Post by splischke on Nov 15, 2011 17:47:11 GMT -5
Out of curiosity, I tested the loaded tension of 3 pairs of oil pressure relief and control springs and thought I'd post my results. First, my test was a little crude using wood blocks and a shipping scale but my findings are in the ballpark.
VW is very specific about spring tension. If the loaded tension does not fall within allowable ranges, the oil bypass system may fail to function properly. One possible consequence is reduced flow through the oil cooler resulting in high oil temperatures. Below is a table with the loaded spring tension values VW specifies:
Below is an image of the 3 pairs of springs I tested. The OEM springs (some people call them that) are easily identified as the darker, non-chrome plated springs. The chrome plated springs are all EMPI and I believe all are "booster" springs.
The following are images of the test. I used 13/16" and 1-3/4" thick wood blocks. The 1-3/4" block for the relief spring is shown. The blocks have holes in the middle to keep the springs stable when being compressed. The springs were compressed to the top of the blocks -- or the "loaded length" -- and the scale's readings recorded. Again, this test is a little crude.
Pressure Control Springs: (6.8-8.4 lb specified)
Pressure Relief Springs: (12.3-16.0 lb. specified)
The EMPI oil control spring highlighted in red was much stiffer than what VW calls for. If used, the valve may never open and may cause the well engineered and finely tuned dual bypass system not to function properly.
I guess the point I'm making, if I'm making a point, is to be mindful when selecting springs. Just because they're new and chrome plated doesn't mean they're the best choice!
If this topic doesn't liven the forum, I'll start another topic on how using higher viscosity oils totally screws with your finely tuned oil bypass system.
-Scott
VW is very specific about spring tension. If the loaded tension does not fall within allowable ranges, the oil bypass system may fail to function properly. One possible consequence is reduced flow through the oil cooler resulting in high oil temperatures. Below is a table with the loaded spring tension values VW specifies:
Below is an image of the 3 pairs of springs I tested. The OEM springs (some people call them that) are easily identified as the darker, non-chrome plated springs. The chrome plated springs are all EMPI and I believe all are "booster" springs.
The following are images of the test. I used 13/16" and 1-3/4" thick wood blocks. The 1-3/4" block for the relief spring is shown. The blocks have holes in the middle to keep the springs stable when being compressed. The springs were compressed to the top of the blocks -- or the "loaded length" -- and the scale's readings recorded. Again, this test is a little crude.
Pressure Control Springs: (6.8-8.4 lb specified)
- OEM: Length = 32 mm, Tension@20.20 mm = 8.1 lb.
- EMPI, Length = 36 mm, Tension@20.20 mm = 18.0 lb.
- EMPI, Length = 34 mm, Tension@20.20 mm = 8.7 lb.
Pressure Relief Springs: (12.3-16.0 lb. specified)
- OEM: Length = 81 mm, Tension@44.10 mm = 12.5 lb.
- EMPI: Length = 83 mm, Tension@44.10 mm = 13.7 lb.
- EMPI: Length = 78 mm, Tension@44.10 mm = 18.2 lb.
The EMPI oil control spring highlighted in red was much stiffer than what VW calls for. If used, the valve may never open and may cause the well engineered and finely tuned dual bypass system not to function properly.
I guess the point I'm making, if I'm making a point, is to be mindful when selecting springs. Just because they're new and chrome plated doesn't mean they're the best choice!
If this topic doesn't liven the forum, I'll start another topic on how using higher viscosity oils totally screws with your finely tuned oil bypass system.
-Scott
