Rough idle? $20 Intake manifold leak fix - M62 - M62TU

[sfgearhead]

After replacing the intake manifold gaskets and valley pan, I got to thinking... there has got to be a cheaper/easier way to fix some of these leaks.

So I came up with a "phase 1" approach. Does anybody with idle issues want to test the theory? Here's my proposal on how to tackle some of the intake vacuum leaks for $20.



1. Remove the CCV on the rear of the intake manifold and replace the gasket, careful not to break any nipples or strip the torx screws: - Part # 11-61-1-729-728 (#12 above)
2. Remove the throttle body and spacer and replace the gasket between the throttle body spacer and intake manifold. Part # 11-61-1-729-727 (#14 above)
3. Also replace the throttle body to throttle body spacer gasket - part # 13-54-7-510-433
4. Loosen all, then re-torque all 10 intake manifold bolts to 15 Nm. The theory being that the rubber spacers harden and shrink, which releases pressure on the gaskets. Loosening and re-tightening might tighten the seal on the gaskets.
5. Inspect all vacuum hoses for splits, leaks.

None of this requires removing the intake manifold. Before doing this it is probably worth looking for signs of coolant leaks at the back of the intake manifold. If you see them, you might want to just bite the bullet and do the full valley pan job, and also replace the 4 intake manifold gaskets under the intake. There are already a few DIYs on the valley pan, so I'm not going to cover that again.

If you've got more $ replace the CCV while it's off, as you might break one of the plastic nipples (I did) while removing the vacuum hoses.

I figure this should be a 2-3 hour job, not 8-10.

Thoughts? Discuss.

[yacob555]

I think that could work. May even be worth replacing those 10 bolts since they are really what is holding down the intake (since they have the rubber grommet thing which is probably holding the gaskets down).

I think you're right. Not sure how the intake manifold gaskets would really ever become bad. They're a pretty simple part.

[ElleShooTiger]

I think you're right. Not sure how the intake manifold gaskets would really ever become bad. They're a pretty simple part.

These rubbery-plastic gaskets can harden up or shrink over time due to the heat, causing vacuum leaks down the road.

Thats why many car companies use gaskets that cover most, if not all, of the machined surface and are made out of some kind of paper or rubber which will either last longer, or is harder for air to penetrate. Metal intake manifolds also help, since you can bolt them down directly without using the rubber washers which can also release tension on the gasket as they get old.

BMW's designs work very well and are great pieces of engineering, but their long-term viability can leave a lot to be desired.

[motorade1]

Im gonna try this. I replaced my CCV but still have vac leaks and rough idle when cold, but idles fine once it warms up. Codes 1C and 1D for lean idle on Bank 2. Indy smoke tested it and said he found several leaks. (I asked him if I could watch the guy do it, but he said no, they dont allow that. I dont think Im going back to this mechanic.) I asked him if there was any one place where it was leaking the most, and he said "under the manifold". So, Im gonna try this and see if it helps.

[Wolfen]

I replaced my CCV with the manifold in the car. It was actually pretty straightforward and the car didn't fight me on it at all.

Now years later i know i have a leak on the throttle body gasket. Im not sure if it's possible to do this with the manifold on the engine. Seems like some of the bottom bolts may not have direct straight access to them.

[motorade1]

Well, I did this and it worked.

In the past couple of months, there have been a few times when it would crank up then immediately die. Most of the time, it would crank, stay running, but immediately just start a wump, wump, wump type of idle. Then most recently, it would crank, and idle ok, (only ok), but then after about 45 seconds, when the engine drops down to normal idle speed, it would start the wumps.

It would take about 15 minutes of driving before this went away. At a stoplight, while in gear, if you went to creep up a little, the car would surge forward with the wumpy idle. I was getting codes 1c, 1d, etc.... for multiple misfires, and lean bank idle codes.

I replaced the CCV, but that didnt help. I then loosened and retorqued the intake manifold bolts, that might have made a LITTLE difference, but not much. I then received the throttle body gasket and spacer gasket, a round one that goes from the TB to the spacer, or "flange" as its called, and another one that goes between flange and intake manifold. It was this gasket, the one between flange and IM that I think was the main culprit. It looks identical to the one for the CCV. Most of it came out in one piece with some needle nose pliers, but then the lower left corner broke off. I had to dig that out of the recess in the intake. The gasket was very brittle and hard all the way around and would break apart into small pieces.

This morning was the real test. I went out and cranked it up and immediately thought good things. But I waited to see what it would do when the idle speed drops about 45 sec. in. Fingers crossed, it dropped down and just purred like a kitten at around 500 rpm.

