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will9000
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Apr 29, 2007, 7:27 PM
Post #1 of 22
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1998 Sunfire Overheating
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Well I am stumped. I have a 1998 Pontiac Sunfire (2.2L) that is overheating. Here is a list of new parts, Radiator, Head, Head gasket, Water pump, Thermostat, and Temperature Sending Unit. And i have bled the system 3 times. The only thing NOT new is the hoses. It's weird because the car will idle all day long at normal temp, but when I take even a short drive the temp starts rising almost instantly. Even with the gauge reading almost in the yellow, the coolant in the reservoir isn't bubbling, but it is hot. Any suggestions would be great. Thanks,
Will
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Indytech
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Apr 29, 2007, 8:35 PM
Post #2 of 22
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Re: 1998 Sunfire Overheating
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Is your cooling fan switching on .?
........Indy Tech
,
http://www.flatratetech.com
staff tech
Indy Shop owner
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will9000
User
Apr 29, 2007, 9:23 PM
Post #3 of 22
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Re: 1998 Sunfire Overheating
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Yes the fan is working and it's coming on when it gets hot. (baffled)
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Indytech
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Apr 30, 2007, 4:54 AM
Post #4 of 22
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Re: 1998 Sunfire Overheating
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Then the only thing that comes to mind is your radiator is most probably partly blocked
best way to clean is to remove radiator and have it opened, and scrubbed out professionally
a simple flush will not clean it well enough( hardened caulk)
,
http://www.flatratetech.com
staff tech
Indy Shop owner
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DanD
Veteran
/ Moderator
Apr 30, 2007, 5:31 AM
Post #5 of 22
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Re: 1998 Sunfire Overheating
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What you’re going to need to do is confirm whether the engine is actually getting hot. Temporally installing a mechanical gauge; I think would be the easiest way?
Next would be to check whether the PCM was receiving, interpreting and sending out the proper signal to the instrument cluster. You would need a scan tool to monitor serial data and compare mechanical temp readings to PCM’s interpretation of the temperature. If mechanical and electronic readings are similar, then you possibly may have a problem in the instrument cluster. There could be an internal short too power on the temp gauge circuit? That when you start moving the vehicle, the stepper motor for the speedo is feeding the gauge a false source of power; sending the gauge toward the hot position?
I know something as simple as a temperature gauge isn’t quite as simple as it use to be.
The instrument cluster itself is a computer and when working properly is a lot more then just a set of gauges and warning lights but an information center and a big part of the security system (anti theft). Telling you everything from tire pressures, what direction you’re traveling and if your left butt cheek needs to be scratched. LOL.
Do we need all of that, not likely but people like it (until it breaks). We call these things “creature features” and as long as the manufacturer can use these features as a selling point, it’s not going to stop; neither will the cost of repairing creature features.
Dan.
Canadian "EH"
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Apr 30, 2007, 5:42 AM
Post #6 of 22
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Re: 1998 Sunfire Overheating
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Fan must work as said. A/C request should force it on hot or cold and find out why not if it doesn't, motor, relay wiring etc.
You bled out this system 3 times? Did it continue to have air? That would be a problem. If this cooling system build up pressure from cold real fast which can be felt at a radiator hose, from totally cold you may have air/exhaust getting into the cooling system.
Why did the car need a head gasket to begin with?
T
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will9000
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Apr 30, 2007, 7:28 AM
Post #7 of 22
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Re: 1998 Sunfire Overheating
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Thanks for some suggestions guys, to Tom: Fan works great and comes on when it's supposed to, I am going to check the coolant temp with a candy thermometer today and see what I get. The system did not have air in it after the first time I bled it...I just wanted to be sure that all air was out because I have a 1995 Grand Prix with a very similar problem, turned out to be a blown head gasket. Well and as far as the question about why it needed it... I'm not sure it ever did I think the people I got the car from got taken to the cleaners. They took the car in and said it was overheating then the "mechanic" went for the big stuff, new head, gaskets, and radiator. He never even changed the water pump or t-stat...go figure.
