Guest Leadguy Posted October 10, 2009 Share Posted October 10, 2009 A few months back I had a problem with cooling fans not kicking on when necessary, making car overheat. I changed the fan relays - no change. Next, I changed the coolant temp sensor and that worked. However, the temp gauge never registers more than 118 F.Car has been very hard to start. I changed spark plugs twice, fuel pump, fuel filter, fuel pressure regulator.This morning I installed another new temp sensor and still no dice - 118. I noticed that some here have said that only one wire goes to the coolant temperatue sensor; however there are actually 2 wires that go to mine. Could this 118 F thing be the rough start/run issue? I will go out and get a new thermostat in a few minutes and give that a try too. Link to comment Share on other sites More sharing options...
rjfranken Posted October 11, 2009 Share Posted October 11, 2009 (edited) Yes, if you have overheated your engine the thermostat (don't forget to get the NEW O-ring) will likely fail-stuck open now in your case. You get really bad gas milage, but the performance curve isn't bad. A infrared thermometer is handy to check your upper and lower hose temps, they should stay well apart until it opens and they catch up with each other. On that thermo outlet bolt, it (7/16) may well be almost stuck. Don't bully it out, a little bit out and back in, out and in, repeat...it wil get a little farther out each time. You don't want to break this one! About the fans; a bad thermo will not allow circulation properly and cause overheating too. Fix one thing at a time or you'll never know what fixes what. Edited October 11, 2009 by rjfranken (see edit history) Link to comment Share on other sites More sharing options...
DAVES89 Posted October 11, 2009 Share Posted October 11, 2009 leadguy you really should have two posts going, one for the temp gauge and one for the hard start. That said, When you do your first start in the morning does it hard start, and then start well the rest of the day? Or does it always hard start? For me it was the relay on the firewall for the hard start first start and then fire good the rest of day. If it hard starts it may be your ICM located just under the coil pack. Look for a gunky ooze that has fallen onto the radiator hose. [i think Bob resolved your temp gauge issue.] Link to comment Share on other sites More sharing options...
rjfranken Posted October 11, 2009 Share Posted October 11, 2009 (edited) Thanks Dave, look to upgrade your coil pack to the Delco (after 92) and plugs too if not already. ez. Search Padgett link. Also, do you hear the fuel pump at key turn (2 secs behind you) crank, off and on, crank, again; starts. fuel pressure is maybe being lost from leaky injectors, do the seafoam (search) thing at the tank (x2) first...IMHO Edited October 18, 2009 by rjfranken (see edit history) Link to comment Share on other sites More sharing options...
Guest Leadguy Posted October 11, 2009 Share Posted October 11, 2009 On that thermo outlet bolt, it (7/16) may well be almost stuck. Don't bully it out, a little bit out and back in, out and in, repeat...it wil get a little farther out each time. You don't want to break this one! Did it before I got your reply - and - I broke it (the water outlet housing, not the bolt). Thought it would be a salvage yard replacement but I was shocked to find that AZ had them for only $8.99 so no harm done.Installed, saw no leaks as I let it run for quite a while in driveway, and drove around the block a few times. Later got on freeway, and started getting steam from thermohousing area.Question about gasket placement. The thermo I took off had 1 donut type gasket that I BELIEVE was in that channel in the water outlet housing (I'm not sure because I broke the housing at the channel which made the gasket appear as if it was simply on top of the thermostat.) Anyway, the new thermo came with a gasket (not donut shaped) while the new housing came with the donut shaped gasket. Finally the question is - did I need to use BOTH? Because I did.Also, there was no difference in the temperature reading after replacing the thermo. Maybe if I do it right today that will change. Link to comment Share on other sites More sharing options...
Guest Leadguy Posted October 11, 2009 Share Posted October 11, 2009 Thanks Dave, look to upgrade your coil pack to the Delco (after 92) and plugs too if not already. ez. Search Padgett link. Also, do you hear the fuel pump at key turn (2 secs behind you) crank, off and on, crank, again; starts. fuel pressure is being lost from leaky injectors, do the seafoam (search) thing at the tank (x2) first...IMHOMechanic said fuel pressure was low at rail, before injectors, so I replaced the fuel pump, filter, and regulator. Plugs were replaced first with OEM delco, then with better platinums. Tried the crank procedure, some time ago after reading in hear- no go.Thx Link to comment Share on other sites More sharing options...
