Hello together, since I had a few waterpumps commissioned for rebuild and/or conversion, some weeks ago I decided to make a simple testing device for checking, whether all is leak free. I wanted something I could look inside to check, that it's filled with antifreeze and as little air as possible. So I made it from PMMA ( Plexiglas, acrylic glass ) . The first one literally 'exploded' while testing (without pump) when applying pressure at 8 bar because I forgot to regulate down my compressor. Calculations with the tensile strength values of the PMMA glue did prove, that I should better have avoided this pressure. But the second try worked and stands 4 bar without problems. That PMMA glue is amazing. There is one bore for filling, one for bleeding and a truck tire valve to pressurize. Now I can test my waterpumps for leak tightness with pressure of 1 bar for one hour. Best Regards from Germany Martin Image Unavailable, Please Login Image Unavailable, Please Login
Clever! Can you also rotate the water pump shaft during testing to check for any out-of-round, flatness, or alignment anomalies that may be present within the assembly?
This is also possible, though I check for axial and radial runout of the shaft, the bearing seat and the seal seat, while rebuilding the pumps. Or prior to cutting work on the shaft and housing for the conversion of the old two piece seal version to the one piece seal. I aim for max. 0.01mm (0.0004") axial and radial runout tolerance, what's the instruction of the seal and bearing manufacturer. That said, I always like to mention, that repro shafts - I once purchased one - have up to decuple radial runout tolerance between bearing and seal seat (0.1mm, 0.004") Best Regards Martin
Excellent! I like the design. Don't you want to test for higher? The cap might blow at 1bar but somtimes people use higher pressures like 1.3 for a reason. Anyone know what industry test procedures are?
Maybe I go up to 1.5 while testing, but I don't want to stress the seal's rubber bellow much more, than what it was designed for. Best Regards Martin
I just had a look onto the engineering drawing I once got from the seal manufacturer, whose seal I use for the conversions. They determine the leak rate at a test pressure of 1.9 bar. Best Regards Martin
I have a similar fixture that I use for 355/360 pumps. Image Unavailable, Please Login Image Unavailable, Please Login
Martin, I'm curious, what prompted the development of testing apparatus? Were you having problems with leaks using the new one piece seal? Sent from my SM-G900V using Tapatalk
Ettore, not at all but I just like to test things as far as possible prior to bringing into service. Something like a last electrocardiogram, prior to leaving hospital During 35 years of industrial activities ( machining, engineering ) I experienced so many faulty machine components out of the box, since no manufacturer is immune against it. Even before China and others were part of the game. This leaves an impression. You once told, that you had problems with leaks before you tackled our conversion. With pumps from a professional rebuilder. Probably it would be a good thing, if he had testing equipment. Best Regards Martin
Hi Martin, Great work and nice to have the visibility that this PMMA formulation provides. This may fall into one of those 'engineer with too much time on his hands' categories, but it would be interesting to source a current 'stock' part and then test it to determine performance versus your improved version, e.g., leak threshold as a function of pressure. Additionally, what about testing the impact of temperature?
Indeed, it was my frustration with the "expert's" multiple unsuccessful rebuilds that led me to your method. As you know, I've now rebuilt several of the pumps with the single piece seal and wanted to make sure you weren't noticing problems with them. The first pump I rebuilt with this method remains in service on my 328 (two years and counting) and it gives me great pleasure to see those weep holes staying dry. Sent from my SM-G900V using Tapatalk
Hi John, temperature impact would require a much more complex system. I just wanted a device for a quick leak test to avoid such surprises I once experienced with a current 'stock' part when it immediately leaked after installation. Regarding your proposal with comparing a current part with my conversion would not be very meaningful, I think, because I am certain, that the problem with the current available pumps is the variation in manufacturing quality. Say, one may be o.k. and the next can be faulty. Quality control is left to the customer. Best Regards Martin
How simple. I like that. I have been lucky. 39 plus years of rebuilding and never a leak. But I don't do many. Tim What do you use as a test pressure or what is your test procedure?
