77 280z

The heater valve on this car has been in a permently open position, I thought it was corroded into that position but I have cleaned it, removed a bunch of silicone gasket pieces but still can't get it to close. When I look at it close up I'm thinking I might be missing a part that connects to the plunger valve or perhaps the rubber seal/diaphragm is so hard with age that it can't move.

In the first 2 pics I have removed the switch that sits on top of the plunger, you can see that there is only about an 1/8" of movement and the valve is wide open in both positions. In the pics #3 and #4 I have removed the cotter pin and the brass cap, so the # 3 pic is in the same position as #1,  #4 is the valve actually in the closed position. I guess the rubber is to hard to be flexible.

 

 

Edited July 16, 20186 yr by grannyknot

Seems like the revious owner was thinking the opposite of me. No fluid=no leaks. I'm about to put a shut off valve before the heater core on my 240. They could be completely different though, 280s & the 240S?

When mine died, it did the same thing... Hot at all times. When you pushed your plunger way in and it finally sealed... It's not simply a problem with rubber that isn't flexible enough.

I took mine apart too, and I went a little further than you did. Unbend the clips and the top plate comes off:

Take off the cotter pin and brass support hat and the top seal will come off.:

With that top seal off, it looks like this:

And that's as far as I went. Now it's been several years since I was in this valve and I don't remember the details, but I'm positive... If it was easy to go further than this, I certainly would have. So my assumption is that it was NOT easy and I tossed it into a box in the garage somewhere and forgot about it. At that point, it was clear it was going to be easier to just move to something completely different than try to fix that one, so I bailed.

I'm assuming there's a rubber seal on the bottom end of that rod that pushes against a machined seat down inside the valve in order to close the valve off. I also assume that rubber seal is completely turned to dust and doesn't seal anymore and that's why it flows at all times. Lastly, I assume from the fact that I didn't go any further than the above, that the assy has been pressed or brazed together making that seat impossible to get to without a torch or a saw.

I'm sure someone has cut one completely open, or if not, I'd be happy to do it if I can find my original.

8 hours ago, Captain Obvious said:

I'm assuming there's a rubber seal on the bottom end of that rod that pushes against a machined seat down inside the valve in order to close the valve off. I also assume that rubber seal is completely turned to dust and doesn't seal anymore and that's why it flows at all times.

Bingo, I can't see any other way that it could work. The seal on the bottom of the plunger must have been longer because there really is only about 3/16" travel on the plunger.  OK, so off to the wreckers to look for a 2000 TL Acura heater valve.

Now that I truly know that the valve is buggered I'll open it up and post some pics, part of my ongoing mission to show the world the inner workings of the Z... or just cut stuff up to see what's inside.

I've found that the various valve options all will flow way way more coolant than necessary to transfer heat.  I even modified the attachment  point on the lever so that it would only open about half way at full open on the panel control.  It is still way more than needed.  When you're building your system you might add some flexibility there.  Otherwise you'll only be using about 1/2 inch of travel on the panel's heat control sweep.

And make sure that you get a good firm closing of the valve using the heat lever.  It's the only way to get cool fresh air.  If the lever is partially open you'll get some heat transfer.  The options that use the vacuum **** to close coolant flow are also limited so only the heat control **** works for that.

For all of the work that they put in to it it's really limited in functionality.

1 hour ago, grannyknot said:

Now that I truly know that the valve is buggered I'll open it up and post some pics, part of my ongoing mission to show the world the inner workings of the Z... or just cut stuff up to see what's inside.

I'm looking forward to the autopsy. I love that sort of thing.

As for what valve you find at the wreckers...  Now that I've been through it once, I don't think you need to narrow your scope to that fine of a net. The 'best" option would be one that flows in the designed direction while having the control lever on the comfortable side and having the action in the proper direction. But since they are pretty much just ball valves inside, I'm really not sure how much the flow direction really matters.

I'm thinking if you can find one with the control lever and actuation direction on the correct side, I wouldn't worry too much about the flow direction arrow.

I don't remember the flow direction, but all the 96-2000 civics used a similar valve. And it wouldn't be a wrecking yard without having at least ten of those.

Also, the mid-nineties Corolla (and Geo Prizm) used a right angle valve if you want to mess around with one of those as well. I didn't try one, but you might find it makes the plumbing easier.

1 hour ago, Zed Head said:

When you're building your system you might add some flexibility there.  Otherwise you'll only be using about 1/2 inch of travel on the panel's heat control sweep.

Thanks, I'll do that.

1 hour ago, Captain Obvious said:

As for what valve you find at the wreckers...  Now that I've been through it once, I don't think you need to narrow your scope to that fine of a net. The 'best" option would be one that flows in the designed direction while having the control lever on the comfortable side and having the action in the proper direction. But since they are pretty much just ball valves inside, I'm really not sure how much the flow direction really matters.

There is also the Four Seasons 74827 heater valve that @mikev88 is using here,

 

Yeah, that's a really slick setup that Mike put together. But I think the brass bodied valve would be the only part I would look into doing different. The new all plastic ball valve types (like the Acura, Honda, Toyota stuff) just moves so easily, doesn't use a rubber seal to block flow, and will never corrode. If I were going to put a valve under the dash (where it wasn't easy to get to in the future), I would really try to use one of the all plastic varieties.

That Four Seasons valve is nice because it has the cable anchoring point built in, but that is a surmountable issue. Heck... In fact, those plastic valves move so easily, if it were that close to the control lever, I might even be willing to try no second anchoring point at the valve at all. With that short of a cable, just the one anchor at the head unit might be enough.

So here's the money shot,  not only is the valve not missing anything, it opens and closes 180 degrees opposite of what I assumed.    When the plunger is up the valve is closed, down is open,  however, the valve was leaking out of the top past the worn out rubber seal so it had to be replaced regardless.

 

So it could be disassembled by pushing the stem all the way down and out through the bottom. Replicating seals could be a challenge  though. Especially the stem seal

5 minutes ago, Patcon said:

So it could be disassembled by pushing the stem all the way down and out through the bottom. Replicating seals could be a challenge  though. Especially the stem seal

I'm not sure how they assembled it but the rubber seal on the plunger is too large to be able to push through the pipe.

Fantastic job with the autopsy!

So if that plunger and lower seal cannot be pushed out the bottom, then I'm not sure about the assembly process either! It's certainly possible that they soldered the assy together after putting the plunger and seal inside, but I consider that unlikely.

Next time I have that box in hand, I'm gonna see if I can find my old valve. Maybe the plunger just needs a little persuasion to be pushed out the bottom?

 

 Using crude measurements, I think it will come out. The restriction seems to be the rolled bead at the end. Might have to open up the end a bit. The bead was probably formed after assembly. If the rubber gets hung up in the bead, I'd cut a piece of beer can to use as an inner sleeve to ease it past that spot.