Conference unifix::sailing

    Check the impeller and also the water inlet filter. Failing that
    ring 0243-371151 (Savages at Emsworth).
    
    Pete  

    Check belt tension too.....

    Thanks for the ideas... keep them coming... and I will check the
    boat next weekend.

    	Just a few things to check:
    
    		Is the thermostat the correct one for the motor?
    
    		Have you tried running without a thermostat?
    
    		Have you over heated the engine to the point where
    		the water boils and deposits salt  in the water
    		passages?
		
		Is this a new condition? What did you do to the 
    		motor before this condition appeared?
    
    		Is the prop fouled by fishing nets or rope?
    
    		Correct fuel?
    
    	Hope some of this will help you...
    
    John W.

    this is a known problem for Volvo diesels.
    
    The cooling inside the cylinder gets clogged with deposits from the
    water.(assuming you have fresh water cooling)
    It is very easy to check.When the engine is running,open the valve
    at the base of the cylinder and check if water is flowing freely.
    This valve is used to drain the cylinder during lay up (freezing).
    If the holes between the cylinder head and the cylinder are clogged,
    you will see only a dribble (sp?).
    
    I was running my engine for more then 1000 hours with completly
    closed cooling.During winterlayup I tried to drain the cylinders
    and could not get any water out of the cylinders.I removed one cylinder-
    head and found the problem.Because I have no alarm,I have not found out
    earlier.
    When I called Volvo Penta: Yeah,you should have...... blabla bla
    
    Peter

Hi John, here is the full story.

My engine has a temparatur display (white green red).When the engine was new,
the temp was just at the beginning of the green zone.After 200 hours running,
I noticed the temp going up for a short time (1 minute),but still well below
the red zone.This happend every 3-5 minutes.
I noticed at the same time a higher oil consumption.But nothing out of spec.
I also noticed steam leaving the exhaust.I changed the thermostat twice.
Then I got the tip that the small hole in the termostat is to
small.I made it bigger and most problems went away for another 200 hours.
Then it started again.Oil consumption was nil during the first 50 hours after
oilchange and then went up rapidly.So I checked every 4 hours.

My boat is in the water during the winter.To make shure,the engine is not
freezing during my absence,I always drain the water from the cylinders.
I noticed that one cylinder had only a little water in it.And the next time
even less.And one day there was no water.

When I bought the boat,I got a boat with a frozen engine.Volvo Penta did not
accept it as warranty and the yard told me it was my fault.But thats an other
story.I had to change all 3 cylinderheadgasket after 1 hour runtime.
Since then,I was never shure if I mounted the gaskets the right way around.
Thats how it works:

Engines are made for different purposes and different ratings,but are using the
same mechanical parts.You can have Volvo Penta engines for recreational or
professional work.They have different temperature and revolutions.The temparatur
is "adjusted" with different headgaskets.There are more holes in the cylinder 
for cooling water then actually used.
My engine has one cooling hole covered with the gasket.When I installed the new
gaskets,at the last moment I found out,that I have put the gasket the wrong
way around on the last cylinder and closed some of the cooling holes.Now I had
a problem.Should I check the other two cylinders as well or take chances ? 
(gaskets are expensive and can only be used once).I took the chance.

Now I had this temparatur problem on my hands and I did not know if the gaskets
have been mounted the right way around.With a heavy heart I opened the first
cylinder and got the shock of my life.The gasket was ok,but all cooling holes
completly closed with a white "stone".(Cylinder and cylinderhead)
I gave it to the local garage to clean it,but they gave up and have send
it to the nr.1 company which does all this valveguides honing,brakes overhaules
etc.
I have done the exhaust concentrator (sp?) myself with vinegar and houshold
    lime remover .I installed a heat exchanger and the engine has been running 
now for more then 500 hours with a steady temparatur display and no problems.
A few weeks later after the sucessful repair of my engine,I told my story
a mechanic doing occasionaly repairs to Volvo Pentas.He told me,this
is a known problem and normaly ends with the engine burnt out due to no
oil.Then the engine gets replaced and the owner gets the information,he
did not check the oil level regulary.
I had to replace several time the sensor for the oilpressure.The switch
inside the black plastic got damaged from the execive heat from the engine 
block.

