tillothehun Posted May 17, 2011 Share Posted May 17, 2011 1996 Lagacy LSI, "seems" to overheat at idle. The car has never "fully" overheated , never gone over 3/4 to 7/8 of the guage. Local mechanic thinks it is not really overheating. Temp never gets over 215 to 220 F. fans do kick on, cool and go off, replaced thermostat, water pump seems fine (flowing), replaced sensor at water exit on top the block. He also doesn't think it is the head gaskets though this is a known problem. Again the car doesn't seem to be really hot (temp wise), with the cap off it never boils over. So.........what is it? I am going to replace the sensor again and make sure it is OEM. Mechanic thinks it "may" be the gauge , possibly the heater box leaking but unlikely. He would like to see more symptoms before he diagnoses anything. Anybody got any ideas? Link to comment Share on other sites More sharing options...
ocei77 Posted May 17, 2011 Share Posted May 17, 2011 Sounds like air in the system or a failing pump. System properly "burped" when coolant ran low? When was the pump last replaced? When a pump starts to fail, it may not go all at once. The temp will rise when engine is at a certain rpm then come down. Varies as to how long this will happen before it completely fails. O. Link to comment Share on other sites More sharing options...
Rooster2 Posted May 17, 2011 Share Posted May 17, 2011 Is the replacement thermostat, an OEM model? If not, is it one of those short coil spring models made by someone like Stant? If so, then this could be your problem. Non OEM thermostats perform just like you describe, not very well. Link to comment Share on other sites More sharing options...
tillothehun Posted May 18, 2011 Author Share Posted May 18, 2011 Mechanic thinks the pump if fine. Said I should have seen the iron impeller when I replaced thermostat. Water is flowing, don't know how hard or fast at idle. Still don't have the burp thing down but I do not think air (or that much) is in the system. Thermostat is OEM. Does the sensor in the top of the block where the water exits control the fans and/or the dash temp gauge (both)? Are there other items to replace to ensure the fans are coming on at the correct time? Link to comment Share on other sites More sharing options...
idosubaru Posted May 18, 2011 Share Posted May 18, 2011 clogged radiator? if it's overheating more during the day or when it's hot outside than at night/cool then it's probably the radiator. if you have the EJ25, which i think you do since my 1996 LSi had the Ej25 - then that motor is subject to frequent headgasket issues. your current symptoms are *not* indicative of the usual failure mode though - so either it's just different or it could have been previously replaced with an aftermarket gasket or something. are you noticing any bubbles in the overflow tank? while idling or after shutting the car off? is the tank black? what does the fluid in the tank look like and does it ever get really full? Link to comment Share on other sites More sharing options...
tillothehun Posted May 19, 2011 Author Share Posted May 19, 2011 Good question, yes it seems to get hotter in hotter weather. My mechanic said it did not exhibit signs it was a head gasket....and added it's not if, it's when. The overflow tank has some "foaming", tan/grey tint. I did not think this was from the head just dirty water. I think he checked for hydrocarbons in the water and found none, said C02 was ok so I assume something to that nature was done and I am not going through fluid. I do not notice bubbles while the car is idling. The tank is opauqe white plastic. Maybe I should try a good flush? Will have to check how, not like the good old days of the Prestone flush kits I am thinking. Link to comment Share on other sites More sharing options...
idosubaru Posted May 19, 2011 Share Posted May 19, 2011 you can drain the radiator and put a hose in it - if it doesn't flow the full volume of the hose then it's clogged. i just did this on a forester last summer and that's what happened. if it is temperature related, that's a pretty good sign it's just not flowing enough to dissipate heat. radiatorbarn has great deals on radiators, last forester radiator i bought was $88 shipped to my door. i hope you know this car has very significant head gasket issues. they eat them like candy. you best bet is to not drive this car at all if it's overheating. that's only going to increase the possibility of it blowing the headgaskets. they very well could last the life of the car though, i wouldn't say it's a matter of "when". they are pretty bad, but plenty never need replacing and after 15+ years yours is doing fairly well! Link to comment Share on other sites More sharing options...
GeneralDisorder Posted May 19, 2011 Share Posted May 19, 2011 (edited) This is VERY simple to diagnose. Check the temp with a gun and then check the resistance reading of the gauge sending unit on the coolant cross-over. If it's where it's supposed to be then the gauge is bad. If the resistance is too low for the reading taken by the gun then the sender is bad. If the cooling fans cycle on, then off and the temp is stable - it's not overheating. Period. The fans are controlled by the ECU via it's temp sender. The gauge and it's sending unit are completely seperate entities and are occasionally prone to failure. Also '96 in particular has known problems with corrosion or loose screws on the back of the gauge cluster causing incorrect readings. You need a new mechanic. This should take about 30 seconds to diagnose. GD Edited May 19, 2011 by GeneralDisorder Link to comment Share on other sites More sharing options...