Ronnie Posted October 11, 2009 Share Posted October 11, 2009 Leadguy, solving your problems is going to be very hard by discussing all of them in one thread. One time the post is about temp readings and the next its about fuel pressure and so on. It gets very confusing to follow. Please start a new thread with what you feel is the most important problem and stick with that topic until that problem is solved. Start a new thread for each additional problem if you want to work on other problems at the same time. If you will do that way your problems will get solved much easier. Link to comment Share on other sites More sharing options...
Guest Leadguy Posted October 11, 2009 Share Posted October 11, 2009 Thanks. However, this thread is about the possibility that the temp problem is causing the hard start. I went down the road of the typical hard start solutions, when the car first started having issuues, with little success (although there's still more I could do of course).However, I have been told by mechanics that the incorrect temp reading could possibly be throwing other things off resulting in the hard start and poor performance. So I am trying to eliminate that issue since it could be offsetting the various sensor and ignition part changes I have made or plan to make. Link to comment Share on other sites More sharing options...
Guest Richard D Posted October 11, 2009 Share Posted October 11, 2009 I agree with Ronnie, Your last post got me confused for a minute because I was thinking about your temp problem. Even with no thermostat installed the coolant temp would go above 118 degrees in different situations, like idling in stop and go traffic or cruising at 65 MPH. That is why I think you have a bad temp sender, the non-contact infrared thermometer is a good idea, you can see what the coolant temp is at the coolant outlet, I bet it is way above 118 degrees. I had to drive my first 1990 coupe without a thermostat for about a week and the temp gauge on the dash would take longer to reach the normal area but it would get there in about 15 minutes of driving. Link to comment Share on other sites More sharing options...
Guest Leadguy Posted October 11, 2009 Share Posted October 11, 2009 (edited) In response to responses I need to clarify: I am seeking insight to eliminate the improper temperature reading in hopes that this may help with clearing my hard start issue. I know these seem to be very different issues (and still might prove to be) but this may be one of the quirky issues that pop up where seemingly unrelated issues are related.Has anyone ever experienced this problem? Is there a method to clear or reset my temperature guage that I should have used when I replaced the coolant temp sensors?Also, how many gaskets should I have used when replacing the thermostat? And if one, should it have been the donut shaped one that came with the new water inlet housing; or the non-rounded gasket that came with the new thermostat? Edited October 11, 2009 by Leadguy (see edit history) Link to comment Share on other sites More sharing options...
Guest Leadguy Posted October 11, 2009 Share Posted October 11, 2009 I think you have a bad temp sender,....However, the temp reading didn't stop indicating correctly until I changed the coolant temp sensor - immediately. It never showed the temp properly after the change - however the fans worked fine.So, I don't believe it is a bad temp sender since it sent the temp just fine with the old sensor installed.I will check the wire connections again, but it's pretty simple, only 2 wires. Link to comment Share on other sites More sharing options...
Ronnie Posted October 11, 2009 Share Posted October 11, 2009 It sounds like you may have the wrong temp sensor installed. It must be a "sender" and not just a switch. Check to be sure you have the correct part. Link to comment Share on other sites More sharing options...
Guest Leadguy Posted October 11, 2009 Share Posted October 11, 2009 It sounds like you may have the wrong temp sensor installed. It must be a "sender" and not just a switch. Check to be sure you have the correct part.Got it from Autozone - part number SU109 AutoZone.com | | Coolant Temperature Sensor | COOLANT TEMP SENSOR Link to comment Share on other sites More sharing options...
Ronnie Posted October 11, 2009 Share Posted October 11, 2009 That appears to be the right part listed if they gave you the right one. Link to comment Share on other sites More sharing options...
padgett Posted October 11, 2009 Share Posted October 11, 2009 Keep in mind that with a constant 118F reading, the mixture will not be rich enough and the idle will not be high enough for a cold start and since it never gets to 146F, other things like the TCC will never turn on. Does sound like the wrong part Link to comment Share on other sites More sharing options...
Guest Richard D Posted October 11, 2009 Share Posted October 11, 2009 I agree, wrong or defective part. My 94 Thunderbird with the new at the time 4.6 V8 had a pressure switch hooked to a gauge with a resistor in between to always show the needle at half way. Ford said their reason was at idle the engine had low oil pressure by design and would cause owners to worry. I guess you would call it an idiot-gauge. There are instructions on which sender to install and how to jump the resistor. Link to comment Share on other sites More sharing options...
2seater Posted October 12, 2009 Share Posted October 12, 2009 Coolant temp. sensor is two wire as you stated. The water outlet neck uses a rubber o-ring to seal and a rubber ring spacer that sits on top of the thermostat to take up the space between the outlet neck and the thermostat. The outlet neck rarely sits flat, and it isn't important if it doesn't, the rubber ring between the two is flexible to take up the uneven space and hold the t'stat in place.Does the coolant temperature ever read lower than 118* prior to starting? What does it read if you disconnect it? Link to comment Share on other sites More sharing options...
