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Thread: Previa valve cover

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    Van Enthusiast pdgizwiz's Avatar
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    Previa valve cover

    I haven't posted anything here in a long time, mostly because my '91 Previa hasn't needed a thing. I replaced my valve cover gasket a little over a year ago and it's been as smooth and trouble-free as any car I've towed home and patched up before.
    But now my valve cover is leaking again. The tell-tale whiff of burned motor oil as I park and get out has been irritating me for a few weeks, and I've confirmed the cover as the source of the leak.
    Any sage tricks here that anyone will attest to being sure-fire? I sealed it before with some RTV, but perhaps that was a mistake. Or maybe I didn't hold my tongue right when I did it.
    Thanks

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    Administrator timsrv's Avatar
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    Re: Previa valve cover

    The VC gasket is certainly a trouble spot on the Previa. Seems like I'm replacing mine every 3 or 4 years or every 30k miles or so. The distributor shaft can also leak oil. When that happens the oil runs through the distributor, drips out the cap, then onto the heat shield, then onto the header. This usually creates rough running too though, so if it's running smooth then it's probably just the VC gasket again. Personally I much prefer the Toyota FIPG (Form In Place Gasket) over silicone. It's a bit more money but IMO it's well worth it. It should be used sparingly. You should only use a tiny bit on the corners where the gasket goes over the "bump" in the back, then just a very small dab on the front where the "half moon" plugs mate with the head. Tim

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    Van Enthusiast pdgizwiz's Avatar
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    Re: Previa valve cover

    Thanks, Tim-
    I feel better now, knowing that someone with a dozen Previas gets three years out of a VC seal job. My one isn't bad for a first pass, I guess.
    My old gasket had hardened and cracked, so it was clear why it was leaking. I haven't removed the new one yet, but after I do I'll report here what I find.
    I'm not sure what RTV silicone I used. It's white, and may be something I brought home from a past job from the "expired" bin. I know to avoid the types with corrosive cure agents and cheap generic bathtub sealants, of course. RTV silicone comes in a host of formulations. I expect that the Toyota FIPG is one as well. I assembled a wasserboxer engine once and the gasket kit came with a tube of VW-issue black RTV for the head seals. It worked. I suspect that Permatex "ultra black" or "ultra gray" are similar, but perhaps I'll try Toyota's finest this time. Would that be P/N 00295-00103?
    Since this engine lays on its side, getting a seal here is more critical than if the engine were of the conventional upright type. Oil pools right against the seam, and will ooze out of the slightest imperfection. I think that it's funny that Toyota placed a "gutter" underneath this joint, with a "downspout" directly over the exhaust collector where it will burn rather than fall to the ground. Was this a "solution" to a known leak problem? If so, someone in Japan is still chuckling to themselves.

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    Administrator timsrv's Avatar
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    Re: Previa valve cover

    Lol, just ask the parts guy at Toyota for a tube of FIPG. They keep changing the part number so I quit keeping track of it. The stuff is probably a formulation of RTV, but yet different. It has a different "feel" to it and is much harder to clean off you hands than black silicone. I use a lot of different sealants in my line of work. The ones that are the messiest and hardest to clean up are almost always the best when it comes to performance and longevity.

    During troubleshooting I've run Previas before with the valve cover off, and man let me tell you it's unbelievable how much oil sprays out. If you ever do that you're going to want plastic over everything. I even made some sheet metal shields to knock it down (otherwise it's like a garden sprinkler). Even then you're limited to just a few minutes or the engine will run itself out of oil. Considering that, plus the fact it's on the side (gravity issues), this can certainly be a problem area. Now just add a couple years of heat exposure and you have a recipe for leaks.

    Quote Originally Posted by pdgizwiz View Post
    Since this engine lays on its side, getting a seal here is more critical than if the engine were of the conventional upright type. Oil pools right against the seam, and will ooze out of the slightest imperfection. I think that it's funny that Toyota placed a "gutter" underneath this joint, with a "downspout" directly over the exhaust collector where it will burn rather than fall to the ground. Was this a "solution" to a known leak problem? If so, someone in Japan is still chuckling to themselves.
    Lol, looking at the design of that heat shield I've also wondered the same thing "is it really a heat shield.......or a gutter for oil? " It is kind of funny how it's the perfect angle for oil to travel front to back, then set up perfectly to drip right onto the distributor shield. The little lip on the edge is for strength, but it almost looks like it's a little trough intended to direct the flow. Then of course there's the little hole on the distributor shield right above the header........looks like a drain hole to me . Very curious indeed. Tim

