85 2m4 SE / 2.5 Temperature Issues (Page 4/7) sleek fiero DEC 26, 10:52 PM Todd I believe your temp gauge has two coils in it that work by creating a differential field that moves the needle. If one coil is only partially operating or sporadically functioning that would explain your crazy readings.It might not show up on a bench test. I would try another gauge. sleek 82-T/A [At Work] DEC 27, 09:49 AM quote Originally posted by Riney: Any updates on what you have found with this? My guess is wiring to temperature sending unit or the sending unit itself. Something grounding our or touching one of the wires? You said you temperature gage is correct. I do not think this has anything to do with the 70/30 mix of antifreeze. I'm starting to think that's it. I just had my gauges professionally re-done, and they were tested and one of the only things that WAS correct on the gauges, was the temperature gauge. I know I replaced the temp sensor connector, and I removed the old vestiges of the 1984 high/low fan switch connector (which does nothing in the 85 harness, but is still there), and I can't remember what I did with the wire after I cut it. Someone else here (maybe Patrick) said I should try to read what temperature the engine is seeing (which comes from the other sensor on the water neck). I have to find my ALDL connector, and install that software on a laptop and see what the ECM sees. The car drives amazing, so I doubt it's really reading 300+ degrees. I'll see if I can get that done today. quote Originally posted by Riney:Also, you said the tach was messed up. Is it bouncing around like the tach filter is bad or just reading incorrectly? My tach started reading abnormally high, i actually had a conversion chart to compare it to the correct engine RPM. I had an extra gauge set I picked up years ago so i pulled the tach out and put the other one in and tRMP's are reading correctly now. There is a write up on this forum somewhere about fixing the issue with the tach, sounds like it is a common problem. I resisted the urge of rolling back the odometer to zero when i had it open, I did roll the spare one back just because. Yeah, I was having a major issue with the tachometer. I remember when my daughter first got the car (it was running, but barely), the tachometer was jumping all around... but abnormally high, like really high. The car and all it's components sat not running for the greater part of a year while my daughter restored the variouss components, and completely rebuilt the engine. We totally repaired the wiring harness, and even installed a new tachometer filter from Rodney Dickman. When we started the car, it ran really well... but the tachometer by that point would literally peg-out. As I mentioned above, I sent my gauges out to Jack Gunsett (my daughter will be posting a video in the next couple of weeks) and had them completely gone through and repaired. My tachometer now works *PERFECTLY.* The tach doesn't bounce around, it matches the engines RPM's perfectly. He determined that there is a resistor on the tachometer board that typically fails, and he replaced that for me. It immediately solved the problem. (user is JGunsett on here) If your tach is bouncing around, it could be your tachometer filter (we replaced that too, as I said), but if it's reading unusually high... then it's probably a failing resistor. quote Originally posted by sleek fiero: Todd I believe your temp gauge has two coils in it that work by creating a differential field that moves the needle. If one coil is only partially operating or sporadically functioning that would explain your crazy readings.It might not show up on a bench test. I would try another gauge. sleek Thanks Sleek, I do have a spare set of gauges somewhere that I might just hook up... but I'm starting to hedge my bets on it being shoddy wiring on my part. It was one of the only things I did for my daughter, haha... and it's possible I screwed something up. The gauges were totally redone... so it's probably me. 82-T/A [At Work] DEC 27, 09:27 PM Ok, I ordered another temperature sending unit from Rock Auto, this time from a different manufacturer, just to be sure. I also ordered a set of CD-Rs from Amazon because I have no way to install the ScanTool software without downloading the ISO... haha... so I'm going to be doing that. I'll probably end up having to wire up the sending unit separately. I'll study the shop manual over the next few days... no way I'm undoing the wiring harness... especially when the car runs so nice. What's the best way to test the wire from the gauge connector all the way to the sending unit? Am I supposed to measure resistance or something? Thanks! sleek fiero DEC 27, 09:42 PM Todd I believe if