Volbvo MD 2010 D (2002 vintage )Overheat Alarm

[TSB240]

Last weekend had two alarms both times after working engine hard (flat out for 30 minutes) and then slowing down to a little less than light speed!

Alarm sounded for a short period and I lost a little coolant through the expansion cap overflow on the heat exchanger.

Outlet water in exhaust warm but not hot. Exhaust elbow could be touched. Usual amount of water in exhaust outlet.

Heat exchanger just too hot to hold hand against for any length of time.

I checked impeller and it was in good condition (new this year).

However the wear plate/ cover is quite badly scored/worn and gouged in one spot.

Strainer had a few broken shells but clearly was not blocked.

Other info still getting max revs, no smoke and slightly above hull speed 5.5 knots with a 10 hp engine on a 30 footer.

No signs of oil leaks or water leaks from any other part of the engine.

My thinking.

I don't think it is a thermostat problem!

My first thought is to fit new wear plate and new impeller kit. (I have actually ordered a speedseal kit)

I am thinking that at lower revs the raw water pump wasnt supplying quite enough cool water to take away the reisidual heat that builds up on a long run.

The next step if that does not solve the overheat is to pull the HE tube and clean it out.

If that doesnt improve the situation then a new circulation pump is a possibility as is a new expansion cap or temperature sender. probably in reverse order of expense!

Anybody had a problem with pressure cap blowing off too early and or duff temp senders.... would you expect a circ pump to fail after 13 years?

I am trying to keep my expenditure low and solve the problem asap as we only have a couple more weekends before lift out!


Steve

 

[VicS]

Refurbishing the RW pump does seem to be called for. look at the cam plate too they do wear and should then be renewed. Some pump makers offer a high lift cam which can be a sensible mod if one is available.

I would definitely consider cleaning the HE. You have to take the whole caboodle off to get at the thermostat I believe on a MD 2010.. That should just begin to open at the marked temperature and be fully open at the second temp if another is marked. The owners manual should also tell you the lower one, maybe both.

Checking the temperature sensor would be sensible and easy to do. You say two alarms. If one was the overheating warning what was the other ?
I take it you do not have a temperature gauge?

Impellers can come off circulation pumps although I have never had it happen. It's a whole new pump if there is anything wrong with the VP one and one of those will blow your low expenditure policy out of the window.

 

[TSB240]

Refurbishing the RW pump does seem to be called for. look at the cam plate too they do wear and should then be renewed. Some pump makers offer a high lift cam which can be a sensible mod if one is available.

You say two alarms. If one was the overheating warning what was the other ? Two occasions same alarm and same condition on wind down!

I take it you do not have a temperature gauge? No but have access to heat temp gun for next time

Impellers can come off circulation pumps although I have never had it happen. It's a whole new pump if there is anything wrong with the VP one and one of those will blow your low expenditure policy out of the window.

Thanks started my savings plan now then!

Steve

 

[peteK]

Last weekend had two alarms both times after working engine hard (flat out for 30 minutes) and then slowing down to a little less than light speed!

Alarm sounded for a short period and I lost a little coolant through the expansion cap overflow on the heat exchanger.

Outlet water in exhaust warm but not hot. Exhaust elbow could be touched. Usual amount of water in exhaust outlet.

Heat exchanger just too hot to hold hand against for any length of time.

I checked impeller and it was in good condition (new this year).

However the wear plate/ cover is quite badly scored/worn and gouged in one spot.

Strainer had a few broken shells but clearly was not blocked.

Other info still getting max revs, no smoke and slightly above hull speed 5.5 knots with a 10 hp engine on a 30 footer.

No signs of oil leaks or water leaks from any other part of the engine.

My thinking.

I don't think it is a thermostat problem!

My first thought is to fit new wear plate and new impeller kit. (I have actually ordered a speedseal kit)

I am thinking that at lower revs the raw water pump wasnt supplying quite enough cool water to take away the reisidual heat that builds up on a long run.

The next step if that does not solve the overheat is to pull the HE tube and clean it out.

If that doesnt improve the situation then a new circulation pump is a possibility as is a new expansion cap or temperature sender. probably in reverse order of expense!

Anybody had a problem with pressure cap blowing off too early and or duff temp senders.... would you expect a circ pump to fail after 13 years?

I am trying to keep my expenditure low and solve the problem asap as we only have a couple more weekends before lift out!
Check water injection point on exhaust elbow,these can become partially blocked.

