ademid

Hi all

Its time to try and harness the Scoobynet collective knowledge. I'm having some issues with my car, I can't name who's dealing with it or to many details as the situation is not yet resolved, but I'm trying to ensure I'm not being led up a long garden path...

I took the car in to have the head gaskets done (car is a pre facelift MY96 uk turbo) the only symptom it was showing was pressurizing the water system if you had an enthusiastic run, other than that it was running like a dream. It has been reasonably modded running about 300-330bhp i guess (was 298 on powerstation rollers then had 440 injectors fitted and a gems ecu/re-map). The only time I had it at santa pod did three runs and clocked 13.2 so not too bad.

Anyway when I picked the car up I had a steady drive home and then did two journeys again keeping things steady, on the way home and at a number of different times I smell a burning oil smell inside the car. I called the garage about it and was told not to worry things settling in so on. Ok I thought. The car was parked in my garage on the sunday night until the next friday. When I started the car got a knocking which quickly quietened, I moved the car onto the drive until the next day, the same thing happened when I started it on the saturday I then went to drive it to a local supermarket and got no further than about 50yrds before decideing that it was knocking and sounding awful I turned around and when home. Complete mileage after picking the car up just under 130miles. Called garage car was collected and was then told the big ends gone

Have just been told that the oil pump had siezed and that was the cause of the failure... If this a common failure? and Would the oil pressure warning light not have illuminated if the oil pump had failed?

Help me please as I just want to be sure I'm not having the wee wee extracted..

Thanks in advance

Ade

john banks

The valve on the oil pump can stick open I believe which then leads to low oil pressure. It has to be really low to illuminate the dash light - so low the engine has probably already failed.

What was the oil level like the few times you drove it? A more significant leak could have meant the oil level was too low, also leading to low pressure and engine failure.

ademid

Thanks for your reply John.

I checked the oil and water levels everytime I started the car after I picked it up (as they advised). And they were fine.

As I said I not disbeleiveing anyone I just want to understand what has happened and make sure that it is a reasonable explaination of what has happened.

Ade

john banks

The oil pump if it got some debris in it could have seized open causing the failure.

A lot of people will take the opportunity of having the engine out to renew the oil pump unless they know its status, not saying anyone is negligent in not doing though.

To take every chance of stopping a tuned Subaru engine blowing up I would have at least the following:

Knocklink
Oil pressure gauge
AFR meter
Boost gauge

Then you have warning of most of the common things that go wrong - e.g fuel system problem - leak/fuel pump/regulator/injector, knock - MAF/fuel, oil pressure for sudden massive leaks or dodgy oil pumps - might just get the chance to shut it down in time.

These are I would say the biggies for possibly preventable engine failures. I would think an oil pressure gauge would have given you early warning, big ends could have gone regardless though.

john banks

It will feel very $hi**y for all concerned to lose the engine after 130 miles though. Perhaps you might be able to reach an arrangement with the garage?

ademid

Thanks again John.

The garage aren't being unreasonable (they seem to be being very fair at the moment) but I don't want to confuse that with the possiblity that I might have missed something. Sounds like its reasonable to accept that has happened then.

Thanks again

Ade (keeping fingers crossed that the bill doesn't get silly)

APIDavid

iTrader: (4)

Oil pumps don't seize, they're driven by the crank and the energy of the crank will always overcome the resistance of the oil pump. The starter might not after it's all cooled down, but generally it'll still turn.

Just a point of discussion JB; for the relief valve to stick and create low oil pressure it must have gone past the point of normal position. Say that the O/P is normally 60 psi, that's where the relief valve will position itself. Thus if it sticks, the ultimate pressure will be 60 psi not less. Agreed it will take a little longer to reach 60 psi as the valve is open, but if the pump is functioning it MUST reach 60 psi. Loss of pressure is usually because the bearings are slack and are leaking it out of their sides.

The pump and relief valve are downwind of the filter so debris cannot really reach the pump or the valve in normal circumstances. A poser, l agree.

We have now done something like 500 rebuilds since we really started counting in January 2001 and have only ever replaced about 5 pumps that were absolutely destroyed in a mega failure. We have fitted 2 modified oil pumps that customers insisted that they had, customers always right isn't that so??

Otherwise ALL oil pumps get stripped, cleaned, linished valve, oiled and refitted. Never had an engine of ours fail for O/p problems. only EVER had 7 fail at all to be frank, out of over 500?

7's too many, but those are the facts and some of those people post on here and will attest to their warranty treatment at API.

David APi Engines / APi lmpreza

john banks

Thanks for the input David. I am probably just recycling false information used to sell people uprated oil pumps?

I guess I wasted my money on an "uprated" Roger Clarke oil pump?

One other mystery in the Subaru big end problem?

john banks

This is the ad in Scoobyshop:

"It's well known that the pressure relief valve is prone to sticking in the stock oil pump.

At best this can cause premature component wear, and at worst, lead to engine failure.

Roger Clark start with a new Subaru oil pump, and modify the pressure relief valve, to prevent it sticking. Then the gears are stripped, inspected, and de-burred.

Highly recommended for all engine builds, and well worth doing at the same time as a cam belt service."

stockcar

never had a std pump in bits yet that doesn't have side wear and 'stiction' marks................virtually always one sided, so is obviously travelling at an angle to the bore...............

we now source and modify our own and to be fair at the same cost as the std pump from "subaru" why would you not??

alyn - asperformance.com

rb5037

Mmmm sounds like my story, only the're not helping (Subaru dealer)

Posted "Short block" (can't get the bloody insert link to work )

Mine went into Subaru dealer to have,

New clutch + bits

Minor service

Fix oil leak (turned out to be arond the cambelt area so guess what)

New cam belt and other odds in that area.

