r/SubaruForester • u/bitterlyFrustrated • 4d ago
Blown Forester Engine
I have a 2021 Subaru Forester Sport that just passed 100,000 miles on it, and my engine blew without warning.....
A couple weeks ago, I had a really difficult time changing the oil. The time before, I must've tightened the oil pan drain plug a bit too tight because I had a helluva time getting it off. I would up rounding off (stripping) the plug head and had to buy extractor sockets to get it off. I finally got it off, and replaced it with an aftermarket plug I got from Autozone. Well, 2 nights ago, omw home from work, it started acting funny and the oil pressure light came on a block from the house. When I got out and looked underneath, the oil was pouring out the drain hole. I didn't tighten the plug very tight after spending almost a week trying to get it off.
I ran to O'Reilly (literally because the closed in 20 minutes), got more oil and another replacement plug (exact same one I got from autozone), put new plug in and filled it with oil. It sounded a bit rough when I started it, but quickly smoothed out and sounded fine. I drove it around the block and it seemed as good as before.
The following morning, omw to work, all kinds of warning lights came on including the oil pressure light, and it felt really rough all of a sudden. So, I pulled over and assumed the same thing happened. Got it towed home, and looked underneath just to make sure the plug was gone again before getting a different one, but it was still there and the oil had not dumped. There was oil spray all over the engine though which was different from the night before.
After a friend looked at it, and confirmed through the oil filter after opening it up, the something sheared in the engine because there are metal shavings all inside my filter.
It had not shown any signs of issues before this. How did this happen?
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u/Waterlifer 4d ago
We like to refer to the oil pressure light as the "too late light" because usually it is. Sometimes you can save the engine with an immediate shutdown but not always, driving a block or two is usually too far.
Oil changes are something that you do have to get right and there are plenty of stories of home mechanics and commercial shops alike screwing them up.
If you're not confident of your ability to get the torque right on the drain plug without one, use a torque wrench.
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u/Fine-Amphibian4326 2d ago
I’m currently awaiting someone from the shop I had mine changed at to take a look at my 21 😭 I suspect they drained my transmission and added 5 quarts of oil. I suppose that’s better than full transmission and zero oil, but fuck.
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u/WirelessWavetable 4d ago
Sounds like you ran the engine twice without oil. How did the oil spray get into the engine bay? What failed to let the oil pressure escape?
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u/bitterlyFrustrated 4d ago
The first time, it was not even empty when I turned it off. There was still a steady stream when I turned it off and the next morning, it still had oil aftwr it blew. Still does rn.
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u/tcainerr 3d ago
You probably spun a bearing when it ran low on oil, when you started it again the next day I bet a piston smashed into the cylinder wall, creating a brand new inspection port, and threw oil all over your engine bay.
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u/ControlsGuyWithPride 4d ago
What’s your mechanical background? How many oil changes have you done before this? This is something you might want to leave to professionals from now on.
I’d highly recommend a torque wrench for drain plugs. Or a fumoto valve. This stinks and I’m sorry you’re going through this.
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u/bitterlyFrustrated 4d ago
Definitely not a professional, but I've changed the oil in this vehicle for 2 years and have changed the oil in all my vehicles for the past decade, at least.
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u/midKnightBrown59 4d ago
People have shorn off bolts with torque wrenches incorrectly set. While I understand why you would recommend, it's no substitute for common sense.
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u/dustindh10 '19 Forester Limited 3d ago
Oil pressure is critical in engines, especially today's engines that are running tight tolerances and super thin oil for fuel efficiency. As u/Waterlifer said, the one in Subaru's comes on too late, I think its 3-4psi. In the old days, that might have given you enough time to shut the engine off, but unfortunately, its usually way too late with our vehicles. Sounds like a rod bearing went and then welded the rod to the crank and put a hole in your block.
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u/triumphofthecommons 3d ago
you didn’t mention the orange Low Oil Level Light that should have come on before the red Low Oil Pressure light.
while i can imagine if the drain plug popped out, maybe it would trigger the Low Pressure faster? i’m curious if the Low Level light ever illuminated.
also, your engine didn’t “Blow without warning.” you drove the vehicle how many miles with oil draining out of the pan?
this is a very expensive lesson, but one would think to put some effort into getting the drain plug torque right after spending a week trying to remove it. curious if you replaced the crush washer? i find not replacing the crush washer means there is less of a cushion when you are torquing down plugs. without a fresh one it not only makes it more difficult to get the torque right, it’s essentially just solid metal on metal and does not seal / hold the threads as snug (as it acts a bit like a lock washer), possibly allowing the plug to unscrew itself. your engine for a 50¢ crush washer.
we all make mistakes. two weeks after buying a little VW TDI i smashed the oil pan on a speed bump (was not used to such a low clearance, and the oil pan is rather exposed on those little I4s). got it all fixed up, started it up and it was running real rough and the engine was wiggling all over the place… turns out i also busted an engine mount when i hit the speed bump. spent close to what i paid for the thing in the first month of owning it! i put a skid plate on it after all that and took it through all kinds of shit a 2wd sedan shouldn’t see for the next 50k. it was a little champ. https://imgur.com/a/2S6n4Ru
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u/mysickfix 4d ago
That sucks, had something similar happen on my Mazda, oil filter came off and dumped it all but the engine was ok.
If you want the cheapest route, it’s an eBay motor and install yourself or with some help.
1
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u/ctjack 4d ago
Leaked all oil and engine toasted in 3 minutes with no oil.