erratic cooling on 500sec

1985 500sec, just had new rad, thermostat and waterpump,
the temp sits at 85, for 2 minutes then in the space of 10 secs, goes up to 102, sits there for 20 secs then drops down to 85 in 10 seconds again, no matter what speed im going at, fast or slow, and the whole process starts all over again....

just found that the heater control valve is locking shut, no heat, and there is a constant drip from underneath it, i know i have to change it, but do you think this could be affecting this up and down heating problem, im getting very nervous about taking her out

help please


sam

[mpnye]

FIRST . . . CHECK that you DON'T have too much coolant . . . go for a 50 / 50 mixture . . .

[mbshop]

without a little more info it sounds like you have air in the system.
fix the valve and then fill the system again when its cold. after its warm, open the heater. must run the engine at about 2,000 rpms. after this recheck the level when cool again.
do not overheat the engine!!

thanx for the replies,
ill change the valve, check the coolant mix and run the system thru.........watch this space


sam