Steve

 

[Heckler]

Last weekend had two alarms both times after working engine hard (flat out for 30 minutes) and then slowing down to a little less than light speed!

Alarm sounded for a short period and I lost a little coolant through the expansion cap overflow on the heat exchanger.

Outlet water in exhaust warm but not hot. Exhaust elbow could be touched. Usual amount of water in exhaust outlet.

Heat exchanger just too hot to hold hand against for any length of time.

I checked impeller and it was in good condition (new this year).

However the wear plate/ cover is quite badly scored/worn and gouged in one spot.

Strainer had a few broken shells but clearly was not blocked.

Other info still getting max revs, no smoke and slightly above hull speed 5.5 knots with a 10 hp engine on a 30 footer.

No signs of oil leaks or water leaks from any other part of the engine.

My thinking.

I don't think it is a thermostat problem!

My first thought is to fit new wear plate and new impeller kit. (I have actually ordered a speedseal kit)

I am thinking that at lower revs the raw water pump wasnt supplying quite enough cool water to take away the reisidual heat that builds up on a long run.

The next step if that does not solve the overheat is to pull the HE tube and clean it out.

If that doesnt improve the situation then a new circulation pump is a possibility as is a new expansion cap or temperature sender. probably in reverse order of expense!

Anybody had a problem with pressure cap blowing off too early and or duff temp senders.... would you expect a circ pump to fail after 13 years?

I am trying to keep my expenditure low and solve the problem asap as we only have a couple more weekends before lift out!


Steve

Steve
wear plate sounds like it could be the prob but also check the exhaust elbow for blockage
S
PS still piggin hot here!

 

[Ruffles]

Interesting question as to what temperature the outside of the heat exchanger should reach in normal operation. As it's an open system it must be less than 100C or you'd have a steam engine.

Is the temperature sensor on the block? A large difference in temperature between the engine and the heat exchanger would indicate a fresh water problem. The engine must be reaching 100C as it's boiling somewhere so if the raw water system is working the heat exchanger should also be near that temperature as the thermostat should be fully open.

I tend to think that the raw water system must produce more cooling effect than is ever used as it is unregulated. (And is often restricted by weed on our boat!). The engine regulates it's temperature using the fresh water system which should remain steady once the engine has warmed up.

 

[TSB240]

Steve
wear plate sounds like it could be the prob but also check the exhaust elbow for blockage
S
PS still piggin hot here!

Thanks Stu I am not convinced its the elbow as no sign of loss of power smoke or reduction in waterflow in outlet and elbow is cool to touch. Also its a 10 hp motor that has basically run near flat out most of its life!

Wont be able to fix it for a couple of weekends or so as we are going to be in even hotter climes than you for a while!

Fed up with our wet welsh weather this summer so taking a week off in Kephalonia where we might meet up with our long term Boatie friends..

Oi have you met any Frenchmen with no balls recently? Tee Hee....

Steve

 

[VicS]

Interesting question as to what temperature the outside of the heat exchanger should reach in normal operation. As it's an open system it must be less than 100C or you'd have a steam engine.

Is the temperature sensor on the block? A large difference in temperature between the engine and the heat exchanger would indicate a fresh water problem. The engine must be reaching 100C as it's boiling somewhere so if the raw water system is working the heat exchanger should also be near that temperature as the thermostat should be fully open.

I tend to think that the raw water system must produce more cooling effect than is ever used as it is unregulated. (And is often restricted by weed on our boat!). The engine regulates it's temperature using the fresh water system which should remain steady once the engine has warmed up.

The heat exchanger is part of the pressurised coolant system. the pressure ) being controlled by the pressure cap. In theory it could get above 100C but should normally between the initial opening and fully open temperatures for the thermostat (75C and 87C respectively)

The coolant consisting of 50% ethanediol will boil at approx 126C at the pressure maintained in the system of approx 13psi.

the temperature sensor is located in the HE. I beleive it is set to sound the alarm at 120C

 

[TSB240]

Ok to follow on. I have replaced the impeller and cover and getting plenty of seawater circulating. After running at full revs for 10mins had overheat alarm and lost coolant. Spent yesterday afternoon clearing out a slight blockage of a couple of tubes on heat exchanger but not much. Reassembled and ran engine hard again this morning. No difference. The exhaust elbow is not blocked and was cool to touch as was sea water in exhaust. Clutching at straws before going for a new circ pump do the thermostats fail open or shut on these engines otherwise. Is there a likelihood the pressure cap is us? I am bracing myself for a New circ pump. Is there a history of impeller failure on these. I have checked no circulation pipes have collapsed .

