forester2002s

Is the coolant-level in the overflow reservoir behaving as it should? i.e. is the coolant-level when cold lower than when you stop the hot engine at the destination? And does some coolant then get sucked back into the radiator, as the hot engine cools down to cold (say overnight)?

Take lots of photos (of wires, connectors, hoses, belts etc.) before you disassemble anything.

On my 2017 Forester (TR580 CVT), the periodic drain-&-refill only changes about 1/2 of the total CVT fluid. The drain-plug is at the very bottom of the trans. And there's no mention of a CVT filter-change. I wonder if the periodic drain-&-refill is not about refreshing the fluid, but is really about flushing out any wear-debris from the bottom of the case?

Each time that I have bought a replacement rubber-boot, it came with replacement grease and replacement mounting-bands.

Sure sounds to me that this is valve-train related (in olden-days, this would have been called 'noisy tappets'): - either incorrect clearances around the cams; - or in need of an oil-change.

I've rigged up a chain-hoist from the garage-rafters. And I use a Load-Leveler from Harbor Freight, similar to this one. But I really like your idea of used long studs in the upper mounting holes, to guide the assembly together. It sounds easy to just line up the engine and trans, and it will all slide together easily. But in practice, it just ain't that easy!

That's a great idea. Thanks for the tip.

Did this problem occur just after you filled up with fuel? Could be bad gas.

Is there water in the spare-wheel well in the back? That might indicate a roof leak near the rear. Or are the front carpets wet? Might be a leak from the windshield.

+1

Long shot: Does the passenger seat-sensor enable the air-bag circuit? Check those connections under the seat?

Could it be a belt-tensioner flopping around?

That MLS gasket is intended for turbo engines, but it fit my 2002 EJ251. It seals tight, and the engine runs fine.

Can't help with gasket kits. But I highly recommend that you get the MLS (Multi Layer Steel) Head Gasket, Subaru #11044AA642. It'll last for ever...

My 2017 Forester has the TR580 CVT. It runs well, but that's not going to help you with your research. According to Wikipedia, the Ascents have the larger TR690 CVT. So you should be looking for info on those transmissions.

What does the existing heated-seat look like underneath? Does it look like the heating-element is easily accessible, and perhaps therefore easily replaced? Or is the heating-element buried in the guts of the cushion?

My 2017 Forester has the TR580. Do you recall how much replacement fluid you needed for the drain-and-fill?

And another question: How much replacement CVT fluid is needed after draining the old fluid? Subaru FSMs give the total amount of fluid required for a dry fill. But I have read that much less fluid is required after a simple maintenance drain. So how much fluid should one have on hand for the refill?

Time for an oil change?

Yes, and take photos before you take it apart

Try using jumper-cables to bypass the +ve cable from the +ve battery-post to the 12V input on the starter. This can be tricky. Wear safety-glasses, and connect the jumper-cable to the starter FIRST, and to the battery-post LAST. Then try to start the car. EDIT: Just had another thought - the 12V input on the starter is usually a stud on which is threaded a hex-nut. If that hex-nut was loose, it might explain your symptoms.

I use 10W30 non-synth in my 2002 Forester, and I change the oil & filter at least twice as often as recommended. Still on the original engine (but with new head-gaskets and belt etc,) I use 0W30 or 5W30 full-synthetic in my 2017 Forester, and also change the oil & filter more regularly than specified. I don't get too excited about buying super-expensive brand-name oil. I just buy what's on sale, and change it sooner than is required. And I've never used any oil additives.

Tire pressures are usually shown on the driver's side central door-post. I usually go about 2psi over (measuring the pressure when tires are cold)

I guess that posting on USMB (as I'm doing), and discussing the foibles of our cars, is useful info to someone. And even though I'm using an alias, I suppose that it would be easy for a snoop to find out more about me.

Sure sounds like a gradually-developing HG leak to me. Look on the bright side: at this stage, you can plan a HG replacement in an orderly fashion. Leave it too long, and you'll be in a panic to fix it.