Murphy Posted July 30, 2013 Share Posted July 30, 2013 How do I know if this little device is working? Wire is connected, lamp illuminates when I start the car? After my Q-jet rebuild this weekend, I took the Monte out and drove her a bit hard (sorry) wanted to confirm the secondaries were working. Yea that's the reason...... Anyway, she got a little hot, it was 105 yesterday afternoon. But the temp lite never came on and after shutting her down she was bubbling abit into the overflow cannister. New thermostat a few months back (195) Is there any test for the temp sensor or just replace it as it's $12-$15 bucks??? SBC350 Quote Link to comment Share on other sites More sharing options...
72-CLASSIC_RIDE Posted July 30, 2013 Share Posted July 30, 2013 When I replaced my 350 CI with a 402, I purchased a Temp Sensor from a local Auto Supply and found it did not read the correct Temp. I discovered thru a thread here that the newer sensors don't function well with our later model cars. I ended up using a heat sensor infrared gun at different points on engine to confirm false reading. Replaced Temp Sensor with earlier model design and reads correctly ever since. Been awhile back but found what I was looking for by either a web search or someone here directed me to it. Before you make a Temp Sensor change, verify the thermostat is functioning correctly. Even new ones can be faulty! If access to a infrared Heat Sensor gun, check engine temp at different locations. Not sure at what temp your warning light should activate. Also, how is your anti-freeze mix. Should be a 50 50 mix. Anti-Freeze boils at higher temp than water and you may think that engine was to hot. Last but not least, if sensor and thermostat check out, the culprit could be a restricted Cooling System such as clogged radiator. That's all I got! Doug Quote Link to comment Share on other sites More sharing options...
Murphy Posted July 30, 2013 Author Share Posted July 30, 2013 Thanks Doug, good info. My antifreeze mix is probably too high (technically)It's more like 80 antifreeze 20 water. But that shouldn't hurt, right?? I'm definitely questioning the thermostat. It has a 195 now, do I dare go with a 180 in this climate? Have been looking as some higher quality units which have better flow......they're all pretty cheap actually. Quote Link to comment Share on other sites More sharing options...
wallaby Posted July 30, 2013 Share Posted July 30, 2013 You have an idiot light? If so, those are really set up to give warning at the "almost too late" stage...I want to say 230 degrees but could be wrong. When you turn off the engine the water stops circulating so temps will climb above normal. It's normal for the expanding water to push out into the reservoir, that's why it's there. In fact, a standard system with no coolant return uses a 14 lb cap, where a coolant return system uses a 7 lb cap. If your cap is the return type and working correctly it will draw back the fluid it pushed out as the engine cools down. Quote Link to comment Share on other sites More sharing options...
Murphy Posted July 30, 2013 Author Share Posted July 30, 2013 Yes I have the idiot lights, I added a reservoir tank last fall but haven't changed the cap, Do you think I should? I'm going to pull the thermostat and test it this weekend, in this HOT climate should I stay with the 195 unit or go to the next option which appears to be 180? Quote Link to comment Share on other sites More sharing options...
Leghome Posted July 30, 2013 Share Posted July 30, 2013 I always have my water antifreeze mixture 50/50. That could be a part of the problem. even here where it gets quite chilly in the winter the highest recommendation I have been given is 60/40 antifreeze to water Quote Link to comment Share on other sites More sharing options...
72-CLASSIC_RIDE Posted July 30, 2013 Share Posted July 30, 2013 If the Engine specs call for a 195 degree thermostat then typically that is what you should use. I'm no techno geek but the engine performance in part is based on that engine temp in simple terms. I don't have the idiot light in my car so wasn't aware of at what temp it would trigger the light. As Wallaby indicated, 230 degrees triggers it then it's time to shut er down and figure out why. As Wallaby described, Was the water boiling or was it just flushing back to over flow? If expansion of heated water caused what you thought was boiling but merely forced from radiator into overflow, then your Temp is probably in correct range. Because water expands with heat and contracts when cold, keeping the radiator full requires the use of the overflow. Otherwise, when the water expands it gets pushed out and your radiator is never full. Just one last thought. You can put the thermostat in upside down and then you have a problem. Doug Quote Link to comment Share on other sites More sharing options...
