Oil Level on Dipstick Varies Each Time I Check it

[rwidman]

Originally Posted by KenK

I have a 1984 Perkins 4-108 with 2689 hours. It's been running fine. No excessive smoke. Leaks some oil. I check the oil level before every startup. My issue is that sometimes the level is readable (high, middle, low.. whatever) but many, many times I can't get a reading. The dipstick is covered above the marks. I clean it and check again, and again, and again, and can't get a reading. Then, the next time I will get a reading. Then the next three times, I can't get a reading. Etc. Etc. I read on this and other forums about Perkins owners who had fuel leaking into their oil via the injection pump seals. If this is the problem with my Perkins, then why isn't it consistently over the mark when I take a reading? Thanks in advance for your advice.

Have you had this problem for 26 years or did it just start? Did it start all at once or has it been building for a while? Has any work been done to the engine that could have caused this? If you have fuel leaking into your crankcase, it might evaporate once the engine warms up to operating temperature. You could probably send an oil sample out to check for fuel dilution.

Not to send you away, but this is a very good marine diesel forum:
http://boatdiesel.com

You have to pay to get the best answers but it may be worth it.

[KenK]

Thanks for all the suggestions. Just to clarify, when I said I've been doing this routine for over 40 years, I was simply referring to the act of checking engine oil with a dipstick--any engine, whether it be a car, lawnmower, generator, boat, etc. I've had my current boat, with the Perkins, for six years. It's only been over the past and current season that it's been difficult to get a clear reading. Some days I can clean it, and re-insert it four, five, or six times and still not get a clear reading. Then other times, I get an obvious oil line right where you'd expect it to be. Again, thanks for all the suggestions, tips, hints, comments, etc.

[sigmasailor]

Some dipsticks have a rubber o-ring that might allow some vacuum (lower pressure) in the tube so oil is being pushed/sucked up showing a high reading. The lower pressure can occur by simply allowing the engine to cool (air will contract sucking oil up).
You did figure out that after truing a number of times you mess up the tube so readings do not make any sense. The 5 step procedures discussed should brake the vacuum and give a good reading.

[captain465]

I had the same problem with my Perkins 4-108 (1985 vintage). I had much the same mental meltdowns as you are having, until I discovered that the dipstick cap ( the part that covers the end of the tube when it is fully inserted)has a small interference on the inside, that will make it feel like the stick is all the way inserted, but it is actually short of being fully "home". This gives a false indication of low, or no oil in the crankcase. If you look at the distance between the "full" and "add" marks, you will understand how this can give the false indications. Add oil when the stick is not "home" and the next time you check, it will be overfull!!
Good luck, and please let us know what you actually find.

[Chief Engineer]

That was the word(s) I was looking for.....4 ounces low would be kind of hard to gauge...I have had errant wires get in the way of that little ferrule/cap on the dipstick a couple of times.

Believe me, in the heat of last week...'TWILL cause a mental metldown.

Originally Posted by captain465

I had the same problem with my Perkins 4-108 (1985 vintage). I had much the same mental meltdowns as you are having, until I discovered that the dipstick cap ( the part that covers the end of the tube when it is fully inserted)has a small interference on the inside, that will make it feel like the stick is all the way inserted, but it is actually short of being fully "home". This gives a false indication of low, or no oil in the crankcase. If you look at the distance between the "full" and "add" marks, you will understand how this can give the false indications. Add oil when the stick is not "home" and the next time you check, it will be overfull!!
Good luck, and please let us know what you actually find.

[nesatom]

Hi
only posible points for fuel to go to the oil sump is from transfer pump or high presurepump.if fuel goes down to the sump,and oil level goes up it can happend that the mix of oil and fuel goes to the air intake by breader pipe,and than wery bad thing can hapend.you will got so coled run away engine,meaning that it will self ignite and you can not stop the engine.only way is to block the air coming to engine.hapends lot in the old trucks.
happend to me once in the mid Atlantic.
also oil level can somethimes be bigger or lower bcs, oil filter which you use.some have non return valve some das not.also if you check the oil level just after stoping the engine,some oil stays in the filter, and if you let it cool than the oil from filter goes down to sump,it can be half litar diference
sorry for speling, english is not my native thong

[Jon Hacking]

Originally Posted by captain465

I had the same problem with my Perkins 4-108 (1985 vintage). I had much the same mental meltdowns as you are having, until I discovered that the dipstick cap (the part that covers the end of the tube when it is fully inserted) has a small interference on the inside, that will make it feel like the stick is all the way inserted, but it is actually short of being fully "home". This gives a false indication of low, or no oil in the crankcase. If you look at the distance between the "full" and "add" marks, you will understand how this can give the false indications. Add oil when the stick is not "home" and the next time you check, it will be overfull!

