erratic heat/no heat

[wbsterritt]

Happy holidays to all! For the last week I have been "forced" to drive my '83 spider due to my daily driver truck being in the shop. Weather has been in the teens duing this time and my heat has been marginal to non-exsistent. It has been marginal while idling or slowly moving (engine temp only reaches approx. 175 f) and non-existent when going highway speeds (55-70 mph) with engine temp only reading just over 120 f. I spent the day Saturday purging the system of possible trapped air. When it was completed I let the engine warm up. Temp gauge went up to 185-190, electric fan kicked on and had plenty of heat. Thought all was well until on the way to work this morning-same problem as before. Any sugestions are much appreciated. Thanks.

[Exit98]

Keep in mind, I'm no mechanic.

Seems though all the earmarks of a stuck open thermostat. After fiddling around with the system it may have worked for a while but now its stuck open again. You are not overheating, you are getting too much flow. You can check it on the stove, but I'd pop in a new one.

[BEEK]

+1 on a stuck open thermostat

[pressonregardless]

Exactly, you have a stuck Thermostat. I had the exact temps on my '74 years ago (although the T-Stat is in the head water outlet on that model) and it would cool off at speed. Hope that solves your problem!

[ORFORD2004]

Or a blown head gasket

[wbsterritt]

Thanks for the timely reply guys! I'm suspecting the thermostat. Not seeing any evidence of coolant in the engine oil indicative of a blown head gasket I believe, thank goodness. Now to find time to look into the possiblity of a sticky thermostat. Updates forthcomming.

[djape1977]

there's more than one way for a head gasket to go bad. however, first change the termostat