Welcome to Tech Talk, where our resident BMW tech Nick Owen answers all your pressing BMW technical questions, frustrations, and issues. Have a question for Nick? Email him at techtalk@roundel.org. Let’s get into it.
OEM OR AFTERMARKET SHOCKS
Background: South-East Florida-housed 2000 BMW Z3 roadster, owned for four years. It is time to change the shocks, struts, etc. As a retired person who rarely drives the vehicle more than 50 miles per month, I cannot decide whether to install affordable stock BMW, Konis, Bilsteins, or OEMs. The car is basically used as a round-the-towner or a biannual run to Orlando.
Your comments would be appreciated. Thank you in advance.
Stew Webster
If you are not seeking to add any additional dampening to the sub-100-miles per month you drive, OEM shocks would complement the originality of your roadster. While Konis have adjustable rebound, some may dislike the sensation. A Bilstein is an excellent replacement for an OEM shock, but it may add additional dampening.
But if you are looking to increase the dampening on your Z3, then I would recommend a Bilstein shock with an OE aftermarket lowering spring; this setup will barely lower the car by a quarter or half an inch, but add a noticeable difference to how the car drives without being too bouncy on your runs to Orlando.
TIME TO TAKE IT TO A PRO
I have a 2002 BMW E39 M5, and the fuel gauge usually stops at half full and then jumps to empty if I don’t remember to get gas. I would like to know how I can decide which float is bad, and I’m wondering how I should repair this after five years. Should I replace everything. or just the bad parts? It seems like there are two floats and a pump.
I watch videos on how to do the repair, but even using the onboard test tool, which has an adding machine built in, I’m not really confident in troubleshooting the exact float and would just like to know more.
Gordon Gregg
This kind of diagnosis is going to require professional help, because if it becomes necessary, you will need to access both of the fuel-level senders in the tank after removing the back seat and exposing both service holes for each side of the tank. Each side will hold a fuel-level sender, but it will be dirty and dark, with not much space to maneuver your hand inside the tank to manipulate the sensors and see which one is reading incorrectly via a scan tool. Personally, I would replace both so that you don’t have to deal with the issue again. If you are going to tackle this yourself, be sure to have less than a quarter tank of fuel to prevent a big spill.
BUNDLING THOSE REPAIRS
I am the original owner of a 2016 435i coupe (F32) with about 53,000 miles on it. I have maintained the car following recommendations found in the Lifetime Maintenance Guide. Despite a higher cost, all service has been done at my local dealership; I have a good working relationship with my service advisor and the shop.
The car is now at the age that various gaskets are needing to be replaced. The valve-cover gasket needed it last year, and now I need to replace a leaking—just seeping at this point—oil-pan gasket. As I’m sure you are aware, this will require dropping the subframe, making it a lengthy and expensive job. Are there any other items that you would suggest be replaced or dealt with at this time? One thought is the charge pipe; I have read that the stock plastic one is prone to cracking on these N55 engines. If I were to replace it, I would prefer to use an aftermarket aluminum one, but I’m not sure if the dealership would install a non-BMW part.
Your thoughts are much appreciated.
Stacey Wood
Charlotte, North Carolina
If I were going to drop the subframe on a ten-year-old 435i with an N55 engine, I would do a few additional things:
- Motor mounts: They are right there, and there should be no labor to replace them. By the way, a worn motor mount could contribute to a broken charge pipe.
- Electric water pump: Despite the mileage, I do not trust something electric that has been submerged in coolant/water mix for tens of thousands of miles. I did the water pump on my wife’s M2 (N55) at 60,000 simply for the peace of mind.
- Alignment: Lowering the subframe can change the tension on the front suspension, influencing a change in the front toe, throwing off a straight steering wheel. Maybe combine this service with new tires?
- Thermostat—with a caveat: If it’s there by the water pump, do it. But if it’s not and is going to be extra labor, then you can wait. I say this because on the N55 F32 chassis I believe that the thermostat is separated from the water pump, unlike the N20/N52 models, in which it is basically attached to the water pump by two bolts.
Since the thermostat is electronically controlled, you could wait until a fault occurs before replacing it. However, if it is convenient to replace while the vehicle is in for the items above, then I would include having it replaced.
The charge pipe is definitely a 50,000–60,000-mile service item; my wife’s M2 broke one at around 65,000 miles a few months ago! An aftermarket one isn’t a bad idea, and since the vehicle is out of warranty, I don’t see why a BMW dealership wouldn’t install it for you. (I would if I were the technician on your car.)
