Been having problems with my 72 240Z loosing coolant. I tought i found the reason when i changed leaking pipe next to valve in passenger side. It didnt help. Just few minutes ago, i took the driver side carpet away for hoovering and noticed that the insulation foam was soaked wet!! It was worked as a sponge and sucked all the leaked coolant , there was at least a litre sucked in. It was steadily leaking trough summer and i didnt notice a thing, except that every now and then i needed to add a coolant. DAMN.

I wonder how much damage this leaky core has made, i mean if it has leaked to transmission tunnel..

For core replace, do i need to remove dash..? I can seriously say that im not good enough to do that job

All help appreciated

Nope, you do not have pull the dash but you will probably wish you had (just kidding). This is a PITA job because everything is tough to reach. Here are a couple of pics to let you know what everything looks like under the dash. The heater core comes out of the enclosure on the right side. Therefore, the blower must come out first: one hard control wire for the air inlet flap, electrical connections, 3 bolts on the firewall.

After the blower is out, disconnect the flex hose (oval shape), hard control wire on the watercock, heater hoses from the firewall. Unbolt the watercock from the housing, then remove the elbow hose and watercock. Open the heater air flap using the dash control. There is a linkage wire inside to disconnect because the right side flap comes off with the right side cap panel. I think only one screw (visible on front) holds the right side cap panel in place. With the cap panel off, the heater core will slide out.

Be sure to replace the short elbow hose (recommend the pre-bent one) and the watercock while you have everything down and consider replacing the heater hoses as well for the same reason.

Hope this helps and good luck.

Jim

Before you pull everything, make sure it isn't just a leaky water valve. They go bad much more often than the core. If the valve is bad, the water will be leaking outside the case, but if the core is bad, the coolant will be coming from within the case and your windshield will get a streaky coating of coolant on it when you run the defroster. Basically, the windshield will fog over any time it's humid once the coolant is on it.

If it is the valve, you might be able to replace just the valve and not disassemble half the car. I can't recal how much has to come apart for just the valve, but I don't believe it's too bad.

Okay, idea of leaking valve sounds better Actually i changed the hose betveen that valve and core itself, but the valve wasnt that good looking. But how can it leak on the drivers side? Anyway, i gotta remove that blower. After that i might be a bit wiser.

Here are complete repair instructions from a club member who goes by the handle 'PALLADIN'. Excellent write up with examples and part #'s.

I am going to upload this to the Downloads are as well...

If anyone knows who Palladin is, tell him Thanks!

Enjoy.

Heater Valve Replacement.pdf

Nice one. Just im not going to remove the dash...

BUT in case i need to, is there any specific instructions how to remove and put it back?

Edited October 21, 201113 yr by Reverend

this manual has excellent section on dash removal

http://www.xenons30.com/files/1971%20FSM%20Supplement.pdf

Second that!

Or you could check our own Technical Articles.

Here's one I wrote years ago:

http://www.classiczcars.com/forums/content.php?146-Removing-Dash-and-Interior-for-Paint

Which summarizes the procedure and here's the original thread with the added comments by others:

http://www.classiczcars.com/forums/showthread.php?6981-Removing-Dash-and-Interior-for-Paint

FWIW

E

Welll..its a quite the big job. I will try first without removing the dash. is it possible to remove the cardboard glove compartment without breaking it? Also can new one be installed dash on if the box goes bad?

Well i decieded to buy a new glove compartment box, the old one practically vaporized when i tried to tinker with it. One screw away from the fan removal

Well i got the blower out, been sanding that. Just surface rust but i might as well sand it and give it a new paintjob. So the core looks ok, as far as i can see trough the leg heat holes, but that doesnt mean its okay. Still no obvious sights of leaks anywhere except in valve. BUT how can it leak to the drivers side.. Is there any way i can make sure if the core is okay or not?

It could easily follow something across and leak down the driver's side. THE way to know is if the defroster blows coolant. It will smell sweet and make the windshield very streaky.