Is it really overheating?

[purplenissan]

2nd time this has happened now, both on mornings where it's colder than 5 below outside. The truck starts fine, drives about 5 miles when I notice the temp gauge is starting to run high but only cold air comes out the vents. The first time, I stopped and opened the hood looking at the fan and radiator. Fan was spinning, radiator wasn't leaking (I replaced the radiator over the summer). As I started to drive again, I could see the temp gauge needle move to cooler and the vents started blowing heat. This time I did the same thing, but drove a little further before stopping, thinking that something froze closed (?) the first time and just needed to thaw. The temp gauge showed hotter than ever before and took longer for the "thaw" thing to happen, needle to go down, warm air to blow. I don't know if the smells were coincidence, but as soon as it started to work, the cab smelled like exhaust, then 10 or 15 minutes later it smelled like burning plastic. Both smells went away in a minute or so.

I've got a '96 truck, 4 cyl. Any ideas what's going on?

[OLDSCHOOL]

the smell was from it running hot, I would try draining your coolant system, it sounds like your coolant ratio is wrong, too much water not enough antifreeze

[nismopu]

carry some cardboard with you and stick it in front of your radiator before you set off and it will help keep your rad from freezing. Also, now would be a good time to change your thermo stat. peace.

[slammed97]

thermostat could be stuck also.....

[burrsg101]

agreed on draining to coolant. your coolant system is freezing because you dont have the right ratio. get about a 50/50 ratio of coolant to water and you wont have problems. this really isnt good for your engine though to keep letting it freeze and unfreeze, somethings going to crack or break real soon. also if your thermostat was stuck closed it would never cool back down, but replace it anyway just to make sure. there only like 10 bucks anyway, but get an oem one from nissan, not one from a parts store.

[tattoos&minitrucks]

I have an 86.5 HB with the z24....sorry to jump in but I have been haveing the same thing happen but the other way.....I let my truck warm up for like 10 or 15 min. before I go to work and it has not gotten colder then maybe 30....any way the temp will not climb it just stays cool and the air out of my vents is cool not cold but then it heats up alittle as I go on down the road ....it got to about 77 or 78 the other day and as soon as I got going it got up to temp ...which is not to warm to start with ...any info would be cool ..... thanks

[burrsg101]

^^that sounds like a thermostat stuck open, my pathy did the same thing when i bought it.

[tattoos&minitrucks]

thanks

[purplenissan]

No one to blame but me, I was the one that did the coolant last when I replaced the radiator...but yup, re-did the coolant and no more of those kinds of troubles (yet).
Thanks, all!