S4 water pump housing interchangability
 

So my T70 is oil cooled only. I have a split air blockoff plate covering my old coolant inlet, and I have seen that most people tap and thread a bolt into the water pump housing to block the old outlet.

My question is, are the S4 TII and NA water pump housings interchangeable? Since I will be taking if off to tap for the coolant temp sensor anyway, if the housings are the same except for the turbo coolant return nipple, I will just switch it for an NA housing and have a cleaner looking engine.

yes, same housing with the exception of the coolant nip for the turbo

and the water pumps are different, though i do not think the flow is a drastic difference between the 2, a turbo pump won't bolt to an n/a housing as it has 1 extra attachment bolt that throws off the bolt pattern for the bottom of the pump so you'll need the n/a pump to go with it. afaik the pumps themselves have the same dimensions but the turbo pump has more stout bearings/seal as well as the bolt difference.

simplest to do what everyone else does, drill+tap+pipe plug.

lol, no they don't. S4 and S5 are different, but turbo and NA are the same

you are describing the difference between the s4 and the s5 pumps,, s4 is 7 bolts, s5 is 8 bolts and they do not interchange

many parts retailers have the numbers wrong in the cross listing and often have the 8 bolt pump listed as 86-91

86-88 is 7 bolt
89-91 is 8 bolt , and the water pump housing clashes with s4 ( and 12a ) timing covers ( you need to grind the back of the pump housing in one spot )
it also has the inlet leg out at an angle,, to clear the s5 EOMP


n326-15-100 s4 pump aftermarket GMB = WP 4017
n350-15-100 s5 pump aftermarket GMB = WP ?

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if your two bolt thermostat cover 7 bolt water pump has a alt bracket bolt that is long and goes through to the front plate you have an s4 water pump

if you have a 3 bolt plastic thermoneck cover 8 bolt water pump with V pulley you have s5

pics tell 1000 words

https://img88.imageshack.us/img88/3713/pic0511835.jpg
s5 /\
n350-15-100

https://img856.imageshack.us/img856/6512/pic0511837.jpg
s4 /\
n326-15-100
note also this water pump housing also has extra hole fro a tab that locates the OMP lines
( not included in the water pump gasket line )

https://img196.imageshack.us/img196/6300/pic0511836.jpg
12a/ early 13b pre 1985
n232-15-130
( or n232-99-153b for the alum version )
8872-15-010B
,,note the completed assembly in this example has an extra hole for OMP line locating tab while other does not ,, this is not part of the water pump hole count

Cross-referencing on RockAuto, they show the same water pumps for both turbo and NA S4s. If they actually aren't different, I would much rather have a nipple-less housing to go along with it.

i have an 8 bolt pump on my S4 TII, so meh, maybe it is just an oddity but i have seen both types on both series.

Do S4 and S5 water pump housings require the two shim washers between them and the front plate? They do right?

yes, theyre needed. i hear you can crack the housing by tightening it down w/o shims. they compensate to an extent for the gasket thckness

Thanks, I always forget if it's just one series or the other.

Sorry to bump old thread, but does this mean that for NA S4 guys, if your water pump housing is rotted to a million pieces, you can buy a reman turbo S4 housing, plug the turbo coolant nip, and bolt it on no problem? I think it's because the 1st gen guys stole all of them, but those S4 NA housings are getting very rare, considering the dealerships and places like Mazdatrix ran out. All that are left are S5 NA/Turbo or S4 turbo housings.

Ya,you can do that.
I used an N/A housing on my Turbo engine as I was running a T04 and didn't need coolant for it.
Then again I put a S4 TII cover on an S5 TII and used the N/A housing and pump.

Sweet, thanks for the quick response. For future reference, what coolant do you run? the FL-22 is seriously expensive, but I'd rather not get the coolant system rusted out like this again.

I use concentrated Prestone and divide it in 2 bottles along with De-Ionized water.
Like this Stuff..Note, I am in Canada but you should be able to get it anywhere:
Turbo Power Deionized Water, 3.78-L | Canadian Tire
If you want a strong mix,like 60/40 then just don't fill the bottles full with the "other 50%" of the jug.
So,2 Half jugs of concentrated Prestone(about 2ltrs each) and say 1.4l of the Water.,so that the jug is not exactly full..(like about 5/6 of the jug)

Never heard of de-ionized water in coolant systems... I'll have to give that a shot.

So the Prestone isn't affecting your seals? I've read around and it seems it has some sort of corrosive additive that eats the seals, 2-EHA if I remember correctly. Or are you not using Prestone Yellow?

Frankly,I get Prestone..the namebrand..
I read the jug and it looked ok..as long as it wasn't GM shit.
For what it's worth if my engines can last as long as it needs until another Coolant change then the Prestone hasn't had time to eat anything!.
I did a disassembly on my faithful but dearly departed S5 TII engine and the passages were like new...no crap at all.(guy I got it from had cleaned it already,and the engine was bought from him 6 years ago.)