Replacing Water Pump Stud
03-20-2019, 04:02 PM
#1
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Replacing Water Pump Stud
One of the water pump studs broke on me and I was lucky enough to get it out. The stud in question is the far left one (yellow arrow) see picture attached. I bought the water pump stud kit from 944 online and am not sure if it's the shorter or longer stud. I'm guessing it is the shorter stud but want to be sure before making a simple mistake. It also looks like one end has fewer threads, does this end go into the engine block? Thank you!
https://944online.com/index.php/wate...-stud-kit.html
https://944online.com/index.php/wate...-stud-kit.html
03-23-2019, 04:28 PM
#2
Rennlist Member
Wabi, take a look at the thickness of the bores in the waterpump through which the studs (or bolts) pass. Longer / deeper bore gets a longer stud or bolt.
The end with the fewer threads traditionally goes into the block. DIN 939 studs "neck out" (bulge) in the non-threaded portion, which stops them threading into the block (for example) any farther. However, the studs that Porsche sells are not compliant, hence their 999. part number rather than 900. Don't know why Porsche does this. I also don't know about the 944online parts.
Your current studs all look nasty, and I'd replace them all if feasible. Use heat on the block to loosen and break down any thread locker that was used. Double-nut or use a collet-style stud remover to turn them out. Reinstall with anti-seize.
Good luck!
Kevin
The end with the fewer threads traditionally goes into the block. DIN 939 studs "neck out" (bulge) in the non-threaded portion, which stops them threading into the block (for example) any farther. However, the studs that Porsche sells are not compliant, hence their 999. part number rather than 900. Don't know why Porsche does this. I also don't know about the 944online parts.
Your current studs all look nasty, and I'd replace them all if feasible. Use heat on the block to loosen and break down any thread locker that was used. Double-nut or use a collet-style stud remover to turn them out. Reinstall with anti-seize.
Good luck!
Kevin
03-23-2019, 05:28 PM
#3
Drifting
Kevin, when installing studs into the block or head (or wherever), is there a torque specification? I'm asking because I had to put new exhaust studs into my head and the machinist just said "not too tight". I installed them not knowing for sure what is the right way and I bet this info might be useful for the OP and for myself in the future TIA
03-24-2019, 01:53 PM
#4
Rennlist Member
Hi Dan, no torque for threading it into the block. I usually will thread it in until it bottoms out, then back it off perhaps a quarter turn -- for no particular reason I can think of! Torque is used to stretch the threads and ensure that the threaded bit (stud or bolt) stays in place. With studs, you get the stretch at both ends once you torque down the nut on the end that sticks out. So torquing the stud into the block is not necessary or helpful.
Regarding "thread it in until it bottoms out," this assumes the unthreaded middle bit is located where you want it to be. If it isn't, if it goes too deep, then back it out as needed. I hope this makes sense. Good luck!
Regarding "thread it in until it bottoms out," this assumes the unthreaded middle bit is located where you want it to be. If it isn't, if it goes too deep, then back it out as needed. I hope this makes sense. Good luck!
03-24-2019, 02:38 PM
#5
Drifting
Hi Dan, no torque for threading it into the block. I usually will thread it in until it bottoms out, then back it off perhaps a quarter turn -- for no particular reason I can think of! Torque is used to stretch the threads and ensure that the threaded bit (stud or bolt) stays in place. With studs, you get the stretch at both ends once you torque down the nut on the end that sticks out. So torquing the stud into the block is not necessary or helpful.
Regarding "thread it in until it bottoms out," this assumes the unthreaded middle bit is located where you want it to be. If it isn't, if it goes too deep, then back it out as needed. I hope this makes sense. Good luck!
Regarding "thread it in until it bottoms out," this assumes the unthreaded middle bit is located where you want it to be. If it isn't, if it goes too deep, then back it out as needed. I hope this makes sense. Good luck!
03-25-2019, 02:27 PM
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Thank you, Kevin! I found the picture online as I was not able to take one of the car at the time. The studs installed in my car are in slightly better shape so I opted out of removing them. I chased the thread in the block carefully to remove any particulates and installed the short end of the stud with anti-seize, things are looking good! Again, I appreciate you taking the time to respond.
03-26-2019, 01:41 AM
#7
Rennlist Member
The studs are placed where the water pump's threaded holes go through to the water jacket. For this reason, the studs have to be installed with loctite which will seal the threads from weeping coolant.
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03-27-2019, 01:10 AM
#8
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03-31-2019, 02:15 AM
#10
Instructor
03-31-2019, 02:47 PM
#11
Rennlist Member
Yes, any Loctite will seal the stud's threads, but best if the stud doesn't want to come back out when removing the 6mm nut during future maintenance. Typically red Loctite is used for studs to ensure the stud stays in place. 6mm and 8mm studs can still be removed when/if necessary.
Studs used for critical applications like main studs and head studs are NOT installed with Loctite unless they are final torqued right away (see Loctite instructions). Further, their 12mm size makes them much more difficult to remove (more area for the Loctite to grip). For these I use Extreme Pressure Lube #3 on the stud's threads that go into the block. You'll get proper stud clamping force (fastener stretch) and easy future removal.
Studs used for critical applications like main studs and head studs are NOT installed with Loctite unless they are final torqued right away (see Loctite instructions). Further, their 12mm size makes them much more difficult to remove (more area for the Loctite to grip). For these I use Extreme Pressure Lube #3 on the stud's threads that go into the block. You'll get proper stud clamping force (fastener stretch) and easy future removal.