Welcome to our BMW and MINI tech blog!
There are more than 1,000 Q&As and DIY guides posted here. Feel free to search by keyword (upper right), browse by category (lower right), or watch one of our helpful videos. Once you've found the answer to your question, you can get the parts you need in our online store – www.BavAuto.com.
This answer is applicable for many BMWs in addition to the one listed below.
car year: 1997 car model: 528i Is there a way to know if coolant is leaking by the head gasket?
There are various ways in which a head gasket (more properly, the engine cylinder head gasket) can fail. The failures can cause poor engine running, fault codes, loss of cylinder compression, loss of coolant, loss of oil, mixing of oil and coolant … or all of these at once.
Please also see these additional posts that talk about more specific head gasket issues and replacements:
Typical Head Gasket Failure Modes & Symptoms:
1) LOSS OF COMPRESSION: A head gasket can fail in sealing the individual cylinders. In this case, the gasket may fail between two cylinders (this would be the most common) or from one cylinder to the external of the engine/gasket.
* Gasket failure between two cylinders – When this occurs, the compression from one cylinder will leak into the neighboring cylinder. This will result in a rough running engine and a miss in one or both of the cylinders. A compression test on all cylinders will reveal this fault. Two adjoining cylinders will have very low, or no, compression.
* Gasket failure from one cylinder to outside of gasket – Similar to the above symptoms, but only one cylinder will be affected. The compression test will show only one cylinder with low, or no, compression. This failure is more rare, but can happen.
* Coolant in oil – The oil will have a white/tan/yellow foamy look when the oil fill cap or the dip-stick are removed. This is due to the water and coolant mixing in the agitated oil. A test can be performed to see if the froth is from just high condensation in the crankcase (often due to a failing crankcase ventilation system) or if there is coolant present. If coolant is present, there is likely a faulty head gasket, cracked head or cracked engine block.
* Oil in coolant – The coolant will have an oil slick on the surface or blobs of oil showing in the coolant. Often the oil will collect at the expansion tank (or radiator) filler neck and cap. If oil is present in the coolant, there aren’t really any other likely faults to cause this other than the head gasket, cracked head or cracked engine block.
3) LEAK BETWEEN COMBUSTION CHAMBER AND COOLANT PASSAGE: As implied, the gasket fails between one of the coolant passages and one of the cylinders. This failure can actually go on for some time before becoming bad enough to start showing obvious symptoms. Typically, the cylinder combustion pressure (which is much greater than the coolant system pressure) will push into the cooling system. As this happens, the cooling system becomes over pressurized and the relief valve in the cap will vent. This allows some amount of coolant to be expelled from the system. Eventually the cooling system becomes low enough (on coolant) that the engine now shows signs of overheating and low coolant. However, there are no external evidences of a coolant leak. The system is refilled and the cycle starts all over again. Tactile signs that the gasket has failed in this way include:
* Loss of coolant, but no obvious leaks -The coolant keeps getting low and the temperature keeps raising, after the system has been refilled and bled.
* The system hold pressure after the engine and the cooling system have fully cooled back to the ambient temperature. After fully cooling, opening the cap shows noticeable pressure in the system.
Testing for hydrocarbons in the cooling system will reveal if the combustion gasses are leaking into the cooling system. A positive test points to a faulty head gasket. Typically, running cylinder compression or leak-down tests as well as cooling system pressure tests, will not reveal this fault in the earlier stages due to the very small leak in the gasket.
4) LEAK BETWEEN COMBUSTION CHAMBER AND OIL PASSAGE: This will commonly cause oil usage and evidence of oil in the exhaust, such as the bluish/whitish smoke. There are not really any specific test to perform for this fault. A cylinder leak-down test may give some guidance if the leak is large enough.
5) EXTERNAL COOLANT LEAK: As the heading implies, there is a leakage from a coolant passage, past the gasket, to the external engine. This can be diagnosed with a visual inspection of the point of external coolant leakage.
Keep in mind that a failed head gasket may exhibit any one of these faults or a combination of faults. In many cases, the best one can do is to diagnose as far as possible and then make a determination to remove the cylinder head and inspect the gasket and the head. Hopefully, there will be evidence of a fault as expected from the diagnostics and symptoms.
This answer is applicable for many BMWs in addition to the one listed below.
car year: 2002
car model: 330Ci Convertible
I just decided to replace the entire shocks on my car. After removing the old shocks I found the shock shaft doesn’t extend far enough to put the compressed spring back on the shaft then reinstall on the car. This is my first attempt at removing & replacing the shocks on my car. Are there any tip or tricks that I’m unaware of that would help me complete the task and get my car back on the road.
This answer applies to most BMW and MINI models.
When replacing the front shocks/struts with many brands of replacement units, such as Sachs and most Koni (this does NOT apply to Bilstein HD and Sport), the installer may find that the new shock/strut piston rod appears to be too short for the compressed spring and upper mount assembly to be installed. What’s actually happening is that the new shock/strut piston rod is not fully extended out of the shock body. On most twin-tube shock/strut designs, the piston rod will protrude out to the middle of its travel, until the spring is installed and the spring compressor is removed.
When the old unit is being disassembled, the shock/strut piston rod is fully extended due to the spring’s extension force. The spring is compressed (using the spring compressor tool) enough to release the tension on the upper mount, allowing the mount nut to be removed and the strut assembly disassembled. When the spring and mount assembly are attempted to be installed on the new shock/strut, the spring is too long/tall compared to how far the piston rod is protruding from the shock/strut. In these cases, the spring must be further compressed. This may be as simple as further compressing the spring and compressor tool or may require decompressing and removing the spring compressor tool in order to reposition it on the spring so that it can compress the spring tighter (shorter). In some cases, the use of a pro-style compressor may be required. This type of compressor compresses the complete strut, spring and mount assembly all at once. In other words, there are no thick compressor fingers in between the spring coils, preventing full compression of the spring.
The “pro style” spring compressors can be bench or wall mounted, be manually or pneumatically operated and cost hundreds to thousands of dollars. BavAuto does offer a pro style spring compressor that works very well for all types of spring compression, especially when the job requires full compression of the spring, as noted above. Watch the video in the link below, to see the tool in use.
car year: 2006
car model: 525Xi
How do you replace the factory cup holder in the dashboard?
The factory cup holders in the E60 5 series cars (2004-10, 525i, 525xi, 528i, 530i, 530xi, 545i, 550i, M5, X-Drive) are cassette style units. You will need to extend the cup holder into the open position and at each side will be either a Torx or Phillips head screw, remove these screws and withdraw the cup holder. Align the replacement cup holder in the bracket and slide it in until it engages the rear rubber alignment stud. Replace the screws making sure you do not overtighten, as this could crack the plastic.
Click below for cupholders:
(Click link and choose your year and model BMW)