Engine Oil Dipstick

[egldvrbags]

Bayliner 2050LS 1995
Engine model: MCM 4.3LX Alpha 1 gen2
Engine sn: 0F436164

Last weekend after running for an hour or so, I put my boat in the lift for the weekend. Before leaving, I checked the engine oil. When I first pulled out the oil dispstick, it was dry....yikes. I put it back in, pulled back out and it showed full. I always watch the oil pressure when running (plus has an alarm) and didn't notice anything unusual. I just thought maybe the dipstick had come out a little during the run and hadn't noticed it when I first pulled it out.

This weekend, as always, I checked the fluids before starting. The oil dipstick showed full when I first pulled it out. I wiped it off, checked again and indicated full. I made sure that it was pushed all the way in before leaving.

Ran for about an hour or so, oil pressure 40psi at idle (after warming up) and 60psi when cruising - these are the numbers that I've always had.

When I put the boat away, the exact thing happened.....made sure the dipstick was all the way in, I pulled it out and it was dry. Reinserted, checked full.

Any ideas?

Thanks!

Bags

 

[stonyloam]

Re: Engine Oil Dipstick

A guess: The dipstick goes all the way to the bottom of the pan, so if the engine was cooling (and the crankcase poorly vented) it could have created a small vacuum in the crankcase and pulled the oil down to the bottom of the dipstick tube, and as the crankcase vented air back in the oil would refill the tube. I guess I would check your crankcase venting, whatever that is in your particular engine.

 

[dubs283]

Re: Engine Oil Dipstick

some dipsticks do not go all the way to the bottom of the pan, i.e. they only read add-full on say the top two quarts in the pan

so when the engine is running, those two-three quarts are circulating through the engine and not "bathing" the end of the dipstick

where the dipstick enters the top of the tube may be sealed pretty tightly as not to let air in

so, like holding you finger on the end of a straw and inserting into a glass of water, the straw does not fill up - the same is happening with your dipstick tube

once you pull the dipstick out, the pressure is realeased and oil is allowed to enter the tube from the bottom and now reads on the dipstick

as long as the sitck reads full prior to start-up you are fine

 

[Don S]

Re: Engine Oil Dipstick

Here are the specs for the dipstick for your engines SN.

 

[egldvrbags]

Re: Engine Oil Dipstick

I guess I would check your crankcase venting, whatever that is in your particular engine.

Is there a PCV valve?

Bags

 

[egldvrbags]

Re: Engine Oil Dipstick

Here are the specs for the dipstick for your engines SN.

Thanks Don,
I'll measure it per the specs to make sure I have the correct one.

When I change the oil and add the specified amount, it shows full on the dipstick.

I'm usually in the habit of just pulling the dipstick, wiping it off, then checking the
level. So, it may have been doing this for a while......

Bags

 

[K9Deuce]

Re: Engine Oil Dipstick

How long after turning off the engine are you waiting to check the engine oil ? Like it was stated above engines circulate oil and once the engine is turned off it does take some time for that oil to drain back into the engine oil pan where the dipstick gets it reading. This time frame varies depending upon the engine and the egine oil, thicker weight oils take longer to flow back into the oil pan. I would verfiy the dipstick is the correct one, check the engine oil weight being used against the spec from the engine builder. You can start with a fresh oil change this way you know you have the correct amount of oil in the engine and the correct weight. Check the oil level cold and scratch the stick at this level then run the engine shut it off wait a few minutes then check the oil level....

 

[rickryder]

Re: Engine Oil Dipstick

What about some sludge buildup in the oil return passages......that would hold the oil in the valve covers and return to the pan slowly....just a thought.....

 

[egldvrbags]

Re: Engine Oil Dipstick

How long after turning off the engine are you waiting to check the engine oil ? Like it was stated above engines circulate oil and once the engine is turned off it does take some time for that oil to drain back into the engine oil pan where the dipstick gets it reading. This time frame varies depending upon the engine and the egine oil, thicker weight oils take longer to flow back into the oil pan. I would verfiy the dipstick is the correct one, check the engine oil weight being used against the spec from the engine builder. You can start with a fresh oil change this way you know you have the correct amount of oil in the engine and the correct weight. Check the oil level cold and scratch the stick at this level then run the engine shut it off wait a few minutes then check the oil level....

The issue I have is not a time issue to let the oild drain back to the pan. When I pull the dipstick after shutting down, the dipstick is dry. When I put it back in and immediately check it, it's normal (full). So, this takes perhaps 5 seconds. Think of stopping for gas in your car and checking the oil while pumping gas. There is oil on the dipstick when you first pull it out??

I'm guessing it's like what's described above in that a vacuum is being created in the fill tube and when I pull the dipstick it breaks the vacuum (I like the soda straw analogy).

A cold engine always shows full. And, a warm engine shows full after I "break the seal."

