|
Can any of you B.R. Petrolheads explain why, - when I remove the dipstick from my 320d, the reading is absolutely zero, but after wiping with a rag and replacing it, and then withdrawing it again, - it thankfully is on the correct level?? This has been puzzling me for some time, so would appreciate an explanation, because if somebody went by the original reading and over-filled the engine, I don`t think it would last too long !!!! Thanks in anticipation
|
|
If top of dipstick seals completely, oil won't be able to find its own level until you pull dipstick out and reinsert it. ??
|
|
|
|
Sorry can't help you with an explanation, but my old 1977 Mk1 Cavalier from 20+ years ago did exactly the same thing. As far as I'm aware you should always wipe the dipstick, dip again and use that reading.
|
Is the original reading really zero, or is the stick sprayed with oil all the way up so that you cannot see a clear line?
I agree - always wipe then dip again. Incidentally there can be a significant difference between dipping just after running, and when cold and all the oil has drained down to the sump. You need to know whether the marks are for Hot or Cold. My steering pump dipstick has dual marks for the same reason.
|
I have to say this is one thing that is really crappy about my new laguna. The dipstick is fitted to the oil filler cap. The stick is abbout 16 feet long and from the twists and turns it makes and the resitance felt there is no way on earth this can read oil level without being smeared on its journey out. Really carp design. Will have to rely on the oil level guage.
(rest of car is brill tho :) )
|
|
Mty merc has no dipstick so you just check it through the info display on the dash. I would prefer a dipstick and apparently it can be retro fitted but do you think its worth it. I just dont trust electronics that much.
|
|
|
|
|
Cliff - I always check the oil levels from cold, and when I first withdraw the dipstick, it is literally bone dry. I have owned scores of cars over my lifetime, but have never encountered this before. !!!
|
Dude, Coincidence..was only talking to my neighbour this morning about the same thing on my Vectra TDI.
Only difference is that if it is dipped as per the handbooks instructions ie. dip at operating temperature after leaving for 5 minutes for the oil to drain down it shows absolutely no oil whatsoever. Dip again and the correct level is shown.
If you dip when cold the first dip shows at least 50mm too high.
Dip it again for a few times and the correct level is there.
Considering that all you are doing is insterting a steel rod into a sump full of oil seems strange.
alvin
|
|
Modern plastic dipstick ends seem to be oil repelling on one side and oil absorbing on the other. Most of the ones I check show either full or empty on the same 'dip'
|
|
There was a thread here months ago re overfilling the sumps of diesel cars and the bad things that could happen if you did. SAAB actually issued a step by step set of instructions on how to do it which I laughed at until I tried it. You have to dip the sump on the level 5 minutes after a run, the first reading comes out (say) on the low mark. Wipe the dipstick and put it in 5 seconds later and it is up to the full mark! No explanation of why this should be so but, apparently, people were taking the first reading and finishing up with well overfilled sumps and engine problems/damage.
|
|
Thanks for the replies, - but am still not any clearer as to the reason the dipstick should be bone dry on the initial withdrawal. AndrewT has possibly the best explanation, but being a non-techie, it implies that there is a pressure build up within the dipstick tube, which is only released after the well-sealed dipstick is removed and then allows the oil to find it`s own level!!!! Somebody please correct me, if my explanation is up the creek (without a dipstick) !!
|
|
Pressure build-up does sound likely. I've noticed this effect on several cars and always take the reading a couple of times.
|
Just guessing here...
When you replace the dipstick after checking the oil, you can be pretty sure it has oil on it up to some level or other, right? Now when you fire up and go for a blast, the oil is pumped round the engine and up to the galleries etc, and will be sucked out of the bottom of the dipstick tube. Assuming the tube is reasonably well sealed by the dipstick, I'd say that the oil would struggle to get back into it once you switch off and it drains back to the sump. Make sense?
Ed.
|
|
When checking engine oil or auto transmission ATF (latter with engine running in 'P') I always take the dipstick out, wipe it thoroughly clean and leave it out for a few minutes. Then put it in and take the reading. This allows the dipstick tube to 'vent' and any oil carried up the tube when you pull the dipstick out can drain back down - the oil can settle at the right level. In my experience this is particularly important when taking ATF levels - if you quickly shove the dipstick in and out you always get the wrong level.
|
|
|
|
