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Old 28-02-2009, 16:55   #31
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Some more of my thoughts as I have been working through this.
I would have thought that I would have seen oil in my antifreeze since the oil pressure is higher then the pressure in the cooling system. Having said that, the oil pressure would subside immediately upon shutting down the engine and the cooling system would maintain pressure until the engine cooled. Also as I understand it, there may be places within the oil pressure system where the pressure is not that high. I'll have to take that at face value since I don't understand it.
Back to the cooling system maintaining pressure after the pressure is lost in the oil system (when the engine is turned off). This would lead me to believe that the cross contamination is occurring only after the engine is turned off.
Does anyone know if that would make sense and be consistent with the heat expansion and contraction process that takes place in the engine head?

Any thoughts?
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Old 28-02-2009, 17:56   #32
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If you were my customer and I conducted a pressure test of the cooling system and found no leakdown, ran the engine and found no above normal increase in pressure of cooling system while running, saw no steam indicating a blown head gasket, and had good compression on all cylinders. I would adopt a wait and see attitude.
It is at this point where some people/"mechanics" start throwing parts at engines to try to fix things...that costs you a lot of "boat bucks"

As far as the Oil Analysis....How were the other readings for metals/salt/etc.
The ananlyses that I use give acceptable levels and abnormal levels.

One oil ananlysis gives you a benchmark...you may have to change the oil and run the engine for a while and re-test.

If the engine is loosing coolant after shutdown what may be happening is the water is migrating along the headgasketfrom the cooling passeges into the cylinder due to vacuum as the cylinder cools...this is assuming that the cylinder has no open valve.

If the engine is not overheating, and the oil is not milky, and the exhaust is clear
my advice is to observe/record the performance of the engine.

Just a final note....On Yanmars there are a couple of block drains...make sure they are not "weeping"
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Old 28-02-2009, 19:39   #33
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As far as the Oil Analysis....How were the other readings for metals/salt/etc.
Don't have access to them right now, but I do know that they were not ridicules.
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If the engine is loosing coolant after shutdown what may be happening is the water is migrating along the headgasketfrom the cooling passeges into the cylinder due to vacuum as the cylinder cools...this is assuming that the cylinder has no open valve.
Maybe?
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If the engine is not overheating, and the oil is not milky, and the exhaust is clear
my advice is to observe/record the performance of the engine.
Once I retorque the heads (cheap to do), I think that is what I'll do.
Thanks.
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Just a final note....On Yanmars there are a couple of block drains...make sure they are not "weeping"
It's a Westerbeke. Pretty sure there are no such block drains.
Once again, Thanks for thinking about it.

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Old 28-02-2009, 20:15   #34
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Sorry, I read Yanmar on one of the other posts in this thread...One other question, Am i correct to assume the vessel is in Canada?
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Old 28-02-2009, 21:00   #35
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Sorry, I read Yanmar on one of the other posts in this thread...One other question, Am i correct to assume the vessel is in Canada?
You are correct.
The water is VERY HARD here right now.

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Old 01-03-2009, 00:41   #36
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another suggestion would be a leakdown test. This would also give you an idea of ring and valve condition. Compressed air is fed down each cylinder one at a time with the cylinder being tested on tdc firing. On a Diesel you would use the injector as the insertion point. Pressure build up in the cooling system while under test would not only indicate a leak but which cylinder as well. Easier and cheaper than replacing the head gasket if it is not the source.
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Old 01-03-2009, 13:03   #37
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another suggestion would be a leakdown test. This would also give you an idea of ring and valve condition. Compressed air is fed down each cylinder one at a time with the cylinder being tested on tdc firing. On a Diesel you would use the injector as the insertion point. Pressure build up in the cooling system while under test would not only indicate a leak but which cylinder as well. Easier and cheaper than replacing the head gasket if it is not the source.
After retorquing without good results, I assume.

Is there a step by step (simple one) that you could direct me to?
Also how does one ensure the piston is Top Dead Center?
What do you use to pressurize?
How many psi?
How long?
Acceptable parameters?

