Volvo MD2040C Heat Exchanger

[Ammonite]

Having removed the heat exchanger rubber end caps I had to remove the H/E temperature sender as it was fouling on the tube stack (not the tubes themselves but the circular copper supports that maintain the tube spacing) Is this normal? Its as if the sender is too long. Also with the sender installed you can't centralise the tube stack as the sender is exactly where one of the copper supports sits. Its out by about 5mm which seems odd given the rubber end caps are the same on both ends and results in a very marginal seal between fresh and salt water on the input end.

The sender looks original as it was a pig to remove and is painted green but I guess someone could have painted it by hand.

The copper supports dont have any slots in them that would clear the sender when rotated in a particular position so Im a bit confused. What am I missing?

It's an isolated two wire sender but when i searched for a replacement on parts4engines they only list a switch i.e. one for a buzzer rather than a temperature guage but this does appear to be a few mm shorter and I would expect it to clear the stack however at this stage im unsure which temperature sensor (the engine one or the H/E) supplies the gauge in the cockpit)

Thoughts?

 

[VicS]

It's an isolated two wire sender but when i searched for a replacement on parts4engines they only list a switch i.e. one for a buzzer rather than a temperature guage but this does appear to be a few mm shorter and I would expect it to clear the stack however at this stage im unsure which temperature sensor (the engine one or the H/E) supplies the gauge in the cockpit)

Thoughts?

Can't help with the problem of interference between the tube stack support and the sensor. You are sure you are fitting the tube stack correctly?

Maybe this helps with the sensor identification,
12 is the sensor for the alarm ( it should have white/brown and black wiring).
11 is the sensor for the temperature gauge ( it should have light brown and black wiring)

I an surprised your C version has two-wire sensors. I thought they were only fitted to the A version, with an isolated electrical system, and which pre-dated the isolated transmissions.

 

[Ammonite]

Thanks VicS
I think I may have found a solution that will allow me to centralise the stack in the H/E. Someone has forcefully tried to remove the stack in the past without removing the temperature sender which has pushed one of the copper supports out of position (I was only trying to extract it by hand so it wasnt me!) however as the stack appears symetrical I should be able to put it back the other way around. The are no location marks as far as can see so far but even if there were youd still need to remove the sender to extract the stack.

Thanks for the diagram. Thats really helpful which tells me the H/E sender is a switch!

Parts4engines list the following as the correct part for my engine which is for the b, c and d versions in line with what you say

Volvo Penta MD2040 high temperature switch

However the sender i have looks like the two terminal version pictured here

Perkins 4.99 Water Temperature gauge & sender 12V

Im going to check later to today but I "think" the negative is wired to the alternator earth?

Do you know the best way of checking that the switch is working correctly?

 

[VicS]

Thanks VicS
I think I may have found a solution that will allow me to centralise the stack in the H/E. Someone has forcefully tried to remove the stack in the past without removing the temperature sender which has pushed one of the copper supports out of position (I was only trying to extract it by hand so it wasnt me!) however as the stack appears symetrical I should be able to put it back the other way around. The are no location marks as far as can see so far but even if there were youd still need to remove the sender to extract the stack.

Thanks for the diagram. Thats really helpful which tells me the H/E sender is a switch!

Parts4engines list the following as the correct part for my engine which is for the b, c and d versions in line with what you say

Volvo Penta MD2040 high temperature switch

However the sender i have looks like the two terminal version pictured here

Perkins 4.99 Water Temperature gauge & sender 12V

Im going to check later to today but I "think" the negative is wired to the alternator earth?

Do you know the best way of checking that the switch is working correctly?

I was wondering if the tube stack could be turned end for end and if that would make any difference. I think early ones can't be because they are enclosed with holes in the enclosure which must be orientated correctly. If yours is just an open tube bundle then I guess it can be fitted any way.
You can test the alarm sensor by heating it through the temperature at which it should close ...........(95C, ITYWF, See page 73 of the workshop manual. Volvo MD2010 Workshop Manual (Page 73 of 81) | ManualsLib )

The negative connection goes to the engine / alternator / battery negative

 

[Ammonite]

Can't help with the problem of interference between the tube stack support and the sensor. You are sure you are fitting the tube stack correctly?

