1999 Mailbu Cooling Issue

Hello everyone. I came here not knowing what else to do besides spending hundreds of dollars to have someone check out my car, possibly just to tell me it's done for. I'm hoping someone here can give me at least a little insight and help me decide if it's worth taking my car in to get it fixed or not.

I drive a 1999 Malibu 6 cylinder M 3.1L, and this past week it has had a big issue. I noticed when driving to work that it started to heat higher than normal, then drop back down to a normal temp. It kept getting worse and almost overheating, so I went and bought a new thermostat (as I was told that was probably the issue) and a new radiator cap since I knew mine was old and leaked a little bit. Before putting the thermostat in, I had a neighbor look at it, and found some gunk in the coolant tank.

I took it in to get a coolant flush, but when I told the guy at the shop what I found, he told me that because these Chevy's used dexcool, if any other coolant was used, it would gel and therefore start clogging my system and that a flush would do nothing, and that I was looking at a repair that would be more than I was willing to pay.

My question for all of you is should I still go in to get someone to really look at it, get it flushed and put the new thermostat in? Or is the situation that the last mechanic presented probably the issue? I'm pretty broke, and don't want to spend money that I don't have to. But, if $100 will allow my car to run for awhile longer, I would rather do that then have it sit and die while I take the bus. Any insight would be so greatly appreciated. Thank you so much!

Nick

Just read your post Nick. Yes, GM used dexcool in your car and it is crap. It is known to cause problems with the lower intake gasket. What I would recommend based on what you wrote is to completely flush the system of dexcool. It's an easy process. Drain all the dexcool from the system and then run clear water from a garden hose through the system. Be sure to run the car so it gets hot and turn the heat all the way up but have the fan off. This will ensure getting dexcool out of the heater core. Once you see no more dexcool coming out then shut the car off and let it cool down. Reconnect all hoses and fill it back up with 50/50 mix of regular antifreeze. Keep in mind your Malibu has a bleeder valve so once it is hot you'll need to bleed the air out.

You wrote about gunk being in the antifreeze. My concern here would be a bad lower intake gasket. Which means your oil and antfreeze are mixing together. Take a look at the inside of your oil cap and the overflow cap. If there is a mustard looking goo on them then your intake gaskets are leaking.

I don't believe Dexcool is your problem. When was the last time you had a coolant system flush and refill? It should be done at least every five years with Dexcool. You need to figure out what the gunk is in your coolant system. I would start with a flush and refill and see where it leads from there, making sure the air is bled out of the system. You can also get some cooling system cleaner that you pour in after getting all the old coolant out. This cleaner will dissolve all the gunk. Then you flush it out and refill. You could have trans. fluid in your coolant system from a bad radiator, you could have an intake manifold leak, which would mean coolant in your oil, or you could have a head gasket leak, which would be blowing all your coolant out as you drive. You have to narrow it down.