Got a few problems with my 1998 vt commodore

[Chooms]

So I bought a 98 ss vt commodore a few weeks back and I've noticed some problems with it, so just seeing if anyone here can help me diagnose some of the problems.
(Need two people to open hood)
(Car keeps fluctuating between operating temp and very cold) which is making it run rich and all weird)
( Hear a grinding/rattling noise when revving high and going fast) only happens at like 140+
(Also it has the super six engine if that makes any difference)

Any help would be much appreciated.

 

[BOR15]

my mum has a VS that we couldnd lift the bonnet. I purchased 2 new bonnet struts only to find that the hinges has seized a bit. WD40 to penetrate and all is good.

 

[2O4TS]

Try bleeding the air from the cooling system (3 bleeders on the L67?) and re-topping your coolant. My radiator just blew a hole and it also fluctuated temps pretty wildly while I limped home. If it drops to cold you may not have a thermostat installed or it may not be functioning properly. I live in Qld and rarely need the thermostat and sometimes have had it out but if I drive inland in the colder months at night where it's regularly near zero it runs so cold that the cabin heater is basically useless so that could be part of your issue if you're also driving in very cold conditions.

If there's air in the system there'll be times when there's little water flowing through your system and it'll heat up then the water goes through and it cools down until you hit the next air 'bubble' and up goes the temp again.

TL;DR Coolant level, bleed system, check thermostat function.

 

[c2105026]

Hear a grinding/rattling noise when revving high and going fast) only happens at like 140+

Well you know what I'm going to say the remedy for that is.....