Maybe this helps with the sensor identification,
12 is the sensor for the alarm ( it should have white/brown and black wiring).
11 is the sensor for the temperature gauge ( it should have light brown and black wiring)

I an surprised your C version has two-wire sensors. I thought they were only fitted to the A version, with an isolated electrical system, and which pre-dated the isolated transmissions.

View attachment 98656

Hi VicS
Are you sure you have 11 and 12 the right way around. I am under the impression the sensor in the side of the heat exchanger is part 827151 (edit: I said 873569 initially which is a combined oil and water sensor kit) which is described as a temperature sensor (120 degrees) while the one that goes in the cylinder head is a 95 degree relay switch (873598) which I thought would be the one that feeds the alarm. I could be completely wrong of course!

The parts4engines switched i referenced earlier also looks like the one that goes into the cylinder head ie. the switch version if you Google a few pics of the engine

 

[Ammonite]

I finally found a sufficiently detailed and upto date schematic and it looks like I do have the right H/E temperature sensor which you need to move to extract the tube stack on the C variant at least.

The only problem is that when you Google the part number (827151) most versions have a single wire whereas mine and the version in the diagram below have two!

https://www.volvopentashop.com/epc/...eDieselEngines/7740690/7740690_30/7740690_101

 

[VicS]

Hi VicS
Are you sure you have 11 and 12 the right way around. I am under the impression the sensor in the side of the heat exchanger is part 827151 (edit: I said 873569 initially which is a combined oil and water sensor kit) which is described as a temperature sensor (120 degrees) while the one that goes in the cylinder head is a 95 degree relay switch (873598) which I thought would be the one that feeds the alarm. I could be completely wrong of course!

The parts4engines switched i referenced earlier also looks like the one that goes into the cylinder head ie. the switch version if you Google a few pics of the engine

I snipped the diagram from here Electrical System - Volvo MD2010 Workshop Manual [Page 64] | ManualsLib

You should be able identify which is which from the wiring color code by referring to the wiring diagrams in your owners manual, where you will see that the light brown wire is the connection to the temperature gauge and the white/ brown wire is the connection to the warning light and alarm panel.
You should be able to confirm which is which by measuring their resistances. The sensor for the warning light will be open circuit when below 95C. The sensor for the gauge will have a measurable resistance which will vary with temperature

The reason why you are finding two-wire sensors is that early (A) series had an isolated electrical system because the transmission was not isolated from the engine as it is in all the later series. No reason why you should not use a two wire sensor on a later engine. It just means that one terminal will have to be grounded to the engine block

I suggest you refer to the official parts lists at Volvo Penta parts and accessories - MarinePartsEurope.com to find the correct part numbers.

 

[Ammonite]

Hi VicS
Is there anything wrong with the volvo penta store references I linked to above? This specifically relates to the C and D variants of the 2040 (see top left) and it looks like these were supplied from the factory with a two wire temperature sensor. The official part numbers are on the RHS. The link you refer to says its for the MD2010?

 

[VicS]

Hi VicS
Is there anything wrong with the volvo penta store references I linked to above? This specifically relates to the C and D variants of the 2040 (see top left) and it looks like these were supplied from the factory with a two wire temperature sensor. The official part numbers are on the RHS. The link you refer to says its for the MD2010?

The manual covers the whole range of engines from MD2010 to MD2040 and A,B and C versions. ( presumably published before the D versions came along)

The two wire sensors must be used on the A versions because it has an isolated electrical system , ie the engine block is not used for the negative return. This is because the transmission is not isolated from the engine block.
In theory it wont matter if you use a two wire sensor on a later version engine but one connection will have to be earthed to the engine block. There does, however, seem to be some variation in terminal type.

I assume you have found that your alarm sensor is faulty. If so identify the correct part number from the official parts list and order whatever parts4engines supply for that part number. If there is any discrepancy between the official parts number and parts4engines website contact them for clarification. They are I believe very knowledgeable and helpful but the part numbers and parts4engines description for the alarm sensor does seem to tally.

When you refit the sensor in the HE grease the threads so that next time you remove the tube nest the sensor will be easy to remove.