I think Captain got it right, as we have a similar issue with our Yanmars. The seal at the top of the dipstick is good enough that when I take a reading (engine cold) it ALWAYS reads low. The first time I saw this I immediately added a bit of oil & suddenly it was too high!

Our problem is that gas is getting into the dipstick tube & not getting out the top, so the first reading is always too low. Now I know to wipe it off (not really necessary) & take another reading immediately, which is usually right where I expect it. Not sure this is the OP's problem, but it's another data point.

[Pete the Cat]

Originally Posted by Steve W

On my Universal M-18, the dipstick will always show no oil level at all unless I pull the dipstick and replace it after about 15 seconds. Other Universal owners told me this is common to many Universals and that a slight backpressure prevents the oil from moving up the dipstcik tube until the dipstick is removed and replaced. Seeing no oil on the dipstick invites near-heart failure everytime, but it has done this for the 11 years I have owned the boat. No leaks, no smoke, never moves off full between changes. Maybe your dipstick is not getting the same seal around the dipstick every time you replace it. Long shot, I know, since you have been doing this for 40 years.

Exactly the same experience with my new Yanmar 3JH4E. Shows no oil often when dipstick is pulled first time. Then when reinserted a few seconds later shows correct level. Seems like capilary action of some kind in dipstick tube causes it.

[GordMay]

Greetings and welcome aboard the CF, nesatom.

[captain58sailin]

Welcome to the forum nesatom. Something I learned from my Father was the same as you are doing. If I am having trouble getting a reading, I pull the stick wipe it down and then wait for a minute, then reinsert the stick and wait for maybe 30 sec. and usually I get a repeatable reading.

[DeepFrz]

Something I learned from my Father was the same as you are doing. If I am having trouble getting a reading, I pull the stick wipe it down and then wait for a minute, then reinsert the stick and wait for maybe 30 sec. and usually I get a repeatable reading.

Funny, but that is pretty much how I have always done it except I don't wait for 30 secs after wiping the stick down.

[captain58sailin]

The reason I started doing that is, I thought perhaps (maybe wrongly) that if the cap at the top of the stick created a suction when drawing out the dipstick, it may cause the oil to show higher on the stick. If you are making oil because of diesel ingress, all you have to do is wipe the stick with your fingers and rub them together and smell, if there is diesel in your oil you will smell it. Also your oil will be thinner and not have the viscosity.

[Capitain Mike]

Originally Posted by DeepFrz

Funny, but that is pretty much how I have always done it except I don't wait for 30 secs after wiping the stick down.

I always have pulled it out and wiped it after checking the level when pulled out the first time. To make sure its the same on pulling out the second time.

A carpenter/joiner I knew always said check twice and cut once!

[gjordan]

Ken, since your problem only started in the last season, and was OK before that, I have two suggestions. First is check to see if the oil filter is the same brand as was used before all this started. Most oil filters dont allow drain back since the engine would run with no oil pressure for a few extra seconds at each start up, but maybe you used a differant brand or got a faulty filter. Changing out the oil filter at this time wont cost much and might solve the problem. The other thing you might want to check is if your engine has a form of positive crankcase ventilation? Most engines have a line(hose) from the valve cover to the intake manifold, so that oil vapors get sucked back into the engine and burned rather than going out into the atmosphere. There is usually a small valve in that system. These valves tend to get clogged up or intermitant and could cause differant vacuem in your crankcase that might give you faulty dip stick readings. If your Perkins is old it might not have the vent system, but it is worth looking for. These are WILD ASS GUESSs Good Luck with it. ____Grant.

[SkiprJohn]

I picked up a copy of this book in the library and found it a very good read. If you have it in your library there is an answer to this question.. The answer slips my memory just now but I'll check it again the next time I pop into the library.

http://www.amazon.com/Practical-Boat-Mechanics-Commonsense-Mechanical/dp/0071445056/ref=sr_1_12?ie=UTF8&qid=1338840996&sr=8-12#reader_0071445056

I know that isn't too helpful but this is a book recommendation to anyone with an inboard boat engine.

kind regards,