Sounds like the exciter wire that the alternator sends inside is sending too much amperage to the cluster. Is the alternator a higher output than the last one?
Temp gauge issues after high output alternator install
- Thread starter crotchss
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you mentioned that with higher revs your gauge jumps to 220º so if you pulled off the belt it wouldn't harm the engine to rev it up for a few minutes without the water pump working. That should give you time to see if the temperature gauge still acts strange
Well still dealing with this issue, just got the car out today after winter hibernation. Let it warm up for 10 minutes then drove down the road about 2 miles and back. Temp climbs to 220-230 on the gauge after 1/2 mile, got back home, checked various parts on the engine with my thermal gun. Heads by the sender 220, outside brass on sender 230, thermostat neck 180, inlet side radiator 150, outlet side 110. IDK WTF is going on, it never ever runs warm. So checked the 180 thermostat in pot of hot water along with a 160 stat I had. Both open and closed at the correct times, so I thought I would try something. I put back together without a thermostat and drove it. Sitting there idling it eventually got up to 170 and the fans turned on after 10 minutes of idling. Then took it out on the road again thinking if it's getting up to 220-230 with a 180 stat it still should run warm without. Well as soon as I got on the road it dropped to 140-150 and stayed, drove it pretty hard to see if it would heat up. Ran it up to 7500 rpm in first, second and third; stayed at 150. I only drive it when it's nice out but that's a little cool for me, granted it was 60 out but still. I never lose any coolant and the hoses never balloon, so I don't think there is head gasket issue. Weird thing is after I got done driving with no thermostat the inlet side of radiator read cooler than the outlet, unless I just had my thermal gun pointed in the perfect spot. Any guesses fellas? Any and all help is appreciated
Without a thermostat you are not getting an accurate reading of the engine temp. The coolant flows too quickly without the resistance of a thermostat which creates a condition where the coolant cannot dissipate the heat in the block. The block can be overheating even though the coolant temp is well under the temp where the engine would be overheating.
Ok, so maybe this is a dumb question. If my fans switch on at 170 and both the fan switch and my gauge sender are in the heads, they are reading the same temp. When my fans turn on my guage reads slightly below the mark between 100-220. So I am guessing this is correct? I am definitely stumped. Also a few months before everything started acting up I had switched to a bigger solid roller cam and had the heads milled a tad. Idk if this has anything to do with it or not.
Also when I got back from the no thermostat drive my intake read 100, side of the block read 180 as did the heads.
Do you have a "Painless"-brand sender for the fans? I would verify that the fans are actually coming on as they should. I have had 3 of these fail on my 67 442. I got so paranoid that I wired an emergency bypass in parallel with the relay trigger, so I could turn them on manually if the temp gauge spiked. Also, verify voltage with a DVOM as mentioned.
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