forester2002s

Sorry, but can't help. However, looking through those 10+ year-old posts, I see that 'nipper' was part of the conversation. Whatever happened to 'nipper'? Seems to have disappeared off the scene.

I'm not familiar with a 1998. But if it has a hydraulic-actuated clutch, then the slave-cylinder may need replacing (located at the top-rear of the engine-block). If it's cable-actuated, maybe the cable is sticking.

True. But the subject line says that this is not an EJ, but an EZ30D. Different engine.

It would be best to start a new post with this engine-related issue.

I get the P0420 on my 2002 EJ251 every few months, and then I delete the code. My car normally just does local runs. But once in a while, I go on the freeway at high speed; if it's a hot day, the CEL comes on and it's a P0420 code. So I delete it. Been doing this for years. The engine runs beautifully!

Check CVT fluid level?

Blown fuse?

Could be a blocked fuel-filter. It probably needs changing anyway.

I did a google search; there's lot of info available on line, mostly sponsored bu additive sellers. Here's one helpful article: Does gasoline go bad?

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?