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Tom Greenleaf
Ultimate Carjunky
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Apr 30, 2007, 9:00 AM
Post #8 of 22
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Re: 1998 Sunfire Overheating
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Checking coolant temp: Get as close to the outlet of T-stat as possible. If that hose goes to other end of radiator from the cap then the reading won't help to much.
A heat gun would be perfect or perhaps tape your probe carefully to the right spot would work - never tried that myself but bet it would work.
A thought (watch out when I'm thinking!) -- could the T-stat be in backwards? Some simply can't go in backwards others can,
T
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will9000
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Apr 30, 2007, 10:51 AM
Post #9 of 22
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Re: 1998 Sunfire Overheating
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Well I kinda thought the t-stat might be in backwards too, but this housing actually has wires in the t-stat housing so it can't be put in backwards...
Does anyone know what temp I should read inside the resivoir? I would guess not over 200-210 or so? It is a 180 degree thermostat. I will also try taping or holding it on the t-stat housing.
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Tom Greenleaf
Ultimate Carjunky
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Apr 30, 2007, 4:39 PM
Post #10 of 22
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Re: 1998 Sunfire Overheating
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The highest temp should be at the thermostat and not more than about what it's temp is for. 180 is a cold thermostat for a newer vehicle. I don't think I've seen one OE below 192. Either one should be wide open to cool near their #s so you can't fix an overheating engine by just putting in a colder thermostat. Put them in a pan of water on stove and you'll see they are both wide open when hot.
There is a problem taking a thermostat out which only worked in very few engines namy decades ago. They need the by-pass of opening and closing to keep the entire engine the same temp. without one it actually will over heat unseen away from water pump as it never gets all mixed up,
T
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will9000
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Apr 30, 2007, 5:54 PM
Post #11 of 22
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Re: 1998 Sunfire Overheating
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Yeah the 180 seemed kinda low... I think OE was a 195, but I'm not totally sure. I think I may have discovered the problem, but I need about $60 first. The car has a metal pipe running from the head to the upper radiator hose. Well when I looked closer at that pipe today I found that the whole bottom side of it had been repaired with quicksteel or something similar. It looked like the repair was not holding up to the heat so well to say the least. I am going to try to replace that pipe and see what happens. It's a dealer only part and no junkyards within 50 miles have this engine, go figure. I'll repost when I get funds and update.
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Tom Greenleaf
Ultimate Carjunky
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May 1, 2007, 5:55 AM
Post #12 of 22
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Re: 1998 Sunfire Overheating
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I think you found the problem. Bet that assists in keeping uniform temp in engine.
Also bet that 195 was OE t-stat and should be left that way,
T
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will9000
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Jun 9, 2007, 4:55 PM
Post #13 of 22
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Re: 1998 Sunfire Overheating
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Well, I replaced the coolant pipe and I still have problems, the car will sit and idle just fine, but as soon as I rev the engine, the temp will rise. It does not "overheat" it just runs hot. You can see the coolant come up in the bottle when I rev it, the go back down when I let off. The fan comes on when it should, but the engine cools down randomly, then climbs back when I rev again (even with the heat on full blast). I'm thinking the lower radiator hose might be collapsing. I think I'm just going to replace all of the hoses and see what happens. It's only money right?? LOL Any other suggestions would be appreciated. Thanks in advance.
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Tom Greenleaf
Ultimate Carjunky
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Jun 9, 2007, 5:29 PM
Post #14 of 22
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Re: 1998 Sunfire Overheating
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Long thread now and I didn't re-read the whole thing. You mentioned the lower hose collapsing in your possibilities.
That was one of those problems in the Stone Age (where I'm from) which was solved by putting a spring in the lower/inlet hose to water pump.
Cars that need them come with them. However replacement hoses don't all come with them and they used to so now I take them out and put them in the new one. I have never had a problem but have watched hoses almost collapse even with some pressure in the system. At full pressure they shouldn't but they made those springs for a reason. If you can't get a hose with one get a spring somewhere - I keep a spare from a junkyard which will cut to most hoses. Just bend any sharp wire end so it can't poke the hose.
