I got my 75' running after it has not been started for about 7 years.
Now it is overheating. First thing I thought was to change the thermostat out. After I opened the housing I was surprised that there has never been a thermostat in it ! I put a new one in but I cant get any coolant into the upper radiator hose. I though maybe there is a (small) chance that the thermostat I got was defective so I got a new one, put it in with the same result. The engine overheats. Wather temp is at about 200 degrees when I turned it off.
Somebody told me that there might be an air bubble in the system that prevents the thermostat from opening and that I should leave the radiator cap open when the car runs to 'burp' it out. The coolant level in the radiator started to go up and down and then stayed down after a while. When I turned the heat inside the car on white smoke came out of the vents.
Could it be that the heater core is faulty ?

Crazy thing (at least crazy to me) is that when I take the thermostat out I seem to get some circulation in the upper hose going. Even though it seems not to be much. The water temp is at about 110 degrees and stays there but I cant get any heat inside the car even after a long time running (no white smoke thought).

I can understand there there might be something that is plugged up or a faulty heater core.
I do not understand why there is no coolant going from the engine into the upper radiator hose with a new thermostat though.


Any ideas ?

Thanks as always.
Norman

 

200 degrees isn't overheating...it's about normal more or less. After a car has sat that length of time it can certainly have issues. You didn't say whether the apparent overheating is when the car is idling, driving slowly or at speed.

You should completely flush the entire cooling system and replace all the hoses. The system needs to be pressure tested, including the radiator cap. The hoses could be deteriorated to the point of having obstructions, and the lower hose spring could be rusted away, allowing the hose to collapse under vacuum, creating a restriction.

It's certainly possible you have a bad heater core, but a pressure test could reveal that. If that's the original core you may want to replace it regardless.

The seals around the radiator could have deteriorated. They're critical to maintaing good air flow and keeping the temperature down.

It may not be a bad idea to replace the temperature sending unit. The old one may be bad from crud forming on the sensor and causing it to send an inaccurate signal to the gauge.

If the car hasn't been started in such a long time, you should also have the brakes completely gone over. It doesn't matter if the car overheats if you can't stop it.

 

I agree, a good flush , pressure test , make sure all the fan shroud pieces are there, same with the brakes , just go one system at a time and enjoy it.Ron

 

Water pump ???

 

water pump should be fine. I will try to flush it out this weekend.
I still do not understand why the thermostat wont open though.
Also think that the temp sensor has been moved from the thermostat cover, but to where?

BTW the heater core and blower is in the housing on the passenger side in the engine compartment close to the firewall, correct ?

Thanks

 

The best way to test a thermostat is to put it in a pot of nearly boiling water. Use a good thermometer to check the temperature. When the temp gets to the rated setting of the thermostat you should see it start to open. If it doesn't you have a bad 'stat.

Spend the extra for a "fail-safe" thermometer...the kind that if it goes bad it defaults to the open position rather than staying closed. An engine that doesn't fully warm up is better than one that overheats and causes damage.

BTW - are you sure you didn't install the thermostat upside down? Not to impugn your intelligence but we all make mistakes like that.

The temp sensor should be in one of the cylinder heads. I believe the sensor in the thermostat housing may be a switch for the emissions controls, not a temp sensor.

You should get an assembly manual for your year car. That will tell you about the heater core assembly, which are under the passenger side of the dash.

 

200 degrees is normal temperature.

110 is too cold to heat.

The problem is very basic, it's not actually overheating at 200. It actually needs to run at 200 to run properly and heat the car.

 

Clean the gunk out of the radiator vanes. Pressure washers work great for this. Check/replace the radiator support seals.

Chin spoiler in good shape?

 

Sorry I mean 250 deg. It goes into the red area if I dont turn it off.
Tested the thermostat. It works fine and I am pretty sure that the pump is working fine. The hose that goes to the heater core from the engine is hot. The hose that goes to the radiator from the engine is not.

 

Lower hose collasp ?

 

I had the same issue with my 82. I initially thought thermostat as well. I had installed a new 4 row radiator, new hoses, and new thermostat. The engine side would get hot and the temp gauge would approach 220 before I shut it down. The radiator would be ice cold. My problem was fixed by a new water pump even though the old one appeared to be fine. It's still a mystery to me but the cooling system works great now. FWIW my 82 had sat unused for a while, too.

 

Whenever I have my cooling system drained, I fill the block via the thermostat housing, install the thermostat, then button it up and fill the radiator. Helps eliminate air being trapped in the block.

 

IMHO the first thing you need to do is get an IR temp gun so you know what your real temps are. I'm not saying you don't have another problem, but I spent a lot of time working on my cooling system before I discovered that the gauge was reading between 20-30 deg too high.

Disconnect the upper & lower hose from the rad and flush the block (in through the upper hose and out the bottom). Flush the rad. Flush the heater core. When you are done flushing with the garden hose, some recommend you flush with distilled water--I did, went through 3 gallons or so. Again, this is my opinion, but if you have good flow on all components when you flush, you have a bad water pump. Replace the pump and belt(s), make sure the belts are tight, and put it back together. Clean the rad fins as suggested earlier. Another re-assembly tip, many people drill a small hole in the thermostat apron to prevent an air bubble from affecting thermostat operation. Do a forum search for tips on this.

Last but not least, the single biggest improvement in my temp problems came from making sure my timing was correctly set and my vac advance was functioning. There is a great sticky at the top of this forum regarding the procedures.

As several posts have said, once you are confident that coolant is flowing, and your timing is right, don't worry about temps around 200-210 deg, that is normal. Good luck, let us know how it comes out

 

Water pumps are pretty cheap, and not that hard to replace. I'm no expert, but it kinda sounds like the coolant isn't moving, and that makes me think water pump.

Scott