Thanks,

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Old 01-03-2009, 15:08   #38
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Yes retorque first. I would not try the leakdown yourself mainly because of the equipment required. I suggest you get a good diesel or auto mechanic preferably one who does performance engine work. No offence to Marine Diesel guys but most I have met are not the most switched on technicians.
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Old 01-03-2009, 16:16   #39
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Gee you must make friends easily

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Yes retorque first. I would not try the leakdown yourself mainly because of the equipment required. I suggest you get a good diesel or auto mechanic preferably one who does performance engine work. No offence to Marine Diesel guys but most I have met are not the most switched on technicians.
Unless you have the proper adapters and a good knowledge of this procedure don't try it yourself.

I love it when people say "no offense......but" it means you want to be offensive.
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Old 01-03-2009, 16:56   #40
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Dumb question. If there is a blown head gasket would you see air bubbles in the expansion tank when you rev the engine? I think this is a check they do on automotive engines by looking into the rad with the engine running.
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Old 01-03-2009, 17:05   #41
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Yes retorque first. I would not try the leakdown yourself mainly because of the equipment required. I suggest you get a good diesel or auto mechanic preferably one who does performance engine work. No offence to Marine Diesel guys but most I have met are not the most switched on technicians.
Your welcome to your opinion but please do not say that I meant to be offensive when I clearly did not. How many marine techs have the equipment to carry out a leak down test? I would suggest not many and this thread started by the owner having been advised to pull the motor out of the boat without any real reason given, so does that not back up my comment?
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Old 01-03-2009, 17:12   #42
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Your welcome to your opinion but please do not say that I meant to be offensive when I clearly did not. How many marine techs have the equipment to carry out a leak down test? I would suggest not many and this thread started by the owner having been advised to pull the motor out of the boat without any real reason given, so does that not back up my comment?
Not a dumb question! Small leaks can be hard to see via bubbles in coolant tank. Another method would be using a carbon monoxide tester on the cooling system not one of my preferred tests.
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Old 01-03-2009, 17:28   #43
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Dumb question. If there is a blown head gasket would you see air bubbles in the expansion tank when you rev the engine? I think this is a check they do on automotive engines by looking into the rad with the engine running.
Others would have to answer this, I couldn't tell you.
I think though that it would depend where the head gasket is leaking.
Also, I don't think that a leaking head gasket constitutes what most are referring to when they talk about a "blown head gasket". A matter of degrees and failure point I suppose. I could be wrong through.
Hopefully someone else tells us.

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Old 01-03-2009, 18:43   #44
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Sorry mate, I am not thin skinned

Proper diagnostic tools are expensive.....Over the years I have invested in a few.......They have paid off in time and customer confidence.........

One of the best ones is the hand held heat infrared heat gun.

My Voltmeter also read temp via probes

Diesel engine compression testers? Not too many want to spend that kind of money...what with all the adapters you need....or have to make

Battery Load Tester? Got it.

Magna Flux Test Kit..Check

Sea-Land Vacuflush Tester...Makes that job much easier.

Compact Digital Camera.....let's me see into spots better than mirrors.

I am thinking about getting a video scope with a probe...but I am going to wait for the price to come down.

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Your welcome to your opinion but please do not say that I meant to be offensive when I clearly did not. How many marine techs have the equipment to carry out a leak down test? I would suggest not many and this thread started by the owner having been advised to pull the motor out of the boat without any real reason given, so does that not back up my comment?
The hardest part of my job is gaining customer confidence after they have been "hosed" by another "guy".
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Old 01-03-2009, 18:54   #45
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"If there is a blown head gasket would you see air bubbles in the expansion tank "
Not a dumb question. The problem is that the head gasket is keeping 3 systems apart (coolant, oil, cylinders) and you can have a leak across any two or three of them. Then there are "sucking" leaks versus "pushing" leaks. So if the leak is from the cylinders to the cooling passages...typically yes, it will open up when the engine heats up, and you'll get exhaust pushing into the coolant on the expansion stroke, while coolant sucks into the cylinder on the intake stroke. Or sometimes, the gasket will only leak in one direction, just to confound you.

Bottom line, the procedures to test a head gasket are all document in pretty much every engine repair manual, and pretty much the same for all engines.

Ask most dealers about things like testing the coolant for monoxide (there's a dye check) or pressure (there's a pressure gauge that snaps on like a radiator cap) and they'll look at you like you are from Mars. They'd rather just bill you for a headgasket job.
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