NOW THIS ALL COMES AFTER I TOOK IT TO AN INDY, PAID THEM TO DO A SMOKE TEST, WHICH THEY WOULDNT LET ME WITNESS, THEN SAID IT HAS MULTIPLE VACCUM LEAKS, AND THE INTAKE NEEDS TO COME OFF, ETC....AND IT WILL BE ABOUT $1000.

I am sorry to say it, and I dont want to offend anyone, but the odds of finding a mechanic that is both honest AND competent is right up there with the lottery. They either know what they are talking about, but will charge for parts and services that you dont need, or they dont know what the issue is and will keep charging you for different things until they figure it out, so you are basically funding their education. There is only one mechanic that I have found that I trust. Unfortunately, he lives over 2 hours away in Aiken, SC. (Let me know if you want his contact info.)

Anyway, thanks to the OP for giving me this idea. These 2 gaskets cost me $23 and about an hour. And most of that time was spent letting the engine cool off. I just wanted to be sure I covered all my bases before taking the manifold off. And who knows, maybe my manifold gaskets will be leaking soon, but why take it off when you dont have to?

If you have a vacuum leak, or any of the symptoms I mentioned, and you have a M62, try replacing the TB flange-to-manifold gasket.

[Doc325i]

Well, I did this and it worked.

In the past couple of months, there have been a few times when it would crank up then immediately die. Most of the time, it would crank, stay running, but immediately just start a wump, wump, wump type of idle. Then most recently, it would crank, and idle ok, (only ok), but then after about 45 seconds, when the engine drops down to normal idle speed, it would start the wumps.

It would take about 15 minutes of driving before this went away. At a stoplight, while in gear, if you went to creep up a little, the car would surge forward with the wumpy idle. I was getting codes 1c, 1d, etc.... for multiple misfires, and lean bank idle codes.

I replaced the CCV, but that didnt help. I then loosened and retorqued the intake manifold bolts, that might have made a LITTLE difference, but not much. I then received the throttle body gasket and spacer gasket, a round one that goes from the TB to the spacer, or "flange" as its called, and another one that goes between flange and intake manifold. It was this gasket, the one between flange and IM that I think was the main culprit. It looks identical to the one for the CCV. Most of it came out in one piece with some needle nose pliers, but then the lower left corner broke off. I had to dig that out of the recess in the intake. The gasket was very brittle and hard all the way around and would break apart into small pieces.

This morning was the real test. I went out and cranked it up and immediately thought good things. But I waited to see what it would do when the idle speed drops about 45 sec. in. Fingers crossed, it dropped down and just purred like a kitten at around 500 rpm.

NOW THIS ALL COMES AFTER I TOOK IT TO AN INDY, PAID THEM TO DO A SMOKE TEST, WHICH THEY WOULDNT LET ME WITNESS, THEN SAID IT HAS MULTIPLE VACCUM LEAKS, AND THE INTAKE NEEDS TO COME OFF, ETC....AND IT WILL BE ABOUT $1000.

I am sorry to say it, and I dont want to offend anyone, but the odds of finding a mechanic that is both honest AND competent is right up there with the lottery. They either know what they are talking about, but will charge for parts and services that you dont need, or they dont know what the issue is and will keep charging you for different things until they figure it out, so you are basically funding their education. There is only one mechanic that I have found that I trust. Unfortunately, he lives over 2 hours away in Aiken, SC. (Let me know if you want his contact info.)

Anyway, thanks to the OP for giving me this idea. These 2 gaskets cost me $23 and about an hour. And most of that time was spent letting the engine cool off. I just wanted to be sure I covered all my bases before taking the manifold off. And who knows, maybe my manifold gaskets will be leaking soon, but why take it off when you dont have to?

If you have a vacuum leak, or any of the symptoms I mentioned, and you have a M62, try replacing the TB flange-to-manifold gasket.

I'm glad you found a convenient shortcut that worked for you. If that gasket termed "flange" was in that condition, what do you suspect gaskets illustrated as #15 in the above diagram look like? Especially since they're closer to the source of the heat. If budget isn't an issue, I say do it once and do it right.

[motorade1]

I'm glad you found a convenient shortcut that worked for you. If that gasket termed "flange" was in that condition, what do you suspect gaskets illustrated as #15 in the above diagram look like? Especially since they're closer to the source of the heat. If budget isn't an issue, I say do it once and do it right.

I guess they are in pretty good condition considering I dont have a vacuum leak anymore. I say if it aint broke, dont fix it.