WoodsWagon Posted May 20, 2011 Share Posted May 20, 2011 If the cooling fans cycle on, then off and the temp is stable - it's not overheating. Period. The fans are controlled by the ECU via it's temp sender. GD I'll take this one step further and point out it's very easy to hook an OBDII scan tool up and look at the live data from the sensors to the computer. The temp sensor for the computer will tell you the actual temp of the engine, and you can compare that degree reading to the gauge on the dash. I had a 98 Forester that would peg the gauge, the guy figured the headgaskets were gone. Checking the temp reading the ECU was getting told me the engine was fine, and I swapped the gauge and tach out for one from a junkyard car. Fixed the "overheating" problem. Now the flip side of that is the possiblity of the computer's temp sensor going bad. That won't tell the computer the engine's getting hot, so it won't turn on the fans until it gets the right reading. Usually they fail open, so the computer sets a code and turns the fans on full time, but you might have a rare failure mode. The ECTS for the computer is like $35, it's the 2 pin temp sensor vs the CTS being the one pin flat blade connector that runs the gauge. Link to comment Share on other sites More sharing options...
tillothehun Posted May 20, 2011 Author Share Posted May 20, 2011 So my next steps will be to check the radiator for flow and I am going to replace the ECU temp sensor since I already did the single blade one for the guage. My mechanic did elude to the gauage but added the gauge cluster for that model is sold as all one piece at $500 and he would charge me a $1000 to take off the dash to get to. He recommended not doing that. He used his OBCD computer and added "I am not really sure this car is overheating" and suspected the gauge also but I do not think checked resistance. So I have to go look up some specs like the the resistance on the sensor and what is the operating range of the engine. With the OBDC he said it never got over 215F, my cheap one was reading around 220F. What temp is considered the car has overheated and what is normal operating range? I thought 195F. I also plan to add some of that Subaru coolant system conditioner. Link to comment Share on other sites More sharing options...
idosubaru Posted May 20, 2011 Share Posted May 20, 2011 I also plan to add some of that Subaru coolant system conditioner.that's not intended for this engine. your DOHC EJ25D has completely different head gasket failure modes than the later SOHC EJ25's this stuff was intended for. i would focus on properly diagnosing and fixing the problem at hand rather than putting energy, time, and money in something that is guaranteed 100% for sure not to fix the problem nor likely to help anything. Link to comment Share on other sites More sharing options...
WoodsWagon Posted May 20, 2011 Share Posted May 20, 2011 So my next steps will be to check the radiator for flow and I am going to replace the ECU temp sensor since I already did the single blade one for the guage. My mechanic did elude to the gauage but added the gauge cluster for that model is sold as all one piece at $500 and he would charge me a $1000 to take off the dash to get to. Find a different mechanic. Seriously. Pulling the instrument cluster out of one of these is a 15 minute job. You lower the column to it's lowest positon, put the wiper switch arm all the way down, and pull a few phillips screws. The bezel comes off, you unplug the cruise and rear defrost switches, and slide the bezel out towards the center console. Then take out 4 screws from the cluster, flip it down and unplug the wiring from the back, and slide it out the same way. Then, pry apart the clear plastic front off the cluster, take off the black face plate, and remove the 3 screws from the back that hold the temp gauge in. Put your new one in place, screw it in, and clip it all back together. Installation is the reverse of removal... Working slowly, the whole job could take an hour. I'd like to get paid $1000 for an hours work. You could pull the cluster out of a car in a junkyard to get experience taking it apart, buy the cluster (last one I got was $25), carefully take the temp gauge out of it, and tackle yours. Now, I'm not saying it's your gauge at fault, I'm just saying your mechanic is quoting you outrageous prices for easy jobs. 220 F is a bit high for idling. 195-210 is where they usually sit. But if the fans are cycling on and off on their own with the A/C off then the computer is happy with the temp readings it's getting. If the mechanic got the 220 figure from the OBDII scan tool, then that's what the computer is seeing. Checking that against an infrared thermometer pointed at the cooling crossover pipe wouldn't hurt, or just replacing the ECTS. Link to comment Share on other sites More sharing options...
GeneralDisorder Posted May 20, 2011 Share Posted May 20, 2011 I agree - the gauges ARE sold seperately (from the dealer) and the temp gauge itself is no more than $75 or so. As noted it's about 20 minutes to pull the cluster and about an hour total to swap out the gauge. Your mechanic is a hack and has no idea what he's doing. Instead of actually finding out what the procedure is and THEN quoting you a price he's just assuming it's a horrible job and would take many hours. He also isn't properly diagnosing the cooling system. I noted that it takes about 30 seconds to get a resistance reading from the gauge sender...... You are being ripped off. GD Link to comment Share on other sites More sharing options...
idosubaru Posted May 21, 2011 Share Posted May 21, 2011 and if it was $500 at the dealer, big deal, these things don't fail enough to warrant that cost, used is just fine and inexpensive. Link to comment Share on other sites More sharing options...
tillothehun Posted May 25, 2011 Author Share Posted May 25, 2011 Ok I have not tested anything yet and just ordered a new ECU sensor. I will try the whole dash myself if the guage looks bad. Sounds like I'll skip the coolant conditioner. Glad to find out all the info. Thanks everyone! I do think my mechanic was leaning more to just thinking it was a hard job. In the end they have been honest with me. After all it would have been at least $1000 at the dealer who also would have added I need new rotors and brakes or what ever they could make up which I think I have heard everytime I have been to the dealer nearest me. Link to comment Share on other sites More sharing options...
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