Engine temp reads at 'RM' in NORM ?

90coug

Registered User
Ok, so I've been battling this problem ever since I rebuilt the engine. Car starts and runs like a champ but before I tore the engine down the temp gauge would ALWAYS read before the 'N'. Now the car reads somewhere around the 'RM'. I think it's important that I say that after I rebuilt the engine not to too far into driving it around I had a lean mixture problem on the passenger side. So after diagnosing I found out that the intake manifold passenger bolts had come VERY loose. I took it back apart and gave it new gaskets and sealed it back up again and now the lean mixture code is gone. My theory is that when the intake manifold was loose that the coolant didn’t flow through the intake manifold from the heads and maybe the heads got too hot? Is this a possibility since the intake manifold was loose? I've tried a new thermostat; a diff used radiator and flushing the system many times. I've replaced the temp sensor and switch. Haven't replaced the water pump but I've been told unless it's coming out the weep hole not to worry about the water pump. The engine was slightly bored out to rid of the tapering, could the oversize result in a hotter engine? If memory serves me correctly I was running at the right temp before I noticed the lean mixture problem, but I could be wrong. So I’m exhausted on trying to figure this problem out, I'm almost at the point of buying a thermo gun and reading the diff parts of the engine for hot spots. Could the intake manifold being loose cause the coolant to stop flowing correctly? If so wouldn’t the car have overheated? Should I buy a new radiator, it worked before. Should I buy a new water pump? Oh and I tried running the car without a thermostat, it took longer to get hot but it eventually got there, thermostats back in now. Could the aluminum heads cracked, or are my new gaskets thrashed now? Thanks
 
I don't know about the impact from all your engine work, but if the gauge has climbed from N to RM now - I would suspect that your low speed fan is not functioning and the temp is rising to like 228 deg before the high speed fan kick in. You can test it by running a KOEO test or by simply putting on your a/c or defroster while it's idling. Either of those 3 conditions should cause your low speed fan to run. At least you can then eliminate one common cause before doing more extensive diagnostics.
 
With the KOEO test the fan will kick in but while driving the fan never turns on until the car get's to the 'RM', which I believe this is the fast RPM. When I kick on the A/C the fan will not turn on either, only time the fan runs is when it's hitting the high temperature. I don't have the A/C condenser hooked up but the compressor is still plugged in and turning. What would cause the low speed fan not to turn on at the right time? I do believe this is the problem because there was one time that I heard the fan go on right around the normal operating temp range but it never happened again. Maybe I need to get a new condenser and plug it back in and charge the system, could that be a reason the low speed fan doesn’t turn on?
 
i would try a 180 thermostat and a range colder plugs , i dont believe my fan kicks on till about the r but mine hardly ever goes above half im mostly on the highway more than city driving
 
Did you ever figure what the word 'NORM' stands for?
Maybe; perhaps, NORMAL? So if your in the 'NORM' range, its NORMAL! :)
 
The 'RM' is not the correct place for the gauge to sit, the few SuperCoupes I've ridden in all have stayed before the 'N'. So my new question is, what would be a reason the low speed fan wouldn’t kick on even when the A/C is switched on, the fan will turn on with the KOEO self test. When is the low speed fan supposed to turn on, at what temperature or point on the gauge?

Thanks
 
Re: ...

The low speed fan should turn on with the A/C on. But if your A/C is out of freeon, eventually the lower speed fan will quit working. and only the high speed will kick on near RM.

To get the low speed fan working again....... you would have to unplug the dryer's preasure switch, and jump a wire across the two contacts on the plug. then unplug the compressor electrial connection. Once that is done, go start up the car and turn on the A/C. The lower speed fan should come on now.

Hope that helps..... :)
 
Yes - I'd say restore your a/c system. If you particularly don't want to do that, then you could jump out the pressure switch on top of the accumulator and disconnect the power to the compressor as mentioned (you don't want to run the compressor with low refrigerant or oil). However, you also loose the benefit of a defroster. Other than that you can cut wire #14 at you IRCM relay (in front of your air filter/behind the headlight), that will run your low speed continuously. I do that myself during the summer months and it keeps the temp. nicely between 200-210 deg even on 95deg/95% days. Our low speed fan comes on with the a/c, goes off at a highway speed of around 47mph and comes back on again when the temp has reached 222 deg. That's way too late and then the low/high fans cycle on/off trying to keep the temp below 228deg (roughly around the RM on our gauges, which is the situation you are facing). Bringing the low speed fan on early or below the 222 deg definitely gives you better control over the engine cooling.
 
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