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Brucey
'17 3.6
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Discussion Starter #21
The only way there is 0 compression on all 4 cylinders is if the crankshaft gear is about 20-45° or so off from the cams or by some freak accident valves on every cylinder got hit. The latter would mean that intake and exhaust valves would be damaged. Doing a leak down is moot when no matter what the problem is being caused by, the engine would have to be removed and disassembled to correct it. As long as the timing is correct now.

There is another way, but since the engine was running prior to the belt popping off it's unlikely. The other way is valves are out of adjustment on the 4 cylinders and can't close or a good number of stem seals or seats is lodging them open. A leak down would tell you which is open on each cylinder, but that still leads to a tear down.

Are you sure the timing mark on the crank is correct?
I'm like 99 percent sure the timing is correct.

The timing marks were all lined up and matched the marks on the belt even. I spun it a few times by hand and it still lined up.
 

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Simple trick to verify TDC to make sure the mark is still good on the crank, put a drinking straw in the #1 cylinder sparkplug hole. Just make sure the straw is long enough at BDC so you don't loose it in the cylinder. As you rotate the crank just watch the straw (or even use a small wooden dowel) extend out the sparkplug hole.

Now, since the timing belt 'slipped', and you are dealing with an interference engine, you are really rolling the dice on getting it running. The problem is if the pistons really did hit the valves and damaged them, you really need to go deeper than just the heads and valves. Once pistons 'hit' something on the compression/exhaust stroke, you really need to look at the pistons and the connecting rods.

You will most likely find the piston(s) head(s) to have a ding, or worse a hole in them. Which then will require replacing the piston(s) and while you are at it the connecting rods. And since you are at the point, you should have the crank shaft looked at to make sure that it isn't bent or damaged.

It's really amazing how much force is transferred into the piston, connecting rod, and finally to the crankshaft if something uncompressible gets inside the cylinder. It's a chain reaction of forces and one or all the parts below and above most likely get damaged/bent.

I wish you all the luck Brucey in getting things sorted out. But... I have a gut feeling that you will be going down a deep, dark, expensive, rabbit hole.

The only time I recommend someone trying to fix an interference engine with a slipped/broken timing belt is for a 'kid' learning how to fix cars, and they are willing to take the time and expect to do a complete rebuild (to learn). Or for someone who just wants a 'project' car and want to dabble. Other wise I just say to go get a 'new' engine (salvage or rebuilt, or just really a new one).

This is why I REALLY, really hate interference engines with timing belts vs chain. If an interference engine uses a belt, I will change the belt at the FIRST sign of anything being wrong, or half the recommended life span. It's just to expensive to deal with a broken belt. IMHO timing belts are the stupidest thing to put on an interference engine, period.
 

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Brucey
'17 3.6
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11,904 Posts
Discussion Starter #23
Simple trick to verify TDC to make sure the mark is still good on the crank, put a drinking straw in the #1 cylinder sparkplug hole. Just make sure the straw is long enough at BDC so you don't loose it in the cylinder. As you rotate the crank just watch the straw (or even use a small wooden dowel) extend out the sparkplug hole.

Now, since the timing belt 'slipped', and you are dealing with an interference engine, you are really rolling the dice on getting it running. The problem is if the pistons really did hit the valves and damaged them, you really need to go deeper than just the heads and valves. Once pistons 'hit' something on the compression/exhaust stroke, you really need to look at the pistons and the connecting rods.

You will most likely find the piston(s) head(s) to have a ding, or worse a hole in them. Which then will require replacing the piston(s) and while you are at it the connecting rods. And since you are at the point, you should have the crank shaft looked at to make sure that it isn't bent or damaged.

It's really amazing how much force is transferred into the piston, connecting rod, and finally to the crankshaft if something uncompressible gets inside the cylinder. It's a chain reaction of forces and one or all the parts below and above most likely get damaged/bent.

I wish you all the luck Brucey in getting things sorted out. But... I have a gut feeling that you will be going down a deep, dark, expensive, rabbit hole.

The only time I recommend someone trying to fix an interference engine with a slipped/broken timing belt is for a 'kid' learning how to fix cars, and they are willing to take the time and expect to do a complete rebuild (to learn). Or for someone who just wants a 'project' car and want to dabble. Other wise I just say to go get a 'new' engine (salvage or rebuilt, or just really a new one).

This is why I REALLY, really hate interference engines with timing belts vs chain. If an interference engine uses a belt, I will change the belt at the FIRST sign of anything being wrong, or half the recommended life span. It's just to expensive to deal with a broken belt. IMHO timing belts are the stupidest thing to put on an interference engine, period.
I'm kinda over Subaru 4 cylinders all together.