I do not know what the "white" stone is.I operate my boat in salt and fresh
water.Does saltwater contain lime ? My engine has 1800 hours total,ca 1200
in saltwater,the rest in a lake with a very low lime concentration.

If you have the same problem as I had,I would try vinegar (leave it in the
engine for a week or two and see what happens.I'm not shure,but I believe
you can see the deposits if you open the thermostat housing and shine a light
inside the first cylinderhead.

Peter


    

  Peter, thank you for sharing your experience.  Mine, I hope won"t
  be similar but...here's what has happened so far. 
    
    Last weekend we finally ventured out into Long Island Sound for
    the first time. Our previous experience had been short trips of
    several hours on the Connecticut river, sometimes under sail but
    mostly under power. During this time the motor acted normally with
    temp at 180 degrees and oil pressure at 40 lbs.
    However, out on the sound the temp steadily climbed over 180 and
    approached 200. I checked the oil, water supply and exhaust water.
    All seemed normal but we slowed to approx half speed and continued.
    The temp dropped some and we continued on our trip. At Plum Gut
    near the tip of Long Island, we needed full power because of the
    tidal conditions and the temp soared to 230.
    We slowed again but this time the needle stayed "pinned". As we
    were in a relatively safe area by this time we shut her down.
    When she cooled I checked the water inlet...plenty of water, the
    impeller...looked ok and water flowed fine there, removed the 
    thermostat...no blockage there. All hoses and tubes were clear,
    but a 3/8 inch cast iron elbow that supplys water to the water jacket
    was plugged with a grainey black material similar to carbon.
    After cleaning this out the engine ran fine and because I never
    replaced the thermostat the temp never got above 150 degrees. Of
    course, similar to your experience my oil pressure sending unit
    doesn't work anymore. The next day she ran for another five or
    six hours with no problem.
    	My questions are as follows... 
    
    			What do I look for for damage from this?
    
    		        Can I use a radiator/block flush to clean
    out any more of this stuff that may be waiting to block things
    up again?
    			The stuff I have in mind has oxolic acid 
    in it...has anyone out there done this before?
    
    By the way, my engine is a 16 year old Volvo MD2B with raw water
    cooling.
    
    Thanks again, John W.
    
     	
    
   

    Best to flush with with the approved solution from Volvo, the solution,
    whose name I have forgotton, is the one used to flush the system
    prior to winterisation. If you experiment you could end up with
    an expensive repair job. I had a wander through my Volvo course
    notes and promptly left them at home..... but a another short term
    fix without chemical.........is to put a freshwater hose on the
    inlet side whilst hand cranking the engine. never tried it and it
    sounds painful.........maybe the expense of chemical is not to bad
    after all.........
    
    
    
    Pete                                            

    Well,  the weekend is over and after installing a new thermostat
    (an expensive Volvo thermostat,I might add) the engine ran fine
    and never exceeded 140 degrees F. That is aprox what 58 degrees
    C. works out to but I still would feel better if I flushed her 
    out. The 58 degrees was stamped into the valve of thermostat.
    In any event, Pete would you look up the "approved" Volvo solution
    or better yet send me a copy of your Volvo course notes. Some
    _thing like that would be invaluble to me. I'm at the Enfield
    (ENO) facility.
    
    Thank You, John W.
    

    Well, the week is over, and basically the engine ran fine....
    
    But before that my brother-in-law took about an hour working on
    the engine, and produced a hollow copper pipe about 5 inches long,
    1/2 inch in diameter, with a hole in the side about half way along.
    
    We enlarged the hole to the size of the dents in the metal, cleaned
    out the gunge and carbon and deposits from the inside, and then
    put the tube back (breaking the end!! - but that is another story).
    
    After that the water circulated around the engine correctly, and
    it didn't over heat.....
    
    Thanks for all your help, 
    Chris
  

    Well, it's clearly time to revive this note:
    
    I've got a Volvo MD-17C engine. 3-Cylinder, 35hp, raw water cooling. 
    I was running it this weekend after doing some general work and noticed 
    that after 15-20 minutes that when I touched the various cylinders, 
    front, middle, back, I noticed that I could hold my hand on the front 
    valve cover top and it was barely warm, the middle one was warmer
    (mildly uncomfortable to hold onto for very long), but the rear one was
    blistering hot! I opened the side drain valve of the rear cylinder  to
    see if water would come out. I only opened it enough to allow it to
    come out slowly, so I don't really know the flow rate on it. Water did
    come out and it was scalding hot. 
    
