Here are some things I can think of:
1. Partially blocked rad core. Had this once on my yota truck. Chems
wouldn't get it clean. Way to test for it would be: 1. Does it get hotter
when you drive faster? or 2. Let the engine warm up. Mist water onto the
rad fins. See if the water dissipates evenly across the surface.
2. Don't know of this applies to the rover, but head gaskets might be
leaking, allowing air into the system. Again, had that trouble with my yota
truck. when I took the head gasket off, I could see a little line going to
the water hole where air was leaking in. to test, you might let the engine
warm, then squeeze one of the hoses. Or a rad shop will have a pressure
tester. Also check the rad cap. If the spring is warn, it will not allow
enough pressure to build up.
3. Have you tried to richen the mixture? I know a lean mixture will cause
the engine to run hotter, but I don't know if will heat up that much.
That's all I can think of right now.
Oh yea, check the thermostat. I know of you bought one from autozone (not
sure if they even have them) it might be a piece of junk. You can get a
dozen stats before you find one that works. get a good thermometer and heat
some water in the microwave. drop the thermostat in the water and see it
opens at the right temp.
Hope one of these does it,
Mike
>
>As the really hot weather has come, my BGT has started to run very hot.
>It has not yet overheated, but only because I have found a place to get
>off road & let it cool.
>
>Specifics: 4.2L with street cam, Buick front cover, Buick 300 water
>pump, oversized radiator, 2700 cfm electric fan. I ran this setup for 2
>years with a 215, ran cool, never a problem.
>
>I had a Mallory magnetic distributer, no vacuum advance, since the cam
>caused a low vacuum situation, timing set at 10` initial, 34` total. It
>was running a slight bit warm before the V8 convention, so on good
>advice, I set the timing up 2` to 12` initial. Everything was fine at
>Champagne, & the weather was hot, you will remember, if you were there.
>
>The last 2 weeks or so, the engine has been running slightly warmer each
>day. I have fiddled the timing up & back, & totally confused myself. I
>have replaced the thermostat & water pump, flushed the cooling system &
>used a commercial 10 min cleaner, twice.
>
>Today, I replaced the Mallory with the old Buick points dizzy, ran with
>timing from 5` up to 12` initial. Still running at 225`, even on the
>road at 65 mph. If it gives any of you real mechanics out there a clue,
>with only 9.2 : 1 compression, it needs 93 octane gas, pings like crazy
>on 87, while the old 215 at 9.6 ran on 87 just fine.
>
>As this is my deaily driver, 60 miles of highway each day, I really need
>to solve the mystery soon.
>
>Thanks for any help or suggestions.
>
>Jim Stuart
>
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