Volvo 2002: why does oil spit out of dipstick?

[NorthUp]

Another possible source of white exhaust smoke is a partially blocked exhaust elbow. Fuel injectors in need of a service usually, but not always, lead to black exhaust smoke and poor starting. At full load on the engine, this restriction can cause raised crankcase pressure ' cos the exhaust gasses cannot get out...

The crankcase pressure is caused by the gasses in the cylinders ( when it 'fires') leaking past the piston rings into the crankcase. This is normal, and why there will be a way for these gases to escape to the atmosphere or into the inlet manifold or air filter. The point at which engine wear causes this 'back pressure' to be a problem is when it overwhelms the vent system and causes oil leaks, or the lack of compression leads to engine cold starting problems.

If it was my engine I would be checking the crankcase vent system and then check the exhaust elbow was clear before anything else.
Good luck!

 

[RichardS]

I'm really grateful for all the advice and suggestions but there are different and conflicting views here which are a bit confusing; the problem is in the absence of the skills, experience and tools to do it myself, it costs significant money to find an answer through testing, which is dead money if a new engine is needed.

1. Since the engine starts OK the compression is probably OK (bit of history it was compression tested 4 years ago and both cylinders at lower end of permissible range and about equal - since then done +/- 150 hours and v.rarely run above 2200rpm).
2. V.recently started blowing white smoke under load at higher revs - diminishes considerably at lower revs - no white smoke even at max revs in neutral. (BTW this seemed to follow a visit to Newton Ferrers when I uncharacteristically abused the engine - once to get off the Spit and second in an unsuccessful to spring the bow out against a strong ebb)
3. There is a film of oil in the bilge which has to be coming from somewhere; I may have over-topped up the oil but since the engineer query I've sucked some out. Recently I feel it's starting to use a bit of oil. use Halford 15-40 mineral oil/change oil and filter every 50 hours.
4. "Engineer/mechanic/whatever reports excessive crankcase pressure from evidence of hand over filler cap and spitting oil form dipstick (the latter I can confirm); c25% of respondents to this thread think all engines spit oil if dipstick removed.
5. I don't think there is a cooling problem - seems like a healthy flow of water from the exhaust.

So my conclusion is:

a. The injectors need serving but that's normal for that age of engine and probably a good idea anyway
b. It's not obviously in need of a head job although (although if the prognosis on the engine was otherwise ok it may be worth at some stage taking the head off to do what's needed to maintain compression.
c. There is no consensus about the relationship between excess crankcase pressure and wear in the engine - e'g bores/pistons rings. So, if the breather (wherever it is) is blocked that could be the sole explanation - it may even be the only explanation. Surely if you have excess pressure in the crankcase this proves the cylinders/rings are sealing since, if they were excessively worn this would provide an exit route for gas? (unless there is a sticking exhaust valve?)

Confused

That is an excellent summary. You clearly have a good grasp of the issues.

With regards to crankcase pressure, all internal combustion engines will spray some oil mist from the dipstick hole and a lot more through the oil filler cap unless that is baffled, which is unusual but not unknown. Putting a hand over the oil filler hole will always allow you to feel the pulsating pressure of the pistons going up and down .... but, and it's a big but ..... it's all down to the design of the engine and how bad the pressure symptoms are, and that's impossible to assess remotely.

A blocked or constricted breather will always exacerbate any crankcase pressure and, as you say, could be your only problem.

If the compression was tested 150 hours ago and it was within spec, even if at the bottom end, and you have been using proper oil at the right level, then I cannot see how the bores and/or rings would have deteriorated so quickly. If the engine starts within a spin or two of the starter motor and the compression feels good when you do a manual crank then I doubt whether you have anything to worry about in that regard.

Richard

 

[<152587>]

This is confusing - I don't think i mentioned the name of the "engineer" (I admit I haven't checked his qualifications) - are you guessing from my location? Is it ethical to post the name of a self-employed marine engineer (as opposed to a significant company) and invite an internet vote on whether he/she is any good - I thought not but I'm open to alternative views.






I did ask around and haven't heard anything adverse and I know he has fitted a Beta engine - also I would have thought it may be more lucrative for him to do a major overhaul rather than fit a new engine transplant job so the drift of his advice is roughly "you could do this and then see whether further work required but a more extensive rebuild what with the cost of replacement pistons could be very high and I would think about whether a new engine is a better idea" doesn't seem unreasonable.

Quite agree with your sentiments regarding the name and shame.

As an ex Ships Officer (Engineering) it was my duty to appraise my staff on knowledge and technical ability.

In my considered opinion a person is operating in this geographical location with, shall we say, a vivid imagination.

