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WP leak post mortem - used 219 Viton O-rings (220 could fit)  1 Saabers Like This Post!
Posted by Mark in Marine [Email]  (#1837) [Profile/Gallery]
(more from Mark in Marine) on Sat, 25 Nov 2017 17:59:35
In Reply to: Trying out Viton O-rings this weekend & experiment update, Mark in Marine [Profile/Gallery]
, Tue, 14 Nov 2017 18:00:55
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Post-mortem for the leaking water pump on my daughter's 2006 SC.
Confirmed O-rings on the block-to-pump pipe were the issue, particularly the block O-ring. Those were "OEM" O-rings slathered in Permatex Ultra blue. Still, the block O-ring had an extreme "D" cross section, and so did the one on the pump side, but less extreme.
I tested each of my four Viton(R) O-ring sizes on the pump-pipe joint, and I went with the 219 size. The 220 can just barely be jammed in, but when I did that the stress was so high that I couldn't get the joint to stay square. These O-rings come in a 10-pack from McMaster Carr for about $7. The package is labelled with the lot cure date and a 20-year shelf life. I ordered brown, so they can be easily told apart from Buna N O-rings.
I used a white lithium anti-corrosive lube similar to Gleitmo. The connector pipe was hard to push into the block with the 219 size O-ring, which is what I wanted. The 218 is still a compression fit, but not as firm. After reassembly I pressure tested. I detached the expansion tank coolant line, plugged it, and used a Motive Products pressure bleeder (as air pump only) to apply about 10PSI through a piece of 1/4" fuel line to the expansion tank. I didn't go higher because I was unsure how accurate the gauge was, and I didn't want to create a leak. I finished reassembly and ran the car - no leaks !
Comments on the pump: Old pump was an "Airtex" pump from Rock Auto, made in Spain and with similar/same markings as SAAB OE pump. The pump itself was in great shape, but since it has 22K miles and two years on it, I replaced it using a new Meyle waterpump, which looks very cleanly welded and machined. That pump came with one "small" O-ring and one "large" one, per 9-3 fitment. These and the small side pipe O-ring appeared to me to be silicone or a blend - they are softer and glossier than Buna N O-rings. The cross section for those O-rings is about a 3mm, while the SAE O-rings I used are about 3.5mm unstretched. I ordered a second "small" O-ring on the same order, but it appeared to be standard Buna-N material. I'll bother a former colleague to confirm my guesses about ID of the materials with Infrared spectra.
I am hopeful that this fix will last a long time - we don't get down to the -10F or -20F temps that often, and even then the time spent at that temp is very small. And I may not know the answer for years. Oh, daughter number two just told me that she had to add coolant last week, so I guess I will get to do this at least one more time =).
Hope this adds a little info to the knowledge base.
Mark in Marine
, Thu, 9 Nov 2017 19:21:54, Tue, 14 Nov 2017 18:00:55, Sat, 25 Nov 2017 17:59:35 <-- Viewing This Message
1, Tue, 6 Aug 2019 20:21:381
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