2001 Hyundai Elantra Temperature gauge and sender

Tiny
PAULBEAR
  • MEMBER
  • 2001 HYUNDAI ELANTRA
  • 4 CYL
  • FWD
  • MANUAL
  • 150,000 MILES
Waiting to gather money to replace head gasket. Meanwhile, using Bar's Stop leak and oil/gasket conditioner. Am keeping an eye on temp gauge. Was working properly (going up and down when stat open and closed). Now starts out at cold and goes up to just below halfway and stays there. No fluctuation in temp gauge at all after it reaches that halfway point, but I know that stat and water pump are working. Do you think the sender is gummed up, or is the gauge is sticking? Car is idling OK. Running smoothly. But once in a while, not all the time, after driving for a while and shut it off, then restart, have trouble starting and runs real rough. After started and going, runs fine again. Always starts easy when cold. I'd like to replace the sender and/or gauge to make sure I'm not overheating it. I've noted that resevoir coolant is hot, and it has overflowed, but probably because I overfilled system. I keep the resevoir cap unfastened. Afraid of too much pressure. Should I take out some coolant and fasten it? Finances are very low. Is this a do it yourself job or not for a kind of unskilled guy. I do some things, oil changes, flushes, plugs, brakes. Little stuff. Normal set of US/metric tools. Any advice on what to look for and what I can do would be appreciated. Just got to keep it going till I can get it fixed.
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Sunday, March 29th, 2009 AT 8:49 PM

3 Replies

Tiny
JAMES W.
  • MEMBER
Apparently, if you need a headgasket, exhaust is leaking into the cooling system. This would explain why the coolant in the reservoir is hot. The temp gauge moving up to operating temp and staying there, is considered "normal" operation. The gauge moving up and down as the thermostat opens and closes is "not". The thermostat shouldn't fluctuate that much.
I wouldn't be too concerned about the reservoir level being too full. I will seek it's own level. You just don't want it to get too low.
On your reservoir cap, if your coolant pressure is high enough from the headgasket leak, you want to leave it loose or you could blow a hose or even the radiator.
The rough running on start up is probably coolant entering a cylinder(s) after shutdown and fouling a plug(s) until it clears out after re-start.
Youcould replace the headgasket yourself, BUT, I highly recommend you buy the best book you can on your particullar car and follow the instructions "step by step". We handle the Mitchell line at this site which I believe is one of the two best available. Hope this helps.
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Monday, March 30th, 2009 AT 11:14 AM
Tiny
PAULBEAR
  • MEMBER
"The thermostat shouldn't fluctuate that much." I bought the car a month ago. Had everything checked on it, compression, coolant pressure, leaks, everything. It was in great condition and ran so-o-o-o smooth. The temp gauge would fluctuate between just below half to just above half, so it wasn't that much. One day it overheated suddenly. My mechanic could only guess that the thermostat had stuck closed. He said it looked like someone had done a "Mickey Mouse" job of installing it, with epoxy sloppily put on it. He replaced the thermostat but the damage had already been done. That being so, the temp would rise to 3/4 then back down, it was erratic. The check engine light stayed on all the time, and it ran rough. One morning it stayed near cold for ten miles, the next day it would threaten to go near the red. I added 1/2 bottle Bar's coolant sealant and it really improved a lot, almost normal. The check engine light went off, and it idled and ran smoothly. The temp gauge would move around halfway + or - a bit. Last wednesday I took it out, stopped at a store, and it wouldn't start. The temp read below halfway. I put a friend on notice that he might have to come with some plugs and tools, but wait until I called after I let it cool down. When the gauge said it was completely cool, it started right up, no cough, sputter, didn't have to give it gas, was a perfect start. I drove to an automotive store, bought some more sealant, but didn't put it in yet. Waited for it to cool down, and it started right up again. Now I noted that the temp would always rise to just below halfway and never move again. Since then that is exactly how it has worked ever since. It always starts at cold, moves up to the exact same spot on the gauge, and does not move even a hair no matter how hot or cold it is out, running, idling, A/C on or off. You may say that it shouldn't fluctuate much, but my (short) experience with the car says that it normally does fluctuate SOME. I don't feel good about driving the car around with a blown gasket, but I would feel a lot better if I could keep an eye on the temperature so I could drive or stop accordingly. What amazes me at this point is that the plugs haven't fouled yet, or if they have, they magically clean themselves by the time the engine cools down. Maybe the moisture evaporates, I don't know. Every cold start is perfect. So back to the temp gauge question. Is it worth the trouble or do I take my chances until I get the gasket replaced? I don't think that I'm up to taking the dashboard apart if you think the gauge is sticking. But if it could be the sender, is that hard to get at and replace? Thanks for your help.
Paul
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Monday, March 30th, 2009 AT 5:35 PM
Tiny
JAMES W.
  • MEMBER
Are you sure you have a head gasket out? Water leaking into a cylinder isn't like oil which carbons up and fouls spark plugs. Coolant actually "steam cleans" the plugs and the combustion chamber. BUT, if enough coolant leaks into the cylinder after shut down, it will "short out" the plug(s) until the engine restarts and blows the water out.
The one thing I need to caution you on is the engine oil. If the oil starts to look like a chocolate malt you have antifreeze mixed with the engine oil. Antifreeze DRASTICALLY reduces the lubricating ability of oil and it will destroy the engine bearings.
The coolant temp sensor should be mounted in the thermostat housing if you feel inclined to change it.
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Monday, March 30th, 2009 AT 8:31 PM

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