Whilst personal recommendation can go a long way, how is that assessed? The fact that an engine may be returned from the dead is black magic to some people. Lets say a problem with lift pump. By pass lift pump, rely on gravity, engine starts. Excellent man, will not have a word said against him. When a person with some technical knowledge views the system they may note that approx. 1/4 of the tank capacity is below the engine level. Will gravity still be sufficient now? In my opinion boat is a danger to those who sail her. (True)


As has pointed out by others in the forum we cannot understand how a cylinder head overhaul can possibly rectify crankcase compression. There is no link.

I think you have enough information to form your own judgement from the information.

Whilst I am familiar with this range of engine albeit in SOLAS form in lifeboats, I cannot remember for the life of me the crank ventilation system.

 

[VicS]

Quite agree with your sentiments regarding the name and shame.

As an ex Ships Officer (Engineering) it was my duty to appraise my staff on knowledge and technical ability.

In my considered opinion a person is operating in this geographical location with, shall we say, a vivid imagination.

Whilst personal recommendation can go a long way, how is that assessed? The fact that an engine may be returned from the dead is black magic to some people. Lets say a problem with lift pump. By pass lift pump, rely on gravity, engine starts. Excellent man, will not have a word said against him. When a person with some technical knowledge views the system they may note that approx. 1/4 of the tank capacity is below the engine level. Will gravity still be sufficient now? In my opinion boat is a danger to those who sail her. (True)


As has pointed out by others in the forum we cannot understand how a cylinder head overhaul can possibly rectify crankcase compression. There is no link.

I think you have enough information to form your own judgement from the information.

Whilst I am familiar with this range of engine albeit in SOLAS form in lifeboats, I cannot remember for the life of me the crank ventilation system.

I think, but I might be confusing it with the later MD2010/20/30/40 series engines. I think the crankcase breathing is internal ........ I vaguely remember something about getting one of the gaskets fitted the right way round so as not to obstruct it.

 

[<152587>]

Are you all missing something here? Blocked breathers usually manifest themselves by blowing lube through the crank seals.

The engine is some 30 years old, compressions are a little deficient, to be expected, so the problem is a mild case of blow by rather than any constriction.

 

[eddystone]

Another possible source of white exhaust smoke is a partially blocked exhaust elbow. Fuel injectors in need of a service usually, but not always, lead to black exhaust smoke and poor starting. At full load on the engine, this restriction can cause raised crankcase pressure ' cos the exhaust gasses cannot get out...

The crankcase pressure is caused by the gasses in the cylinders ( when it 'fires') leaking past the piston rings into the crankcase. This is normal, and why there will be a way for these gases to escape to the atmosphere or into the inlet manifold or air filter. The point at which engine wear causes this 'back pressure' to be a problem is when it overwhelms the vent system and causes oil leaks, or the lack of compression leads to engine cold starting problems.

If it was my engine I would be checking the crankcase vent system and then check the exhaust elbow was clear before anything else.
Good luck!

I had assumed elbow was OK because of healthy flow of water which increases with revs. I hadn't thought it could be OK on water injection but restricted in passing exhaust gas. As these engines are known to burn exhaust valves (I'm told) could this have anything to do with crankcase pressure?

 

[RichardS]

Are you all missing something here? Blocked breathers usually manifest themselves by blowing lube through the crank seals.

The engine is some 30 years old, compressions are a little deficient, to be expected, so the problem is a mild case of blow by rather than any constriction.

As I said in post #42, it's all a matter of degree. Virtually all engines have an overall positive crankcase pressure although it is pulsed so at any one instant it might be positive, negative or zero. Whether the pressure is enough to blow out oil seals, blow out the dipstick or blow off the filler cap depends upon how over-pressurised the crankcase is relative to its design parameters.

Richard

 

[lw395]

As I said in post #42, it's all a matter of degree. Virtually all engines have an overall positive crankcase pressure although it is pulsed so at any one instant it might be positive, negative or zero. Whether the pressure is enough to blow out oil seals, blow out the dipstick or blow off the filler cap depends upon how over-pressurised the crankcase is relative to its design parameters.

Richard

That may be true of diesels. Many petrol engines run the crankcase at manifold pressure or just downstream of the air filter.
Single cyclinder and 360deg twins often had timed breathers to only open as the piston was going down.
I think modern engines would fail emissions if the breather was open to air?

 

[lw395]

Are you all missing something here? Blocked breathers usually manifest themselves by blowing lube through the crank seals.
...

Do they?
The crank seals are often facing the oil pressure, not just the crankcase pressure.

 

[<152587>]

it appears to me that you are too focused and worried about the condition of your engine. The fact you state that it starts easily reflects the reasonable condition. Take it from me that if something was seriously wrong then you would be cranking all day before it fired, diesels are like that. They rely on the compressed air to reach sufficient temperature to ignite the fuel.

No, nothing to do with exhaust valves burning out.

