Volvo MD 2020 D Overheating

[steveej]

Morning all,

My engine on the new to me boat is overheating.

I fired it up on Saturday and noticed no water coming out the exhaust. Turned it off and checked the impeller on the raw water pump and surprise surprise all the blades had disintegrated. I emptied the broken black bits from the lower hose but not the upper hose that leads to the heat exchanger and I have a feeling there may still be some there.

After sticking a new impeller in I went for a sail and had no problem leaving the marina under motor. However, a few hours later I fired up the engine whilst at sea and almost immediately the engine overheat alarm came on. There was now a mug full of coolant in the engine bay that was steaming hot and a bit of smoke came out when I opened up the engine cover.

I was sailing at the time so there was a slight heel but I don't believe this was an issue and the intake is in the centre of the boat.

I sailed all the way back to the marina entrance and fired up the engine once again and maneuvered to the berth under tick over (no alarm went off but I was careful to not put any revs on).

It was then dark and I needed to leave for home so no further investigations were carried out and I am now trying to work out what has gone wrong.

Could it be that some remnants of the old impellar have travelled up to the heat exchanger and are blocking it?

Could it be anything to do with me accidentally opening the calorifier drain valve and emptying the entire contents into the bilge the week before? I thought that was a separate system.

Anything else?

 

[Heckler]

Morning all,

My engine on the new to me boat is overheating.

I fired it up on Saturday and noticed no water coming out the exhaust. Turned it off and checked the impeller on the raw water pump and surprise surprise all the blades had disintegrated. I emptied the broken black bits from the lower hose but not the upper hose that leads to the heat exchanger and I have a feeling there may still be some there.

After sticking a new impeller in I went for a sail and had no problem leaving the marina under motor. However, a few hours later I fired up the engine whilst at sea and almost immediately the engine overheat alarm came on. There was now a mug full of coolant in the engine bay that was steaming hot and a bit of smoke came out when I opened up the engine cover.

I was sailing at the time so there was a slight heel but I don't believe this was an issue and the intake is in the centre of the boat.

I sailed all the way back to the marina entrance and fired up the engine once again and maneuvered to the berth under tick over (no alarm went off but I was careful to not put any revs on).

It was then dark and I needed to leave for home so no further investigations were carried out and I am now trying to work out what has gone wrong.

Could it be that some remnants of the old impellar have travelled up to the heat exchanger and are blocking it?

Could it be anything to do with me accidentally opening the calorifier drain valve and emptying the entire contents into the bilge the week before? I thought that was a separate system.

Anything else?

The calorifier drain valve? There is a good possibility you have emptied your engine of fresh water coolant!
The engine coolant goes to the calorifier to warm it up!

The bits from the impellor, whilst important to remove from the end of the heat exchanger, would not usually be sufficient to overheat the engine. To remove them, undo the two rubber top hat clips and remove the top hat. Make sure you get them back on in the corrct position otherwise you will mix fresh and salt water.

 

[steveej]

The calorifier drain valve? There is a good possibility you have emptied your engine of fresh water coolant!

The coolant is green and the water in the bilge was definitely clear and fresh and tasted like tap water to me.

 

[steveej]

It was the red handled ball valve I opened which as far as I am aware is a calorifier drain valve though I am now not sure whether this drains the water that is in the coil or whether it drains the tank. Given the water in the bilge I believed it was the tank that was drained because it was clear and tasted fresh.

We also have hot water from shore power so I think the tank / calorifier must be full.

 

[wiggy]

I would hazard a guess that the tap empties the tank not the engine cooling system.

 

[steveej]

I would hazard a guess that the tap empties the tank not the engine cooling system.

That would make sense to me as a way of emptying the tank to stop it freezing in winter.

 

[XDC]

We literally lost an impeller blade. For a while.

Noticed water flow not as normal. Checked impeller. One blade missing. Took off rubber boot mounted to heat exchanger. Couldn’t see anything. Assumed it had flushed through. Reassembled. Flow marginally better in my mind but still just “not right”.

Looking at Volvo diagrams realised a blade couldn’t flush through the stack pipes/heat exchanger (I was working from the aft of the engine looking into the boot not back at the stack pipe).

Took boot off again and there was a black rubber blade in a black rubber boot. Just didn’t see it first time.

Took the blade out and never had a problem since.

I think that RTFM applies here for me, or at least in this case look at the exploded diagram.

How many blades did you find?

If you’ve dumped engine coolant my assessment is not enough salt/cooling water is going through the stack pipes/heat exchanger so inevitably your engine is overheating.

