Engine too cold

[MIPS]

I'm trying to find the receipt from the shop when they reinstalled my engine but I swear it mentioned that they installed a new thermostat.
Now that we're below 0c during the day I'm noticing that the car is awful at keeping warm. Normally I'm out in the morning, unplug the block heater, crank it and I'm off and by the time I'm on the highway the needle is halfway up and then the thermostat opens and everything's happy.
Now I hit the highway and I'm another 3 or 4km down the highway before it reaches 1/4 up the gauge, then the thermostat opens and starts regulating the coolant temperature barely above the C on the gauge. The heater is weak and defrosting takes forever.
The engine isn't getting hot enough. At this point the TAC switch is pulling intake air over the exhaust stove but the exhaust manifold is cold enough that I'll pull up to my first light ten minutes later and the intake air temp is still too cold for closed loop. You have to sit there for a minute or two hot soaking before it satisfies and drops the RPM's. Sometimes if I'm puttering around town and not loading the engine it gets cold enough again the engine will drop out of closed-loop and kick the idle RPM's back up until it's warm.

What was the OEM temperature rating for the '82 model year?

[AMC of Houston]

According to the manuals, should have a 195-degree thermostat.

[TheBirdman]

I think 195 is stock, so it sounds like they put in a 160 or something. For an interrim fix, some cardboard in front of the rad would help.

[AMC of Houston]

Could just be a junk Chinese replacement T-stat.   Chinese junk is, well, Chinese junk!   Some of my local car club pals have had trouble lately with replacement T-stats.  I turned them on to the Robertshaw-style high-flow T-stats; which seem to be a bit more reliable IMHO.

[TheBirdman]

Yeah dont ever cheap out on thermostats, especially when the best ones you can find are around $10. A couple years ago the cheap chinese thermostat that the """motorcraft approved""" rebuilder put in my trucks engine 15 years ago snapped almost completely in half, the engine overheated and cracked both heads.

[MIPS]

Boy I wish I had tried another thermostat.
At -30 this morning, the block heater plugged in and a cardboard sheet on the radiator the engine never warmed up. It's gone through a quarter tank of gas in the last three days and the heater is just about useless.

[86Woodgrain]

I would replace that thermostat ASAP if I was you. When I first got my Eagle it wouldn't ever warm up, I swapped in a new 195 thermostat and it instantly fixed things. I also flushed the heater core (GENTLY) using the garden hose too. https://forums.amceaglesden.com/index.php?topic=46749.0

You didn't say how long ago the thermostat may have been replaced but if it was put in by someone else it may be the wrong rating or could have just been a cheap garbage one that didn't last.

[MIPS]

Yeah once it's warmer out I'll drain down the engine and pop the housing off but right now it's too cold to be working in a car park.

The thermostat is about 6 months old, but I don't know what temperature rating they installed. Bit of a tough one because you cna't guess the value and hope you got a hotter rated thermostat without taking the current one out LOL!

[86Woodgrain]

Just put in a 195, I wouldn't bother checking what's in there, it's obviously not working for your needs as is and is likely failed.

[SpreadEagle]

Too bad you don't have one of those point and click thermals. See what is actually heating. The Harbor place used to have them reasonably priced. My luck would be they never put a thermostat in or it's backwards.. Not  in this case just saying. Have a great day. Woke up here and it was only 2 not -30.

[Illeagle1984]

Yeah checking in at a balmy 6F down here.  I can't believe you're still dealing with the aftermath of that botched engine job!  Wish I could have done that one right for ya.

It does sound like the thermostat is stuck open; at the shop we've had some bad ones out of the box, all Stant.  195 is the stock temp.  Doesn't matter which one you buy, it's all cheap crap from China.  Maybe not including $20+ pieces from Edelbrock or Mr. Gasket, but I've never used them.  If you have one of those big plastic pinch pliers you could partially restrict one of the radiator hoses for increased heat as a quick fix.  Doubt you could get her to overheat in this cold.  Also I have seen cute little cigarette lighter heaters in cars that come in with no heat, I bet it's better than nothing.

Otherwise it is just about the easiest thermostat ever.  It's supposed to warm up next weekend (for me at least), might be a good time to tackle it.  Or maybe give a new shop this simple job and see how they do.  Cuz you need a new shop man.

Either way, even a quick fix is tough to do in this cold.  Good luck and stay warm out there.

[MIPS]

Yeah my plan was to drain the coolant below the thermostat, do the swap and refill again with the temperature sender to purge the air. Easy job.

Now that I'm thinking about thermostats I need to look at my old head and see if I left the thermostat in it. I might still have the original one from 82 that still worked when I did the swap.

[MIPS]

Thermostat was finally replaced. New one is a Gates 33009 (195 Degree, OE Spec.) and interestingly the thermostat pulled out was also a Gates 33009. Wasn't stuck open and it doesn't look faulty. Might boil it in the kitchen to see what it does but I'm not sure what happened. Perhaps when the engine was hot tanked they boiled something out of the coolant channels that was making it run excessively hot? *shrug*

[MIPS]

Yeah, something modern is being a bit too efficient.

New OE radiator, new water pump, new OE thermostat and new OE fan clutch. Didn't overheat once in the summer (but did get it 3/4 the way up the gauge) and didn't suffer from poor economy, but the first cold snap of the year and it's back to sitting just at the cold mark like it's just too willing to reject heat.

[vangremlin]

Both of my Eagles sit right at the bottom of the range indicator, rarely move except right before the thermostat opens up.