Ive had a delay between the time the windshield wipers wipe and when the fluid hits the windshield. When researching, starting a few years ago, I never found a definitive solution to the issue, or whether it was really an issue vs bad programming. Knowing that there were at least a few instances of people saying their fluid came out at the exact same time the wipers would wipe, meant I had to investigate to find my solution. I figured it was either a check valve or a pump.

When I scanned the pump with xentry It was pulling slightly too much power. I replaced the pump but this did not fix the delay. Being that my car is a wagon, it has two pumps so make sure to buy the correct pump. While I was in there I replaced the grommet for the pump as well as the level sensor and grommet for the washer fluid since it was getting wonky because of the type of design it is. I had hoped that the pump had the check valve in it as well but it does not.

Next was to find the check valve. There is a likely aftermarket solution but I did not try it. Its an elbow that connects at the junction of the line and pump. I didnt want to waste the money if it did not work and since a proper fix isn't much. Please report back if these work.


I have the heated nozzles and the check valves are built into the nozzles. I suppose I could take them apart and clean them but the new heated line with nozzles was only 79 bucks so I figured it was worth replacing. Replacement took under an hour and was very easy. I got my wis back up and running and the instructions were clear and comprehensive.

After replacing the line I have waited a few days to report back. The spray now comes out at exactly the same time as the wipers start to wipe with no delay. I hated potentially scratching my windshield each time I wanted to clean it. The rear wiper never had delay but because it was a separate pump, it was hard to correlate if I had an issue.

So, If your pump is good and you have a delay between the wipers wiping and the pump squirting, a proper solution is just an hour away.

 

Nice work - here's the 2021 thread for others to refer to from your post

https://mbworld.org/forums/e-class-w...-solution.html

 

yes, I had seen that thread, but it is honestly a bit too messy. Just using the check valve I linked from Amazon should connect right between the pump and the line. There’s no wire to worry about there.

just a quick connect. You can see the wire inside, but that wouldn’t be disturbed.

 

So this valve goes on the pump down behind the pass. tire/splash guard? I'm guessing the root cause is bad check valve somewhere else in the system?