1998 Sunfire 2.2 troubles

I recently acquired a 1998 Sunfire 2.2 automatic. It idles at a comfortable temperature. It heats up inconsistently when driving (sometimes higher than others), then quite badly at stops. The fan relay was bad, and I changed it. Now the fan works. I replaced the thermostat. It still acts the same. The low coolant switch in the coolant recovery tank was bad, so I replaced the tank. That's when I got worried.

There was a bit of black crud in the bottom of the old tank, and it had a slight crack in one end. I cleaned it out, collected the muck, and dried it out. The dried crud responds to a magnet. I pulled hoses. There was a small amount of black crud inside each hose. I let them dry, cracked the crud out, and collected it. Once again the crud responded to a magnet. I pulled the radiator and will get it thoroughly flushed when I get to town. (I live in the mountains some distance from the nearest "city.") I ran a bit of filtered tap water through the radiator and it came out a rather black, bringing small amounts of black muck with it. So far I have collected an ounce or two of this dried crud. I assume it is corrosion from the inside of the water jackets.

I have ordered all new hoses. No doubt I should flush the heater core in some manner. What else comes to mind? The previous owner ran Dexcool. I believe I won't. NAPA makes an additive to prevent corrosion that I use in my other vehicles. Should I use it in this one? How about the temp sending unit? Clean, replace, or ignore? How about using a cooling system flush after I get this little critter back together? I don't know how that would work on this interesting design, given the problems just getting the system filled and bled. Should I be directing any attention to the water pump?

It also appears that there is some damage under the front end. There is a slight dent in the radiator support, the wiring harness at that point looks like it took a hit and its carrier/support is twisted and cracked. The splash guards are cracked as well. Is there supposed to be some sort of scoop under there?

Thanks for any help.

Yardpilot

All done, with no left-over parts. That's a bit weird for me. <G> It runs. No sign of heating up at idle. No sign (so far) of overheating when running. However, when I ran it twenty miles at 60 and let it idle a few minutes at home, it jumped right up to 210-215 degrees (or what appears to be about that on this guage) before the fan kicked in. It ran for thirty seconds then stopped, bringing the temp down about ten degrees. The temp went back up, the fan kicked in for 30 seconds again and brought the temp back down about ten degrees as before. It did this through about 7 or 8 cycles, then came on and stayed on till the temperature dropped to about 180. Just idling earlier the fan kicked in at about 180 and ran for some time. What's the story?

The new coolant is turning black already. I figure it's crud out of pipes and the block. Run it for a week or two then change it out?

Yardpilot

Could this black crud (iron? iron oxide?) be abrasive enough to have harmed the water pump?

Yardpilot

I would buy the cheapest antifreeze if you are going to keep flushing the system with it. Otherwise, use water and a mild liquid cleaner (not dish soap) let it get hot and let it sit to cool. After a 2nd heat up and cool drain it out. The antifreeze has probably never been flushed before. And never run with straight green antifreeze. Use the Dexcool approved stuff. The J's will run hot as hell on green. Keep an eye on the head due to the possible pin hole crack problem GM had. Causes no leaks but sucks in air into the antifreeze areas of the head making air pocket. This causes the antifreeze to backflow to the resevoir and blow the cap all while driving. Head job = $1300 average I have a '96 with 223863 miles and keeps going. I have owned it since 67,000.

Could you expand on the pinhole crack problem? I would like to know where and what to watch for if that is a problem.

You are probably right about it never being flushed before. IMO, the guy I got it from likely ran it till he had trouble, dumped in some clean Dex, and sent it out the door.

I ran a pretty strong cleaner in the car, then LOTS of water. I flushed all directions through every possible orifice using water straight from the well. After I filled it back up, a large amount of crud showed up in the tank and fluid, leading to the conclusion that it was still clearing the engine. I flushed everything out again thoroughly, then filled it up with 50/50 and anti-scale from NAPA. It is running great. I have a shelf full of antifreeze in the shop. (It's really a shed, but I call it a shop to make it feel better about itself).

From what I have seen with several other vehicles, Dex is pure poison. I am using a "all-vehicle" type, and it seems to be working fine.

Cleaned up, filled up, and taking a six-hundred mile jaunt Wednesday next. I'll let y'all know the results of that little test.

Regards,

Yardpilot

The factory dex cool is a waste. The Prestone "all type" or "dexcool approved" styles are the better choices. Regular green you would use on earlier models (pre 95) run to hot. The Pin-hole crack problem is that GM had a recall on all 2.2L from 96-99 to remill the head due to so many came out faulty for some reason. My cav 96 had this happen in 2000 at 70,000+ miles and took 3 months for the dealership to find it. Part was shipped to California for inspection and was sent back with an aluminum replacement due to a "pin-hole" size break in the head. All costs were covered and the head has run now into the 223,000+ range. When this happens you will have the temp go from norm to HOT and shut down instantly with no warning. This happens on highway or at speeds involving higher gears where the engine is cycling faster. Small amounts of air are sucked into the head building an air pocket. The coolant can not pass the air pocket so the pressure builds until something blows and that is the resevoir cap. The coolant backflows to the tank and the pressure blows the cap causing your coolant to go out down the road. Now to physically look for it...see for small drops anywhere on the head during cooldown. Otherwise it has to be removed and bench tested by dealership. But, if it has run this long you shouldnt worry. FYI there is a starter recall for a relay that has been wired in backwards (morons) and there used to be a mudflap recall (again morons lol). Best of luck to ya.