| [GMCnet] Dip stick calibration question [message #271367] |
Sat, 07 February 2015 17:51  |
glwgmc
Messages: 1014
Registered: June 2004
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The dip stick tube on the Clasco was found to be loose during the R&R of the new engine. It was replaced and secured in what should be the factory location. It was a major leak point so could have been part of the cause of the mysterious oil going somewhere issue.
When I got it home I noticed that the forward end of the dip stick tube in the Royale was way shorter than where it is in the Clasco. I found the dip stick tube in the Royale also was loose but could only pull it up to a point that it is still about 2" shorter than where the forward end of the dip stick tube is in the Clasco. The oil reads about 2" over full on the dip stick when it is pushed all the way in.
So, the question is how do I know for sure where full is in either engine? Conventional wisdom says the system holds 6 quarts when filled from dry and 5 quarts with a drain and fill, but KenH posted a bunch of pictures a while back of measurements he made with an engine on a stand. http://www.gmcmhphotos.com/photos/455-oil-pan-capacity/p10641.html.
His measurements show that the front of the pan holds right at 1Q that will not drain back into the rear sump with the coach level. That matches conventional wisdom. His measurements also show that full on the factory dip stick occurs with only 3 quarts in the rear sump part of the pan. Conventional wisdom says it takes 5 quarts to fill the system at an oil change. Three quarts drained out of the rear sump, 1 quart stayed in the front of the pan, some (half quart?) stayed in the old filter so another quart and a half must have drained out of the radiator cooler and lines in order to equal the 6 quarts originally added to a dry engine.
In KenH's pics it takes 4 quarts to fill the sump end of the pan to just where it would spill over the hump, yet that is 1" higher than he measured relative to the full line on a factory dip stick so the engineers apparently thought it best to show full with only 3 quarts in the sump. The add mark is where you only have 2 quarts of oil in the sump which seems scary low to me.
So, back to the original question, how can I know for sure that either dip stick is properly calibrated? The Clasco showed a bit below the full mark when it was first filled with 6 quarts from dry, run for a bit to fill the filter, lines and cooler in its aluminum radiator (which is bigger than the stock radiator oil cooler by some amount) and its external engine oil cooler. When I got it home it showed lower than that so I added oil to bring it to the full line assuming the original six quarts from dry did not fully account for the difference in the size of the aluminum radiator cooler and the fact that the external oil cooler also stayed in place so it logically would have taken a bit more than 6 quarts to get to full.
Since the front end of the dip stick tube in the Royale appears to be about 2" further back from where the front end of the dip stick tube is in the Clasco, I added a temporary 2" spacer and measured the oil to be right at full in the Royale. So all appears ok, but I really would like to find a definitive way of knowing where full is on both engines.
Assuming KenH's measurements are spot on it would seem one way would be to drill a small hole in the side of the pan 4.5" down from the flange, drain and fill the engine, run it for a bit and add oil until oil weeps out that hole and then seal the hole. That should be full no matter how the capacity differs from stock given the aluminum radiator, larger lines or filter or any external oil coolers or how far the dip stick tub goes into pan if I am thinking correctly. The dip stick could then be calibrated to properly show full. Any thoughts or ideas from the brain trust?
Jerry
Jerry Work
The Dovetail Joint
Fine furniture designed and hand crafted in the 1907 former Masonic Temple building in historic Kerby, OR
Visitors always welcome!
glwork@mac.com
http://jerrywork.com
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Jerry & Sharon Work
78 Royale
Kerby, OR
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