Find all the blades sitting between the saltwater pump and exchanger parts 2 and 3 here

https://www.marinepartseurope.com/en/volvo-penta-explodedview-7740690-26-4159.aspx

 

[TSB240]

I think you are possibly treating a symptom and not diagnosing the problem.

What caused the old impeller to disintegrate?
How old was it?
Was it starved of water?
I would look for a solution to this first especially as this should not have happened even if you had drained the engine coolant.
I would want to check you are getting a good inflow through your seacock. If you have a saildrive check for musssels growing inside the leg and that the leg is clear of growth especially tube worm possibly blocking off the flow into the leg.

Even having replaced the impeller you have flow of sea water for cooling but still have overheating?

I had this problem on our 2010 with loss of coolant despite good flow with the sea water in the exhaust. The water in the exhaust was not warm even when alarm went off.
This pointed to a blocked heat exchanger.

No blockage found in heat exchanger....

Eventually I found a blocked spigot connecting the water circulation pipe to heat exchanger from the engine circulation pump.

Good Luck...

Steve

 

[RichardS]

What is the output from the exhaust with the new impeller fitted and how hot does the water coming out feel? If you have a limited output and/or the water is more than lukewarm it would point to a blockage somewhere.

Richard

 

[steveej]

I think you are possibly treating a symptom and not diagnosing the problem.

What caused the old impeller to disintegrate?
How old was it?
Was it starved of water?
I would look for a solution to this first especially as this should not have happened even if you had drained the engine coolant.
I would want to check you are getting a good inflow through your seacock. If you have a saildrive check for musssels growing inside the leg and that the leg is clear of growth especially tube worm possibly blocking off the flow into the leg.

Even having replaced the impeller you have flow of sea water for cooling but still have overheating?

I had this problem on our 2010 with loss of coolant despite good flow with the sea water in the exhaust. The water in the exhaust was not warm even when alarm went off.
This pointed to a blocked heat exchanger.

No blockage found in heat exchanger....

Eventually I found a blocked spigot connecting the water circulation pipe to heat exchanger from the engine circulation pump.

Good Luck...

Steve

Quite possibly......

It is a new to me boat that although in great general condition appears to have been lacking some basic maintenance.

One of the difficulties is that I have not managed to assess what is normal, and what is not normal as I bought the boat in February, it had 3 weeks on the hard sorting the seacocks and lifting keel and is now back in the water where I have had a chance to do a few short sails and so my attention has now turned to engine and rig.

I have discounted the calorifier drain as that just doesnt make any sense.

I think it might be something as simple as bits of the old impeller getting sucked up to the heat exchanger and then the coolant super heating, expanding and bleeding out.

Saturday is the start of our week long easter holiday so I think it's going to be a case of send them off the Plymouth aquarium whilst I hopefully fix the problem.

I have plenty of spare coolant and a new impellor ordered, so fingers crossed it is just a blockage at the heat exchanger.

 

[steveej]

Ok, so latest developments...…..

Got to the boat and took off the forward boot of the heat exchanger and there were a couple of bits of impeller still in there so removed them. The coolant seemed a bit gunky around the heat exchanger and could probably do with a clean.

Sailed from Plymouth to Newton Ferrers no problem. On the way back, motoring, engine appears fine but when we got back there was lots of sea water in the bilge. Turns out, the water trap has cracked and is spewing exhaust salt water (and exhaust fumes) into the transmission/prop shaft area.

Luckily managed to source a replacement and am now confident that it is now fixed. I checked it every so often from Plymouth to Fowey and back circa 40 miles and all under engine over easter bank holiday circa 40 NM at 2,200 revs.

Some water coming in from volvo seal so I am going to try an get some grease in that next weekend.

However, main concern now is that when I pull the engine T-Bar stop lever, the alarm does not come on! Now, when I sorted the boot and bits of imellar and filled back up with coolant, when I turned it on it still showed the temp guage warning light so I pushed the alarm test switch down. the light and alarm both went off.

The alarm now seems to have stopped working altogether! Have I done something with the switch? as it needs to be raised every time to warm up the glow plugs to start the engine and that's all ok, or is this corrosion from the water trap spraying some of the electrics with exhaust salt water?

Why has the alarm stopped when pulling out the T-Bar before turning off the electrics, and does this mean the engine overheat alarm is knackered and therefore I haven't actually fitted my overheat problem?

Monday was a nice day when the only thing I fixed was the toilet seat hinges!

Help.