928 Waterpump failure, warning device
10-15-2009, 09:03 PM
#31
Team Owner
Thread Starter
well from just hand spinning the WP the tab makes the pulley sing, but i am sure it will be much quieter with a belt running on it
10-15-2009, 09:06 PM
#32
Three Wheelin'
Join Date: Jun 2008
Location: Surprise, Arizona
Posts: 1,914
Likes: 0
Received 0 Likes
on
0 Posts
Give her a running engine test. If it screams???
When do they go on sale? You might have to experiment with different alloys and heat treatment to get the best sound...
When do they go on sale? You might have to experiment with different alloys and heat treatment to get the best sound...
10-15-2009, 09:38 PM
#34
Basic Sponsor
Rennlist
Site Sponsor
Rennlist
Site Sponsor
Another reason to stay clear of rebuilds.
Stan,
New pump on its way to you.
Stan,
New pump on its way to you.
__________________
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014
928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
10-15-2009, 09:51 PM
#35
Rennlist Member
Join Date: Feb 2004
Location: Milwaukee, WI
Posts: 297
Likes: 0
Received 0 Likes
on
0 Posts
Hey wait guys, its a German car, let's make this as complicated as possible!! I think if we throw in 2 or 3 micro switches, a relay, 1 fuse, 8 spade connectors and 2 to 3 car lengths of wiring that this should work. Oh great, there I go again, being sarcastic and all!!! I like the simple idea. Looks like it should work perfectly. Joe
10-15-2009, 11:01 PM
#36
Team Owner
Thread Starter
I think that this could be made in a machine with final fitment done for each installation, it might be a good idea to incorporate this if a rebuilt pump is being used.
It takes me about 30 mins to make a part, but i think that each install will be a bit different.
The last part will be silicone to hold this steel to the WP, even though the cover does capture it, I may also file a small groove into the cover to make sure this piece wont slide sideways
It takes me about 30 mins to make a part, but i think that each install will be a bit different.
The last part will be silicone to hold this steel to the WP, even though the cover does capture it, I may also file a small groove into the cover to make sure this piece wont slide sideways
10-15-2009, 11:23 PM
#37
Rennlist Member
Not wishing to hijack the thread.
I have been thinking about this for a while. It seems to me that a lot of our WP problems are related to the bearing which ids driven by a tightish belt several cm's on one side of it. This seems to apply a lot of twisting pressure in the shaft and bearing. Would it be possible to engineer a bracket that mounted to some of the WP bolts that held the pulley within a bearing on the outside of the pulley. This would mean that the pulley was supported by a bearing on both sides, thereby reducing the stress on it.
The bracket would ideally be three legged and fit over the pulley once the belt was loosely in place.
Any ideas if this would be possible or work?
A bit of play in the mounting holes would allow for adjustment to fit individual pumps.
Might be a problem if the pulley outer hubs are all different sizes.
Regards,
Myles
I have been thinking about this for a while. It seems to me that a lot of our WP problems are related to the bearing which ids driven by a tightish belt several cm's on one side of it. This seems to apply a lot of twisting pressure in the shaft and bearing. Would it be possible to engineer a bracket that mounted to some of the WP bolts that held the pulley within a bearing on the outside of the pulley. This would mean that the pulley was supported by a bearing on both sides, thereby reducing the stress on it.
The bracket would ideally be three legged and fit over the pulley once the belt was loosely in place.
Any ideas if this would be possible or work?
A bit of play in the mounting holes would allow for adjustment to fit individual pumps.
Might be a problem if the pulley outer hubs are all different sizes.
Regards,
Myles
10-15-2009, 11:45 PM
#38
Team Owner
Thread Starter
There are quite a few different rebuilt pulley versions
10-16-2009, 01:44 PM
#39
Rennlist
Basic Site Sponsor
Basic Site Sponsor
Except the pulley never moved...the impeller just fell off.
__________________
greg brown
714 879 9072
GregBBRD@aol.com
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
greg brown
714 879 9072
GregBBRD@aol.com
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
10-16-2009, 01:56 PM
#41
Team Owner
Thread Starter
I would also suggest that if your installing a new to the car waterpump rebuilt/ new that you add some Green Loctite to the shaft/impeller and let it dry.
Sorry to hear of the impeller falling off Greg
Sorry to hear of the impeller falling off Greg
10-16-2009, 03:41 PM
#42
Craic Head
Lifetime Rennlist
Member
Lifetime Rennlist
Member
Stan, looks good and if it makes noise when you turn it by hand I'm sure it will work with the engine running.
For those of you discussing the warning system: I think the 3 minute delay is only upon startup. Thereafter the warning light is an instant latching relay that can be reset (!).
So it's a normally closed contact to ground that triggers if the circuit is opened after the initial 2.5-3 minute 'grace period' after startup.
So possibly in place of (or in addition to?) Stan's 'squealer' we might want to consider a break pad wear sensor with the loop just beyond the reach of the lower edge of the pulley. If the pulley moves it would wear through the circuit and open it (I think).
The questions are:
How much movement is too much?
Is there enough time between when the pulley starts to move and when it starts to eat parts to make a difference? Apparently in the failure mode that Stan saw, there is.
Myles, I agree. In the S4 there is a bracket to help secure the shoulder bolt that is the pivot point of the stock tensioner roller. This is presumably to help take the strain off of that bolt. If a similar bracket or pump mod could be created it would alleviate the real problem: The fact that the WP pulley has a tremendous amount of strain on it and the bearings are just press-fit in the WP housing and are on one side. IMO a bad design that beefier bearings and beefier housing just mask but don't address.
For those of you discussing the warning system: I think the 3 minute delay is only upon startup. Thereafter the warning light is an instant latching relay that can be reset (!).
So it's a normally closed contact to ground that triggers if the circuit is opened after the initial 2.5-3 minute 'grace period' after startup.
So possibly in place of (or in addition to?) Stan's 'squealer' we might want to consider a break pad wear sensor with the loop just beyond the reach of the lower edge of the pulley. If the pulley moves it would wear through the circuit and open it (I think).
The questions are:
How much movement is too much?
Is there enough time between when the pulley starts to move and when it starts to eat parts to make a difference? Apparently in the failure mode that Stan saw, there is.
Myles, I agree. In the S4 there is a bracket to help secure the shoulder bolt that is the pivot point of the stock tensioner roller. This is presumably to help take the strain off of that bolt. If a similar bracket or pump mod could be created it would alleviate the real problem: The fact that the WP pulley has a tremendous amount of strain on it and the bearings are just press-fit in the WP housing and are on one side. IMO a bad design that beefier bearings and beefier housing just mask but don't address.
10-16-2009, 03:55 PM
#43
Rennlist Member
What about a knock sensor?
10-16-2009, 03:55 PM
#44
Rennlist Member
What about a knock sensor?
10-16-2009, 04:47 PM
#45
Inventor
Rennlist Member
Rennlist Member
Is a new water pump pulley conductive through the cassette to the pump body? If yes, how much resistance? How conductive is the coolant? What is the resistance as installed?
I'm thinking that the pulley or impeller touching the pump body will decrease the resistance significantly. If you put a carbon button (like in a distributor cap) through the cover, touching the center of the pulley axle, you could connect that to the coolant temp light through a variable resistor? (Adjust the resistance so that the light just stays off.)
I'm thinking that the pulley or impeller touching the pump body will decrease the resistance significantly. If you put a carbon button (like in a distributor cap) through the cover, touching the center of the pulley axle, you could connect that to the coolant temp light through a variable resistor? (Adjust the resistance so that the light just stays off.)