scooby seb

iTrader: (1)

hi, just changed my engine oil to 10/50 morris fully synthetic oil and now on lift off engine knocks, is the oil to thin or is the news i did'nt want to know and time for a rebuild????

car is a 2.0 sti classic and has covered 69k

KAS35RSTI

iTrader: (73)

did you just do a normal oil change? or did you try and crank it?

Splitpin

10/50 certainly isn't "too thin". As Aladdin suggests, did you pre-fill the oil filter and establish pressure prior to firing it up after the change?

Also, can you describe the "knocking" to us in more detail? Can you hear it at idle? Did you do any other work on or around the engine during the oil change, or was that all you did?

Jamz_

iTrader: (12)

Aye you didnt use engine flush did you?

scooby seb

iTrader: (1)

i just changed it as i normaly do, i dropped the oil changed the filter, filled it up and started it till the oil light went out then turned it off and checked level, i had it running for a while and i've done about 25 miles in it, as i was coming out of town just doing 30 then just eccelerated and heard a faint nock then got back to work and now when i rev it up to about 3.5k and let off i get a knock, was fine when cold???

scooby seb

iTrader: (1)

no i did'nt pre fill the filter, the knock sounds like the mains, its a very solid nock??? i changed the cam belt to, but car runs fine and is very quiet on tick over???

turbomax

iTrader: (5)

from what i have read which you cant allways belive they can be a bugger after an oil change. some ppl go to great lengths to make sure its primed b4 starting it. my self i fill the oil filter allways have on all my cars apart from mr2 where it was upside down(dont ask). i also removed coil lead and kept turning it over untill i was happy. then put on lead and fired it up not revving it untill few mins.

if the light was on surely this ment it was low pressure for a while and possible oil starvation? any body else wanna comment.

regards max

Splitpin

Oops. This is not the best way to change the oil on an Impreza. Hopefully not academic just yet.

What model year is this car? If you changed the cam belt (and especially if we're talking 99/00 STi5/6), how did you compress the tensioner ram?

The best way forward for you now is probably to get the engine looked at by someone who knows their stuff. The knock could be a duffed cambelt tensioner, or it could be failing bearings caused by the transient oil starvation immediately after the change, which you can minimise by pre-filling the oil filter and preferably cranking over without the crank position sensor for a few seconds. Either way it needs to be diagnosed properly and there's only so much we can do over the internet.

scooby seb

iTrader: (1)

its a 97 version 3/4, i fitted a new tensioner, i've just fired it up again and its doing it from cold now and is a very solid knock from the back of the engine, i'm sure its the mains gone, since i've put this post up its the 1st time i've heard of pre filling the oil filter? i was a tech at ford for 8 yrs and never heard of that??? surpose every one does things differently. oh well onwards and upwards, better start saving my pennys, thanks for all your help, advice and tips lads

cheers scott

KAS35RSTI

iTrader: (73)

what do u mean? did you turn the ignition on to see if the oil light was on or did you just start it? if so how long was it running for? seems like you have not allowed the oil to settle and started the engine straight away, hence the damage.

dj219957

my money is on the big ends, especially because you say you get a knock when you lift off the revs at 3500rpm. sorry. not pre filling the filter will be the cause.

Splitpin

Yes, if you used a new belt tensioner it sounds that way. Bad luck mate.

Thing you have to bear in mind is that Ford hasn't made a horizontally opposed car engine in living memory, let alone the time you were working there. If they had, you might be more aware of this as a potential issue. Different engine designs have different quirks, strengths and weaknesses, and this is something that's a known issue for the Subaru EJ series.

It's also a simple fact that it's physically impossible to pre-fill the oil filter on many other engine designs, at least without most of it pouring back out as you screw it on. If more manufacturers aligned it with the "thread up", like on the Subaru engine, you could do it - and, if you can do it, it's worth it.

scooby seb

iTrader: (1)

yes thats all true and most of the ford engines were pretty simple like they say, you learn somthing new every day, i just learnt the expensive way lol thanks again for your help and advise much appreciated

cheers scott

hodgy0_2

the official Subaru technical workshop manual filter change procedure does not suggest pre-filling the filter

this is a bit of a myth imo (athough i would always pre fill the filter)

but not prefilling the filter is NOT going to fvck an otherwis perfectly healthy engine, remember --- the official Subaru technical workshop manual filter change procedure does not suggest pre-filling the filter

also most decent oem filters have non return valves so perfectly possible to pre-fill the filter in horizontal/vertical fittings

Splitpin

Hmmm, on the one hand you quote the "official Subaru technical workshop manual" and use this to suggest that this is all a "myth", then on the other, say that you do, nevertheless, always do it yourself. A contradiction?

So why, then, is there such an incidence of engines failing immediately after oil changes? You could contend, with some justification, that some of these engines may have been suffering underlying issues but the fact that it takes an oil change to push things beyond critical suggests that something that happens during the change makes matters worse.

From one point of view, you're right: it's not the failure to pre-fill the filter that screws an otherwise perfectly healthy engine. It's the few seconds of oil starvation on the next startup caused by the pint or so of fresh air introduced into the oil system.

So, if the perceived need to do so is a "myth", why do you do it yourself?

Eh? Whether a filter is internally valved or not, if you fill one up and turn it through 90 degrees, are you trying to tell us that nothing will spill out?

JohnD

iTrader: (5)

[QUOTE=Splitpin;8796125]
Eh? Whether a filter is internally valved or not, if you fill one up and turn it through 90 degrees, are you trying to tell us that nothing will spill out?[/QUOTE


Yes, only the oil retained in the "inlet" side of the filter will stay put.
The "valve" is a simple rubber "flap" that is supposed to allow oil in, but not out, although on an inverted filter the oil will eventually seep past the valve, leaving a partially empty filter on cold start-up (eg MR2 - as mentioned)
Fortunately, the Subaru filter hangs down, so no loss of oil. The filter doesen't actually need the valve - as per some after-market filters for this car.

JohnD

scooby seb

iTrader: (1)

just found out what could be feesable to why my engine died, my boss was chatting to andy at ATM and he said he had rebuilt a few impreza engines that had died after they had sat for a while, (which mine had sat for 8 months) he said that if there is any sludge or muck in the oil pump it slide's down into the pressure relief valve and hold's it open and as they oil pressure light switch only needs to see 2.2lb of pressure to put the light out you would'nt get the light to come on to tell you there was a problem!!!

turbomax

iTrader: (5)

oil can sit around for years it wont just start to sludge up. only emulsifers (spell check)when water is present. i have stripped other engines that have been sitting around for ages and allways very clean in the oil ways etc. the days of sludged up crispy burnt oil in modern engines is long gone. old cvhs and vauxhall lumps from the 80s maybe. are scooby engines are known for this as i have not taken one apart?

regards max

you must have been running engine before you drained oil out of it? just seems weird if engine was fine then oil changed, dash light on which means very low pressure at switch which is when damage was done. why dont they make the pressure switch setting higher? on one of my cars when the oil pressure was low it used to cut the ignation off completly so you could not drive it. on that same car my oil drain on the turbo came off pouring oil every where all down the road etc. we drove to my yard and filled it up again and car was fine. i did have a load of that zx1 oil stuff and the one off sky tv in the car maybe it saved it maybe it dident? hope that all makes sense.