[Mgs] Running hot

Simon Matthews simon.d.matthews at gmail.com
Sat Jan 30 12:23:16 MST 2021


Why does your car have an electric fan? I had a '74 MGB in Dallas and
it never overheated. The seats got very hot, but not the engine.

Are you sure the fan or fans are blowing air in the correct direction?

Have you tested your thermostat?

Have you checked that the radiator is really working? Check the
temperatures at the top and the bottom.

Simon

On Fri, Jan 29, 2021 at 6:14 PM <rolindsay at yahoo.com> wrote:
>
> Hello friends. I haven't written to bother you for a long time, but now I do so because I need advice. My recently resurrected '72 MGB's engine runs hot. It doesn't boil over but it 'overheats'. Here are the details from two tests.
>
> 1972 MGB, idling from cold start, bonnet open, 50:50 antifreeze mix, heater valve open, new water pump, flushed radiator, 10# radiator cap, timing set correctly, air:fuel ratio set correctly, carbs balanced.
>
> First day tests, w/o electric fan on:
>
> Time
> Since     Coolant            Gauge
> Start      Temperature   Reading
> -----------+‐--------------------+--‐----------
> 0 min         71°F             minimum
> 1 min         72°F             minimum
> 5 min         160°F           1/4 scale
> 10 min       195°F           5/8 scale
> 15 min       220°F           7/8 scale
>
>
> Second day tests, with electric fan on:
>
> Time
> Since     Coolant             Gauge
> Start      Temperature    Reading
> -----------+‐--------------------+--‐----------
> 0 min         63°F             minimum
> 1 min         64°F             minimum
> 5 min         159°F           1/4 scale
> 10 min       195°F           5/8 scale
> 15 min       228°F           edge of 'H'
>
> Conclusions:
> 1. Engine starts easily, idles smoothly, and runs great.
> 2. No boil over in either test case.
> 3. Electric fan 'on' cannot overcome whatever is causing the car to run hot.
> 4. Temperatures measured at top of thermostat housing, but verified to be the same at the radiator top neck.
> 5. Charge is neither lean nor rich.
> 6. Timing is set correctly.
>
> What product might I use to flush debris from the block and head, if that is indeed the problem? Thoughts? And thanks.
>
> -Rick, in Houston, TX
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