# 1990 Stanza Auto - *under*heating and transmisson problems



## dirtwheels456 (Jul 25, 2007)

*under*-heating. Haha.
Yeah, if the outside temp is 60*F or less, the thing takes 10-15 miles to warm up to were it normally runs. Dont get me started on when its 30*F outside. It will never warm up unless it sits at idle, and evene then, once I get going down the road at 60mph, it cools back off to about half of what it normally runs on the guage. It isnt too big of a problem right now but it needs to be fixed. I replaced the thermostat and this didnt help at all. I've tried blocking half of the radiator with a peice of cardboard, this helped, but very little. I've gotta do something about this before next winter!

As far as the transmission goes. 2 problems. 
1 - Sometimes when I put it into drive, nothing happens. I have to put it down into 2, the D, then it goes fine. 
2 - I can be driving along at 60mph, with it in OD, and it'll suddenly downshift to 3rd. It will stay in 3rd until I let off the gas, or give it some gas, then it'll shift back into OD. Sometimes it'll go my full 60 miles trip without doing it, sometimes it'll do it 10 times during a 30 mile trip. It does it far less at 70mph, and never does it at 80mph.

I'm thinking problem 1 is in the linkage to the transmission? Like, when the shifter is in D, sometimes the transmission is half-way between D and N?

Problem 2 could be related? Or vacumn line? Or throttle position cable/sensor? Does this car have a TP cable?

Trans fluid is fine, it was at proper level and looked pretty good when I got it, though I changed it anyway. 

Car has 180,000 miles on it, and I've put 6,000 on it with both these problems happening.

One last thing. The exhuast manifold glows orange if you pop the hood at night, even after a 60mph highway cruise. It's an even orange, not just in spots. I've read this to be normal on some cars, but not on others? I thought the CAT may be plugged, I took it out of there. I even ran it with nothing on from the flex-pipe back and it still glows orange. So I have pretty much written it off as normal, but just checkin?


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## smj999smj (Jan 1, 2006)

What does the coolant gauge read? Nissan thermostats tend to work better than aftermarket 'stats. If the coolant is reaching proper temperature, the need should be near dead center of the coolant gauge. If the coolant gauge is reading cold or "low," then I would recommend a replacement, OEM Nissan thermostat. If the coolant is reaching normal operating temp, than there is probably an issue with the temp mode door on the heater case...most like an issue with the cable. Is is possible that the heater core is clogged/restricted or a slight head gasket failure causing combustion gases to be pushed through the core, but these are usually pretty rare and I would only consider them if the heater mode door operation is found to be okay and the coolant temp is good.

As far as the trans, I would look at the shift cable bushings, especially the ones above the converter heat shield which tend to melt over time. 

As far as the car, make sure it isn't cracked and leaking. Otherwise, I would remove the O2 sensor and install a back pressure tester to check for an exist restriction. If that was okay, I would then have to break out a scan tool and check the rich/lean switching and O2 sensor operation to see if the engine was running too lean or rich.


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