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Thread: DISA Valve Possible Vacuum Leak - Advice

  1. #1
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    DISA Valve Possible Vacuum Leak - Advice

    My 2003 E46 has a fuel trim code, I had a specialist come look at it, and he suspects the DISA valve has a vacuum leak, and or the valve cover as well. Fuel trims were 11% high. I'm pretty new to this, so I just take his advice, because I'm an old school mechanic.

    Also, the engine also makes a very high squealing noise when I first start it, like an electronic noise, nothing to do with fan belts. But it also makes the noise when I turn the key on, before I start the engine, and then once the engine is running, it's engine speed dependent. Very strange, almost like feedback from the radio. Extremely high-pitched, it's not a fan belt, it's an
    electronic noise

    Recommendations for disa valve? I've got to get my check engine light off, so I can get the car inspected
    Last edited by CORVAIRWILD; 06-29-2022 at 10:44 PM.

  2. #2
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    DISA o-rings flatten and harden over time and can absolutely cause a vacuum leak. It may not be the only one though, so a smoke test is advisable.

    If the valve works as normal, you can get the o-ring through G.A.S. pretty cheaply. You can also upgrade the flapper door from them too. I just did mine. It didn’t help the fuel trims, but it cured the P0171/0174 codes. Mine needed a mass air meter to restore the trims.

  3. #3
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    Can you figure out from where the electronic noise is coming? Is it the audio system, some place under the hood, etc.?

  4. #4
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    there is a small fan on the driver footwell that draws airthrough the electronics box on the driver side firewall. the fan is notorious for a high pitched cricket chirp. just a suggestion. good luck.

    Sent from my SM-G973U using Tapatalk

  5. #5
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    Quote Originally Posted by MarcoZandrini View Post
    Can you figure out from where the electronic noise is coming? Is it the audio system, some place under the hood, etc.?
    Even tho I'm 62, the squeal is really sharp. It's like a ghost noise, just coming from somewhere??? I wonder if I can record it

  6. #6
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    What kind of "specialist" comes out, doesn't tell you which codes you have, and "thinks" the DISA is leaking?? I'd change specialists.

    Smoke test the engine first and foremost. If there's a DISA leak it will be obvious. Technically, the seal on the '03 isn't serviceable, but there are kits to replace the o-ring.

    Have somebody with a decent scanner find the codes that are illuminating your SES light. Maybe that will help with diagnosing the squeal, maybe not, but you'll still need them.
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  7. #7
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    I agree... He removed the disa valve, struggled to apply vacuum to it with a hand pump, and declared it defective. I was a mechanic many years ago, but changed careers as cars were getting too complicated, and I didn't have an interest to learn about fuel injection and abs etc. But I agree, and I have a '99 Chev 3500 6.5 turbodiesel that runs funky, and I believe I should buy a smoke tester to diagnose that truck as well. What smoke tester do you recommend? And he did scan my wagon. I should have made a video of his scan, which is my usual mo. I admit, I blew it. The disa o ring looks simple enuff to change. He also suspected the valve cover gasket was producing a vacuum leak. I know they have a propensity to leak, but even tho this car suffered from infrequent oil changes (the oil fill cap underside is sludgy), it runs well, smooth and quiet. I did change the oil immediately after purchase 9 years ago, but only drove it under 1000 miles before storing it bc of a seized rear caliper and dead rear shocks. The cel was off when I bot it. I'm not into firing the parts canon, and if a part can be repaired, or a better one salvaged from a junkyard, that's my better path. I did change the oil for synthetic, but that was 9 years ago, and it was parked up on blocks for 9 years soon after. I will be changing it before I head out for the next road trip. I only use synthetic, but always the cheapest one. Recommendations? I've watched project farm on ytube, and I know better oil costs more, but owning so many cars, I have to compromise
    Last edited by CORVAIRWILD; 07-02-2022 at 07:31 AM.

  8. #8
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    Amazon has a bunch of smoke testers for well under $200. You don't need anything fancy. If you don't have a compressor, get one with its own air pump. Pull off the MAF and stick in the cone shaped thingy. Smoke it and check for leaks. The DISA will leak around the base. Valve cover leaks will be obvious, too. You might also find leaks around the intake boots.

