bigbl

i would agree with you dipsy,when draining the oil,all the lubricated parts are still lubricated with a film of oil,i have always just filled the oil filter before fitting(as well as filling engne haha) with no engine problems.i have never unplugged the crank sensor and turned it over but this does sound like good practice and for the extra 2 minutes i will be doing this in future

wrighty338

iTrader: (33)

is it deffinatly a tapping from the engine?

i had a rattle once and spent hours thinking it was something to do with the pedal box, turned out to be the gearbox dipstick rattling on something, just twizzled it round and it went lol!

wayner845

iTrader: (2)

It May be worth checking the turbo heatshield isnt rattling probably not what it sounds like if i'm honest but i would rule as much out as poss.Process of ellimination an all that.

Splitpin

Your point being? If you go through it you'll find stacks of procedures that represent obvious best practice that aren't mentioned. You'll also probably find enough errors and omissions in a typical Subaru workshop manual to result in a broken car if you follow it slavishly and without reference to common sense and the experience of others. Search the term "camshaft cap torque" if you want an example.

Subaru are well aware that the oiling on these engines can be marginal under certain conditions - as they've modified a number of parts over the years, not least the crank, in order to try and improve it.

Of course. However, as mentioned above, that can be momentarily displaced by air being forced through the oilways as the pickup and pump reprime after the change.

It's not sufficient merely to have "some oil in the bearings", it needs to be under consistent pressure throughout the engine before you have combustion forces acting against it.

If your view is that this is a lot of fuss about nothing, it'd be interesting to hear how else you explain the repeating phenomenon of engines failing very shortly after an oil change. I recall one fairly recently in which the unfortunate owner heard the it start to knock the first time he started it up after the change, which puts your "and just start the car and let it idle" comment into a slightly broader context.

As Bigbl says, taking the extra steps costs you a minute or two per oil change and has the potential to save a stack of disappointment and money. Other than bloody-mindedness, there's no reason not to do it.

DIPSY

Each to there own how they won't to change there oil .I get the garage to prefill oil filter they start the car switch it of leave it then check oil level .

Tomwrxppp

Thanks for the information, i have managed to get in touch with a local lad that builds these engines and races his own, hopefully he can come have a look tomorow, also i shall be ringin scooby clinic to try n explain prob to em n c if they can point me in right direction, help is much appreciated. Does anyone know if this problem usually mean new block or w.h.y?? what damage does this normally result in? ive been told the mains prob failed, can anyone shed light on what this means???? thanks tom

nick172sport

iTrader: (6)

any news mate

Splitpin

The block will probably be alright but you will be looking at main and probably big end bearing shells, and likely a new crank, plus all the ancillary bits - gaskets, seals, bolts and the other bits that need to be changed when stripping and rebuilding the engine.

Inside your engine the crankshaft is supported in the block by bearing shells - basically semi-circular bits of metal that fit in pairs into the block around the crank journals. The bearing surfaces of the crank sit inside these shells with a very precisely measured clearance between them. Oil is pumped under pressure into this gap and actually forms the bearing - the crank effectively floating on a film of oil molecules that is constantly renewed

A similar setup exists in the big ends of the con rods, in simpler form at the little ends, and the camshafts (and in other places - like the turbocharger shaft). All of these bearing surfaces are machined to an ultra-smooth finish so that the oil can flow freely round and out of them.

If your suffer an interruption in oil pressure to these bearings when the engine is running, the forces generated by the rotation of the engine - and particularly the force of the pistons pressing down under combustion, will break down the oil film and force the crank into direct, metal to metal contact with the shells. This contact damages the surface of the bearing faces, even if the oil pressure is instantly re-established, compromising, slightly, the bearing from that point forward.

This makes it even easier for the metal to metal contact to occur in future, and sooner or later, you will get to a point where the fluid aspect of the bearing is severely compromised and requires less and less force to overcome. A vicious circle.

It sounds a lot like that process has happened to your engine. It's obviously not possible for any of us to be sure what parts have been damaged, how seriously, and why - but the fact that you recently had the oil changed, as you've seen, raises alarm bells, for the reasons explained earlier.

It might simply be that your engine has suffered a totally unrelated oil pump failure (or stuck pressure relief valve). The only way to know is to disassemble it and assess the damage properly.

jef

iTrader: (13)

great explanation/post splitpin

cant really see the point in not following the procedure of unplugging the crank sensor

i mean if you really cared whether you damaged your engine or not, and the fact that your doing an oil change in the first place would suggest you do. it takes what 15 seconds to unplug the sensor?

obv all this info may be incorrect for all i know, as ive done literally 1000's of oil changes and never done this before (not on subaru engines) and never once had a problem - however i certainley know what ill be doing come oil change ime.

OP hopefully its not the noise you here, let us know tho.

2000 sport

iTrader: (1)

Have to agree with SplitPin on this..

I have had Subaru's for the last 8yrs now. I have always looked after them myself, mainly as I don't trust many garages to take the same amount of care as I do.

When servicing them, I have always used a good quality oil, pre-filled the filter & removed the crank sensor following the refill.

I don't want to tempt fate here, but I have never had any engine failures..

I really don't see why you would not follow SplitPins method, it is tried and tested !

To the OP - As stated above, let us know how you get on ?

joz8968

iTrader: (13)

API, ZEN, and numerous other specialsits employ Splitpin's procedure (or, at least, just turning it over on the starter by bridging batt to starter with a temp bit of batt cable).

