Jump to content
Ultimate Subaru Message Board

Recommended Posts

So I bought this 98 OB wagon 2.5 automatic

Now...when it starts,,,you would always here that sound...like when you just changed the oil and the pressure needed to build up? Not sure if it is the main bearings or what...but its due to the lack of built up oil pressure

 

But this car did it always ...unless it was still warm

In fact, on its maiden run,,,i noticed that at idle in drive, the oil light would flicker...i said oh crap! I bought it for a song so i expected anything

 

I changed the oil to 20/50 and no light

 

well...a few weeks later, theres a heavy oil leak from behind the t belt cover

ends up one of the cam seals pushed out some and was leaking

so i do a complete t belt/pulleys/wp/seals...and here's the thing

I pulled the oil pump off to replace o-ring and make sure screws are tight behind the oil pump

Well...a few were a bit loose and one was backed out several turns

 

so i blue loctite them all in

I never understood what this plate was all about and the screws...still dont,,and dont really care

But guess what? The oil pressure when the car was off must have been drainning out becasue of this,,,because now...absolutely no knocking sound at cold start up!!!

I'd ask if this is the reason but it has to be...I did nothing else

 

Needless to say I was quite relieved...and i learned something new

Share this post


Link to post
Share on other sites

Yep, seen that quite a few times, unfortunately usually with the opposite results. Good save!

Share this post


Link to post
Share on other sites

That is interesting. Especially since my 2001 Forester with 106k is suddenly using a quart of oil every 2 months....and my timing belt is due to be changed now anyway. I will definitely be checking out that oil pump and the plate and bolts while I am in there! Thanks for the post!

Share this post


Link to post
Share on other sites

is this an issue on the MY98+ cars? when I did my oil seal I never bothered to pull the pump and I never had any issues with it with the 36K I put on the car.

Share this post


Link to post
Share on other sites

If you search here, or ask here about "resealing" a 2.5 folks will tell you to pull the oil pump and chack those screws. Most of us find one or two loose. Most Loctite them - I just usually tighten them.

 

BTW this also leads to the discussion usually of whether to install the crank seal into the oil pump then put it over the crank. Or to install the oil pump on the crank then install the crank seal.

Share this post


Link to post
Share on other sites

20-w50 is also not the best choice, most of your wear is on startup, and trying to pump that super thick oil is just making it worse, If you've fixed your leaks go back to 10-w30.

Share this post


Link to post
Share on other sites

BTW this also leads to the discussion usually of whether to install the crank seal into the oil pump then put it over the crank. Or to install the oil pump on the crank then install the crank seal.

 

Once I thought...gee...this would be so much easier to put the crank seal into the oil pump while i had it on the bench...so i did

Come to find out...for some reason I had a heck of a time getting it back in place correctly...the circular spring (not sure what it is called) inside the seal kept coming out when i would try to put the pump over the crank shaft....you wouldnt think it should...but it did

I dont do it that way any longer

Share this post


Link to post
Share on other sites

A neat video for how an eccentric gear oil pump works. http://www.motoetc.com/home/2010/03/eccentric-oil-pump/

To expand on that. This design needs to e closed in tightly on both sides in order for the pressure to build properly. The backing plate on the pump is what creates the "enclosure". So if it gets loose the oil will "bleed out" through the gap between the rotors and the backing plate.

 

I will definitely be checking out that oil pump and the plate and bolts while I am in there! Thanks for the post!

The "plate" is on the inside, and will not cause oil to leak externally. Oil being pushed out from behind the plate goes back into the crankcase.

 

is this an issue on the MY98+ cars? when I did my oil seal I never bothered to pull the pump and I never had any issues with it with the 36K I put on the car.
This is a potential issue on every EJ series engine. The screws on my pump were tight. But the expansion rates of the two different metals (aluminum and steel) that the pump is composed of, mixed with engine vibration, can cause the screws to loosen and back out.

Share this post


Link to post
Share on other sites

thats a nice site I've always wondered how the oil was pumped.. but I have a question.. if the oil all drains back to the pan how can the motor crank so slow with thick oil? Does the oil move that quick up the pickup tube?

Share this post


Link to post
Share on other sites

Typically it doesn't drain back. The pump will in a sense hydro-lock with the engine off, and only a small amount if any will flow back into the pan. This assumes the Anti drain back valve in the filter is working correctly.

But these are a very efficient design and do move quite a bit of volume.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×