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stlthe 10-14-2021 11:01 PM

c7 dipstick calibration
per CAT, ive got the 19qt oilpan and want to confirm dipstick accuracy before delving deeper into low indicated oil pressure.

does this 19 qts include the filter? i think so but want to be sure (i personally would figure a 19qt pan excludes the filter, but that is me)

as i understand the procedure,
1) get to operating temp
2) drain the oil (the longer the better, but at least 20 min.) and replace filter
3) add oil to intended 'add' mark. i want 2 qts between add and full marks on stick so i would put in 17 qts
4) run engine to fill filter and circulate oil
5) let sit awhile, then pull the stick and mark the level as ADD
6) put in 2 more qts, let sit awhile, then pull stick and mark the level as FULL

have i missed anything?



mmoore6856 10-15-2021 09:08 AM

get a oil analysis kit . do this first if you see oil on the dipstick and getting a low oil pressure indication. low oil will not (unless its way below the end of the dipstick) will not in most cases cause that fault. my guess is really worn out oil, oil leak (internal or external) or broken or worn internal components such as rod bearings. a oil analysis will let you know if you have lots of bearing material and other contaminants in your oil. however the procedure you listed is great for dipstick calibration

Booyah45828 10-15-2021 09:42 AM

Don't listen to cat, verify what pan your engine has yourself by looking at page 2 here.

The shallow pan is sheet metal steel, and the deep is cast aluminum fwiw.

The capacities in the chart is total oil makeup volume. So, if you have the shallow pan, it takes 19 quarts after an oil/filter change, and that includes volume in the filter. So long as you don't have any extra filters, centrifuges, or coolers in the system.

Your steps to recalbirate the dipstick are close. Here's what the service manual says. To remark/calibrate your dipstick, you can use a scribe, but I prefer a sharp flat cold chisel.

If you've got the 19 quart capacity/shallow pain. Drain oil and replace the filter. Add 17 quarts, start the engine and let it idle for 2 minutes. Shut it off and wait 10. After the wait, remove dipstick and mark where oil level is. Reinsert the dipstick, then add remaining 2 quarts and wait another 10 minutes. Scribe line at new level and you now have your add and full lines.

The c7 had an original design oil capacity of 5 and 7 gallons, but cat quickly found it was too high and created excessive crankcase turbulence. Lowering capacity a quart or two solved the issue.

cadillackid 10-15-2021 04:26 PM

ive come across several C7s that indicated low oil PSI on the dash.. they ran perfectly fine and did it for long periods of time, but the real way to test oil pressure would be with a mechanical gauge into am unused oil port on the block. I usually expect to see low oil pressure with old worn enginesthat seem noiser than normal and have significant blowby.. but the C7s ive run across this way all seemed like very healthy engines. . (I wasnt buying them so i didnt go any further than quick visual, audible and smell (smell for fuel in oil) checks. ..

Dash gauges can and do go bad or get wonky so its worth tapping a mechanical gauge in to see how close the 2 match

stlthe 10-20-2021 11:02 PM

thx booyah, i checked the link and mine is indeed 19 qts due to similar shape, which is helpful in distinguishing. i hadnt read your post when i did this, so i let idle a little longer (5 min) and sit a little longer (20 min) on the positive side of things, i did not end up changing the stick so i still can do it properly. the results i got were really close to the stick as it was.

mmoore6856, thanks. i got an analysis through ring power (local cat dealer)who sent it off to tampa less than 300 miles ago(1.5 yr i dont drive nearly enough), my last oil change, it came back clean. i changed it the other day primarily to confirm dipstick settings, which were correct. the day i changed it i forgot to take a sample from the crankcase, by the time i thought of it (which i did) i had already corrupted the oil collection pan (unrelated metal filings) and drained the oil filter into it. i appreciate the reminder about the analsis... doh!

cadillackid, thanks for the encouraging words. Ive suspected the gauges since the one i can read on cat et (water temp) reads a bit low. i just replaced the cluster for $78 new old stock + my time and still get the same results. i cant seem to identify the oil pressure sender to check it (i assume it plugs into the oil manifold but my EF model is tight reaching and hard seeing).

there has been an odd symptom to me that showed up while testing the new cluster. i ordinarily set high idle2 at 1200 and let it sit there for maybe 10-15 minutes and call it a day the oil always reads low and doesnt move much with acceleration. when i put in the new tach and was working to calibrate it, i gassed her up a few times to the redline, 2600, and back to around 2k. the process took me maybe 15 minutes or 20, but when i had finished with the tach the oil pressure was reading higher... maybe 18 psi at 750 rpm instead of 12 psi, moving as expected with the pedal, and hitting 40-50 psi at wide open.

i think i need to buckle-down/exhale, reach-up and find the oil manifold, pull and check the sender (however that is done) and screw in a manual gauge. the fact that it sporadically reads sensibly has got me intrigued. can i put in a gauge with a hose, and route up to the cockpit, or do i really only need to check it once against the dashboard gauge?

i read here i think that with the heui system, true low oil pressure would stop the engine, and that if it was running, the actual oil pressure was ok. btw there have been no codes on cat et.

sorry for combining the old details with the new instead of a new post.
thanks all!

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