fourizza Posted May 14, 2012 Report Share Posted May 14, 2012 Hello everyone, Ive brought my 98 monte carlo z34 to my dad who has been a mechanic for 40+ years. We went through the car and everything looked good for the most part. One problem he seemed to be really worried about was the temps and the fans not coming on. When driving around the temp gauge sits at 1/4 or 1/3 depending on the outside temp. But when idling in the garage it shoots up to around half way or 3/4 and the fans still don't turn on. Ive done some research on this forum and google and I think this is normal but my dad thinks other wise. The both fans do turn on when you turn on the AC, we checked all the fuses and the fan relays and they are all working. We changed the coolant temp sensor and put in a new thermostat. The car is from Florida so its pretty clean inside, we checked all the wires non seem broken but we are not sure where to find the ground wires for the fans. From what Ive seen on the forums this might be normal but he thinks I'm going to "cook the engine". Is there anything wrong here or is this normal for this car? Quote Link to comment Share on other sites More sharing options...
AL Posted May 14, 2012 Report Share Posted May 14, 2012 It sounds normal to me... hook up a scanner and let us know what the actual temp readings are... also, check for leaking lower intake gaskets Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted May 14, 2012 Report Share Posted May 14, 2012 ^ ditto that. factory fan temp calibrations are stupid high, but will come on.... eventually. Quote Link to comment Share on other sites More sharing options...
skitchin Posted May 14, 2012 Report Share Posted May 14, 2012 Yeah, temp gauge isn't always the most accurate, though it should be somewhat accurate. Would definitely be scanning to confirm weather or not the fans should be coming on at the temps you've observed. I just replaced my radiator because it wasn't cooling worth a shit - my fans used to do all the work of cooling things off, but now they hardly have to kick on. Now when my thermostat opens, it actually brings the temp down, rather than letting the temps climb all the way up till the fans kick on. Quote Link to comment Share on other sites More sharing options...
fourizza Posted May 14, 2012 Author Report Share Posted May 14, 2012 No leaks all the gaskets have been changed but he will be bring home a computer from his shop. We'll hook it up and see whats going on Quote Link to comment Share on other sites More sharing options...
fourizza Posted May 15, 2012 Author Report Share Posted May 15, 2012 The snap on guy took the computer to update it so hopefully he'll get it back by the end of today. I'm beginning to think its the fans or a bad ground for the fans. The first time I tried the AC both fans came on but they seem to be spinning slow. Tried the AC again this morning and giving it about 2000 rpms with the temp gauge going right to the red line, the fans never came on. I'm going hook up the fans to the battery to see it they spin quickly or at all( which is what I should have done to begin with). I also replaced one of the fan relays just for shits and they still didn't spin. does anyone know where the ground wire for the fans are located on this car? Quote Link to comment Share on other sites More sharing options...
fourizza Posted May 16, 2012 Author Report Share Posted May 16, 2012 We ruled out the fans and wiring, we took out fan 1 relay it was I believe and manually jumped it with a wire and the fan spun right up. So I'm going to replace all the relays and hope for the best Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted May 16, 2012 Report Share Posted May 16, 2012 have you guys attempted to watch the coolant temp via the datastream, rather than the coolant temp gauge? you probably don't even need to replace the relays, just make sure that the gauge just isn't that messed up. i'm not 100% up to date on 3800 fan on/off temps, but with the 60V6s, it's something like ~226*F will turn on fan #1 (in your case, probably both fans on low) and ~230 will turn on fan 2(or both fans on high). Quote Link to comment Share on other sites More sharing options...
fourizza Posted May 16, 2012 Author Report Share Posted May 16, 2012 the snapon computer is still getting updated but once he gets it back we'll hook it up. Regardless you can just feel the engine getting super hot, now I understand engines run hot but this seems hotter than normal. Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted May 16, 2012 Report Share Posted May 16, 2012 just as an anecdote, but the 1.5 clusters suck... coolant temp gauge is usually off, gas gauge goes crazy with the slightest bump, speedo is usually accurate at least, but the tach is almost always off.... it really wouldn't surprise me if it's just the gauge. but being an engine with a plastic intake, i'd say as long as you're not sitting still for too long, i wouldn't worry about it until you can get some good data out of the ECM to see what it sees. Quote Link to comment Share on other sites More sharing options...
fourizza Posted May 16, 2012 Author Report Share Posted May 16, 2012 I replaced the other 4 pin and the 5 pin relay and the fans turn on now. So I guess it was a relay Quote Link to comment Share on other sites More sharing options...
fourizza Posted May 17, 2012 Author Report Share Posted May 17, 2012 If anyone is interested, we hooked up the computer to the car. Driving it runs around 180-190, mid point on my temp gauge is 200, fans turn on at 220 then shut off when it reaches the mid point on my gauge which is 200. Also like said in a previous post the tach was off, gauge said 1000 but its more like 750 Quote Link to comment Share on other sites More sharing options...
ReBlown47 Posted May 17, 2012 Report Share Posted May 17, 2012 (edited) thats how my cluster is speedo is about 1mile off, rpm about 300 off, fuel gauge act weird when it gets low like going to empty then having half a of quarter fuel left like maybe reserve fuel is kicking in.Temp gauge i dont even bother with cause sometimes it barely moves so mines probably like 80-90 off Edited May 20, 2012 by ReBlown47 Quote Link to comment Share on other sites More sharing options...
z34Phoenix Posted May 19, 2012 Report Share Posted May 19, 2012 Just FYI stock fan turn on temps are as follows for a 98/99 Z34 Fan 1 turn on at 222.83* turn off at 219.17* Fan 2 turn on at 230* turn off at 226.41* short of rewiring them to come on when the engine is running or adding in an aftermarket harness the only way to change the fan turn on temps is by retuning the PCM. these cars normally have temp at about half way and go up when not moving. being down here in florida the temps can go 3/4 the way on the cluster. Where in florida are you? im over in daytona. if you want i can reflash the pcm and lower the turn on temps. and if you want tuning PM me and we can plan it out. Quote Link to comment Share on other sites More sharing options...
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