CarbonMad

hi everyone.... really need some help....

i've got a STI Bugey import with 20k miles, had an oil change 3days ago using Motul 10W40 @ my local garage, the next day the car starting to make some grinding noise at the buttom front of the engine.... it makes that noise every 1sec... until the oil temp is @ about 70c!!! the noise is gone when the car is warmed.... but it sounds really bad at cold start, car drives fine and pulls fine..


HELP
John

CarbonMad

320bhp

Firstly they should of used fully synthetic oil, 5w-20 or 5w-30. Sounds like bigend trouble, If the thin film of oil is removed then this causes metal on metal between the bigend and the shell. The oil filter should of been filled first and the engine cranked but not started, to coat the surfaces.

[Davey]

What is all this talk of filling the oil filter?? I have never in my life pre-filled an oil filter or heard of anyone doing this??? When the oil is cold and the viscosity is high the oil pump can run at over 100psi, the oil filter will be fully flowing in a second or so, and the shells will already have a decent coating of oil.. I'd be boody impressed if you can drain an engine dry!

CarbonMad

i have been told that motul 10W40 is the one to use??

when the engine is fully warmed the noise is gone?? so its the bigend then?? but the car drives fine?? no oil leaks no smoke???

[Davey]

IMHO Big end noise would normally be more evident once the car is warm (and the oil is thinner) or the car is under load.

use a long flat head screwdriver like a stethescope, push one end against the middle of the engine where the crank is, clasp your fist on the other end and put your ear up against it. If you can hear any deep knocking then start to worry..

The major moveing parts at the lower front of the engine are the water pump and oil pump.

The Zohan

I have done this on pretty much every car i have had i was shown this trick by a good mechanic.

[Davey]

It makes no sense though? The oil will not flow through the filter until it is under pressure?

jaytc2003

iTrader: (1)

5w20 or 5w30???? thats a bit low, thought the recommended by subaru is 10w40

Oil filter doesnt really need to be prefilled due to the way it is fitted. As soon as you put oil into the engine it will fill the filter up anyway (saying that I do prefill mine)
There will be no difference in cranking the engine without it starting. If you crank it, your turning the engine over so as long as you dont rev the car initally after start up (which you should never do) there will be no difference with it firing. In fact with it firing it will help as the engine will spin at a constant faster speed so the pressure will build up quicker than slow cranking without firing which in my opinion is liekly to cause more damage.

Like Davey says, it will be very hard to rid the engine bearing surfaces of all oil. Possibly if you drain the oil and leave it for a few days or something but even then I doubt it.

Back to the topic though, could it be piston slap (not heard of it affecting bugeyes but always a chance). Best bet though for peace of mind is to take it to a specialist (preferably not a subaru main dealer)

CarbonMad

if the oil pump faulty, will it make these noises and will the sound goes away when warmed?

thanks again

jaytc2003

iTrader: (1)

if the oilpump is faulty I cant see there being any difference in sound when the oil//engine is warm. Do you have an oil presure gauge? If so whats your readings on this.
I would take it back to the garage who did the oil change and get them to look at it

vindaloo

Not nice finding new, worrying noises.
As previously suggested, try taking the car to the garage.
OTOH, whip off the cambelt covers and have a nose at the cambelt and auxiliary belt(s). Check there's nothing touching either the pulleys or the belts.

If the belts are fine, grinding sounds more bearing(y) than anything else. Maybe a dodgy water pump or alternator bearing or similar.

J.

ALi-B

iTrader: (1)

What other work was performed on the car?

Bets on, as above it's an dry bearing on a belt driven ancillary component(PAS pump, Alternator or A/c compressor), cambelt tensioner/idler pulley, or waterpump.

It's possible that the garage may have tightened the ancillary belt if they found it to be slack or needed to remove/replace it (i.e cambelt change). This can make a bearings on an ancillary become noisey if they are dry or on their way out.