Volvo Penta Md2020 Overheating problem

[mnrkks]

Hi Guys,

I need your help. I recently bought a sailing boat which has volvo Penta Md2020. I did all below;

• Change all filters (air, oil, water filters, anti-sifon)
• Changed impeller, changed & tightened the belt.
• Acid cleaning the heat exchanger (now looks like new..)

but still, after 2 hours of motoring in 2.000 revolutions I had overheating problem... Water is exhausted correctly and no issues there (smoke and etc...) I opened all the hatches and opened the cover of the engine (the stairs) so that it can cool down. And like this I returned to the port in 1.300 revolutions without overheating issue....

So what would you suggest from all this story? I have spent quite amount of money to the mechanic but I lost my confidence because he came 4 times and did not solve the issue....

Any feedback is appreciated.

Thanks

 

[VicS]

If you are sure that the seawater flow is adequate and the heat exchanger tubes are clean, inside and out.

Test the thermostat. It should just start to open at 75C ±2C and be fully open at 87C.
( unfortunately you have to remove the HE to get the thermostat out of it on an MD2020)

IIRC some owners have found the outlet from the HE to the coolant pump can become blocked so another point to check while the HE is off.

What is you indication that the engine is overheating ......... arethe gauge and alarm both accurate or could it be an instrumentation fault ?

 

[mnrkks]

The alarm goes on with the light on the gauge.. And I am thinking that the gauge works ok because after opening all the hatches and the cover of the engine, it goes well at 13--1400 rpm. with no alarm. So I would suspect the gauge is failing.

So two things to check, thermostat and the elbow just after the HE?

 

[VicS]

The alarm goes on with the light on the gauge.. And I am thinking that the gauge works ok because after opening all the hatches and the cover of the engine, it goes well at 13--1400 rpm. with no alarm. So I would suspect the gauge is failing.

So two things to check, thermostat and the elbow just after the HE?

Yes check the water injection into the exhaust elbow. If that is restricted the seawater flow through the HE will be reduced

 

[TSB240]

How hot is the ejected water from the exhaust when the high temperature alarm occurs?

I had a similar problem, the ejected water was not so warm that you couldn't have your hand in the stream.
I had a clean heat exchanger and an unblocked elbow and a new sea water pump.

It turned out that the aluminium outlet spigot for the closed loop cooling circuit from the exhaust manifold to the water pump was nearly blocked. This was likely due to lack of rust inhibition caused by not following replacement of antifreeze every two years. Check that the hose from this spigot to the pump has not collapsed as this will give the same problem.

This resulted in poor flow to heat exchanger and insufficient heat transfer to expelled sea water at higher revs. Low revs the alarm would not sound.

 

[mnrkks]

How hot is the ejected water from the exhaust when the high temperature alarm occurs?

I had a similar problem, the ejected water was not so warm that you couldn't have your hand in the stream.
I had a clean heat exchanger and an unblocked elbow and a new sea water pump.

It turned out that the aluminium outlet spigot for the closed loop cooling circuit from the exhaust manifold to the water pump was nearly blocked. This was likely due to lack of rust inhibition caused by not following replacement of antifreeze every two years. Check that the hose from this spigot to the pump has not collapsed as this will give the same problem.

This resulted in poor flow to heat exchanger and insufficient heat transfer to expelled sea water at higher revs. Low revs the alarm would not sound.

Wow yes this could be my problem because previous owner did not maintain the engine for few years.. And when we cleaned the heat exchanger first, it was full of rubbish, calcium and etc...

I did not not check how hot is the ejected water...

Can you please show me which part exactly you are mentioning? I am pretty new to engine staff so any photo you might show or refer would be perfect Thank you

 

[Never Grumble]

have you checked the exhaust elbow?

 

[Just_sayin']

This may be useful:

Volvo Penta Marine Diesel Engines | MD2010-C;MD2020-C;MD2030-C;MD2040-C;MD2010-D;MD2020-D;MD2030-D;MD2040-D | Volvopentashop.com

 

[TSB240]

Wow yes this could be my problem because previous owner did not maintain the engine for few years.. And when we cleaned the heat exchanger first, it was full of rubbish, calcium and etc...

I did not not check how hot is the ejected water...

Can you please show me which part exactly you are mentioning? I am pretty new to engine staff so any photo you might show or refer would be perfect Thank you

I don't think I have a photo but from memory the aluminium spigot is low down on the rhs looking aft where the rubber pipe feeding the engine water pump connects to the engine manifold. On our boat you couldnt see the spigot or get a spanner and handle on it without removing the manifold.
It was blxxdy tight also.
Why do Volvo mix aluminium with cast iron?

 

[mnrkks]

have you checked the exhaust elbow?

I will check it, I am now far from my boat and this is one of the thing I will check for sure... thank you.

 

[mnrkks]

I don't think I have a photo but from memory the aluminium spigot is low down on the rhs looking aft where the rubber pipe feeding the engine water pump connects to the engine manifold. On our boat you couldnt see the spigot or get a spanner and handle on it without removing the manifold.
It was blxxdy tight also.
Why do Volvo mix aluminium with cast iron?

Thank you TSB240.

I will try to find the part you are mentioning and let me see if that is my problem. In the meanwhile I bought an IR Thermometer, maybe it will help me to find where exactly the problem is... But I suspect either thermostat or something is full of dirt in some of the tubes that coolant water circulates...

I will keep you updated, thanks a lot!

 

[TSB240]

Thank you TSB240.

