My Engines Not Overheating...Right?

[1987 GMC Jimmy]

Okay, so I wanted to see what you guys think about this. My Jimmy has been reading a high temp (about 230*F) on the gauge since I got it. The engine only has about 325 miles on it. There's no coolant loss and no combustion gas getting into the cooling system. I have put a new radiator cap, new upper radiator hose, new water pump, new ecm temp sensor, two new 195 degree thermostats, new temp sending unit, and I've flushed the system. I did an inspection of the radiator while running, and the little core jets were pushing water nicely. I also felt the radiator hose to know when the thermostat opened, and when I ran to check the temperature, it was slightly below that 230 level. Both hoses are piping hot so I know the radiator is clear. I know I could get an OBD1 to USB cable and see what the other temp sensor says, or I could get a temp gun and point it at the tstat housing, but I wanted to make sure I wasn't missing something, and to also see if you guys have had faulty gauge readings and what you did to fix them. Thanks.

 

[rich weyand]

You may have the wrong sensor. The temp sensors were matched to the gauges, but many original temp sensors are no longer available. The replacements listed in parts store books are not exact matches, and in many cases are bad matches.

Read the first five posts in this thread on another forum, especially post #5.

http://67-72chevytrucks.com/vboard/showthread.php?p=6714978

 

[crazy4offroad]

^^^ What he said. If the instrument cluster was replaced from a different year break that more than likely will be the problem. With my dad's truck the needle barely goes above the "C" on the gauge but everything is warm/hot like it should be and I know he replaced his cluster some years ago. A cheap Sunpro mechanical temp gauge would tell you where it's running.

 

[1987 GMC Jimmy]

I know that the cluster in there is the 1987 factory unit. I replaced the sender with the one that the auto parts store recommended for the truck. I assumed that it had something to do with resistance correspondence between the gauge and the sender. Should I just try another sender and see if that works or what?

 

[87scotty]

Mine was that way I put a 180 in it and now it runs 200-210

 

[87scotty]

Mine was that way I put a 180 in it and now it runs 200-210

Thermostat

 

[Georgeb]

Mine was that way I put a 180 in it and now it runs 200-210

If I had a 180 T-stat in and saw 200-210 something would be highly suspect in my book. I will agree more so on the mismatched sender/gauge issue and wold look into that more.

 

[rich weyand]

This is probably what you want.
http://jnjvette.com/store/index.php?route=product/product&product_id=632

 

[bucket]

It could be just a faulty gauge. My old C20 burb that Towjoe now has is a good example, the gauge always read around 220-230 when actual engine temp was the proper 190-200. The truck was all original and parts hadn't been swapped around.