After measuring the dipstick (will be a week or so before I'll get a chance) and ensuring it's the correct one, I'm going to run it w/ the dipstick just slightly unseated (not enough to allow oil to squirt out) and see if it still does it.

Bags

 

[K9Deuce]

Re: Engine Oil Dipstick

Sometimes it is difficult to converse and exchange ideas through forums. I would agree that my first thoughts would have been there should be oil on that dipstick when first pulled. Depending on the length of the a stick and the tube, the stick maybe bathing in some amount of oil all the time or only bathing in oil when the engine is shut down.
If this is a vacuum issue you may look into the PCV system ( Postive Crankcase Ventilation), I can not recall where or if there is a replacement valve is on your engine but a quick search of the shop manual should locate it

 

[K9Deuce]

Re: Engine Oil Dipstick

Sorry somehow I got logged off and the above thread posted. The PCV works off of engine vacuum and helps to elimnate crank case fumes.. A stuck or partial stuck valve can cause a lot of different issues. PCV valves should be changed at reg intervals the cost between 10 and 14 dollars. If you have not changed it in a while you might want to.

 

[egldvrbags]

Re: Engine Oil Dipstick

Sometimes it is difficult to converse and exchange ideas through forums. I would agree that my first thoughts would have been there should be oil on that dipstick when first pulled. Depending on the length of the a stick and the tube, the stick maybe bathing in some amount of oil all the time or only bathing in oil when the engine is shut down.
If this is a vacuum issue you may look into the PCV system ( Postive Crankcase Ventilation), I can not recall where or if there is a replacement valve is on your engine but a quick search of the shop manual should locate it

Here's what the Merc Manual says......I didn't know it was a replace once a year item!!!

"Positive Crankcase Ventilation (PCV)
The Positive Crankcase Ventilation (PCV) valve
should be replaced once a year."

Also, here's the oil checking procedure from the manual:

1. Stop engine and allow boat to come to a rest.
2. Allow oil to drain back into oil pan - approximately
5 minutes.
3. Remove dipstick. Wipe clean and reinstall. Push
dipstick all the way into dipstick tube.
4. Remove dipstick and note the oil level.
5. Oil level must be between the FULL and ADD
marks.
6. If oil level is below ADD mark, proceed to Steps
7 and 8.
7. Remove oil filler cap from valve rocker arm cover.
8. Add required amount of oil to bring level up to, but
not over, the FULL mark on dipstick.

When I comply w/ this, all is OK. It just seems odd that the dipstick is dry when I first pull it out on a warm engine.

Bags

 

[K9Deuce]

Re: Engine Oil Dipstick

I didnt know it was a once a year replacement item. Being a car mechanic ( Ford/Mercury/Lincoln) I know most Ford engines are 3 years/36K or 5/50 with few exceptions in between there. PCV has been known to cause alot of issues including sludge build up in engines, seal and gaskets leaks etc. Thanks for looking that up, I am adding my replacemnt to my spring ck/replacement list.

 

[egldvrbags]

Re: Engine Oil Dipstick

I didnt know it was a once a year replacement item. Being a car mechanic ( Ford/Mercury/Lincoln) I know most Ford engines are 3 years/36K or 5/50 with few exceptions in between there. PCV has been known to cause alot of issues including sludge build up in engines, seal and gaskets leaks etc. Thanks for looking that up, I am adding my replacemnt to my spring ck/replacement list.

It's also listed in the maintenance section of the manual (1B-2) as a 100hr or yearly (whichever occurs first) item to change.

I wonder how many boat owners actually change it?

I have my boat serviced every year at our local 5-star Merc dealer and to my knowledge, they've never changed it.

Bags

 

[John_S]

Re: Engine Oil Dipstick

It's also listed in the maintenance section of the manual (1B-2) as a 100hr or yearly (whichever occurs first) item to change.

I wonder how many boat owners actually change it?

I have my boat serviced every year at our local 5-star Merc dealer and to my knowledge, they've never changed it.

Bags

Does your Merc 4.3 have a PVC valve? I thought most GM based Mercs didn't get a PVC valve until latter, ie 2000ish year models. My '96 1/2 5.7L has plastic pipe in the valve covers, but it is not a pvc valve. They just connect to the flame arrestor to draw access crankcase fumes in. No carb or intake manifold vacuum hook-up.

 

[egldvrbags]

Re: Engine Oil Dipstick

Does your Merc 4.3 have a PVC valve? I thought most GM based Mercs didn't get a PVC valve until latter, ie 2000ish year models. My '96 1/2 5.7L has plastic pipe in the valve covers, but it is not a pvc valve. They just connect to the flame arrestor to draw access crankcase fumes in. No carb or intake manifold vacuum hook-up.

Not sure if it does. I won't be able to take a look for a week or so when I get back to my boat. I was just going by what the manual stated. I'll report back what I find.

Bags