    My temp gauge reads normal, right where it has always read.
    
    The engine does burn some oil.
    
    Is this temp variation between cylinders normal? I don't recall this
    being the case in the past but am unsure. Am I about to experience a
    major problem here? Is this something I should be concerned about?
    Is there something I should be doing to fix it- if so, what?
    
    All ideas and suggestions would really be appreciated.
    
    Thanks,
    Robert

    The blistering hot cylinder doesn't sound normal to me.  The variation 
    in temp. sounds too extreme to me.  I would be suspicious of a partial
    water blockage into the 2nd and 3rd cylinders. Was this engine used in
    salt water?  Can you 'revere flush' the block?
    
    Jeff

    The boat was used in salt water for 12 years. We just brought it up
    into fresh water earlier this year. I don't know of a way to reverse
    flush the block as the water inlet goes from the top front of the
    engine (thermostat location) to top rear of engine (exhaust head) and
    tilts back about 15-20 degrees. I'd be afraid to dis-engage the exhast
    pipe and shove a water hose up it to blow water out the front for fear
    of filling a cylinder with water or some other equally distasteful and
    disasterously bad event.

re .11:

At a guess, there is a blockage in the water cooling passages and the 
very hot cylinder is dangerously overheating (you could well be burning 
oil in this cylinder or have damaged cylinder walls and/or piston 
rings).

The salt in seawater forms scale when the water temperature exceeds some
value well below 212 deg F. This scale is an excellent insulator. After 
12 years in salt water you quite likely have significant internal 
corrosion and scale. I don't think flushing the block will help much.

I'd discuss this situation with a competent Volve mechanic. I'd also be 
prepared to buy a new engine or pay a very large repair bill. 

Nigel Calder's book on diesel engine repair is a good reference.

Happy New Year?

Alan

Hi Robert,


dont worry about your engine. A Volvo is an engine which smokes,
oils, smells, ratles, vibrates and sometimes overheates. But: it seldom 
breaks completly down and as long as it has engine oil, it will not destroy 
itself. But watch out, the longterm reliability is at risk with your
overheated cylinder. The rubber rings around the valve stems may get
hard and may leak oil in the long run. That is exactly what happend to
my engine. 


This is my opinion of your problem if Murphy is not at work: 

     1 cylinder gets hot, 1 is warm, 1 is cold , burns engine oil


Cooling system ok. The hot water from the hot cylinder hits the 
thermostat, thermostat opens up, distribution of cold water is bigger
than it should be, cools down the "good" cylinders to a temperatur below
normal. The engine thermometer will show a normal reading, as the 
cooling water has the right temperatur mix:  

	1 too hot + 1 warm + 1 cold  =  normal temperatur/ reading ok

Only Murphy could block one cylinder and not the others. When my MD17D cooling
was blocked, all 3 cylinder had the same problem and that gave the strange 
reading at the thermometer.(pulsating reading)

Ok, good so far. Your cooling system is ok. The problem lies most probably
with that particular cylinder.

What could be wrong in a cylinder:

Injector, valves, piston and pistonrings 

How to check each of this:

Valves:   feeler guide.   no problem
Injector: This is the most probable cause. 
          An injector is a part which has to be maintained from time
          to time. Cost: the replacable part costs 50$ in Switzerland
          The holder has not to be replaced, only the "nozzle". The spring
          inside the injector gets tired and has to be adjusted every 
          few hundred hours running time. (Volvo Penta seems to have a
          problem here, a proper engine should go for decades) 
Piston    check compression 

Conclusion: no problem, pull the injectors and you are all set.
Engine oil gets burned by the overheated cylinder.

If Murphy has hit you: 
 
leaking cylinderhead gasket: almost impossible in a marine diesel.
The high pressure inside the engine will blow a damaged gasket to
pieces. The engine would run very rough and possibly water in the
engine oil. 
Worst case scenario: damaged valve/piston/pistonring. Unlikly,
not enough running time on the engine. Can easely be diagnosed with
compression check. I assume you have less then 10000 hrs on your engine.
Injector pump: unlikly, if no water enters the pump, no problem during the
life of the engine.

