hey all,

i need some serious advice for this truck..... 1998 tahoe 5.7L 165K miles

i am getting cat codes, but i dont want to replace them (price of course) but mainly because i think it has a bigger issue and i dont want it to ruin a new set.... heres the symptoms

---when its idleing, it smells like gas a lot
---the antifreeze dissapears, but it never overheats (res goes empty). if i fill it, and drive, when i stop i hear it bubbling in, and after a while the res is empty again. i dont even fill it anymore since it doesnt overheat, i just carry a jug in the truck incase
---i changed the oil a month ago and it looked like dark brown chocolate milk


any help/advice is much appreciated!

 

Sounds like it had coolant in the oil last time you changed it. You either have a bad intake gasket or head gasket. If you have been driving it that way you probably have severly damaged the engine.

 

thanks MDTAHOE---- i talked to a buddy and he said the intake gaskets go on these motors a lot.... im hoping its that. i changed the oil and have been checking it on the dipstick (the level and the color) and it has looked decent.... its our backup vehicle so i only drive it when im working on a car or when its been sitting for 3 weeks or so. but it runs great..... hoping your wrong about any engine damage! its got 165k right now so im just trying to keep it going to 200 or fix it and sell it soon.

i did forget to add however, that every once in a while it wont start---- itll turn great but wont fire and smell like gas.... then i let it sit and itll fire up fine the next day
and
when it does run, the exhaust drips a good amount of liquid-- (i have a small hole right behind the muffler at a low spot)

 

Most likely this is water. Most mufflers have a small hole at bottom rear to allow it to drain out. Once the engine has warmed up and the exhaust system is hot, the moisture doesn't condense and is carried out. However short run cycles w/o complete warmup will allow liquid water to collect in the exhaust system.

 

the hole im talking about is from rust, at a hanger weld. i thought it was dripping all the time, but i will need to check.