miles but I just made a 300 mile trip to seaworld all interstate and barely burned any. Mechanic buddie said for me to look into the intake manifold gasket but said its not that much just change whole manifold that its plastic and ports tend to warp. Kinda made since interstate constant throttle where as city i on and off and may pull more coolant. Google seems to show this is a common problem but you guys think intake manifold. Truck really dont seems to smoke out tailpipe a little but its got 140k on it so.


Any advice is greatly appreciated.

 

[SunlitComet]

Manifold is two pieces. Plastic and aluminum. Read your spark plugs to see if it is burning coolant. It may be burning on a hot engine part once leaked out.

 

[97Yukon4x4]

Coolant

I had the same problem with my 97 Yukon. Found out it the smell was coming from the overflow tank, when the radiator cap was releasing coolant back into the bottle. It is designed to suck coolant into the radaitor from the bottle, not the other way around. My radiator cap was going bad, the smell would only happen in traffic situations. I guess cap couldn't keep the pressure that was needed. Once I replaced the cap, the smell and coolant dissaperance problem have stopped.

 

[jfruauff]

Has a new cap already.

---------- Post added at 01:46 AM ---------- Previous post was at 01:45 AM ----------

But when its running you see no signs of external leak like smoke or anything.

 

[HDRock1]

Has a new cap already.

---------- Post added at 01:46 AM ---------- Previous post was at 01:45 AM ----------

But when its running you see no signs of external leak like smoke or anything.

If it's a small leak, you are most likely not going to see any smoke or steam, do you see any puddles in the driveway?
Could be your heater core , do you smell any antifreeze in the cabin?

 

[SunlitComet]

uh, you mean heater core right?

 

[HDRock1]

uh, you mean heater core right?

Ya ,Ha to many things on my mind

 

[KPOD]

Change your oil and see what it looks like, that will pretty much narrow it down.

 

[jfruauff]

Yeah no smell inside. Only outside. Probably gonna pull plugs, change oil, maybe even get some of that UV dye today and try and hunt the leak down. Never any dripped or puddles.

 

[Bigbody250]

Mine does the same thing... 99% sure it's the intake manifold. No worries, I check it every few days and when I get my new spider injection in I'm going to swap it out.