I will try to find the part you are mentioning and let me see if that is my problem. In the meanwhile I bought an IR Thermometer, maybe it will help me to find where exactly the problem is... But I suspect either thermostat or something is full of dirt in some of the tubes that coolant water circulates...

I will keep you updated, thanks a lot!

If it is thermostat you have to take the manifold off to service or replace it.

You also can more easily remove the exhaust elbow complete with the manifold. This will also ensure you have good access to the tiny nuts retaining the elbow. The elbow studs tend to shear as the nuts are usually badly corroded. Job is much easier to do in a workshop vice. Use a full face socket or you will round your nuts! From memory they are an odd size af smaller 9mm? If you replace your elbow with a stainless fabrication you can fit a full size nut as there is more clearance.

You can always tell if a volvo engine has been maintained properly by a volvo tech as this elbow should be removed every two years cleaned and checked.
Mine had the original paint sealing the threads and nuts when it blew the paint off the casting after 19 years of use. Refit with copper grease on the retaining nuts and threads.

The spigot on the manifold is not shown on the 2020 or the 2010 as a seperate part but item 10 connects to it at the bottom of the heat exchanger behind and above the alternator and in front of the starter. Another great Volvo design so if you do get a slow leak it drips onto the two most essential electrical parts.

Volvo Penta 26 Cooling System | Heat Exchanger MD2020-C, MD2020-D | Volvopentashop.com

 

[Marinaio]

Hi all,
I have similar issue on my MD2020. I did all suggested check but I do not understanding where is this aluminium spigot.
Anyone could help me?
@ mnrkks did you solve the issue?

Thanks a lot
Marinaio

I don't think I have a photo but from memory the aluminium spigot is low down on the rhs looking aft where the rubber pipe feeding the engine water pump connects to the engine manifold. On our boat you couldnt see the spigot or get a spanner and handle on it without removing the manifold.
It was blxxdy tight also.
Why do Volvo mix aluminium with cast iron?

 

[Tranona]

The blocked hose he refers to is item 10 on the link and the spigot is where it attaches to the bottom of the heat exchanger. This hose takes the fresh water between the Heat exchanger and the engine water pump. If it is blocked then there is insufficient flow of cooling water into the engine and it will overheat. As he says it is difficult to see and access without removing the heat exchanger. marinepartseurope.com/en/dealer/mpe/category/marine%20diesel%20engines/product/md2020-c/explodedview/54164640?catalog=7740690&functiongroup=Cooling%20System&img=48378.png&header=Heat%20Exchanger

 

[mnrkks]

Hi all,
I have similar issue on my MD2020. I did all suggested check but I do not understanding where is this aluminium spigot.
Anyone could help me?
@ mnrkks did you solve the issue?

Thanks a lot
Marinaio

Hi Marinaio,

Let me tell you what I have done so far,

1. Sea water filter replaced with new
2. Sea water pump replaced with new
3. Thermostat replaced with new
4. Cleaned heat exchanger (Acid cleaning)
5. Cleaned heat exchanger housing
6. Exhaust elbow replaced with new
7. Exhaust water silencer replaced with Vetus LP45

Then I did a trial, and after one hour, the overheating alarm came again....

After a few months, I put a water temperature sensor and last week I did a trial again for 45 minutes and no alarm. Water temperature was between 87-88 degrees while running 2400 rpm's.

So I cant say that I totally solved it but I believe I did all what I can. Still open to any suggestions. When cleaning the heat exchanger housing I did not see any spigot... Maybe I did not pay attention... but the hose was pretty clean and housing as well..

Let me know if I can help you..

Thanks
Onur

 

[Tranona]

Just a couple of questions about waterflow. If you have a saildrive, have you checked that the intake passages in the leg are clear. If you have a conventional drive is your seawater intake 3/4" which is what the engine needs for adequate flow.

 

[mnrkks]

Just a couple of questions about waterflow. If you have a saildrive, have you checked that the intake passages in the leg are clear. If you have a conventional drive is your seawater intake 3/4" which is what the engine needs for adequate flow.

Hello Tranona, mine is conventional drive and seawater intake is 3/4".

 

[Daydream believer]

Some hoses have a fabric inner lining, or a lining of a different layer. If the lining becomes detatched from the outer covering it may collapse as negative pressure on the pipe draws it in. This may reduce flow. It might be worth checking the condition of flexible pipes

 

[tsekul]

My MD2020 has just started overheating. Trying to figure out why.

Over the winter I replaced the coolant , is it possible to get an air lock when you refill it ?

The other possible cause is I replaced the oil as usual but the supplier sent a different filter to one from previous years it looked smaller. I queried this with them and they said they had changed supplier and that it is correct for MD2020. Can the engine overheat with the wrong oil filter. I think am going to get one from a volvo dealer to compare.

I am just trying to go through what has changed since last year before I start dismantling the engine.

We don’t use the engine much,last year we only got through about 50 litres of fuel as we predominantly race.

We were motoring for about 3 hours at 2200 rpm, the wind perked up so we put her in neutral and the alarm went off. We let it cool down , checked all the levels and the impeller. It hasn’t done it since but we haven’t motored for 3 hours plus since.

I’m kind of hoping it was an obstruction on the sail drive but any thoughts greatly appreciated

T

 

[tsekul]

I There

Just a couple of questions about waterflow. If you have a saildrive, have you checked that the intake passages in the leg are clear. If you have a conventional drive is your seawater intake 3/4" which is what the engine needs for adequate flow.

how do you check the inside of a sail drive leg ? I clear the 3 holes of debris and push a long screwdriver up the hole in the bottom, there is always shell debris that falls out. I did consider putting a pressure washer down the entry hole in the water strainer, but thought better of it