If a water pump is leaking very slowly, does the entire unit need replacing?
if so what's a new pump worth aftermarket?
The leaking is inconsistent, has heavy patches then doesn't leak for a while.
Thanks.

yes replace the pump,usally the bearings or water seal fail,the water seal in your case has rubbish or something between seals,can play up or come good,but seals are now damaged,new pump about $120 and fit yourself.i changed my pump 3 months ago,a week later the timing case cover started leaking,ford $840 -i rang around and coventry parts cambelltown sells after market ones under $400,the pump runs water into the heads through it,corrosion kills them.try wollongong auto parts for pump,south coast agencies ,ring a few for price. not worth cooking the motor because pump let go,my mates head servicing work gets about 5-8 a week,blown head gaskets,water pump failures,overheated.some heads crack and repairs are not cheap -go for pump also flush radiator- system and add inhibitor to water.

should the temp gauge start going up if the pump is on it's way out?
If it does go, will it start to cook the motor straight away?

may be a thermostat problem,staying closed to long and then openning,dont forget the water leaking from pump,the system is not pressurized and water temp will be higher -212 no pressure and i think 250-258 pressurisd,the motors run hot

My EL went through this problem just recently. I went to pull the water pump off to replace it, but one of the bolts that goes into the timing case snapped off. Had to have it towed to the mechanics. They had to call in a thread doctor to get it out. Messy stuff.

The pump will start squeaking usually... it means the seal has given way and there's coolant in the bearing on the input shaft. Then only a matter of time before she lets go.

I got a new aftermarket pump for $120 from sprint auto parts.

Its can be a bugger of the job - be careful not to snap any bolts - there's a few which go through the pump, through the timing cover and into the engine.

I broke two. Thread doctor knocked me back "nah mate, cant do those ones" lol. Took a week to get it off and then had to drill out the bolt from the timing cover... risky business considering new timing cover is worth $600!!!

Make sure you inspect the timing cover while the water pump is off. look for wear on the cover behind the waterpump impeller. I had mine go on me. Ended up removing the heads only to discover the timing cover had had a pin hole in it.