Honest advice is to check the exhaust mixer elbow for blockage. They are known to be a problem and cause steam in the exhaust.

Accept that the motor is not up to new spec because it is of a certain age but serviceable.


Very doubtful if the breather is blocked.

Best advice is to check exhaust elbow and go and enjoy your boat. Stop worrying all will be fine.

Sincerely from a qualified marine engineer.

 

[<152587>]

Do they?
The crank seals are often facing the oil pressure, not just the crankcase pressure.

I despair!

 

[eddystone]

it appears to me that you are too focused and worried about the condition of your engine. The fact you state that it starts easily reflects the reasonable condition. Take it from me that if something was seriously wrong then you would be cranking all day before it fired, diesels are like that. They rely on the compressed air to reach sufficient temperature to ignite the fuel.

No, nothing to do with exhaust valves burning out.

Honest advice is to check the exhaust mixer elbow for blockage. They are known to be a problem and cause steam in the exhaust.

Accept that the motor is not up to new spec because it is of a certain age but serviceable.


Very doubtful if the breather is blocked.

Best advice is to check exhaust elbow and go and enjoy your boat. Stop worrying all will be fine.

Sincerely from a qualified marine engineer.

Thanks I'll do that. I'll need to replace the section of hose between the elbow and the trap as its probably welded on.

 

[<152587>]

This is my last post to this thread,

If the o/p wishes to pm me he is welcome to attend my residence and peruse my resume. If he will kindly transport me to his vessel (I can no longer drive, medical condition) to provide an honest appraisal of the machinery at no cost or any obligation of any further work.

 

[pvb]

I vaguely remember something about getting one of the gaskets fitted the right way round so as not to obstruct it.

Perhaps you vaguely remember post 9?

 

[PaulRainbow]

Do they?
The crank seals are often facing the oil pressure, not just the crankcase pressure.

Not in any engine i've ever worked on.

 

[RichardS]

Not in any engine i've ever worked on.

I think LW means that the spring lip on the crankcase seals at either end end of the crankshaft face inwards into the sump. I think that's the normal fitment, although I'm not really sure why it's relevant to Third Engines point.

Richard

 

[PaulRainbow]

I think LW means that the spring lip on the crankcase seals at either end end of the crankshaft face inwards into the sump. I think that's the normal fitment, although I'm not rally sure why it's relevant to Third Engines point.

Richard

I'm not sure either then.

I have known engines with excess crankcase compression, caused by blow-by to force out out of the seals, as third engines said.

 

[Pete7]

Well yes, on any other engine not a problem, but this is a VP 2002 with those copper seals. The injector might come out okay or it might bring the copper seal out too which is then a head off job.QUOTE]
Total fantasy, but, it will cost many shekles to buy the tool.. Can point you in the direction of someone that has the Volvo tools if necessary.

Excellent, clearly you are an expert on these engines and have many hours of practise pulling the injectors and never having the copper seal come loose. Gosh even the local VP engineers were reluctant last time I asked.

I am sorry you can't drive or I would have asked you to pop along to Gosport and remove them for me, but I will follow your advice and have a go myself after all you implied it won't be a problem. If it goes pear shaped how much will a second hand set of tools to reset new copper injector tubes cost me?

Pete

 

[<152587>]

Excellent, clearly you are an expert on these engines and have many hours of practise pulling the injectors and never having the copper seal come loose. Gosh even the local VP engineers were reluctant last time I asked.

I am sorry you can't drive or I would have asked you to pop along to Gosport and remove them for me, but I will follow your advice and have a go myself after all you implied it won't be a problem. If it goes pear shaped how much will a second hand set of tools to reset new copper injector tubes cost me?

Pete

From experience a few years ago, the boatyard I integrate with had a 2000 series with leaky inserts come in. They tend to leak coolant rather than combustion gas. We could not find a set of extraction and insertion tools from VP dealers locally which led the yard to purchase a set from VP at some cost. To my knowledge the tools have to date only 1 outing I am not sure if they wish to sell or hire the set, I will enquire. Maybe explains the reluctance of dealers involvement.

 

[Frankklose]

I had the job done last year. Reasoni for taking the injectors out was that one was leaking. In the past this injector was glued into the sleeve with epoxy. I called the Volvo mechanic. He had a job to take out the glued in injector. He also had a ginding tool, but he did not get this injector sealed...In the end I had to take the head off. We were also not able to replace the sleeve since no more available from Volvo. I was lucky that it happend in Poland. He grinded the head to get it flat, grinded the valves and also the sleeves and tester all three Injectors. It turned out that the glued in injector was bad....Had to order the nozzel in Germany from Bosch since no more available from Volvo. It cost me Euro 67 for the nozzel ( incl. Shipment Germany - Poland) and Euro 250 for the labour.
Now I have Volvo 2003T which doesn't smoke anymore.