I drive a 2005 BMW 3:18ci, I went to an approved dealership to get my aircon regassed.
Whilst there, they gave my car a “complimentary health check”. During this procedure they determined that I need to replace my rocker cover gasket and my vacuum pump.
I had a look at the top of the engine and I don’t see any oil leaking anywhere although I know next to nothing about this stuff. Should I have the gasket replaced?
Also, what is a vacuum pump and how important is it that I get it replaced, assuming it is malfunctioning?
IANAM (Well, not a professional mechanic. I think I do qualify as a shade tree mechanic, though.;))
I’m not sure if this will be of any help but I’m fairly certain that on most American made vehicles, the vacuum force that is needed in the operation of certain systems is provided via the intake manifold. I’ve never come across a car with a dedicated vacuum pump.
I’m pretty sure that a Doper with more automotive knowledge than I, will be along shortly.
Not meaning to sound chauvinistic, but what is your gender? (If you don’t mind my asking. :))
Yeah, I’m with JBD on this one. The ‘vaccum pump’ is your engine.
Also, I’ve never heard of the term “rocker cover”. There’s a valve cover. And there’s rocker arms. I’m no BMW guy, but I would assume that you have and OHC engine. You may or may not have rocker arms with an overhead cam, but I’ve never heard of the cover being called anything but a valve cover.
Bzzzt!
Wrong answers.
While the engine itself does provide vacuum in the intake manifold many modern engines are equipped with variable valve timing for power and to lower emissions.
When you dink with the valve timing their might not be enough engine vacuum for the power brakes to work properly. This is particularly noticeable when the engine is cold and you are in the mountains.
Rick may be more familiar with newer engines than I am, but yes I have heard of cars with vacuum pumps. Engine vacuum has long been used for miscellaneous little tasks such as power brakes. Years ago they said you couldn’t use engine vacuum if you had fuel injection. Now most cars have FI and few have vacuum pumps. I guess that wasn’t the SD.
So yes, your car may have a vacuum pump, and if so, it may need replacing.
As for the rocker cover, If you aren’t seeing any leaks or having to add oil, I would ask for more explaination.
Rocker arms go back a long ways with over head valves. They disappeared on the earlier dual overhead cam engines, the cam directly operating the valve lifter*. Very short ones are back to provide a roller in the valve train. The cam covers on my Ecotec engine are little more than 2’’ wide, but have the camshaft, rocker arm, and valve lifter all in there somewhere.
It could that BMW calls the cover a cam cover, but the service writer pulled up the older term.
*Lifter? In most OHC engines, they are pushing the valve down.
You use the term “aircon” which we have to assume is meant air conditioner.
You also plead ignorance about *such things. *
Please note that it is a German made auto. As such the components have different names, having been translated from German to English. Therein lies the rub. You should have asked the dealer’s service manager to answer any questions you may have at the time and explain the need for each and every part of the service order that you do not understand. That is a part of their job, to educate the customer/owner of a high precision machine which cost a few dollars more than most other autos on the market today.
The rocker cover is a cover that runs along the top side of the cylinder head and contains the valve operating mechanism, which includes rocker arms. These covers can leak at the gasket to the head and the oil runs down the engine. That oil may not even hit the ground if it burns off on the exhaust manifold first. There it can smoke and even be a fire hazard in extreme cases.
There are several vacuum devices on modern vehicles. One can be used to operate the doors that open and close to move air to either the windshield, your feet or your body. I presume this is the device they found defective while checking the AC. If the door does not function properly, you can get hot air instead of cold.
Another important vacuum device is the power brake booster. If this fails, you can lost power assist and braking can be difficult.
*aircon: *an open-air science fiction or comics convention. (Rarely used.) regassing: removal of pants immediately after an attack of flatulence, thereby re-exposing oneself. (Also rarely used.)
No seriously: I figured out pretty much immediately that OP was having the BMW’s air conditioner serviced with fresh refrigerant (a gaseous substance, thus “regassed”). I r smrt about language but not so good with cars.
Sorry I was in a hurry to get to work. Yes cars with variable valve timing have vacuum pumps. Yes the vacuum pumps fail. Typically these systems if used on an exhaust cam will advance the exhaust cam when the engine is cold to reduce emissions and light the converter faster. Advancing the exhaust cam absolutely kills the manifold vacuum, particularly at higher altitudes. On some cars if the vacuum pump is dead, they are close to unstoppable when the engine is cold and being driven in the mountains.
All cars that I can think of have either a 2 piece head or a valve cover/rocker cover. Yes they can leak. Is the OP’s leaking? Don’t know, I can’t see the his car from here. Note: The oil leak may not show on the top of the valve cover. Due that thing called gravity, oil leaks downward not upward. So if the valve cover gasket (located at the bottom on the valve cover) were to leak, I would expect to see the evidence on the cylinder head and engine block, not the top of the valve cover. You may need a flashlight or to get under the car to see it.
Aircon and regas are not commonly used here in the US. AC and recharge or service would be terms we are more familiar with.
I’m curious how they decided the vacuum pump needed replaced. Indeed, cars with engines that don’t produce enough vacuum will have a pump for assistance with the power brakes. Was there any warning lamp or failure message displayed on your dash? Have you noticed any difference in brake response, especially at low speeds?
I don’t know any specifics about your vehicle or whether you need a new one or not, but many BMWs have vacuum pumps because they don’t have conventional throttles.
A quick search on eBay revealed BMW vacuum pumps for the purpose of being a brake booster. In fact, all the cars that I have owned that have ABS have a vacuum pump for the purpose of brake boosting even though it may not be called so. Also, these are commonly used in RVs, large trucks, etc.
However, I am absolutely sure, that with a car with ABS, will have a vacuum pressure sensor in order to maintain the proper vacuum. If there is a continuous low vacuum condition, say after four starts or maybe two starts, then a check engine light should go off. How they found out is by connected an engine scan tool, which will read the data off of the car ECU(s). Even if there are no check engine lights, you will have what are called “pending” malfunctions. Basically, if the condition has been met once but not twice, it will be logged in “pending” but not as an actual malfunction. The reason why you have pending is that sometimes you actually meet the conditions once but never again. Say, for example, you went on a long trip and did not drive your car for a couple of weeks. Unless BMW has somehow engineered a perfectly sealed braking system, then you will loose vacuum. When you start the car, it sees a low vacuum condition, logs it into pending, vacuum pump restores vacuum for proper brake function, and you drive merrily away for months on end with no problems.
The real way to tell is to get a hold of your service manual and look up the conditions for a low-vacuum condition. Also, if someone tells me such things I ask for the engine code so I can look it up myself.
Way back in the day, the cars did in fact use the intake manifold for vacuum shortly after they came out with hydraulic brakes --before hydraulic, brakes were cable pull. This is the reason why a lot of old cars jerk when they stop as the vacuum pressure was uneven and unreliable and you really had to press on the pedal. My dads 1966 Buick Riviera GS is like this.
On large trucks which use air pressure not vacuum there are warning horns and a gauge for air pressure in the event of a problem.
On vacuum boost systems I have never seen any type of warning for low vacuum as vacuum is such a variable parameter. Typical readings for a non VVT /vanos engine at sea level might be 17" idle, 21" cruise and 0" at WOT. Where do you set the warning? Everywhere from 0-21 is normal. Abnormal is 0 and that is in the normal range.
It for sure won’t trip a check engine light as only items that effect emissions do that. A dead vacuum pump has no effect on emissions.