[240sxguy]

I replaced my IM gaskets when I did my valley pan. They were incredibly hard after 175k miles. Like plastic, not rubber. Glad your solution worked but pulling the intake is actually pretty easy, so if you have to.. don't worry about it. Also you can't retorque the intake, the rubber washers under the spacers set the torque, not how tight you tighten the bolts.

[motorade1]

My point is, if you have a vacuum leak, dont automatically assume its the intake manifold gaskets and that you have to go all the way. This gasket is serviceable independent of the IM. Furthermore, you can replace the intake manifold gaskets without touching the throttle body, flange, or CCV gaskets. It can all come off as one piece. So they can be two separate procedures. The IM bolts are supposed to be torqued to 11 ft. lbs, so I just wanted to be sure they were tight enough.

[aspensilver540]

There is also a tiny vacuum hose that comes off the back of the passenger side of the fuel rail that was nearly completely withered on my car until i replaced it. I hadn't seen it mentioned in DIYs so I had to find and order it part # 13537560069

don't know if M62TU has it. I guess you could use standard vac hose too.

[ForceFed7]

Subscribing.

[sfgearhead]

Cool! Glad to see that this procedure helped someone. And even if it doesn't you haven't wasted any time, you can still do the rest without disturbing the ones you just replaced.

[motorade1]

Pretty cold here this morning, (32*), car still starting right up and idling great. No codes since I did this repair. Drives great!

Cool! Glad to see that this procedure helped someone. And even if it doesn't you haven't wasted any time, you can still do the rest without disturbing the ones you just replaced.

Exactly!

[scott99540it]

I am about to do this procedure today, but I am having trouble locating the spacer in #3, I dont see it in the diagram. Can someone advise please? Thanks!

[motorade1]

#3 is not in that diagram, but it is what goes between the throttle body and the "flange" which is kind of just a spacer between the TB and intake manifold. The flange then mounts to the IM with the gasket labeled #14 in the diagram. I ordered the 2 gaskets from ECS Tuning.

[scott99540it]

same here, ECS all the way.

ran into a major problem, got it all apart, except for the torx underneath the throttle body, and of course it is now stripped. how can I get this out? I have put it all back together for the time being, only replacing the gasket between the flange and throttle body. this sucks!

[dgdoc]

I had the cold weather, rough idle, problem on my 2001 540 (with 160,000 miles - original owner) and picked up all the parts to replace front cover, rear cover, and intake manifold gaskets.
Before beginning, I sprayed some brake cleaner around all the gaskets and noticed that the front cover (Gasket #14) - was where the biggest leak was by far.

I took the throttle body off, then the front cover, and found the old gasket petrified and more plastic than rubber. The throttle body to cover gasket appeared OK, but replaced it while I was in there.

Fired it up in 35 degree weather and.... no more rough idle!
In fact, it idles smoothly now whether hot or cold. Hasn't run this well in a long time.

I'm still planning to do the intake manifold gaskets, rear cover, and valley pan, but will wait until the weather warms up a bit. For now, am happy that this simple job provided such a significant improvement.

[wizardstsi]

^ Look at all that gunk under the intake mani! Mine looks the same

[dgdoc]

^ Look at all that gunk under the intake mani! Mine looks the same

Tough crowd - If you had told me that you were coming over I would have cleaned the place up a bit.

[RPW44]

Yes, thank you lord baby Xmas Jesus, I will be giving this a shot!
I love you guys. Even if this doesn't work.

My 2000 540 m-sport has 170k miles, and developed a vacuum leak. No codes, just rough idle upon cold mornings, then once warmed up zero symptoms.
Thought CCV from my research but I'm not burning oil or coolant or anything. Just vacuum leak. I do have slight oil leaks.

Took my car to an Indy BMW mechanic, he did a vacuum test and said I'm leaking out the front, back and sides of the manifold... told me needed new CCV, new gaskets everywhere and new valve cover gaskets. He replaced my spark plugs and charged me $180 for the smoke diagnosis and plugs. Now my car has a check engine light and runs even rougher (thanks, pro mechanic!)
I don't doubt he's right to an extent BUT: in 2009 I had the entire cooling system redone (new valley pan, hoses, CCV, new spark plugs etc). In 2011 had new valve cover gaskets (done by a stealership). My point being my car was running brilliant so how do I need all this sh*t replaced?? Those spark plugs were fine for another couple years I guarantee.
Thanks to this thread I'm going to spray some clean on the throttle body and I'd bet $$$ that's where my vacuum leak is. I'll replace that gasket&spacer. I'll go ahead and retighten the manifold and (carefully) the CCV in the back. Assuming this works I'll post a pic of me toasting you guys a cold beverage and another pic of me d*ck punching that Indy mechanic haha jk :P

I love these forums and thanks again to everybody who shares helpful info.