You can feel if you have one now and if so don't lose it,
T
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will9000
User
Jun 9, 2007, 8:41 PM
Post #15 of 22
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Re: 1998 Sunfire Overheating
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Well the hose does have a spring... but its only for a short section (about 5") I'm just lost because it does not overheat until the engine is revved up. The hoses are the last old parts in the cooling system. If they don't fix the problem they can all go on a newer motor anyhow so I guess it's not a total waste. I had someone suggest the EGR. Would that have anything even remotely to do with this problem?
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Tom Greenleaf
Ultimate Carjunky
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Jun 10, 2007, 4:48 AM
Post #16 of 22
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Re: 1998 Sunfire Overheating
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The 5" spring may be enough depending on length of that hose to rule that out. I doubt the EGR is causing this as I think if it failed it wouldn't run well and a code would be set.
Are you suggesting you want a new motor over this??
T
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will9000
User
Jun 10, 2007, 8:44 AM
Post #17 of 22
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Re: 1998 Sunfire Overheating
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By no means do I want to shell out for a new motor... I was just saying if it came to that, I would have many new parts for the new one. If I replace the hoses, there will be no old parts in the cooling system, short of the reservoir bottle. So I really wouldn't know what to do after that. Is it possible to have a blockage in the cooling port in the block? And if it is, can it be fixed?
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Tom Greenleaf
Ultimate Carjunky
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Jun 10, 2007, 8:58 AM
Post #18 of 22
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Re: 1998 Sunfire Overheating
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I didn't think you really wanted to give up this motor!
As far as blockage: I suppose possible but why? Some cars have problems when sealers have been used and they have to be flushed out to really fix leaks. That almost always starts with a plugged heater core or radiator so full of that junk it can't flow.
In general don't use sealers but I have but only one specific brand and not more than 1/4th of what it says to use or the problem gets fixed. I reserve that for tiny leaks in tough places or expensive to fix and do ok with about 75% good results. Some auto makers are now putting some sealer in new cars at the factory as they don't want the warranty work. Wish I had a list of those to publish as I think that's cheating,
T
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will9000
User
Jun 10, 2007, 7:42 PM
Post #19 of 22
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Re: 1998 Sunfire Overheating
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Well I got another brainstorm.... I'm going to bypass the heater core tomorrow and see if that might be the problem. Looking at how the system is set up, the coolant flows from the upper radiator hose, through the heater core and then to the thermostat. If the heater core had a blockage, wouldn't that keep it from opening the t-stat? It's a easy test, so I figure what the heck... I guess I left out that one other part that was not new! Maybe, just maybe that will fix it. I'll repost and let you guys know, maybe this would be a remedy for a few others also and save them from spending the cash like I did.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jun 11, 2007, 2:15 AM
Post #20 of 22
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Re: 1998 Sunfire Overheating
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That's a good thought. It's been ions but I've had to do that and recall that I could use a deep socket that tapered that fit the ID of the two different size hoses.
So right! The bypass system is to keep the engine a uniform temp while keeping the thermostat informed of that temp. Let us know,
T
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will9000
User
Jun 12, 2007, 9:28 PM
Post #21 of 22
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Re: 1998 Sunfire Overheating
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Ok, so today I bypassed the heater core to see what happens. Well guess what....problem gone. I guess I need to buy a new heater core now. Maybe some other people with a similar problem might want to try this. Take out the metal pipes that run to and from the heater core and cut the short one off (The 2 pipes are brazed together and mine were in bad shape and need replacement anyway) Use this short pipe to connect the hose from the back of the thermostat, to the upper radiator hose. Clamp it down, refill coolant and off you go. My car kind of sputtered a little bit when I did this, so I'm going to just replace the core and those 2 pipes. Hopefully this can help someone else out. Thanks for the suggestions guys.
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Tom Greenleaf
Ultimate Carjunky
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Jun 13, 2007, 5:33 AM
Post #22 of 22
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Re: 1998 Sunfire Overheating
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Thanks for posting your results. This will get searched out and really shows how what might look like a simple problem can be complex.
Good luck with the heater core job,
T
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