Rich wrote:Also check that you have the right dipstick. Lycoming actually has several different length dipstick/filler tube pairs listed for IO-360's. If the plane had an annual done at a shop that was working on other planes at the same time, maybe the dipsticks got swapped.
I checked my dipstick today and have the offending one (LW-16783-18) addressed in this bulletin. An excerpt says:
This replacement is necessary because recent validation tests show that oil level gage P/N LW-16783-18
incorrectly gives higher oil level indication when the oil level is actually less than 5 quarts (5 liters).
So maybe you think it has 4-1/2 but it actually is already down to 4 - maybe.
does apply to the IO-360-M1A, so I ordered the replacement today. Price will be credited back upon my returning the old one. I'll try and get comparison shots of the two when it arrives.
rwtucker wrote:Where did you order from Rich? Was is something like $160?
The weird thing is that i did an empirical calibration of my 5-qt notch. It fell at the expected place on the gradations.
First step is to check to see which dipstick part number you have. The stated inaccuracy starts when the level is below 5 quarts. FWIW, my dipstick has no marking at 5 quarts - just 6 and 8.
When I change oil, I put in 8 quarts + just under a pint of camguard. The dipstick shows just above 7 - every time. Now some of that goers and hides in the oil filter. It doesn't look like an entire quart of oil would be retained in the filter itself, but maybe in the filter plus the related internal plumbing. Anyway, with the M20 I installed years ago, it no longer purges that level above 6 quarts.
I realized I didn't answer the question about where I ordered it. It was something like $190, but it'll be refunded when I return the old one, after getting a RMA. I ordered it from Aviall. They wanted me to go through my regular shop, but accommodated me anyway. I didn't want to bug my regular shop, though I'm sure they would have ordered it.
I figure I'm out shipping costs, but thankfully this isn't a 3-bladed prop
I wasn't clear on this update. I have the dipstick in question. Mine did not have a 5-qt mark either. I created one empirically; i.e., when I knew that I had exactly 5-qts in the system (oil filter full). The 5-qt mark is exactly where you expect to see it, midway between 4-qt and 6-qt. I believe that the calibration is designed to be accurate when the filter is in place and full. It would be strange to calibrate w/o the filter or with it empty, given that it is an integral part of the system.
I did some digging and Lycoming lists the capacity of the engine as the sump capacity. And while there is some ambiguity floating around in various manuals and such about what you're actually measuring, clearly a dipstick actually shows you the level of the oil in the sump relative to the top of the filler neck. The dipstick could be calibrated to include oil lurking in such things as the oil cooler (and hoses) and oil filter, but I suspect they're not, as these can actually vary with installation. For example, Champion actually made the oil filter we use smaller since we took delivery of the DA40.
Here's something else I realized, which may be a bit more on point: The level of oil in the sump is not always linearly related to the volume of the oil in the sump. This is because the 4 intake manifolds pass through the sump and their collective volume is non-trivial compared to the volume of the sump. So there is a region where the horizontal cross- section of the oil-containing volume of the sump is considerably smaller than when full or almost empty. The manifolds are also basically tubular, which means that even within this region the relationship between the change of level with change of volume varies in a non-linear fashion. So extrapolation is particularly questionable if this region lies within the level where the dipstick probes. I don't know where this region of non-linearity is relative to the dipstick markings, but to my eye it looks like it's a factor.
Hi everyone, new DA40 owner (2004 DA40). Been catching up on all of these threads. Huge amount of info. Thanks to everyone.
I’m having this same issue and am in the process of determining what level of oil my Diamond likes to keep without blowing it over (it’s definitely less than 6). I know the POH says the minimum is 4 qts, and then states 6 for IFR. I personally haven’t seen two different requirements like that before. Does anyone know why they have a higher limit for IFR? An Austrian cert standard maybe?