So I've owned a lot of older Subarus (1990 - 1999) and have recently purchased my first 2002. I believe these come with the ej251? Regardless I bought it with a bad transmission and replaced it as well as the clutch. Changed the engine oil and started driving. Car ran great until I was climbing mountain passes. At 10,000 feet on I-70 the engine begin to slightly overheat not even at the 3/4 mark. Immediately after Crank bearing failure and knocking began. I removed the engine replaced it with a good one and began driving again. Drove over two 10,000 ft passes this morning and on my way back home engine failed in the same place as before with the same symptoms. Never once did the temp gauge go above 3/4 but rather went up only slightly before the crank started knocking. And this occured going up the pass on I-70. I have always used Valvoline 5W 30 and 10W 30 motor oils on my Subies with no lubrication problems. Fresh coolant and antifreeze, no coolant leaks seen at time of failure. The first engine could have had headgasket issues but this second one I really doubt it. Any thoughts? I don't want to have a third running engine installed and get this happening again. Both engines failed within 100 miles of the oil change. No codes, or check engine lights ever came up.

A bad run of luck.  The EJ25D (used in the older engines) was known for bad head gaskets leaking internally causing bubbling in the overflow tank.  The newer EJ25 SOHC engines generally had issues with external leaks (oil and/or coolant).  I suspect another issue other than the engine.  Has the radiator/thermostat (OEM) been replaced as part of the engine replacement?

Thermostat and radiator were not replaced however they were not bad as far as I could tell. No overheating to the point at which gauge climbs into hot zone, only climbed slightly below 3/4 mark at first signs of issue, no coolant leakage. Clean engine everywhere on the second one. First engine had oil and or antifreeze near the bottoms of the HG's and had for some time it had seemed. Radiator has coolant.

1. Make sure temp gauges are working properly. Maybe it's overheating worse but you're not seeing it?

 

2. What's the story of the EJ25 you bought? I'd try to avoid cheap questionable EJ25s. I have one that's never been overheated but too far.

 

3. The first one sounds like it was trashed before hand and is no surprise. Second could be bad luck, it would t be shocking at all, particularly depending how it was sourced.

 

4. These engines aren't easy to burp. Ale sure you're getting all the air out.

 

These engines don't throw bearings until they've been significantly overheated - this doesn't sound like what's happening here , so the first run hot event is not causing this. 3/4 yo the gauge doesn't hurt these, particularly that fast. No way.

 

Issue was pre-existing or temp gauge is wonky.

Edited June 9, 20178 yr by grossgary

I pulled the second engine from a wrecked Outback. It seemed very clean, the impact caused the passager cam to slip one tooth. I've seen these run fine when timing is corrected with good belt and parts. This second engine also went about 120 miles over 5 mtn passes at hwy & interstate cruising speeds before the 6th mtn pass back to Frisco killed it.

First engine owner said ran fine when tranny failed. That engine never made the first one, Loveland Pass out of Denver. Other than oily the first one drove good around the city it seemed to for me to be okay.... Anyway if a car can survive Colorado mtns it's good to go long distances I figure.

Hopping between Denver, Frisco, Leadville, Vail, and back through the mtns to Denver is what I do normally in my car on a weekly basis.

If it was caused by the vehicle the temp gauge would have pegged. That pretty much rules out the entire cooling system.

 

That's why I say it has to be the gauge or engines.

 

Both of them registering 3/4 before similar failure sounds too similar. It's one thing to have two engines fail - but back to back nontraditional identical failures is too coincidental.

So dash gauges are a possible issue although neither times spit coolant or oil. Nor is there reason for second to fail it went twice as far and hard which still was only an extra 80 miles. I think the slight increase in temp without overheating (pegging) is possibly due to bearings failing. Still I find the similarities strange as well....

Edited June 10, 20178 yr by iriejedi

00 to 04 Legacy engines have 7mm oil pumps.....

 

We replace with 10mm pumps as a routine measure against low oil volume.

 

We see a higher than normal incidence of rod bearing failure due to low oil volume. As these engines age the #2,3,4 main journal clearances open up due to crank flex - it deforms the aluminum case and causes increased clearance and oil volume requirements. When rebuilding the Subaru split block engine it is essential that the main line be honed after cutting down the smooth case half to restore proper main journal clearances.

 

In the case of used 251's from pre-05 models the 7mm oil pump can't keep up with volume demand due to increased bearing clearance (not wear) on the main line.

 

GD

Edited June 10, 20178 yr by GeneralDisorder

GD, I don't understand what you mean about oil pump sizes. They where both similar engine's being 2000 - 2002 in years.

Sorry wasnt done posting - see my revised post.

 

GD

GD. So if pulling and installing a good used engine you recommend swapping in 10mm oil pumps with used engine installs? I'm grateful we can get info like this. Your experiences are genious!

Edited June 10, 20178 yr by iriejedi

Yes we generally install 10mm pumps, new piston rings, 2.5 turbo head gaskets, and we run all EJ engines with over 100k on 5w40 oil. Our high HP turbo builds run 15w50 race oil and 11mm pumps.

 

GD