    Peter

    So Peter, if I interpret what your saying correctly.... its 'normal'
    for his engine to be running with one HOT cylinder, or, at the least
    its tolerable?
    
    I don't know of any engine in which its normal for the cylinders to run
    at major differences in temperature.
    
    It sounds to me as if scaling/rust/corrosion has limited the water flow
    through the water jacket of the hot cylinder and its just a matter of
    time until he has major ring damage and cylinder wall scoring in that
    cylinder, unless its already happened.
    
    Jeff

I'm not so sanguine as Peter about your engine. The temperature 
differences you describe between the cylinders sounds quite abnormal 
and definitely cause for concern, even alarm. I would assume that at 
some places all the cooling water goes through one passage (eg, past the 
thermostat). At other places the water must have parallel paths. It 
wouldn't work very well to have series flow of water past the cylinders 
since you would get very uneven cooling. This would imply that it would 
be possible for one blockage or restriction to keep cooling water from
one cylinder and not the others. 

If a fuel injector is clogged, the engine will likely idle very roughly 
since the cylinder with the clogged injector won't be firing. If an
injector is stuck open, the engine will likely run roughly, but only for
a short time until the fuel washes enough lubricating oil from the
cylinder wall to cause piston seizure. 

No fuel water separator is 100% effective, so there will always be some 
water to cause corrosion in the injectors and injector pump. (I've 
discussed my injector pump problems in another note. After some 1200 
hours over 12 years, our injection pump needed major repairs because of 
corrosion, and we have two water separators in series in our fuel 
system.)

A compression test may detect valve, piston, and piston ring problems. 
But because of the very high cylinder pressures, a rather expensive tool 
is needed to make the test. As I vaguely recall, the compression tester 
used by the mechanic who diagnosed our Westerbeke cost over $1000. 

I'd get professional help, and I'd certainly not ignore the problem. It 
isn't likely to fix itself. Sigh. But better to find the problem now 
than during the sailing season.

Alan

    oooh, my english needs some upgrade.... 
    
    What I tried to say:
    
    The uneven heating is of concern and has to be repaired.
    But I would not be to much worried, without checking the most
    obvious things like compression, injector and valve clearing.
    Its like checking a powersupply on a malfunctioning computer.
    I know, we prefer to swapp the CPU module first.......
    
    Injector do not clogg open or closed. Injector do leak, have wrong
    opening pressure due to tired springs and have burnt out spray holes not
    producing an even spray pattern.
    
    If the engine is blocked inside , then a total rebuild of the 
    engine is in place. There are two 8 mm holes leading the water from
    the cylinder to the cylinderhead. This get easily blocked from
    the chalk in lakes. It happend to me twice (MD2B and MD17D). But then all 3 
    cylinders get blocked at the same time and then you have a different
    problem. The amount of water available to cool the engine is limited
    to the water in the housing of the thermostat. The thermostat opens
    like a explosion and lets in cold water and closes immediatly again.
    This creates a strange reading on the thermometer. Below temp slowly
    rising just above normal and very fast sinking back below normal.
    Thats a clogged cooling system. Robert does not have this.
    
    So I did recommand to do the most basic work in such a case:
    
    measure the compression and check the injectors. There is a 90% chance
    that the injector needs servicing. Any other fault would need a partial
    rebuild of engine. (or, how do you change a burnt out valve  without
    opening up the engine ? )
    
    Alan, you are correct on checking the compression. Cars have different
    size of injectors and the adapters do not match. It has to be done by
    a professional. But I do not agree on injectors. Injectors need regular
    service. Also in trucks and cars. I also do not agree with the injector 
    pump. If you get water into the pump, the engine stops working. The pumps
    have no rings, nothing, just unbelievable exact pistons. If any water
    enters the pump and creates rust, (15 minutes is all it needs), then
    its gone. I have it from a reliable source, that under normal
    conditions the injector pump needs no replacement ever except in case of 
    waterdamage. Robert did not say that he has any problems in starting
    the engine. So his pump should be ok.
    
    Now, I'm going back to read-only mode. I will be busy rebuilding MY engine,
    starting tomorrow. During my atlantic crossing, the heatexchanger broke
    off and the engine overheated to such an extend, that the paint was
    starting to burn. Thats how I found out about it. The smoke ..... 
    Now, I have some spare time to replace all gaskets, check all valves and 
    check the injectors. (by the way, the engine did run for more then 1000 
    hours after the "near burn out").
    
