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Thread: motor/engine and transmission mounts

  1. #1
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    motor/engine and transmission mounts

    Hey there,

    I recently picked up a 97 Previa SC All-Trac with 240k miles. Loving the Previa so far! Overall the van is in good shape, and the previous owner had a decent amount of recent maintenance done at a shop, although not in a holistic manner. I've got the factory service manual, and have already dealt with the leaking valve cover and am working my way through the fluids.

    While stopped in drive there's a good amount of engine vibration, while in neutral it is smooth. I'm thinking this would rule out a SADs issue? I'd like to replace the engine mount(s) as a first step, but can only find reference to the right side mount. Surely there's not just one? Also, for the transmission mounts, do you have to buy the inserts and press them in, or can you get the entire mounts somewhere?

    I tried various searches, but couldn't find a thread specifically about mounts so apologies if this has been covered.

    Cheers,
    Matt

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    Re: motor/engine and transmission mounts

    Ah, while checking the supercharger oil (what a pain) I found the other engine mount... RockAuto only has a right side mount listed. Anyway, I'll update this thread once I've figured out the source of the vibration.

    I'm thinking of buying a long dipstick and getting some tubing and fittings to extend the supercharger dipstick up to an accessible location.

  3. #3
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    Re: motor/engine and transmission mounts

    Welcome to Previa ownership, or at least to the toyotavantech site. It's nice to see new posting members in these days of 30 yr old Previas.

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    Re: motor/engine and transmission mounts

    Thanks! Yeah, first Previa for me. They weren't really on my radar until seeing some recent youtube videos that at least made me aware of the AWD option and funky design. I'm a sucker for 90s Toyotas.

    So I scanned the CEL, and turned out that the EGR had low flow, despite the EGR valve having been recently replaced at a shop by the previous owner. I followed the advice of this blog post and cleaned out the carbon build-up between the valve and intake manifold (it was almost entirely blocked). The clamps on the air tubing from the front to the intake manifold were barely tight, and there were signs of a boost leak, so those got tightened down nicely. I was expecting the CEL to be for the EVAP system, because when I remove the gas gap voluminous amounts of vapor come rushing out, but no.

    I also took some throttle body cleaner to the throttle body while I had the airbox and intake tube out to access the supercharger (which had maybe 1 oz of oil in it)... there's lots oil contamination coming into the throttle body from the PCV system, so I'm going to add a oil catch can soon.

    Now the van idles a bit lower and the vibration has been significantly reduced. Sitting at a stop in drive doesn't feel like the van is pushing against the brakes anymore. Seems to have more power up top, so perhaps there was a boost leak as well.

    Still needs new motor mounts I think ;-)

  5. #5
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    Re: motor/engine and transmission mounts

    I think it would be hard to install an extended dipstick since it screws in and its impossible to see the hole from above without a mirror. But if you pull it off, post pictures! On my 95 I tied a string to the stick just so I could find it again. On my 97 I fashioned a "fishing hook" out of heavy wire to get it off and tighten it once I maneuvered it into place. I've always gone at it from above.

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    Re: motor/engine and transmission mounts

    Re your egr issue, hopefully you've fixed the problem by cleaning the passageway. I believe that the passageway gets blocked by carbon at the throttle body when the egr system stops functioning and no gas flows through that passage to keep it open, so the blocked port at the throttle body could be a cause OR a symptom. Time will tell. Just for kicks, and because it is fairly easy, I'd pull out the vacuum modulator and give that a look, plus the pipe tree it's connected to. Check out this thread for more info... https://www.toyotavantech.com/forum/...cuum+modulator
    Specifically check for any leakage when blowing into the big bottom hose, and check that all the tree pipes are clear.
    Last edited by Jonny; 06-14-2021 at 11:32 PM.

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    Re: motor/engine and transmission mounts

    Thanks Jonny, you are absolutely correct (sorry I didn't see your reply until today). I continued to get the EGR low flow code after cleaning the exhaust passage from EGR to throttle body. So then I checked the pipe tree, and sure enough some of the passages were clogged/rusted. I bypassed the pipe tree with vacuum lines. Then I checked the VSV and the port from the modulator to VSV was completely blocked with carbon. The VSV didn't work after some cleaning, so I replaced it with this one (HY-SPEED 718-502):

    https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

    Not a direct replacement, but it functions the same.

    After that, I worked on the modulator, and it was super clogged with carbon too. I thought I had gotten it functioning, but that turned out to be wrong!

    So after driving some more with no luck, I pulled the throttle body, and sure enough one of the vacuum ports was completely clogged. I gave the throttle body a thorough cleaning, and used my bike pump to blow out the carbon...

    Then I checked the metal EGR vacuum pipes that go from under hood to the engine, and one of them was completely blocked with carbon... (I blew into them with the bike pump). So I basically ran new silicone vacuum line directly from the throttle body back to the vacuum modulator, bypassing all metal pipes (but keeping the one-way orange valve thing).

    I've now realized the the modulator is indeed bad as well, because if you blow into the large port on the bottom, which should pressurize the diaphragm, air comes out through one of the upper ports, meaning the diaphragm isn't intact. So i've ordered this one (Dorman 911-609): https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

    I read in one of the amazon modulator comments that when the diaphragm fails, the exhaust gasses pass through the modulator into the vacuum lines, and eventually clog them with carbon. That seems to be what happened here because carbon was all over the place in the lines.

    Haven't received the new modulator yet, so fingers crossed this is the last piece of the puzzle.

    I've run various tests and everything else is definitely working now, except possibly the EGR temperature sensor.

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    Re: motor/engine and transmission mounts

    Quote Originally Posted by Previologist View Post
    I think it would be hard to install an extended dipstick since it screws in and its impossible to see the hole from above without a mirror. But if you pull it off, post pictures! On my 95 I tied a string to the stick just so I could find it again. On my 97 I fashioned a "fishing hook" out of heavy wire to get it off and tighten it once I maneuvered it into place. I've always gone at it from above.
    I haven't had a chance to work on this/ might not do it because I've gotten so good at removing the air box and intake piping :-)

    However, I was able to see the dipstick hole from one particular angle! Ok, maybe just half the hole.

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