you key on and ground the wire the gauge should go full high reading. Remove the ground and it should go to the bottom of the scale. If you get this movement your wire is intact. I haven't done this for a while and I might be wrong and it react opposite to the way I descibed. What I did wrong on mine was I switched the wires and the idiot light would gradually come on as it warmed up. I won't make that mistake again. sleek 82-T/A [At Work] DEC 27, 09:48 PM quote Originally posted by sleek fiero: Todd I believe if you key on and ground the wire the gauge should go full high reading. Remove the ground and it should go to the bottom of the scale. If you get this movement your wire is intact. I haven't done this for a while and I might be wrong and it react opposite to the way I descibed. What I did wrong on mine was I switched the wires and the idiot light would gradually come on as it warmed up. I won't make that mistake again. sleek Thanks Sleek, I will try that. You also made me just think of something. When the car "actually" overheats, isn't the warning light supposed to come on? If I remember correctly, the gauge feed and the warning light are two separate pins that are fed to the gauge cluster. At no point have I ever seen the warning light come on. I know all the bulbs in the gauge cluster are good too ... so definitely sounds like I've got a wiring issue. J Gunsett DEC 28, 09:01 AM Yes your over temp light should come on, that is a separate circuit. And you have a PM. Jack 82-T/A [At Work] JAN 11, 01:55 PM Hey guys, just a quick update... I had some time, so I took a look at the car again. 1 - I'm getting a leak again behind the water pump... sigh. Not thrilled about it. I think it's where the waterpump housing mounts to the engine. It doesn't leak while the car is driving, but it leaks AFTER the car has been sitting (and gets hotter since the coolant isn't flowing). My suspicion is that we didn't use enough sealant on the waterpump housing bolts... which could be where the coolant is leaking out of. Again, it ONLY does it when the car is sitting after having been driven. I still see no indication of the car overheating. I'm just going to order a whole new housing, a whole new water pump, and do it all at the same time as I also install the idler pulley system. That way I can make sure everything goes in as it should, properly. Any comments or suggestions? 2 - My daughter installed the new switches for defog and trunk release. She noticed when she was in the car that when she pushes the trunk release button (with the car off)... the trunk pops of course, but also... the temperature gauge twitches. If she HOLDS the trunk release button down, the temperature gauge will go more or less from wherever the needle is currently pointing to the 220 point in the middle. Thoughts on this? Definitely sounds like a wiring issue... either somthing is grounding out or the temperature gauge is getting power to it through a ground. 1985 Fiero GT JAN 11, 04:50 PM quote Originally posted by 82-T/A [At Work]: 2 - My daughter installed the new switches for defog and trunk release. She noticed when she was in the car that when she pushes the trunk release button (with the car off)... the trunk pops of course, but also... the temperature gauge twitches. If she HOLDS the trunk release button down, the temperature gauge will go more or less from wherever the needle is currently pointing to the 220 point in the middle. Thoughts on this? Definitely sounds like a wiring issue... either somthing is grounding out or the temperature gauge is getting power to it through a ground. I would imagine that is not how it is supposed to work, not sure where it could be wrong, but that could definitely make the gauge read inaccurately, as you have seen. 82-T/A [At Work] JAN 12, 06:02 PM quote Originally posted by 1985 Fiero GT: I would imagine that is not how it is supposed to work, not sure where it could be wrong, but that could definitely make the gauge read inaccurately, as you have seen. Haha... yes, for sure. I'm just curious if anyone has seen anything similar... such as a similar issue. cartercarbaficionado JAN 12, 07:32 PM quote Originally posted by 82-T/A [At Work]: My assumption is that it's spinning the waterpump faster, and then drawing in more coolant, more quickly? I should say, "blip" the throttle... not like FLOOR it... so like... I'd have it go from 800 rpms / idle to 1,400 rpms is what I meant. Do you have any thoughts? Kinda sucks... you are describing the formula to a T. the waterpump is not flowing coolant properly and is recirculating inside the block due to excess clearance. some pumps are litterally 5 mm too short and it causes nightmares but only with the Stat installed.