    Happy New Year to all of you.   
    
    Peter
    

    Well, I've found part of my problem. 
    
    I started at the bottom and worked my way up. The first item I found
    was that my water pump impeller was missing 1.5 blades with another one
    smashed flat. Fortunately, I found all the pieces.
    
    I replaced the impeller, started the engine and again observed the temp
    variation. After one hour of pumping very cold lake water into the
    engine (raw water cooled) I began to again notice a difference in temps
    between heads. Now the front (closest to the thermostat and the middle
    are running without any discernable difference in temps. The head
    furthest back on the engine is running much cooler now, but still feels
    about 20-40 degrees warmer than the rest.
    
    Right now, I am assuming I may have had two or more immediate problems:
    1. Lower water flow either created the problem or has now notified me
    of a potential slight cooling system blockage problem that may be in
    the process of forming.
    
    2. I may have had an air pocket trapped in my cylinder head from when I
    last drained it and closed the cylinder head petcock before allowing it
    to refill completely with water.
    
    I still am feeling uncomfortable about the difference in the last
    cylinder. Since I haven't had the injectors looked at since I've owned
    the boat (nearly 4 years) and I doubt that the previous owner did
    (based on other poor maint habits I've discovered), I may pull them and
    have them serviced. I was not aware that they would go out of
    "alignment". But, before I do this, I have a question, should I pull
    the injectors and have them serviced if I'm not blowing any black
    smoke or could it be hidden by the blue smoke? Is this a normal annual
    maintenance item??? I ask because if my temp difference could be caused
    by diesel dribble out of a now weakened injector, I want to have this
    fixed. If it could still be a slight flow restriction then I don't want
    to add to the fix cost by pulling the injectors unless this is prudent
    maintenance. Finally, should I pull the manifold off and attempt repair
    if I now have the difference down to this point?
    
    All thoughts are welcome!

re .19:

Ah, another lesson in "do not overlook the obvious"! I wonder why none 
of us "experts" suggested checking the pump impeller. Clearly, the right 
first step.

Well, I'm told that injectors do clog with algae, the springs do get 
tired, and the nozzles do wear from the high pressure fuel forced 
through them. It was not terribly expensive to have our injectors 
cleaned and recalibrated -- on the order of $40 each a few years ago. It 
certainly wouldn't hurt to have them looked at. Peter may (will) 
disagree with me, but it might be well to have the injection pump 
cleaned and checked, too. Our engine started more easily and seemed to 
use less fuel after an injection pump overhaul. Maybe Volvos are 
different than English-built Westerbeke's (insert smile here). 

Alan

    I know little about sailing and equally little about diesels, but I
    used to know a bit about debugging....  Why not swap the injectors between
    cylinders and see whether the heating moves with the injectors or stays
    with the cylinders ?
    
    Of course getting injectors reconditioned is not a bad idea for PM but
    as a diesel (car) owner I always wait until I've got emission or
    economy problems before so doing....

I worked for a keen sailor once who economised so much on all other areas of his
life to support his hobby that when someone diagnosed old tired spark plugs on
his car as the cause of rough running, he bought one new plug and tried it in
each of the four cylinders until he found the "bad" one...

But I have to admit that at $40 a throw for three injectors, I would look to
localising the problem a little more :-)

- Brian (who is glad he has a single cylinder diesel)

re .21:

In theory, I agree. Reality is a little different. On my engine, at 
least, every removal of an injector means some bleeding of the fuel system, 
which is both time consuming and messy. More importantly, perhaps, the 
pressures in the fuel lines to the injectors are very high. The joint at 
the injector is, on our engine, made by compressing the convex spherical
end fitting (non-replaceable) on the fuel line into the concave
spherical mating surface on the injector. After not very many
tightenings/loosenings the fuel line fitting distorts and getting a
leak-free seal becomes difficult. I've had to replace one fuel line and
the others should be replaced -- $25 to $50 per line or more. And our
engine has four cylinders. 

On an engine as old as the one in question, it makes sense to me to have 
the injectors overhauled and know that they are all good. 

Alan