Heat ain't so hot

[seagull369]

I recently replaced the radiator on my 90tt and while I was in there I changed out the thermostat, too. Put it all back together, drove it and discovered the heat was pretty luke warm, even at hottest setting. It'd get hotter only if car was idling in place for a while or if really gunned the motor while driving.

I drove the car for a good week, checking daily that the coolant level was topped off and any bubbles got purged outta there. Thinking it could be a problem with the 'Duralast' thermostat I installed, I tried a Stant one instead, but am still having the same issue under the same conditions. Before changing anything, the heat worked very well.

The temp gauge is acting normal, and never goes above the halfway point. I installed both thermstats with the jiggle valve at the 12 o'clock position, btw

Anyone know what the problem could be?

[nissanfreak12]

What temp stat did you get?

It very well could be your heater core needs to be back flushed, but if it heats up when it sits, chances are the thermostat is slightly stuck open.

[seagull369]

Thanks for the reply. The stat is rated for 180 open temp. I put a hose to both the inlet and outlet pipe (with stat removed) and backwashed both ways til it came clean. I also drained the new rad several times immediately after driving.

I'm beginning to wish I didn't toss the old stat away =(