carl heath

hi all, i am doing an oil change next week and want to know the procedure where the cam sensor is disconected prior to starting up.i know its by the alternator (i think)but i need to know exactly where and what it looks like.i dont want the "you dont need to disconect anything when doing oil change"as i would rather do it and take no chances,its an my 02 sti,bugeye, many thanks

sc_sjo

iTrader: (7)

I'm interested to know why the cam/crank sensor is disconnected (to prevent fuel/spark) rather than simply holding the throttle down during cranking (to enable flood clear mode)?

I am assuming here the Impreza has a flood clear mode, please correct me if this is not the case.

D1CCY

Easier just to pull out the fuel pump fuse. On a new age this is SBF5 in the box by the battery.

sc_sjo

iTrader: (7)

How is it easier to pull a fuse than to depress the accelerator pedal?

Splitpin

Because holding the throttle open will do everything but prevent it starting. No "flood clear" mode on the ECU firmware I have first hand knowledge of.

Splitpin

Carl: It's usually the crank position sensor that's disconnected, it's underneath the front of the alternator, sitting in the top of the oil pump case behind the timing belt cover. Brown or black piece of plastic with the plug sticking out to the driver's side of the car.

D1ccy's suggestion is just as good though, achieves the same thing.

sc_sjo

iTrader: (7)

That answers that question/assumption then, thanks

L.J.F

iTrader: (31)

So really your better off removing the fuse then as its easier ans quicker! Learn something new everyday

carl heath

ok so remove the fuse,then crank till oil light goes out,replace fuse and start as normal.many thanks splitpin and d1ccy,and all who helped.

splitpin,i have noticed when looking at alternator there is a plastic plug connector pin with a bolt holding it,its a grey colour plug.its directly below alternator(if you stand facing car with legs at front bumper)and above middle pully,whats that plug connector please as i have noticed oil residue on and around it,not oil as in lots and dripping,just an oil residue that stays on finger when wiped.want to sort it if its a gasket from somewhere around there.thankyou.

Splitpin

That's the crank position sensor. There aren't any gaskets, as such, right next to it, but you do have, in pretty close proximity, the oil pressure switch and the oil gallery plugs. In addition the crank sensor actually lives in the top of the oil pump casting.

The pump is (should be!) sealed to the block with Threebond - possibility for leaks here, and in addition a couple of the bolts holding the pump on are exposed to oilways on the inside and should have sealant applied to their threads when they're installed. One of the top two you can actually see above the timing belt cover is in this category, so again there's a possibility a small quantity of oil could seep up and out of it if the thread seal isn't perfect.

Finally, directly underneath the crank sensor, inside the timing belt cover, you have the nose of the crank, timing belt drive pulley - and the front crank oil seal. If it isn't coming from outside somewhere, it's always possible you have a leaking front crank seal, and the drive pulley is flinging some up (as well as all around inside).

So, a few places to look, but you'll probably find the source in that checklist somewhere. Have a close look at the PAS pump and its pipework too.

SkydiveMacca

Excuse my ignorance here people, but what is this technique for, and is it required?

I've bought new oil, filter and sump nut washer ready to do a change tomorrow, but have never heard of this before? Exactly what is required, and is there anything else?

All ive ever done when changing the oil on my other cars is:

Warm the engine to help the oil drain
Undo sump plug and drain oil
Remove oil filter
Wait an hour or so to let the oil drip out (time for a cuppa and some cake usually!)
Fit new sump plug and washer (although my subaru dealer said just change the washer, not the plug)
Fill oil filter with oil and apply a small amount round the seal
Fit filter
Fill engine to required level, regularly checking the dipstick


Help! Don't want to miss anything tomorrow.

Thanks

SkydiveMacca

Forgot to add, it's a 2001 bugeye

Splitpin

The point of it is to reduce wear by preventing the engine from running under its own power for the first few revolutions after the oil change when there's a considerable amount of air in the lubrication system, and therefore no pressure in the bearings.

And no it's not required but it takes seconds, doesn't do any harm, and has the potential to prolong the life of your engine. There's a lot more written about this in other threads so if you want to know more, a click of the search button would help you a lot.

Carl's already pretty much covered the important bit. Before you start the engine for the first time after the oil change, either disconnect the crankshaft position sensor or ECU fuse, turn the engine over on the starter until either the oil pressure light goes out, or about 20 seconds, whichever's longer (do it all in one go, rather than 5 seconds, stop, 5 more seconds, stop etc).

Stop cranking, reconnect whatever you unplugged, go for a gentle drive to get everything warm, and then check your oil level.

The "something else" is to fill your new filter with oil before you fit it. If you haven't already looked, the filters on the Impreza are vertical, top up, so you can do this without spilling any during fitting. Brim it, leave it a few minutes for the oil to soak into the element, fill it again and repeat until the level stays just below the threads. Then fit it.

Doing this will again increase the speed at which oil pressure establishes when you crank the engine over - as otherwise the pump would need to shift 400cc extra to fill the filter up. Pre-saturating the filter medium helps in other ways too.

JonMc

iTrader: (51)

That is the most sensible explanation for cranking that I have seen on this or any other forum. Should you even consider starting the engine without cranking it the consensus previously has been that the engine will almost certainly disintegrate within a few hours use.

Of course the other option for cranking the engine is to run a lead from the battery to the starter as this doesn't illuminate the CEL which would happen if you disconnect the crank sensor. Not sure if the same will happen if you pull the ECU fuse

carl heath

thanks for the detailed explination splitpin regarding possible leaks around cps area.will have a look and most likely sort it along with cam belt soon as not using any oil, so hopefully wont be too bad,many thanks again-carl.

SkydiveMacca

Thank you so much for the help

I always fill filters up before fitting them, but had never heard of this cranking method. Makes absolute sense

SkydiveMacca

Thank you so much for the help

I always fill filters up before fitting them, but had never heard of this cranking method. Makes absolute sense

SkydiveMacca

Just completed the oil change using the above technique (I pulled the fuse). Must say, it's much easier changing the oil on a scooby than it is on a golf!

Quick question, do people here normally change the sump plug as well as the washer, or just the washer? I normally do both, but when buying the bits from Subaru, they said not to bother, and they don't change it?

Used Silkolene 15w 50 fully synthetic on the recommendations of numerous people here. Never seen a red oil before though, a nice change!

carl heath

normaly just change the washer,i do anyway and think thats what most do.

on another oil point-has anyone ever used the millers crx 75w 90 gearbox oil in a 6 speed newage sti ? was reccomended to me by oilman as a good oil,i have used the castrol syntrax last year and is still a bit notchy and stiff sometimes.i know its a common thing for synchros to wear but would like to improve it if poss yet dont want to waste 60 - 70 pounds if it will be the same.

joz8968

iTrader: (13)

Yeah, Pro R 15W-50 or Pro S 10W-50 (although they've had a name change to Titan or something) are great oils in a Classic.

Don't need to replace the sump plug bolt (unless it's a cause of leaks ,obviously). Best to always use a brand new soft copper sump washer, as it's 'crushability' is the thing that creates a oil-tight seal 'twixt sump plug/seat.