 

[oldvarnish]

Had something similar to the OP. Was found to be a detached impeller blade which had caught in the exhaust elbow

 

[RichardS]

Ok to follow on. I have replaced the impeller and cover and getting plenty of seawater circulating. After running at full revs for 10mins had overheat alarm and lost coolant. Spent yesterday afternoon clearing out a slight blockage of a couple of tubes on heat exchanger but not much. Reassembled and ran engine hard again this morning. No difference. The exhaust elbow is not blocked and was cool to touch as was sea water in exhaust. Clutching at straws before going for a new circ pump do the thermostats fail open or shut on these engines otherwise. Is there a likelihood the pressure cap is us? I am bracing myself for a New circ pump. Is there a history of impeller failure on these. I have checked no circulation pipes have collapsed .

If yours was a "normal" engine I would suggest removing the thermostat and try running without it. However, on some Volvos the thermostat seems to work in an odd way from what I have read on the forum so I would remove and test it or just replace it with a new one. Cheaper to rule out the thermostat before moving onto the coolant pump.

Richard

 

[VicS]

If yours was a "normal" engine I would suggest removing the thermostat and try running without it. However, on some Volvos the thermostat seems to work in an odd way from what I have read on the forum so I would remove and test it or just replace it with a new one. Cheaper to rule out the thermostat before moving onto the coolant pump.

Richard

I imagine what you are referring to is the secondary "valve" which closes an internal bypass when the thermostat opens.

By no means peculiar to Volvo. Quite commonplace ITYWF. Both the thermostats in the picture below operate like that. One is from a Ford Fiesta, the other from a Peugeot 106

Ok to follow on. I have replaced the impeller and cover and getting plenty of seawater circulating. After running at full revs for 10mins had overheat alarm and lost coolant. Spent yesterday afternoon clearing out a slight blockage of a couple of tubes on heat exchanger but not much. Reassembled and ran engine hard again this morning. No difference. The exhaust elbow is not blocked and was cool to touch as was sea water in exhaust. Clutching at straws before going for a new circ pump do the thermostats fail open or shut on these engines otherwise. Is there a likelihood the pressure cap is us? I am bracing myself for a New circ pump. Is there a history of impeller failure on these. I have checked no circulation pipes have collapsed .

I Agree with Richard that it would be sensible to test the thermostat but it is not easy to access as you no doubt realise.

Perhaps the way forward is to inspect the coolant pump, checking that the impeller is secure on the shaft. if that is Ok test the thermostat.

Not sure if it applies to your version of the engine but in some it is important that the HE tube bundle is fitted correctly, with a vent hole on the top, so that it does not air lock on the coolant side. Later ones I believe are of a more open construction so this does not apply.

I don't believe the pressure cap will be your problem but inspect it. Anything catastrophically wrong should be obvious. A slight weep/ let by is not likely to cause the symptoms you describe.

 

[pvb]

Ok to follow on. I have replaced the impeller and cover and getting plenty of seawater circulating. After running at full revs for 10mins had overheat alarm and lost coolant. Spent yesterday afternoon clearing out a slight blockage of a couple of tubes on heat exchanger but not much. Reassembled and ran engine hard again this morning. No difference. The exhaust elbow is not blocked and was cool to touch as was sea water in exhaust. Clutching at straws before going for a new circ pump do the thermostats fail open or shut on these engines otherwise. Is there a likelihood the pressure cap is us? I am bracing myself for a New circ pump. Is there a history of impeller failure on these. I have checked no circulation pipes have collapsed .

I really think that it's unlikely to be the circulation pump - this is just a shaft with a pulley on one end and an impeller on the other. Apart from bearings, there's nothing to go wrong. If the belt tension is too low, there might be a possibility of the pump pulley slipping, but again I reckon that's unlikely.

The heat exchanger insert has to be positioned correctly; the workshop manual advises "Make sure that the hole in the insert casing comes opposite the hole in the housing and that the vent hole comes upwards. The insert is marked with UP."

Thermostats will often fail closed. Or they may fail by not opening sufficiently. The workshop manual tells you how to test the thermostat - basically when immersed in boiling water it should open by at least 6mm. I'd either test the thermostat next, or simply replace it with a new one.

 

[VicS]

I really think that it's unlikely to be the circulation pump - this is just a shaft with a pulley on one end and an impeller on the other. Apart from bearings, there's nothing to go wrong. If the belt tension is too low, there might be a possibility of the pump pulley slipping, but again I reckon that's unlikely.

