Problem with Intake Coolant Nipple

[marvelous240Z]

Ok. This one is going to be a little hard to explain. I was going to ask Bruce directly but I thought this would be a good discussion.

So I'm assembling my motor (5/71 L24) and installing a pair of beautiful ZTherapy 4 screw carbs and E46 intake manifold when I notice something weird. I go to install the rear bypass tube and I notice that there is no way that I am going to be able to mount the rear bypass tube to the head stud without it interfering with the nipple sticking out the rear of the intake.

So I'm thinking about what could be wrong when I realize, hmmm, I don't remember seeing that style of nipple on my old intake. I go over to my old intake and low and behold it has a shorter, straight shaft nipple with a slot in it, similar to the nipple that would be on the balance tube for the hose going to the anti-backfire valve.

Notice how corroded this nipple is though. And thinking about it more it has every right to be corroded because why wouldn't there be a bulge at the end of the nipple like there is on the front intake nipple or like the one pictured above? I could imagine that rear hose getting loose, or expanding from the heat, causing coolant to push it's way back up the hose towards the intake.

At first I thought the previous owner had messed with my original intake and swapped the nipples but I was looking at some photos online and most rear intake nipples have this slotted design. I have not yet found a photo of the nipple provided with my ZTherapy carbs/intake.

Needless to say, I have some extra manifolds so I pulled one of the front intake nipples off (the ones with a bulge at the tip) and installed it in the rear and now the bypass tube fits fine.

So I guess my questions are:

1. Is there something I'm missing? Is there a reason why the original rear intake nipple is designed without a bulge and with the slot? (I know the slot is for screwing it on because there is nowhere to grab it with a wrench)

2. What the hell was Nissan thinking putting different coolant nipples on the front and rear of the intake? (I guess that's similar to question #1)

3. Where did the rear coolant nipple that ZTherapy provided come from? Is this a Nissan part or is this a custom solution that ZTherapy came up with for some reason?

Thanks in advance for all your help.

Matt

Edited April 27, 2013 by marvelous240Z

[EuroDat]

That Ztherapy nipple does not look firmiliar to me. Might be alternative because most of the originals are badly corroded by now.

I didnt know the E46 manifolds had water heating. I always thought that was on the E88, N33 & N36 manifolds.

Chas

[Stanley]

Looks like your new setup has the manifold heat control valve. It's the (hot=closed) thermostat for the water tube. A good thing to have since it lets the carbs warm up and also provides a bypass for better flow to the water pump while the main thermostat is closed. once it's warmed up it shuts off the water so you're not recycling hot coolant.

Maybe a short piece of heater hose and a couple of clamps. Seems like you shouldn't have to bend that new rear water tube or the clamp. Maybe a spacer under the rear water tube bracket.

[marvelous240Z]

EuroDat I believe the E46 had water passing through the intake while the other intake you mentioned had water passing through the carbs. Is that correct?

Stanley so your saying that fat piece on the ZTherapy nipple is a valve that closes when hot to prevent coolant from passing through the intake? Would this cause the intake to run hotter or cooler?

I still don't understand how I'm supposed to mount the rear bypass tube. The bracket won't reach the stud without interfering with the nipple with the valve. Even with a shorter hose the bracket doesn't reach. Do I have the wrong bypass tube?

Thanks,

Matt

[Stanley]

That valve looks longer than the other corroded hose barb. Looks like the tube would work with the rusty one, but it's about shot. You could get a 1/4" maybe BSPT hose barb at M-C and run the little heater hose to that. Maybe the control valve can be plumbed in line on the other side of the motor before the tee.

Nice water tube. Maybe it's the wrong tube. Can you bend those? Wouldn't want to wreck it, about $80 for those. Heater hose there wouldn't look as good.

[marvelous240Z]

Well I found a nipple that will work but now I'm curious as to what the ZTherapy nipple/valve is for and if it is indeed a valve. I guess I should just ask Bruce.

Matt

[marvelous240Z]

Can anyone else help identify that ZTherapy nipple? Bruce didn't know and Steve is away at a car show.

Matt

[Captain Obvious]

It's a thermostat. Good picture and description on pages EC-12 and EC-13 of the 1972 manual.

72 is the oldest FSM I have, so I don't know if they used a thermostat in that location on earlier years, but from the fact that it doesn't mate well with the tubing on your 71, it seems the answer is "no".

[Stanley]

Saw a couple cars at the MSA show Sunday with the manifold heat control valve. One is stock, the other has a different type. See the spacer on the stock one? Your water tube looks brand new, seems like it should fit, shouldn't have to bend it or make a spacer.

Also saw a few cars with nice engine bays except for a corroded old hose barb there - guess they are hard to remove (mostly they were removed, some were plugged).

[LeonV]

Ah, I recognize that first one. I believe that's Jim's car (JCan on HBZ). He found a thermostat online somewhere and adapted it to his manifold so that he could keep the loop functional.

[marvelous240Z]

Thanks for the pictures Stanley! From what I understand my 71 didn't come with one stock. I like the feature though and my try to adapt it.

Matt

[Stanley]

Just noticed it might fit better after the exhaust manifold is on. If not, you could get your money back for the chrome water tube and buy about 3 foot of 1/2" heater hose to clamp to the valve, and a 1/2" hose splicer with hose barbs on both ends to clamp to the reducer hose of the other side of the engine. Should only cost about $10 for everything, and just as good except for the bling.

Running without the valve may contribute to overheating.