Hole through the blocks, head gaskets, timing belt failures, crashed heads, starved turbos, etc. Maybe I've just been working on them too long.

Maybe it's why I'm keeping a clapped out LS around for fun?

Either way. I got this one because I liked the build on it. That's about it.

500512


I'd like to keep it on the road because it's rust free and in good shape other than the snapped timing belt.

I suppose I could drop a whole long block in it and call it a day but my main goal with checking compression and slapping a belt on was "Maybe we got lucky and it didn't crash".

I've seen it happen before with a 99 Legacy. Needed two valves and a belt and it's been daily driven for years. This one probably isn't as lucky.
 

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I'm kinda over Subaru 4 cylinders all together.

Hole through the blocks, head gaskets, timing belt failures, crashed heads, starved turbos, etc. Maybe I've just been working on them too long.

Maybe it's why I'm keeping a clapped out LS around for fun?

Either way. I got this one because I liked the build on it. That's about it.

View attachment 500512

I'd like to keep it on the road because it's rust free and in good shape other than the snapped timing belt.

I suppose I could drop a whole long block in it and call it a day but my main goal with checking compression and slapping a belt on was "Maybe we got lucky and it didn't crash".

I've seen it happen before with a 99 Legacy. Needed two valves and a belt and it's been daily driven for years. This one probably isn't as lucky.
Ok, it's a 'project' car. Nothing wrong with that. 😉 I do hope that it isn't a total loss of an engine.

You might want to go to Harbor Fraught and pick up cheap bore scope and take a peek through the spark plug hole. Saves time and effort of pulling the heads off.

I'm actually doing long distance consulting of a friend and his boy on working on a Subaru that lost it's timing belt at idle (best case scenario, but the previous owner did try cranking it over several times before giving up). The boy wants to learn, so this a great opportunity for him to do so. It was a free donor car which is awesome for the kid. He just has to pay for parts and any machining. (Which reminds me I need to follow up with them and see where they are at).

But this isn't just a Subaru issue. There are to many interference engines with timing belts out there from other manufacturers. It was all the rage to use this design to save weight and try to eek out as much fuel economy as possible. But I've notice that the timing belt is s l o w l y being phased out and the return of timing chains, which is a good thing.
 
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Anyone else want to take bets?
S U R E
I have 2 crossthreaded, reverse thread lugnuts, for free to the person with the right diag! If no one gits it, they go to Brucey! o_O

imaginary.of.course.
 
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2010 2.5 CVT Limited
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I thought it odd the gauge needle didn't even flicker one iota in the video. Even with valves hanging open or a hole in the piston, I would have expected some movement on the gauge,
 

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2020 Onyx
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Is the wiring all the same?
Sadly no. I was mostly joking about H6 it's a nightmare but it can be done.

 

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'17 Outback 2.5i Premium
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Bad seats = maybe 10 / 15 psi leakdown from 100 psi
Bent valves, maybe 80 psi leakdown. Maybe more. That's the point of doing the test.
I would have suggested scoping, but I imagine OP neither has one or could get one; at least one that will bend back to look at the valves.
Teslong sell flexible borescopes on Amazon for $50-75 depending on features - they require a PC/tablet/phone for a display (they also sell a dedicated display separately). Either Wi-Fi or USB connectivity. That's a deal that can't be beat.
 

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2020 Onyx
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Teslong sell flexible borescopes on Amazon for $50-75 depending on features - they require a PC/tablet/phone for a display (they also sell a dedicated display separately). Either Wi-Fi or USB connectivity. That's a deal that can't be beat.
I have a teslong borescope and it saved me when there was a cracked and crushed spark plug insulator (not in a Subaru)

Mine is the super cheap one but it did the job: https://www.amazon.com/Endoscope-Borescope-Inspection-Adjustable-Waterproof/dp/B07KF7Q8LT/
 

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That one has an 8.5 mm diameter camera which limits where it will fit; others are as small as 5 mm for the same price. Resolution also varies - the one I bought is a 1 megapixel color camera with semi-rigid cable and a USB connection. They can be had with rigid probes and/or Wi-Fi connectivity, with and without a dedicated display. Prices vary depending on features.
 

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Brucey
'17 3.6
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11,904 Posts
Discussion Starter #40
So I didn't do any of that.

I went to a friend who I borrow cameras off of for Youtube and asked if he had a bore scope.

We call it a butt hole camera.

Here are the results. I'll be breaking into the engine and taking the heads off maybe this weekend. Not like I can get anything done until Monday at this point anyway.

500665


500666


500667


The only thing that caught my eye was the pitting/carbon build up but at 150k might just be normal.

I didn't see any holes in pistons or scorched and the cylinder walls that I could see looked fine. No scoring there.
 
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