The heat exchanger insert has to be positioned correctly; the workshop manual advises "Make sure that the hole in the insert casing comes opposite the hole in the housing and that the vent hole comes upwards. The insert is marked with UP."

Thermostats will often fail closed. Or they may fail by not opening sufficiently. The workshop manual tells you how to test the thermostat - basically when immersed in boiling water it should open by at least 6mm. I'd either test the thermostat next, or simply replace it with a new one.

Apparently pump impellers can come loose. !

If testing a thermostat one should check that it just starts to open at the specified temp (74C ±2) and is fully open ( 6mm ) at 87C. Not just immerse in boiling water

The copy of the 'shop manual I am looking at does not actually tell you how to test the thermostat!


I think on this engine the whole darned HE/ exhaust manifold assembly has to be removed to access the thermostat.......... or am i wrong about that?

 

[pvb]

If testing a thermostat one should check that it just starts to open at the specified temp (74C ±2) and is fully open ( 6mm ) at 87C. Not just immerse in boiling water

The copy of the 'shop manual I am looking at does not actually tell you how to test the thermostat!

Whilst I'm sure your test method might be OK, the workshop manual gives the following guidance:-

 

[duncan99210]

Despite the exhaust elbow being cool and no smoke from the exhaust, I'd check the elbow, both the water injection route and the exhaust side. I had similar problems a few years back where we constantly had problems with lack of cooling water flow. I replaced the impeller, cleaned out the heat exchanger matrix and replaced the pump plate, each time finding faults which I thought must clear the problem. Finally, after advice from here, I removed the exhaust elbow and found that it was somewhat clogged with crud on the exhaust side and that there was a piece of disintegrated impeller wedged into th injection pipe. Still didn't quite fix the problem which was finally sorted by fitting a Speedseal Life plate which resulted in a really great flow rate through the system.

 

[RichardS]

Despite the exhaust elbow being cool and no smoke from the exhaust, I'd check the elbow, both the water injection route and the exhaust side.

Although see OPs post #9. It sounds as if he has covered that possibility.

Richard

 

[VicS]

Whilst I'm sure your test method might be OK, the workshop manual gives the following guidance:-

Thats all very well but it does not check that the thermostat starts to open at the specified temperature (75C for a MD 2010D) and is fully open at 82 C as is also specified. Merely that it is still closed at 68C and fully open at 100C.

I can assure you "my"test method does work and done many times .
My preferred technique is to suspend the thermostat by a thread, trapped under the opening flap, in a large glass laboratory beaker of hot water, a few degrees below the expected opening temperature, together with a laboratory, thermometer then heat gradually noting the temperatures at which it justs starts to open and is fully ( 6mm) open. The initial opening point is often difficult to see but using this method is made obvious by the thermostat falling from the thread.!

It may seem a bit OTT but given the usual lab facilities is the obvious way to do it.

 

[pvb]

Thats all very well but it does not check that the thermostat starts to open at the specified temperature (75C for a MD 2010D) and is fully open at 82 C as is also specified. Merely that it is still closed at 68C and fully open at 100C.

I can assure you "my"test method does work and done many times .
My preferred technique is to suspend the thermostat by a thread, trapped under the opening flap, in a large glass laboratory beaker of hot water, a few degrees below the expected opening temperature, together with a laboratory, thermometer then heat gradually noting the temperatures at which it justs starts to open and is fully ( 6mm) open. The initial opening point is often difficult to see but using this method is made obvious by the thermostat falling from the thread.!

It may seem a bit OTT but given the usual lab facilities is the obvious way to do it.

Maybe VP will change their recommendations, but they perhaps assume that many marine engineers don't have much in the way of lab facilities.

 

[davidej]

I have similar problems with a 2030 - same vintage - no header tank for the coolant.

Mine runs for hours at 1900-2000 RPM with no problems. Wellie it up to 22-2400 and it blows coolant out of the pipe by the pressure cap.

Last winter, I cleaned out the heat exchange stack and the exhaust elbow - neither of which, to my untrained eye, seemed to be blocked. Tha sea-water flow seems satisfactory looking both at the flow in the filter (transparent plastic top) and the output at the transom.

My mate at a Volvo dealer tells me the next step is to take the heat-exchange stack to a car radiator company for chemical cleaning.

This is tomorrow's job and I will let you know how I get on