Hi all,


Initially tried this in Tahoe/ Suburban forum w/ no takers but might see more business on this forum. So i finally found the source of the burnt coolant smell that's been going on for the last year on my 99 suburban. 80,000 mi. 5.7 L, K1500. This is the version similar to the 98 and older Silverados. I have to replace the notoriously bad intake manifold gasket. Since I'm taking all the spaghetti off, what else should I replace while I'm at it. Thanks.

 

I'm going through this myself on both my 98 K1500 Silverado and my 96 GMC Yukon both with the Vortec 5.7L engine.

Make sure you use the Fel-Pro MS98000T gaskets. They use an upgraded material that is less likely to fail. Also, completely flush the cooling system before you do the intake manifold gaskets and put in conventional coolant instead of GM Dex-cool. You have to make sure you flush the system completely because Dex-cool and conventional coolant can not be mixed.

Do NOT use any "extended life" antifreeze. Even if it's green colored if it's extended life it's rebadged Dex-cool. You can either buy pre-mixed 50/50 or buy 100% coolant and mix it with distilled water. No, you can't use normal bottled water or tap water. You must use distilled.

The Dex-cool is what kills these engines, in addition to the plastic intake gaskets. Between the upgraded metal Fel-Pro gaskets and the conventional coolant you should never have to do the work again.

Also consider replacing the water pump, upper and lower radiator hoses, thermostat, radiator cap, and coolant resorvoir tank. If you're willing to spend the money do the radiator as well. After doing all of this work I would recommend doing another coolant flush with fresh conventional coolant maybe a month after everything just to make sure no Dex-cool is left. I know the cost adds up and it's overkill but you want the Dex-cool gone. Also be sure if you take your truck to a shop or you get your oil change done by one of those quick-lube places (please don't, but I understand if you are in a hurry) that they don't top up with "extended life" green or other color Dex-cool...

I know this is a lot of parts, time, and money but these are powerful and reliable engines other than the cooling system problems, and you will get many more years of service out of your Vortec if you do this.

Also be sure to do an oil change right after you do the work because while your intake manifold gasket might be leaking externally if might also be leaking a little bit into the oil which even if you can't see or smell it can still permanently damage the engine.

This information applies to all vehicles using the Vortec 350 (5.7L), Vortec 305 (5.0L), and Vortec 4.3L V6...

 

Mistaake,


thanks for the info. right on about the dex-cool and fel-pro gaskets. I do everything on this beast these days. learned my lesson about taking to the stealership years ago. they did lots of stuff wrong and got paid for stuff they didn't do. Not trying to dis all gm/chevy dealerships or the mechanics that work there, but this one is horrible. It's worth putting the money into this vehicle because when it's treated right it runs like a champ. It can't help it if GM cheaps out on just about every component it can ( shoddy brake lines, abs sensors, brake rotors( well lets just say brakes period), gaskets, fuel lines, a/c components, and on and on). Thanks again.

 

No problem. Glad it was helpful! Dealerships are always scum for any auto maker. They don't want you to keep your old vehicle, they want you to trade it in for peanuts and buy another $70K truck!