Tick, tick, tick. That's the noise that my 1996 BMW E36 328is made. It sounded like valve noise. The noise only showed up when the engine had warmed up. It was most noticeable at idle, when the engine was making the least noise, but it was present at other times too. It sounded like one of my favorite songs, the 60 Minutes theme, but it was entirely inappropriate and embarrassing for the car to "sing" it whenever it wanted. I felt like the car was a rolling Timex ad.

I couldn't tell exactly where the noise was coming from, because of all of the background noise of the engine. Even the ear-to-the-screwdriver trick left me looking for answers. So, I did what anyone would have done, and I started throwing inexpensive parts at the problem.

I thought that the timing chain tensioners might have something to do with it. After all, it seems to work for the 4-cylinder M42 people, so it might work in my 6-cylinder M52, too. I replaced the primary (crankshaft-to-exhaust camshaft) timing chain tensioner, but that didn't solve it. When I found that the original tensioner still had plenty of spring left in its step, I decided to avoid the hassle of replacing the secondary (camshaft-to-camshaft) tensioner, at least for a while, and look elsewhere.

Figuring that if it sounded like valve noise, it might have actually been valve noise, I turned my attention to the HVA (hydraulic valve adjuster) elements. If these become oil-starved, the engine's top end will make a tapping noise. I checked the oil level, and it was correct. (Of course it was.)

Then, by chance one day, I was parking my car while listening to the aggravating beat of the clicking, when I embarrassingly stalled. Although the engine had stopped, the clicking hadn't. I left the car on and popped the hood, and without all of the background noise, I was easily able to identify the source of the ticking.

Here it is.

It's a mysterious little valve attached to the right side of the front left spring strut dome, tucked below the mass air flow sensor. It has a 2-wire electrical connection on top, a vacuum hose on the bottom, and a vapor hose attached to the side. With the help of some wiring diagrams, I identified this part as the evaporative emission control system's purge valve. In BMW nomenclature, it's referred to as the TEV part of the EVAP system, fuel tank vent valve, charcoal filter valve, or evaporative emission valve. Have a look at the parts diagram, the valve in question is part 13.90.1.744.150.

The DME (digital motor electronics unit, the engine computer) calls for the purge valve to open to allow the fuel vapor collected in the carbon canister to be breathed in by the engine and burned. It's supposed to make this call whenever operating conditions permit. The engine needs to be up to temperature, and not under too high a load. I wasn't expecting the purge valve to be opening and closing so rapidly, but the Bentley manual confirms that the purge valve control is indeed pulsed. (See page 130-37, pin 68.) It gives me about 6-8 ticks per second, which is roughly the same interval you might expect of valve noise, except it's not dependent on engine speed. Of course, since you can hear the ticking most clearly at idle, it's easy to overlook this fact.

If you're sufferring from this problem, grab this valve when you hear the ticking noise. If it's the culprit, you'll know right away because you'll feel it kicking with every click.

There's no reason the DME should have been calling for the purge valve to open with the engine stopped after a stall. It's probably just a lucky DME software bug that kept the valve dancing without an engine speed signal. If it weren't for this, I'd probably still be tooling around with dubious solutions like overfilling the oil.

Knowing that the noise came from a silly solenoid and not the valve train put my mind at ease, but I still wanted to be rid of it. Fortunately, the problem was known to BMW in 1996. Their solution was to isolate the valve from the body. This is covered in their service information article SI 13 01 96.

SI 13 01 96 calls for a simple $4 (even on the dealer's price list) rubber mount to eliminate the noise. It's part 13.71.1.259.818, and is the same part used to mount the air box to the body. Here it is, along with a 6mm nut, which the dealer tossed in for free. Thanks, dealer.

Installation is simple. Remove the bolt holding the valve to its bracket (a 10mm deep socket will come in handy), put the rubber mount where the bolt had been, and secure the valve to the other side of the rubber mount with a 6mm nut (once again, use the 10mm socket.) It takes less time to add the rubber mount than it does to read this article. BMW suggests 3 FRU, or 18 minutes, but I guarantee you'll finish it in less time even if you're completely mechanically declined. When you're done, it will look like this, although hopefully your engine bay won't be as dusty as mine.

Start the engine, let it warm up, and marvel at the absence of noise. You won't be bothered by this valve any more. In fact, it'll be so quiet that you'll need to touch it to be sure that it is even operating. (In my car, the DME starts pulsing the valve at about the same time that the water gauge passes out of the top of the blue "cold" region.)

It seems that BMW tried a few different mounting methods for this valve over the life of the M52-powered E36 (323i and 328i models), so this may not apply to all cars. If this solves your ticking problem, or if your purge valve is mounted differently, I'd like to hear from you.

Happy motoring, and enjoy the silence!

Mark
1996 BMW 328is (E36), 83kmi


Pick a different trade.

Mark Mentovai
2004 December 11
2004 December 15