Is it necessary to change the fan clutch while changing the water pump?

Thanks

Not if it is still working.

OK, wasn't sure. Heard both ways. Trying to solve a heater problem, as I have no heat in the car. I flushed the heater coil and changed the thermostat, but to no avail. Almost seems like the pump isn't doing a good job of circulating the water, even though the car doen't over heat. Is there another problem to check for the lack of heat in the car?

Have you checked the heater valve?

Not physically, apart from the "feel" of the controls (sufficient resistance). OK, so, begging your pardon but how do I determine if the heater valve is bad? And do I need to drop the dash to check it?

Thanks,

If the pump weren't doing a good job then the engine would seize. (Ask me how I know this!) Verify that the coolig system is full and that it is purged of air by checking level after engine has cooled.

If you are sure that the hoses are hooked up to the core and that the valve is functioning when you turn it to hot then you have a real puzzle. The valve is on the passenger side by a vent. (A foot from your knee when sitting) Check that the valve is moving when you shift the control lever. It is possible that someone bypassed the heater lines. Check that the lines exit/re-enter at the rear side of the engine.

To eliminate the valve/heater core as suspects you could always disconnect both hoses and flush with water to check for flow. (Valve on/open of course)

One other possibility is that the thermostat you have is rated at a cooler temperature. Don't know if they offer diff temp T'stats for Datsun but they do for other cars I've worked on. Make sure that you installed the theremostat right side up by comparing it to a manual's picture otherwise it may not flow.

Well, the core purged nicely. Tstat is high temp stat (sits midway in the gauge when engine warm). No leaks inside. Not sure what to look for in a faulty switch, but will see what there is to see, based on your location description. thanks.

No prob. If water flows in one hose and out the other(engine cmpt side) then I don't know what to say. You flushed the core by disconnecting both hoses right? Might try reversing the direction of the flush in case there is a chunk of something blocking the valve. Just grasping at straws here.

Jim

I disconnected them from the supply (left attached at the firewall) and did one direction only. Will try the other direction tomorrow. Reason I felt there was no circulation was when I disconnected the lines there was a look of undiluted coolant (from the engine drainage), while I knew the radiator was not that dense. And the lower hose was not as hot as the other hoses.

OOOOOOhh Hey! I just remembered. The doors inside your heater box may be different from mine. It is possible that one of the cables to the various flaps is broke, disconnected or slipping. The result is that the heater core may work fine but not be getting any airflow through it. Check the cable on the opposite side of the heater box for function. You should hear the large door/flap opening or closing in the middle of the box. (When shifting from heat to cool)

Try selecting "Floor" and heat or defrost etc and see what happens. Geez why didn't I think of this earlier. Does anyone know the diffs between ventilation plumbing? (240vs260Z)

This might be it.

Jim

Ahhhh. blower works, but not being forced through the core...hmmmm. I'll see if that is the case.

OK, you have given me something to try. I will let you know tomorrow how the troubleshooting turned out. Thanks, JimmyZ

Well, the server was down yesterday, so no reply. OK, here is what I found: air blows 100% of time across condenser, water travels through the core in one direction ONLY (flushing), and two vaccuum lines are cut in the engine compartment at firewall. Still no heat. BTW, the INLET hose to heater core connects to the BLOCK or the copper tube that connects to the LOWER radiator hose?