[dgdoc]

Yes, thank you lord baby Xmas Jesus, I will be giving this a shot!
I love you guys. Even if this doesn't work.

My 2000 540 m-sport has 170k miles, and developed a vacuum leak. No codes, just rough idle upon cold mornings, then once warmed up zero symptoms.
Thought CCV from my research but I'm not burning oil or coolant or anything. Just vacuum leak. I do have slight oil leaks.

Took my car to an Indy BMW mechanic, he did a vacuum test and said I'm leaking out the front, back and sides of the manifold... told me needed new CCV, new gaskets everywhere and new valve cover gaskets. He replaced my spark plugs and charged me $180 for the smoke diagnosis and plugs. Now my car has a check engine light and runs even rougher (thanks, pro mechanic!)
I don't doubt he's right to an extent BUT: in 2009 I had the entire cooling system redone (new valley pan, hoses, CCV, new spark plugs etc). In 2011 had new valve cover gaskets (done by a stealership). My point being my car was running brilliant so how do I need all this sh*t replaced?? Those spark plugs were fine for another couple years I guarantee.
Thanks to this thread I'm going to spray some clean on the throttle body and I'd bet $$$ that's where my vacuum leak is. I'll replace that gasket&spacer. I'll go ahead and retighten the manifold and (carefully) the CCV in the back. Assuming this works I'll post a pic of me toasting you guys a cold beverage and another pic of me d*ck punching that Indy mechanic haha jk :P

I love these forums and thanks again to everybody who shares helpful info.

Glad to help.
My '01 540 has about the same mileage as yours and its a pretty safe bet that what worked *amazingly well* on my 540 will provide the same result with you. The gasket in the pic I posted between the front cover and manifold had turned to plastic. It was no longer rubber and simply didn't seal when the car was cold. (Please send a pic of yours to compare - I'm sure its in the same brittle condition).

Was interesting that there was a pretty significant difference between this seal and the one between the throttle body and cover - which was still in good condition (replace anyway). I would attribute this to the inner gasket getting more exposure to oil vapor/fumes from the crankcase- (You can see the oily film in my pics).

The leak was really bad and spraying brake-cleaner (when engine is ice cold) made a huge change in idle. No question you have the same problem.

I didn't bother with anything else and happy to report that the engine idles *perfectly* when ice cold and in sub-freezing conditions (19 degrees today). It is a profound difference - hasn't run this well in years.

The total repair time was about an hour - and most of that was spent cleaning the mating surfaces.

One small tip - Before you begin, make sure to use some brake-cleaner (or other quick drying solvent) to clean all the crud and crap out of your Torx screws, so your Torx bit engages fully. These screws strip easily so very important precaution to take. Mine all came out without any issue.

Good luck and look forward to hearing your results.

[scott99540it]

replace those stupid torx with the equivalent hex bolts. they suck.

[tmvE39E53Z32TT]

Will replace these gaskets, along with the VCG and changing spark plugs on Sat.

[RPW44]

replace those stupid torx with the equivalent hex bolts. they suck.

In a different thread, a guy used Hex Bolts M6 1.0x25mm 10mmHex w/ 14mm Flange on the front & back of manifold replacing all the Torx. I'm gonna do that too.

UPDATE - Did the front in an hour - majority of time was spent cleaning stuff. Changed the torx for hex as well. If you see my previous post I had last been to an Indy, he charged me $180 for a smoke test and changed my spark plugs, told me I needed new valley pan, gaskets etc etc etc and was gonna cost over $1000. After the new plugs and smoke the rough idel was WORSE and I got a check engine light. Smashcut to now - I changed just the front manifold gasket and the throttle body gasket, it cured 99% of my rough idle (it's an occasional hiccup now as opposed to bucking and snorting), check engine light gone.

Don't get me wrong, I'm still going to replace the valley pan, valve cover gaskets, CCV in the back, etc, eventually. Here's pics, although I've got nothing new to add to what others have already posted. I used a t-30 torx drill bit, crescent wrench and a little WD40 and carefully removed those damn torx and was extra mindful to not strip them. Good looking out to all the previous posters on that topic, can't emphasize that enough.
photo 1.JPG Here's me getting bent over by the BMW Portland dealership for the gaskets lol (I'll order what I need down the road but wanted to avoid Victor Reinz gaskets as I've read nothing but bad things about them).
photo 8.JPGI cleaned and replaced that guy.

photo 2.JPG