So after paying them £2000 (just under) i had the car back.

They dropped it off at mine on thurs night got into friday morning.

Same as you i noticed a tapping but when turning on and off the engine.

Took it back to them Fri afternoon and they said it was probably a engine bush or heat sheild.

15 miles later on the way home the big end went

Basicly the've told me it's going to cost £3500, possably more, and that's it. I've asked for help but the've said "sorry Mr W we are helping all we can, we're already giving you a % off the hourly rate (Still paying £65 +vat), so in a nice way they are saying "NO! You might be a loyal customer for 2 years but we're not going to help you coz it's one of those things".

I own and run a fireplace company, if a customer has a problem with something that is just one of those things, i will help them out.
Got one at the momment and i'm charging him for the parts, the same price as what the suppliers charging me.

I'll stop now coz i'm getting pissed off

APIDavid

iTrader: (4)

JB,,, Not wasted, just spent unnecessarily. The modified pumps are Ok and a new oil pump would benefit from a looksee before fitting. The 2 modified ones that we fitted were from RCM and they were new and functioned as you would expect them to. Subaru oil pumps do have a habit of loosening the cross head screws that hold the backing plate on. Best to check them and perhaps use a drop of loctite to be sure.

The point really is; The flow rate is governed by the crank speed, thus you can't change it. AND somewhere in the many manuals l have, is a statement from Cosworth [ who know a thing or two ] That ANY [ It's an old book ] engine needs nothing more than 45 psi at 8000 Rpm. So why get a pump with uprated pressure when the 65 odd that most Soobs put out is plenty?

And increased pressure means the pump works harder. that means resistance, that means loss of power.

I note the comments from Alyn, Not our experience though.

David APi Engines / APi Impreza

APIDavid

iTrader: (4)

Ademid and rb5037, if you want to give me a call at the office l'll offer what help i can.

David APi Engines / APi Impreza 01926 614333

john banks

Thanks David.

stockcar

David, all of the pumps on the market are "modified" NOT uprated.................to solve any issues of 'stiction' in the pressure relief valve, the std pressure of the Subaru pump is ample enough !!

to be fair most cars we see are competition modified, though we see our fair share of roads cars for re-builds also...........IMO i wouldn't let an engine out of the door without this simple mod, peace of mind.........

alyn - asperformance.com

R19KET

I've personally seen several pumps with jammed PRV's, all bar one, on engines that had failed.

All had jammed due to minute debris inbedding itself in the pump, and fouling the plunger.

In theory, this should be impossible, due to the position of the filter. In reality, it still happens.

I would also agree with Alyn's comments about wear on one side of the vast majority of plungers I've inspected.

I'm also not certain how a figure of "60psi" mimum, is arrived at.

Firstly, if any engine I saw had a max oil pressure of 60psi (4bar) I would be seriously concerned. IIRC, circa 90psi (6bar) is the norm', with some people seeing up to 100psi (7bar) depending on the oil, and engine.

So what happens if a PSV jams at the circa 90psi position, and then the driver lifts off ?

Oil flow is reduced with the drop in RPM, and with the pressure bleed hole open, there is a serious drop in pressure, way more than just from the resulting drop in RPM.

A similar thing can happen if the PRV jams when the oil is cold, and we see higher pressure. The oil then gets hot, thins out, and pressure drops.

The Roger Clark oil pump has a modified (re-designed) PRV, which is designed to reduce the risk of jamming. The pumps are stripped, and all parts are deberred, before re-assembly.

No one can guarantee to eliminate these issues 100%, all we can do, is improve the parts that contribut to them.

Ade:

I'm not certain that any of the above comments would relate to your issue.

It's very possible that a blown head gasket, could have caused oil, and water to mix, producing an emulsion, which, if found it's way to a bearing, would take it out very quickly.

This happened on my own STi4 engine. There was no sign of water in the oil, or oil in the water, but when the cam covers were removed, there was emulsion in the heads.

Emulsion could be anywhere in the oil system, and not necessarily visable.

I would always suggest trying to flush the oil system out, but there's no gaurantee.

Mark.

ademid

Thanks everyone for posting all this info. I am always trying to learn more about how these beasts actually work.

So from all these posts the main point I'm picking up on is that it is unlikely that anything the garage has done could have caused this failure? And it was just a horrible coincidence?

That's what I wanted to find out as there's a fair chance it's going to get expensive and as it's going to be painful I just wanted to comfort myself that it wasn't avoidable or caused by someone elses mistake.

Thanks again.

Fingers crossed this doesn't force a sale of me scoob

Ade

APIDavid

iTrader: (4)

60 psi, was a nominal figure plucked out of the sky by way of example.

Alyn, we do linish all pressure relief valve plungers to a mirror finish. You can only go on results and ours speak for themselves.

We also build uprated engines, for ANY Japanese car, have done since 1982 when I formed the company. Nowadays we direct our energies to Subaru.

Cosworth know their stuff, if they say [or did say] an engine needs only 45 PSi continuous at 8000 rpm they mean it. You can have too much pressure!

David APi Engines / APi Impreza

R19KET

David,

I think the point is here, that you also modify (fettle) the oil pump to limit any problems.

I can't comment on the Cosworth info, because I have no idea in what context it was written, or if it relates to "all engines, regardless of design".

Mark.