Racing water pump? What do I have?
 

Getting parts ready for the 12a bridgeport, I scrounged for a water pump off of one of the engines sitting around.

The pics below show the pump I found and a stock cast iron one for comparision. This aluminum pump is less than half the weight of the stock one.

The only markings on the pump are GMB Japan. That is cast into the housing and on the seal for the front bearing.

The reason I'm posting this question is, I want to powder coat the housing. The rear bearing has some lateral play in it so it will need rebuilt. It will need dis-assembled for the powder coating anyway.

My problem is it does not have a snap ring retaining the front bearing. There is no provision for it and I don't know if this pump is rebuildable. I'm leary about putting it in the press due to the aluminum housing. I'm afraid I may crack it.

So I put the question out. Has anyone seen one of these, are they rebuildable and if so, where could I source the bearings.

Thanks, Scott.

well not to be an ass and just lookand not say anything. might it be an FD pump? Thats my best guess, but it looks nice wish I could offer more assistance.

Never have had an FD. Took the pump off of a 12a. I don't know if they are interchangeable between the two.

I got this alu pump on my rexes.... I can choose here in The Netherlands if I want a alu of a steel pump. I always take the alu one because they can be delivered next day :). I have had never any problems with them, no cracking or what. I've been fitting these for the last 12 years on 12A's now.
Also nice is the little weight-reducting.

Veering slightly off topic, but I don't like the look of the impeller on the Aluminium one... Looks kinda shitty.

Also, doesn't the aluminium FC water pump housing bolt up to where the stock steel one was?

Thats your standard garden variety auto parts store aftermarket pump for an 1st gen. Yes the stamped impeller is prolly a little less efficient but Ive had no problems with them. Dont waste your time rebuilding it. An Autozone replacement is only like $30 and thatll have new seals. Would suck to powdercoat it and have it fail. They usually carry both pumps. If its a rebuilt Mazda unit, itll be iron with the cast impeller (duh). I ask for them to bring up all of them to the counter and I go thru the boxes to look for the alum ones. ;) They look at me funny but the customer is always right!

To try and answer your question. If they pressed it in during mfg, it should press out, but I would be VERY careful so as not to destroy it. Maybe practice on the one you have and just use it as a core for the new one.

Wonder if you can create a hybrid. Aluminium housing with a cast impeller.

I guess youd need to press them apart and measure the main bores.

go for it then make me one!!! :)

Since the rear bearing is bad, I'll go ahead and press it out. If they are only 30 bucks , then I I'll disassemble 2 of them and see if they match up.

Of the half dozen 12as I've had, this was the only aluminum pump I've seen.

The FC housing has a different bolt pattern than the 12a and won't bolt to the front iron. Haven't checked to see if the pumps themselves are the same.

So from what I'm reading here, for $30 I can get some peace of mind that my WP wont chaw itself and nuke my engine AND shave a few pounds off?

Huzzah! It'll motivate me to change my coolant too!

From what I read here searching, the FC alum. houseing can be made to fit the 12a.
I am in the middle of it now, when I went to purchase a pump for the FC houseing, all the parts store had was hunks of iron, nearly negating the mod., also, the pulley mount is farther from the pump mounting surface than the 12a pump, maybe the FC pulley would compensate for that.

The store did have the alum. 12a pump (the subject of this thread) I think this can be made to fit.

Anyone seen an aftermarket aluminum FC pump?

I have 12a and FC pumps and housings laying around the shop. I'll post pics later tonite.

Caution
 

That looks just like a pump I used one time. I didn't like the looks of the impeller but I had just used my last spare MFR aluminum water pump, so decided to try it. Big Mistake. It had lots of cavitation and excess heat problems but luckily no engine damage resulted before I replaced the POS in short order. The MFR aluminum pump has comparable flow for less power and weighs approx 5 lbs vs. 14 lbs for the cast iron pump; no thermostat though.

My '80 had an aluminum water pump. My '85 and my '83 core engine had cast iron.

Will have a look at my friend's newly acquired '79 to see if it is aluminum or iron.

- Pete (If aluminum, it's one more reason why Series 1's rule over all else)

'73 had aluminum, I think.