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    Van Enthusiast pdgizwiz's Avatar
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    Re: Previa valve cover

    I pulled the old one off and did a post-mortem. It looks like I used Permatex ultra-gray. It stuck fine to the head and the cover, but not very well to the gasket itself. I cleaned everything scrupulously, got a new gasket and a tube of Toyota's black FIPG. It is sealed for now.
    As to whether or not the heat shield is intended to be serve as an oil leak management system, I don't think there's any doubt. The hole at its low (rear) end drips into a feature stamped into a stamping welded to the header which neatly routes the oil over the side and down. The phrase "intelligent design" comes to mind.
    PrevOilDrain.jpg
    So I'll report back on this thread if and when this after-burning system goes back into action. Until I do, assume that my gasket is still holding oil.
    Paul

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    Re: Previa valve cover

    So, Paul, inquiring minds need to know..... What is the current part number for the FIPG ?
    I need to order some online and would love to have the current part number.
    Closest dealer is way too far. I live way out in the middle of Nowhereistan.
    Thanks,
    Robert

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    Re: Previa valve cover

    The current Toyota part number for FIPG is 00295-00103. The discount sites want about $10 for a 3 oz tube.

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    Re: Previa valve cover

    Best Silicone I have ever used. When working at the dealer it was passed out like candy.
    Some of the techs got greedy and were selling it on the side to outsiders thusly abusing the system, which ruined it for all of us. They stopped giving it out so readily.
    Good stuff.
    Once again Tim, Thanjks for all you do.

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    Van Enthusiast pdgizwiz's Avatar
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    Re: Previa valve cover

    Yep, that's the stuff.
    For the record, it's still holding a month later.
    Paul

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    Re: Previa valve cover

    Gents,
    I know this is an old thread.....but are you folks saying that FIPG alone is good enough for the VC gasket?

    I used permatex with a new gasket, and a year later it's leaking again....

    So...would u use a new gasket WITH FIPG?....or FIPG alone?....and did I read right.....only a little bit at the corners?

    Thanks,
    Russ

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    Administrator timsrv's Avatar
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    Re: Previa valve cover

    You would install a new gasket, then just put a little dab of FIPG in the corners where the raised area is for the distributor. Here's a post on Toyota Nation that shows where to put it. Tim

    https://www.toyotanation.com/threads...ctures.365347/

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    Re: Previa valve cover

    Thanks for that, Tim....what a great , detailed and thoughtful tutorial!

    I'm gonna do the distributor o ring and the oil return gasket at the same time.....my wife says she is tired of the oil burning smell....

    go figure.......

    Happy Holidays to all!
    Russ

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    Re: Previa valve cover

    I changed 2 valve cover gaskets and then did a post check and the real problem, at least on mine, is the valve cover gasket bolts bottom out before the gasket crush is good enough to seal the gasket. I had one new gasket seep. I put some think copper washers on the valve cover gasket bolts, up against the head of the bolt so that the crush on the gasket would be tighter when the bolts bottomed out on the bolt shelf and it has worked without any leaks for years now. You don't have to pull the valve cover to install this fix. Just do one bolt at a time. You just need to increase the crush on the valve cover gasket a very small amount.

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    Re: Previa valve cover

    Hi, Thank you for taking the time to respond! I will do what you suggest! Again, thanks. I love these forums because it allows folks to converse in 'human' terms without a profit agenda.....

    Makes me think of how in olden days folks would gather in a pub and just share ideas that helped each other.....without agendas.....

    not sure what I miss more....the gathering or the pub.......

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    Re: Previa valve cover

    Totally agree with you Rainbow Bridge about communications and talking together. You can figure out a lot of things if you are able to talk things out a little.

    On my post above, I noticed a typo about the washers. I used THIN copper washers because I didn't want to crank down too much on the gasket or distort the valve cover. I used copper washers because it was easier to find THIN ones and that is the only reason I used copper.

    I also only used the washers on the bolts on the bottom of the valve cover because I could get to all the bolts without taking the passenger seat out. My oil leak was only coming from the bottom of the valve cover gasket, not the top. I know this is sort of not the right thing to do but it worked and I have a plan to fix it later. I will put washers on the bolts on top of the valve cover the next time I change out the spark plugs and wires.

    I hope this works for you.

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