What should happen if I take out the dipstick with the engine running.

wiggy

wiggy

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As the title says, what should happen if I take out the dipstick with the engine running on tick over, it's an MD2020D.
Only asking as my engine is doing odd things after a complete rebuild.
 
One for the mechanics I think.

I've never done it because I can't see the point: why would you do it? If it started squirting oil out the dip-stick hole I would worry because it would indicate the crankcase is being pressurized and I would suspect broken rings or something like that.

Now let's see what the experts say..............................

Cheers
 
Oldhairy said:
Surely this is normal practice on stationary engines.
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What is it going to tell you though? Surely there will be oil all over the bottom of the dipstick so what does it tell you? Maybe that there is some oil in the motor. So?

Where are the mechanics...................?
 
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wiggy said:
At tick over I've got a build up of pressure if the dipstick is taken out, I am concerned that new rings have failed.
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What was done to the bores before the new rings were fitted? It is quite possible that blow-by might increase if the bores were honed, due to small peaks and troughs in both surfaces. This should reduce during running-in.

OTOH it could be that your crankcase breather is not working correctly.
 
Carefully! I started up my last boat's Yanmar YSM forgetting to replace the combined dip stick/filler.

It sprayed me (at crotch height) and the cabin headlining as far as the fore cabin..

I think I posted a tasteful pic of me in my knicks here....

A worn engine will 'breathe' or puff through the filler or dipstick tube, but so may a healthy one. It's more useful as an indicator if you detect change over time.

What did it do before the recon?

edit- did they connect up all the breather pipes?

edit/edit what are the other odd-nesses?
 
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vyv_cox said:
What was done to the bores before the new rings were fitted? It is quite possible that blow-by might increase if the bores were honed, due to small peaks and troughs in both surfaces. This should reduce during running-in.

OTOH it could be that your crankcase breather is not working correctly.
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The engine has had a re bore and oversized Pistons/ rings (horribly expensive) fitted. Before the rebuild the engineer removed the dipstick and got covered in oil. The other things that concern me are black smoke and oily water from the exhaust if the revs are increased rapidly and a slight metallic scraping noise from the engine.
 
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You should get oil sprayed all over!
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Are you seriously saying that the push fit of a dipstick can contain pressure! Try it on your car, remove it at tickover, nothing happens, if it blows oil out of the dipstick you have excessive crankcase pressure, something is wrong!
 
wiggy said:
The engine has had a re bore and oversized Pistons/ rings (horribly expensive) fitted. Before the rebuild the engineer removed the dipstick and got covered in oil. The other things that concern me are black smoke and oily water from the exhaust if the revs are increased rapidly and a slight metallic scraping noise from the engine.
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Black smoke and oily water can be a sign of blocked exhaust elbow.
 
Davy_S said:
Are you seriously saying that the push fit of a dipstick can contain pressure! Try it on your car, remove it at tickover, nothing happens, if it blows oil out of the dipstick you have excessive crankcase pressure, something is wrong!
Click to expand...

Looking at rivonia's comments he is obviously playing games

He's a troll
 
wiggy said:
The engine has had a re bore and oversized Pistons/ rings (horribly expensive) fitted. Before the rebuild the engineer removed the dipstick and got covered in oil. The other things that concern me are black smoke and oily water from the exhaust if the revs are increased rapidly and a slight metallic scraping noise from the engine.
Click to expand...

How many hours had the engine run since rebuild? As vyv_cox says, it can take a few hours for the rings to bed in properly and there may be slight increase in oil usage until it's run in. There shouldn't be any pressure if the dip stick is removed but some oil splashing out is normal, usual check for crankcase pressure is to remove the filler cap and put your hand over it - but have a rag handy as this will splash as well.

Does the engine start immediately or need prolonged cranking?

The metallic scraping noise may or may not be worrying, presumably the rings were "gapped" properly before fitting?

How much black smoke? Did you have the injectors serviced?
 
I presume that the oil level is at its correct level ie no overfill. Oil usage is higher when cylinders are bored out and new piston and rings are fitted, even higher when the bores are honed and new rings fitted. Check for back pressure by removing the oil filler cap, but there is no rule, although it will be obvious if there is too much crankcase pressure.

There are a number of things that can go wrong eg wrong piton size which will give you piston-slap and plenty of noise as well as oil from exhaust; piston rings not spaced out properly; broken new rings. If you can turn the engine by hand using a handle, and have good access, you may be able to hear "hissing" of air coming out from the inlet valves or exhaust valves or even from the cylinders, passing through the piston rings. Also, I suggest that you get in touch with the mechanic who overhauled your engine.
 
Davy_S said:
Are you seriously saying that the push fit of a dipstick can contain pressure! Try it on your car, remove it at tickover, nothing happens, if it blows oil out of the dipstick you have excessive crankcase pressure, something is wrong!
Click to expand...

I had a crew member who was putting the dip stick back by feel on a 1GM10, but unfortunately missed the hole.

A while after starting the engine, there was oil all over the engine bay. Engine was not young, but also not clapped out. No long term after effects.
 
CAPTAIN FANTASTIC said:
I presume that the oil level is at its correct level ie no overfill. Oil usage is higher when cylinders are bored out and new piston and rings are fitted, even higher when the bores are honed and new rings fitted. Check for back pressure by removing the oil filler cap, but there is no rule, although it will be obvious if there is too much crankcase pressure.

There are a number of things that can go wrong eg wrong piton size which will give you piston-slap and plenty of noise as well as oil from exhaust; piston rings not spaced out properly; broken new rings. If you can turn the engine by hand using a handle, and have good access, you may be able to hear "hissing" of air coming out from the inlet valves or exhaust valves or even from the cylinders, passing through the piston rings. Also, I suggest that you get in touch with the mechanic who overhauled your engine.
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The guy who did the re bore would not do it without the new piston to ensure correct sizing. As to hours I've done approximately 30 hours and been careful to vary revs regularly to help it all settle.
 
wiggy said:
So is it normal to have a pressure release when taking out the dipstick whilst at tick over?
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No not normal. There should be a crankcase breather system which prevents this. Look for something feeding from the crankcase possibly into the inlet manifold that has a valve and perhaps a filter. Check for blocked filter or jammed valve.
 
TQA said:
No not normal. There should be a crankcase breather system which prevents this. Look for something feeding from the crankcase possibly into the inlet manifold that has a valve and perhaps a filter. Check for blocked filter or jammed valve.
Click to expand...

Yes check the crankcase breather which on the MD2020D is built in to the valve cover and includes the separator #33 and the filter #34


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