Guest Leadguy Posted October 12, 2009 Share Posted October 12, 2009 (edited) Coolant temp. sensor is two wire as you stated. The water outlet neck uses a rubber o-ring to seal and a rubber ring spacer that sits on top of the thermostat to take up the space between the outlet neck and the thermostat. The outlet neck rarely sits flat, and it isn't important if it doesn't, the rubber ring between the two is flexible to take up the uneven space and hold the t'stat in place.Does the coolant temperature ever read lower than 118* prior to starting? What does it read if you disconnect it?The temp never moves up or down from 118. Also guys remember that I changed the sensor twice, out of fear that the 1st one was defective. What are the odds that both were bad? Probably not high. I also had to buy and install a new pigtail since the new sensor didn't come with one. The pigtail came with one of those wire connectors that you have to push a metal piece down into the wire. But personally, I prefer to strip the wire ends and use the connectors that you have to crimp on both ends. I will make that change to see if I have a wire connection issue (although it seems well connected)Finally, the aftermarket water outlet that I got from AZ was not smooth on the bottom like the original. It had 2 big protrusions that don't allow it to sit flat atop the thermostat gasket. I am blaming the leak that I got when I installed the thermostat on those humps.However, I went to another apstore (Advance) and their part had the same protusions. Additionally, the original was smoother inside where a gasket fit INTO the lip of the opening that goes over the thermostat. The aftermarket parts were bumpy and irregular inside and it doesn't look like that internal gasket would seat well in them. In general, the original water outlet had an overall smooth finish like it was made of steel instead of cast iron. I know from breaking it that it was actually cast iron, but apparently the original was made much more precisely than the aftermarkets. Anyone have experience or insight on the water outlet replacement? Edited October 12, 2009 by Leadguy (see edit history) Link to comment Share on other sites More sharing options...
Ronnie Posted October 12, 2009 Share Posted October 12, 2009 I also had to buy and install a new pigtail since the new sensor didn't come with one. The pigtail came with one of those wire connectors that you have to push a metal piece down into the wire. But personally, I prefer to strip the wire ends and use the connectors that you have to crimp on both ends. I will make that change to see if I have a wire connection issue (although it seems well connected)What is all this about the sensor didn't come with a pigtail... and you had to buy one? None of that makes any sense. If you got the right sensor you should have just screwed the old one out, screwed the new one in and snapped in the connector. Something doesn't sound right about all this pigtail stuff. Please explain what is going on. Link to comment Share on other sites More sharing options...
Guest Leadguy Posted October 12, 2009 Share Posted October 12, 2009 What is all this about the sensor didn't come with a pigtail... and you had to buy one? None of that makes any sense. If you got the right sensor you should have just screwed the old one out, screwed the new one in and snapped in the connector. Something doesn't sound right about all this pigtail stuff. Please explain what is going on.I broke the original connector when I took out the old temp sensor; so I had to splice a new pigtail on. Link to comment Share on other sites More sharing options...
Ronnie Posted October 12, 2009 Share Posted October 12, 2009 OK that is a different story. Disconnect the sensor and see if the temp is still 118 degrees. If so the sensor is not the problem. In that case I would cut off the pigtail you installed and see if it still reads 118. If it still does you may have a wiring issue or a problem with the ecm or bcm. Link to comment Share on other sites More sharing options...
Guest Leadguy Posted October 12, 2009 Share Posted October 12, 2009 Applying the different connectors on the coolant temp sensor did the trick. Not only is the temperature registering, but it seems to have instantly stopped the hard starting issue too. Link to comment Share on other sites More sharing options...
Ronnie Posted October 12, 2009 Share Posted October 12, 2009 That's Great! Link to comment Share on other sites More sharing options...
charlie1 Posted October 14, 2009 Share Posted October 14, 2009 Thanks for advising the results. Many times I follow these problems only to be left hanging.Good Luck Link to comment Share on other sites More sharing options...
ncgirl05 Posted November 20, 2009 Share Posted November 20, 2009 Okay - we are experiencing the exact same problem Leadguy was having so now I have to ask a stupid question (and I don't like asking stupid questions!) - WHERE is the coolant temperature sensor located?Many thanks guys! Oh - and Leadguy - we have an '86 XJS as well! Hope you enjoy yours as much as we enjoy ours :-) Link to comment Share on other sites More sharing options...
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