Rod knock, but no flakes in oil?

[Leg09]

2009 2.5i AT base sedan. Son was driving home through neighborhood, and pulled over about a mile from home when he heard/felt loud noises and engine shaking. Called me and I went to see, and when he started it up I have never heard such loud banging and screeching, but it settled down in a minute or so to the point we chanced driving it another mile to a known good mechanic. He said rod knock and engine is toast, but it would probably make it home so I drove it a mile to plop it in my driveway. It had very little power going home and was barely able to make it. After reading up about rod knock and spun bearings, I decided to drain the oil (it was low, maybe two quarts and very black) and to my surprise there's no metal flakes to be seen. Now I'm wondering about a timing issue, maybe idler pulley went and if I'm lucky I may not have to replace motor, maybe. Se either way the engine is coming out, and that's what I'm working on. I got the driver side cover off and belt looks intact. The further I get with the work, the more details I will know and can share.

 

Question is: Given the story so far, what would those among you with experience guess at being the problem?

 

I am starting to doubt the spun bearing because of the lack of metal in the oil, and the other horrible noises the car was making and the drastic loss of power. From what I gather a spun bearing will knock and slowly destroy the engine, not give a catastrophic result like what we saw. Am I completely wrong?

[SageAbkatsor]

Idk. With low oil and dirty oil, that sounds like rod knock, but I didn’t hear it.

 

You might be on to something though, if a pulley locked up.

[GEE-OTTO]

Its a spun bearing period and you'll need to rebuild or buy a new bottom. When you get a chance or when you take it in to fix it, look in the oil pan and at the rod bearing that spun you'll see it wont always throw shrapnel around, my 08 2.5i spun a bearing due to low oil and the oil looked like you described.

 

 

 

 

 

The trick is figuring out what all has spun, if its just a rod bearing and all your mains are intact that's not as bad as crank mains and rod(s) be spun. Depending on mileage and overall condition of the car you could be looking at spending more than its worth or about the same as its worth or less.

 

 

 

Low oil is a EJ's worst enemy and the Oil Light for a H4 Subaru is really the "Too late you didn't check your oil and now your screwed" light

[Leg09]

So having pulled the motor, the oil pan has all kinds of shrapnel in it. I see definite play in connecting rod #4 but no play whatsoever in any of the others. Can't really tell yet about crank bearings but I'm hopeful though not sure how to test other than split the case. Mileage is 99K and car is in great condition otherwise. Trying to figure out next steps. I put a downpayment with an auto recycler on a replacement motor out of a 2008 Legacy w/88K miles. I saw and heard the motor run, sounds good so for $1000 I feel okay with that, but what to do with the current motor? How do I know if it's salvageable? I'd actually like to rebuild it, either to sell or as an insurance against the salvage motor going bad someday. It would definitely be fun to tear down and rebuild as a project, but with the bearing material all through it is it worth the effort? I don't know since I don't know how much work it will be. I do plan to test compression/leakdown sometime soon to get more info on condition. Any helpful thoughts or tips?

[Max Capacity]

$1000 for a use motor is a good price.

 

Do you have all the tools needed to do the work of replacing the motor ?

 

If yes, then you might enjoy replacing the crankshaft and parts needed. But most of us would say don't waste your time and money on a 2.5i.

 

Put a new timing belt kit on the junkyard motor, keep an eye on oil usage and drive the car for many years.

[Leg09]

Thank you! I will probably take your advice and save myself the money.

 

But I'm going to ask just so I can learn...

 

So I have all the tools to take it apart and put it back together. What I don't have is experience to decide what MUST be done, and what can be left as-is while its apart. I do know I MUST check/repair crank, rods, and bearings. Is there a reliable process for cleaning out the metal debris from the block and heads? If they cant be re-used there's no point in going forward. Can the oil pump also be cleaned or is that a MUST replace? If pistons are okay, should rings be changed since it's all opened up? How can you tell if a valve job is necessary? Am I completely missing something else that's a major issue? I could use as much advice on stuff like that as anyone would care to give. If a junkyard motor is minimum $1500 to get going, maybe rebuilding the old motor for $1000 isn't a bad insurance policy for the next crisis, or puts me in a position to buy another good Subi with a bad motor for cheap? Thanks in advance for any advice.

[Max Capacity]

Rebuilding a engine is a major undertaking. My long time family friend machine shop owner told me its cheaper to get a new ej257 then have his shop rebuild my engine.

 

The machine shop will inspect your heads, clean them make sure there is no loose metal in the valve covers and other engine parts.

 

I have my own engine hoist and all the tools. Glad I let the machine shop take apart the old long block, check and clean my heads, reassemble the long block with timing belt, and oil pan and valve covers installed. Made my life much easier.

 

If you decide to DIY, have a machine shop check over the parts, clean them, before you attempt to reassemble. You will need new rings, bearings, etc.

 

I did rebuild a V8 back in the mid 1970's and drove that engine for years. The ej25X is more labor then a V8 to rebuild.

[Leg09]

Thank you for the advice! I guess the only remaining question is whether or not the old motor has any value in parts?