Author Topic: 2010 Mazda3 Sport i stop windscreen washer problem  (Read 4933 times)

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Offline aytch

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Re: 2010 Mazda3 Sport i stop windscreen washer problem
« Reply #15 on: August 03, 2023, 12:18:15 PM »
Actually I am now wondering whether I have part answered one of my own queries...re the surmise of there being two individual pumps for front and rear.
On further investigation of the original link kindly indicated to me by Misar, I have found this link which implies there is only one pump...
https://www.mazda3tech.com/washer_motor_removal_installation-873.html (if it applies to my particular Maz3 sport 2010 version), so this has shot out of the water another possible reason for reduced water sprays from the front jets.... :(
(If there IS only one pump, one thing I have noticed is that the pump sounds different when using the rear washer as opposed to the front - whether this is relevant I have no idea)

Offline Engineer Andy

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Re: 2010 Mazda3 Sport i stop windscreen washer problem
« Reply #16 on: August 10, 2023, 11:52:49 AM »
The problems when you design effectively two systems using one pump is that you:

a) Have to design each set of pipes to effectively be of equal (or very close) pressure drop for the flow rate required at the nozzle so that the pump output (impeller speed and pressure developed) does not have to vary.

This can only be done by either varying the pressure drop over the length of the pipes via carying the size of the pipes and/or deliberately adding in restrictions of one sort or another, like hard bends or specific flow restriction devices.

The problem with this, especially when using liquid media and in an environment such as a road vehicle is that contaminents can get into or build up in the system and block certain pipes, more so if restrictions are used.

OR

b) use a variable speed (two speed as a minimum) pump that has sufficient control systems to know which sub-circuit the driver wants to use the windscreen washer for via the steering wheel control and change output accordingly.

A basic version (though still a lot more expensive than a single speed pump) would be a two speed pump, but even then the system design methods employed in a) would likely have to be done as the likelihood of the pump's output matching the requirements of the system without modification is low, unless you get a pump specifically design for the car in question, which would jack up the price even more and make replacements equally expensive as they would be essentially unique to that vehicle.

The other way to accomplish the task would be to use a variable speed pump that uses an inverter to essentially find any flow rate and pressure output you need within the minimum and maximum it can practically / econimically and physically produce.  The pump can also be selected so that it can, to a reasonable degree, take into account some variations in performance requirements caused by blockages over time in the system.  Modern pumps can do this much more cheaply than they used to as the cost of fitting inverters and related controls have dropped significantly since they were developed some decades ago.

Effectively this is what should be done (by best practice) in the Building Services industry when designing pumped water and forced air ventilation systmes, to cope with 'dirty' (full) filters, etc plus a decent margin on top (i.e. good engineering).

In the long term, such a system (without artifical restrictions in the pipes and that use reasonable bore pipes to reduce the instances of blockages) would be better, but of course, we all know that car manufacturers don't always go that route, mainly because the extra reliability (over planned obsolescence) earns them less money from parts replacements outside of the warranty period.

Of course, using two pumps can be done at a far greater cost, but to get the best out of them, they technically need to each be variable speed.  The main advantage is that if one breaks, the other is at least still operational.

Offline aytch

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Re: 2010 Mazda3 Sport i stop windscreen washer problem
« Reply #17 on: August 10, 2023, 11:50:11 PM »
Hi and many thanks for that insight Andy.
One oddity I have so far noticed whilst the jets aren't performing as they should - initially when pulling on the column stick to begin them working, but only for a second, the very first water to come out of both jets would appear to be of normal pressure enough to correctly spray the windscreen. This then immediately drops to the reduced flow which only just manages to get over the wiper blades as they come down to their "parked" position....

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Re: 2010 Mazda3 Sport i stop windscreen washer problem
« Reply #17 on: August 10, 2023, 11:50:11 PM »