I, for one, have oil changes done "that way" - and nothing less will do.

joz8968

iTrader: (13)

As said, the nay sayers are just being bloody minded or in denial, simply because of the flawed argument: "Well, in all of x-years of doing oil changes, I've never had one crank failure... blah, blah..." (see all of Splitpin's posts for full details ),

DIPSY

Thats sound good have you ever tried this your self it can burn and melt bits of starter nuts or damage the thread and the battery pole .

DIPSY

You missed out oil pump and modine and new sump if there is any metal particles floating about in the oil and very good clean of the engine

joz8968

iTrader: (13)

ZEN use this method, and count to 20 (about 20secs). This, in their experience, is more than enough to prime the pump, oilways, etc. (oil pressure light should go out within that time).

I think a 20sec continuous burst on the starter is fine.

joz8968

iTrader: (13)

Yeah, modine should be replaced with a new one after a bottom end failure.

Good practice to prob replace the oil pump too. However, I'm assuming the pump is much easier to clean out than the modine(?). So maybe a pump can be reused(?)...

DIPSY

Bit of a problem with doing mine the intercooler tank is right beside the starter motor on the newage Jdm Sti's

joz8968

iTrader: (13)

Just thread a suitable length of batt cable (or similar thickness cable) down past the IC. Then you can touch it against the starter's small ACC pos terminal from underneath the car, can't you?

Splitpin

I didn't "miss them out", I didn't specifically mention them, which isn't quite the same thing (I did mention "other bits to be changed when rebuilding the engine). I didn't try to do a top to bottom explanation of what may or may not be needed, because the primary intent of the post was to answer Tom's query regarding what may have gone wrong, and, secondarily, he's going to be getting his engine examined. Whoever does that is the best person to advise on exactly what needs to replace - at which point we can all chip in.

As you say the modine should be replaced on the back of internal damage but...

Correct. The pump can be fully disassembled, cleaned and the rotors and PRV easily checked for scoring, clearances and spring pressure. If it comes up in spec there's no reason not to re-use it. Although, with a commercial rebuild there's often a tradeoff between the labour charges from the time taken to do all that, and the cost of a new pump.

DIPSY

That sounds like to much hassle

Splitpin

Can't disagree with that. Quicker to just slide out from underneath, jump in the car and turn the key.

To answer your question from earlier about the starter, 20-30 seconds once every few months won't do it that much harm. However, if you're doing an oil change as part of a service/checkover (and certainly if you're priming an engine that's been rebuilt), you do it with the spark plugs out, which takes all the compression force off the bearings, as well as almost all the load off the starter.

DIPSY

You have lost me with 20-30 seconds each month is that for doing a oil change and having a Jdm STI you need to sit in car with foot on clutch to start anyway and regards removing spark plugs new that anyway

Splitpin

Read my post again and it might make a bit more sense. I didn't say "20-30 seconds each month", I was saying, in response to your concerns about wearing or burning the starter out, that running it for 20-30 secs each time you change the oil won't do it any significant harm.

You wouldn't have to bother with that with the "connect the extra cable" method outlined above, as it would bypass the clutch switch interlock. That said though, just jumping in the car is going to be quicker than fixing an extra cable.

JohnD

iTrader: (5)

The idea of the wire from battery to starter solenoid is that you don't have to disconnect the crank sensor, which you would have to do if you used the key! Saves getting, and having to re-set, the error code.

JohnD

Splitpin

What error code? As per earlier, you shouldn't get one from cranking it over with the crank sensor disconnected. I've never seen one across various classic and newage ECU's, and if any of the later newage ones do throw a CEL, it won't put the car into limp mode and it should self-extinguish after a handful of successful starts.

DIPSY

When i get my oil changed next time i will get the garage to disconnect crank sensor if i had the use of a 2 or 4 post ramp i would do the oil change's my self.The above is a safer way for me than trying to feed a wire to the starter

JohnD

iTrader: (5)

On the occasions that I've used the key to crank the engine with the crank pos. sensor disconnected, (03 STi) there has been a CEL You're right that it is of no consequence and would clear itself (I cleared it straight away using the PSi3 meter I have fitted after reading the code, which confirmed CPS)

JohnD

360ste

iTrader: (1)

Having perused this thread with some interest. The main line of this thread is that when the oil is drained, the oil from the pick up tube will drain leaving air in the pipe. When you refill the engine with oil this air is left in the pick up tube. Surely this will happen in any engine not just a Subaru. I agree with the pre-filling of the oil filter as we do this with big, diesel engine, oil filters due to the time it would take them to fill. But I have never come across disconnecting sensors to prevent a engine firing to allow the oil to push through the engine. I can see the reasoning but cannot see how this is Subaru specific. By the way my 02 STi is on 95k with NORMAL oil changes.

JohnD

iTrader: (5)

Although I've owned Imprezas for over 10 years, I'm still staggered by the notion that the bearings are at risk without resorting to, what some might consider ****, oil change procedures.
I've always pre-filled filters on all cars I've serviced over 40 + years of oil/filter changes as a matter of course and often removed the low tension lead from the coil before cranking the engine but when I didn't it still didn't wreck the bearings! What about all the engines that have the filter the other way up and can't properly be pre-filled? Despite the "one way valve" they still drain down overnight or at least after a couple of days. God forbid that Subaru should use such a filter arrangement - there would be engine re-builds every fortnight!

JohnD

DIPSY

John D and 360Ste i am with you on this with doing oil filter change just prefill oil filter and thats it .Awd in Perth and Checkpoint in Arbroath do prefill the oil filter before fitting