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Lucas gremlin in the temp guage

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Banjo

Banjo

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I'm gonna run this idea by you guys ans see what you think.
My dads car is a 69 MGB He and mom drive the wheels off of it. They love it to death. Lately (this summer) the temp guage has been running fairly high. sometimes even reaching the top of the guage. The car dosen't exibit any signs of overheating necessarily. the engine is definatly at temp when the guage sayse it is.
coming down a hill it will start to fall, but as soon as you get on it at all it climbs right up again
So far to combat this, dad had removed the thermostat, run radiator flush, and carefully refilled with 50/50 coolant mix.
The other day he said he ran the heater, and it planted right at "normal" and stayed there.
Hmmmm. I wondered if the extra heat dissapation is what helped, or if the current draw from the blower motor is effecting a failing voltage stabilizer and changing the guage reading....
I guess I gotta do some testing.
 
Removing the thermostat can cause over heating. After getting the car up to operating temp, turn off the motor and feel the radiator. Cold spots can be indicative of a clogged radiator. Make sure the fins are clear of debri/bugs that will restrict air flow. Vanes in water pumps do wear out and reduce the circulation of coolant. How old is the water pump? Make sure the hoses are not colapsing. Old hoses can colapse restricting coolant flow. Make sure all seals and parts that are suppose to be around the radiator are there. Missing parts can cause the air flow to detour around the radiator instead of through it.
 
I had a BMW 2002 that always ran hot. In summer traffic I had to turn the heat on to disipate the extra heat... I avoided stop and go summer traffic.

How is your fuel gauge behaving while all this is going on? If the fuel gauge isn't dropping and climbing when the temperature guage is, the behaviour you're seeing is likely to be heat related, not stabilizer related.

If the stabilizer fails to operate and its contacts remain closed, the fuel and temp gauges will both read up to 30% high. Likewise, if the stabilizer contacts aren't opening, the electrical gauges will change in response to the car's operating voltage as you suggested. There are several sources for relatively inexpensive IR thermometers (Radio Shack, Harbor Freight, etc). If you invest in one of those and aim it at the header tank of the radiator you'll have a better idea what's going on.

BTW, this isn't a Lucas issue. Smiths made the gauge and the stabilizer.
 
good points all. I'm trying to get over to my dads to have a look. I've already told him to get a new waterpump as we don't know the age or if it's even the right one, and I reccomended a new radiator cap to make sure the system is holding pressure.
Thanks for the info on the gauges Doug. That's what I was wondering.
I think it is an actual heating issue, not gremlins (Lucas or Smith) We'll get it licked somehow.
 
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