Nope, the FC housing wil fit. At least 86-88 will. The pump bolt pattern is different, but manageable. Go over to mazspeed and search. Its been done.

Here are the pics.

The first one is 12a and 13b water pumps.

The second one is the 2 pump housings, from the engine side, showing the difference in mounting bolts.

The third is pumps and housings switched. Note the difference in the upper left of both pumps.

Since the 13b housing has the 3rd bolt where the coolant is transferred to and from the engine, I don't think they will be interchangeable.

The water temp sensors are also of a different diameter.

RxCarl. Not trying to argure, but I would be leary of doing the switch.

It would be nice to have both the housing and pump in aluminum. That would offset some of the extra weight of the holley 600 that is replacing the mikuni.

Oops!
 

This is what happens when I don't reread the FSM. I read it last night and thought I remembered correctly. Wrong.

I put the water pump in the press and tried to press the shaft out from the wrong side. I still haven't found the other pieces of the pump. When it snapped parts went everywhere and the 12 ton jack came shooting out of the press. I may be getting older, but I can still move my feet.

As a side note, this is one reason why I wear eye protection often.

I tried pressing the shaft out of the aluminum pump, but it was distorting the housing. Looks like I will save that one for a core exchange and settle on paint, instead of powdercoat, for now,

Hopefully I've had my ration of stupidity for the day. Time to head back to the shop.

[QUOTE=trochoid]
Since the 13b housing has the 3rd bolt where the coolant is transferred to and from the engine, I don't think they will be interchangeable.

The water temp sensors are also of a different diameter.
End quote;

That hole(in the houseing) gets plugged and filled, or welded shut on the engine side, and threaded or heli-coiled on the other side to accept the FC pump.

Why can't the FC temp sensor be used?

Again has anyone seen a aftermarket aluminum FC pump?

https://www.rx7club.com/attachment.p...chmentid=81663

Wait... That's a 12A housing and a 13B housing with the pumps switched?

Fuck it, if they're both aluminium housings, why swap em... Just look for the aluminium pump and be done with it.

No, the 12a houseing is not aluminum, its 8.5 lbs. of iron.
The 86-88 is 3.3 lbs.

Stevan pretty much summed it up. You can drill and tap and use a flush style (internal allen head) plug to block the extra hole. If you use the FB pump then you can keep the alt in the stock position. Otherwise you can locate it in the air pump positon or get creative and make a new tension mount and keep it in the stock location.

Hows about this:

I recently bought an aluminum water pump housing from a 2nd gen RX-7 to bolt on my new half-bridgeport motor. Here are the modifications that are necessary to put one on a 12A motor.

http://memimage.cardomain.net/member...08_19_full.jpg

This is the front (water pump) side of the housing. The red circle indicates a hole that needs to be tapped and helicoiled so you can put your alternator bracket there. The threads for the helicoil won't be very deep, but they should hold well enough.

http://memimage.cardomain.net/member...08_17_full.jpg

This is the back (motor) side of the housing. The yellow circle is a bolt hole that you must weld up. This is the backside of the hole you helicoiled. It is in the coolant jacket of the engine and will leak coolant out through your alternator bracket mounting hole if it isn't sealed. Make sure whoever welds it up knows how to weld aluminum! The blue circle is a coolant port that will not be used unless you want to plug your first gen choke in. If you want to use the first gen choke-temp-sender you will have to drill the hole out larger and tap threads. Just to the left is a fitting that will not be used. You will need to seal this up before you put coolant in the motor. I plan on using a short piece of hose, some silicone, a bolt, and some hose clamps. As a final note, you will also have to use a 2nd gen water pump, water pump pulley, and alternator bracket. The alternator bracket will need a lot of grinding to clear the distributor.


NOTE: All images and content are stolen without permission. (I assume that should be clear because they are stolen...) If the owner of said content gets word of this and comes here, I give you all credit... In fact, please elaborate, like what year car did the housing come from (1986-1988 or 1989-1991), and which thermostat housing you used, FC or FB? That being said, I am NOT responsible for changes in content. (But please don't change the content. It's really good info...)

Also, what did that pipe, to the left of the blue circle, that needs to be plugged go to in it's original FC engine?

If you just use a mazda factory race aluminum water pump, the alt mounts on the side instead of the top.