    I know of no good way to apply vacuum to the DISA. Pull the DISA, turn it over. There's a vent hole. Open the flapper manually, cover the hole, release the flapper. You should feel a little suction and the flapper should not return all the way. If it does, the internal diaphragm is shot. Check that the flapper moves with some resistance, caused by that diaphragm and spring. If it flops around, bad DISA. Check the rivet thing in the end that serves as the flapper axle. If it's coming out, replace the DISA. You do NOT want that thing coming off and getting sucked into a cylinder. If all is good, you can get a DISA o-ring, scrape some of the old rubber out of the groove, and use the O-ring. It will be a bit snug, but it should fit OK. In an emergency you can use a little RTV. Don't tell anyone I said that. But desperate times, etc., etc.

    Infrequent oil changes don't cause valve cover gaskets to fail. Time and temperature do. They get hard over time and fail to seal. They're not that difficult to replace. Be sure to replace the grommets at the same time.

    Do not skimp on parts, or oil. You get what you pay for. Parts house parts are generally garbage. Unfortunately, for these cars you need to stick with OEM or Genuine BMW, depending on availability. And don't just chase codes. If something, say the radiator, fails then it's time for a complete cooling system overhaul, not just a radiator replacement. If you find an intake manifold leak, don't just replace the gaskets, do the CCV valve and pipes while it's apart. All of that plastic gets brittle and must be replaced on a regular basis. Rear shocks are bad? While you're in there, check all the bushings. Chances are they're also rotten. These things require a fair bit of preventative maintenance which nobody ever does. So, when we get these cars there is always a ton of deferred maintenance to do. But if you do it, and do it right, you'll be rewarded with a reliable car.

    Be very careful about junkyard parts. Those parts are just as old as the part you're replacing. How many times do you want to do the same job? Some of the bigger stuff, like entire engines, HVAC controls, transmissions, etc., can be sourced from reputable recyclers. Used alternators, starters, radiators, etc., are risky.

    My engines used about 1 liter of Mobil 1 every oil change. I switched to Liqui-Moly 5W-40 Leichtlauf and, after maybe a year, the consumption went to zero on one, noticeably less on the other higher mileage/improperly maintained one.
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  9. #9
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    Excellent commentary!

    This might also be useful: https://www.bimmerforums.com/forum/s...0171-and-p0174

    I would get the smoke test done at an independent shop. Just get it done right and find all the leaks. Should be no more than $100

    As for the DISA, if it doesn't provide resistance when you try to remove it, the seal is shot. Buy a replacement o-ring on eBay. The diaphragm is a different issue - see the prior post for an excellent overview.

  10. #10
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    I got one of these off ebay. Worked great to identify vacuuum leaks on a brand new CCV system. Have used it a number of times, well worth the hundy I dropped on it.

    2000 740i Sport | 2004 330xi | 1988 325i Vert | 2003 Z4 2.5 | 1995 Ford F150 | 2018 GTI

  11. #11
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    I wonder if it's made in usa, or china? I noticed a couple of them that I looked at a while ago, we're made in usa. Hard to know, spend less and get drunk, or spend more, and get what you pay for

  12. #12
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    Quote Originally Posted by CORVAIRWILD View Post
    I wonder if it's made in usa, or china? I noticed a couple of them that I looked at a while ago, we're made in usa. Hard to know, spend less and get drunk, or spend more, and get what you pay for
    It’s from China. Hate constantly buying crap from China but seems impossible not to. What are you gonna do?
    2000 740i Sport | 2004 330xi | 1988 325i Vert | 2003 Z4 2.5 | 1995 Ford F150 | 2018 GTI

  13. #13
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    I talked to text "junk", dumb device heard "drunk" lol

  14. #14
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    I just installed this axle from RockAuto... Nice 'n shiny. $70 delivered, no core


    https://photos.app.goo.gl/mDCLLSMkTTveF7y89
    Attached Images Attached Images
    Last edited by CORVAIRWILD; 07-12-2022 at 12:24 AM.

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