wallaby Posted July 30, 2013 Share Posted July 30, 2013 My engine builder recommended a full-flow type thermostat of 160 degrees. 180 is considered normal, and 195 would be good for winter when you need more output from your heater. Quote Link to comment Share on other sites More sharing options...
footballubet Posted July 30, 2013 Share Posted July 30, 2013 Also the coolant getting pushed out of the rad is normal when the level in the rad is too high. The level with a reservoir recovery is about 2" below the filler neck and without is about 4". I would drop to a 180 thermostat. Quote Link to comment Share on other sites More sharing options...
Toppless72 Posted July 30, 2013 Share Posted July 30, 2013 I know this sounds like nit-picking but you don’t have or need a temperature sensor. A temperature sensor works within a computer controlled closed loop system and sends varying voltages to the computer based on changes to the temperature of the engine coolant. This allows the computer to make changes to fuel trim to compensate for atmospheric conditions IE: heat cold etc. The system in these cars requires a temperature sending unit. If you have warning lamps, the sending unit has a metallic contact that expands while the engine warms. Once it reaches a set point in length due to heat it makes contact to ground and lights the tale-tail lamp on the dash. A sending unit for warning lamps is either off or on. There is no in-between. In order for the system to work correctly you’ll need a high quality temperature sending unit. Quote Link to comment Share on other sites More sharing options...
Murphy Posted July 30, 2013 Author Share Posted July 30, 2013 Thanks guys, I'll try to answer all the questions, No the coolant wasn't boiling, just pushing back into the overflow tank after shut down. Just a little bubbling nothing major. Sorry for my incorrect terminology of sensor vs sending unit, I realize & understand the difference. The top hose from the thermostat housing to the rad seem abnormally swelled which I'd not ever noticed before leading me to beleive that the thermostat wasn't opening properly causing pressure on the hose. I'm sure the stat is installed correctly (spring is down)or I probably would have seen problems before now. I'm going to replace the stat with a 180 as per suggestions and delute my coolant mixture some. I'll keep you posted........ Quote Link to comment Share on other sites More sharing options...
Murphy Posted August 1, 2013 Author Share Posted August 1, 2013 Looking at replacing the 2 radiator hoses, top & bottom, as their a bit soft and 20 yrs old. Looked online at NAPA, Autozone and O'Riellys which are local to me and none of their hoses appear(online anyway) to have the correct bends...Possibly will call the local chevy dealer to see what they might have.... Quote Link to comment Share on other sites More sharing options...
zmanabba Posted August 1, 2013 Share Posted August 1, 2013 I got all of my hoses at NAPA I would walk in to the store if I were you. Some of the older parts might not be in the online system. The guy actually had to look mine up in a book. Of course that was about 4 years ago so things might have changed. I would stay away from a chevy dealer for the older stuff. In my experience they don't like to keep inventory. If it helps I was able to use the same hoses for small block or big block. That is unless my CRS has kicked in lol. David Quote Link to comment Share on other sites More sharing options...
footballubet Posted August 1, 2013 Share Posted August 1, 2013 I have an extra set from NAPA since I used the stainless steel on mine. But the shipping would probably be more than to buy at the store. Quote Link to comment Share on other sites More sharing options...
Murphy Posted August 3, 2013 Author Share Posted August 3, 2013 Hey guys, got my hoses at NAPA, exact fit! I was getting ready to fill the rad when I was moving the old hoses out of the way and noticed this long spring inside the bottom hose. It appeared abit corroded but actually the crud wiped right off to reveal a stainless spring, most likely to keep the hose from collapsing. Guess a should put it back in RIGHT? Quote Link to comment Share on other sites More sharing options...
zmanabba Posted August 3, 2013 Share Posted August 3, 2013 Yes put it back in. The lower hose is the suction side the spring is to keep it from collapsing. David Quote Link to comment Share on other sites More sharing options...
Murphy Posted August 4, 2013 Author Share Posted August 4, 2013 Roger that, it's back in....... Quote Link to comment Share on other sites More sharing options...
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