I'm new to flatheads, so this might be a "known issue"...I recently installed a newly rebuilt flathead in my shoebox. Before it was dropped, I had the radiator refurbished and all the gauges in the dash gone through. Now that she's up and running, I can't get the operating temp anywhere close to the mid point. She consistently runs hot. I replaced both sensors as well. Any thoughts? Thanks Michael Posted using the Full Custom H.A.M.B. App!
Are the sensors the right ones? The one with two wire connections is a real gauge indicator,it grounds through the single wire sender. The single wire one opens contact when it reads hot and the needle goes straight to "Hot". I would get an infrared thermometer and see what it is really running at for temp.
Make sure the thermostats are out. Check that your running a 50/50 ratio of anti- freeze and water. Check that your timing is correct. Make sure your exhaust is not clogged. That the fan belt is tight. That your water pumps are good. Have you flushed your engine to make sure all the passages are cleared out. Flatheads can be a P.I.T. Ass when it comes to running hot.
I have found the temp gauges seem to read more hot then the motor acutually is,I built a 51 for my dad that the temp gauge read almost hot but a thermometer in the radiator said 180.
use 2 mechanical gauges ( one for each bank ) donot rely one original gauge for accurate readings--- make sure tune up is correct
Just remember not to let your wife know you are taking her cooking thermometer. I found it can make things a lot hotter around the house and the cooling down period can take much longer than a flattie . In fact don't even let her know you are returning it after you use it if they don't know you have it. Just stick it back in the drawer.
If you take out the thermostats you must use a washer to control flow. Old gauges can be inaccurate, they were kind of a cheap gauge to begin with. Best check it with another thermometer or gauge.
Why would you need to take out the thermostats? If you have 180 stats in then the motor will stay at that temperature as long as your radiator is the right size and good. I have 180's in my 8BA and stays at that temperature in cold and hot weather. Pete
I'll second the motion on an infrared thermometer. You can get one for about $40.00, and they are useful for a lot of things. I found out our oven was running 40 degrees less than the control knob was set. It made the little lady happy for a change. I used mine when it started to read higher than normal on the dash gauge, and found out it was still running 175-180. Checked out the sending unit with an ohmmeter and that was the problem. Changed the sending unit for a good one and all was right with the world. I then used it to check out the differences in temperatures on various locations on the engine, which was quite interesting I'll stick my nose out here and say that unless you have a modified engine build, any one who mentions no thermostats and/or washers is not giving good advice.
Leave the thermostats in. I went through all the "fixes" years ago on my 8BA and found it was not obvious but the block had a crack. The exhaust leaked into the water and pushed water out making me think it was overheating. You need to really know the water temp as others have described. I drove the car carefully for a year then replaced the block. Now I am back to no heat problems no matter the air temp, 50/50 antifreeze mix and no pressure on the radiator.
Thanks for all the great suggestions. Think I'll pickup a therm as noted above to see what the actual temp is. Strange thing today...changed out the fluid and took her for a spin. She ran cold for about 10 minutes and then sprang up past the hot mark (higher than its ever been). Frustrating.
Last question (maybe). I've replaced just about everything I can (fluids, wires, sender, thermostats w/1/8 hole drilled) and I still get goofy readings from my gauge. A quick reading from an IR therm confirms the motor is running at about 165. But the gauge goes to mid point, then straight past hot after about 10 minutes of idling. It's gotta be the gauge. That said, any tips on best way to repair the old gauge? I could install a new mechanical but I'm a fan of nostalgia and would prefer to keep the stock appearance.