Crusader_9x

hey i was wondering if there were any wasy yahl knew of to tell if i had a s4 or s5 motor in my car. the recipt with the car shows a s4 motor. but the shop that didi it swears that its a s5. so i know it has an electric oil metering pump but they said they put all the emissions and other miscelaneous bull off the old one onto the newer jspec that they put in. so my question is this. i want a s5 so how do i tell what i got? cuz my motor just blew and i want to know whether to rebuild or get s5?

scathcart

No way to tell without opening it up, if they swapped on all the extrernal accessories from the old motor.

Crusader_9x

alright htanks, hey do u dtill have that engine removal write up?

CANRX7GX

iTrader: (1)

not too sure abou tthis but would a compression test tell you.?? i believe the s5s have a higher compression ration then the s4s.... but im not 100% on that

HOZZMANRX7

iTrader: (43)

That will confirm the year it was made, thus if S4 (to , say, 11/1988) or S5 (for sure after 1/1989)

LT1-10AE

Pull the temperature sending unit out - the one that is next to the oil pressure sending unit. If it has very fine threads you have an S4. If it has coarse pipe threads you have an S5. The S4 will also have an aluminum washer on the sending unit to seal it.

Crusader_9x

where is the temp sending unit at? in the block? also i did a comporession check 3.7 on the first and sdditn even register on the sencond

LT1-10AE

Find your oil filter. Directly under that, you'll see a bronze colored "bell." That's your oil pressure sending unit. About an inch above and forward of where the oil pressure sending unit screws in is the temp gauge sender. It has only one wire going to it and it's quite small. A 12MM socket is best for removing it.

3.7 on the front and nothing on the second is pretty well toast!

scathcart

they indeed do... but a compression test will not help.

scathcart

SFAICT from the post, the motor is not stock. That's why he has a receipt for a motor.

LT1-10AE

Another way to tell the difference: Knock sensor location. S4 will be in the center iron facing forward at the bottom of the oil filler neck. S5 will be above the trailing (top) plug) on - usually - the rear rotor.

This method is the quickest way to tell.

Crusader_9x

well thanx for all yahlls help i will let yahll know what i come up with for sure

88 SE

If i recall, S5 engines do not have an EGR valve.

If you engine has an EGR valve on it, its probably an S4. anyone have a pic handy?

LT1-10AE

Yeah, S5 turbos don't have EGR, but intake manifolds can be changed. I think when it comes down to identifying a bare block (that hasn't already been built), the temp sending unit and the knock sensor are your best bets.

Crusader_9x

wel theres nothing above the trailing plug on the second rotor bu thtere is something above the trailing on the first rotor.

Detriuch

iTrader: (1)

hmm i wouilda sayed check for manifold,eltric oil metering pump. really no way to tell if they put all s4 crap on it without tearing it apart. see how high it will let you rev!!! hehe

LT1-10AE

If it's a rather large (ie: 1.5" in diameter) six-sided chunk of metal with one wire coming from it, then it's the knock sensor and you have an S5 block.

Crusader_9x

welll looks like i got a s5 thanx or all ur help. nwo jsut got to find out if this one is rebuildable. lol

ZoomZoomH

now let me ask this, is it possible for a cheapass owner/dishonest mechanic to replace a s5 motor with a s4??

LT1-10AE

Yes. As a matter of fact I have an S4 engine in my S5. It's a temporary engine while my S5 gets a full on porting/build.

The S4s will also take more boost due to lower compression rotors.

The only thing to change is the front cover (with OMP), and to do it right, the intake manifold (upper and lower), and the turbo.

Only notable differences:
different compression ratios
lighter rotors in 89+ (different counterweights as well)
different front cover/OMP/waterpump

Those are the major items that are different. The minor ones are placement of senders, thread types, etc. Other than that, with an S4 and an S5 sitting on the ground, they look almost identical.

RETed

I know this is for turbos, but do NA's have the knock sensor too?


-Ted

LT1-10AE

Nope. NA's don't have knock sensors.

They're easy enough to determine series just by looks.

ZoomZoomH

can you tell if this is a s4 or s5 motor by these pictures:







I'm planning to buy this car, the motor has been replaced, I just want to make sure it's been replaced by a s5

LT1-10AE

That's an S5 just by looking at the pictures. The block itself is the deciding factor though, which you can't see in the photos.

I have heard of people putting S5 intakes on S4 motors, but if I recall correctly (I've never attempted it), you have to grind down a boss on the center iron in order for the S5 intake to fit.

Also, the temp sending unit thread pitch difference holds true for the NA's as well. Fine thread with an aluminum washer = S4. Coars pipe threads with now washer = S5.