D1-30 still overheating - try without thermostat?

[jlavery]

Hi all,
My D1-30 overheating problems continue.

Initially was only after an hour or 2 of 2200rpm, but occurred today at manoeuvering revs after about an hour of operation. The engine felt very hot to the touch, so don't think it's a dodgy sensor (but this is subjective).

Getting good sea water flow, so that's not the problem.

Have cleaned the heat exchanger core.

Have tested the thermostat in a pan of water and seems to work - opened at just below boiling.

Have checked fresh water bleed pipe and it's clear.

Have elevated reservoir to help bleed any air out of fresh water side.

Am getting hot water in calorifier, so think flow around fresh circuit is OK.

I wonder if the thermostat is in fact sticking - is it worth trying running the engine without the thermostat to remove that from the equation?

 

[DownWest]

Put the thermostat in a pan of water and it heat it on the stove. Should open at 80°C or so. They usually do or don't.

I find one of those B&Q heat sensor 'guns' quite handy when checking temps.

 

[jlavery]

Put the thermostat in a pan of water and it heat it on the stove. Should open at 80°C or so. They usually do or don't.

I find one of those B&Q heat sensor 'guns' quite handy when checking temps.

Thanks - have done that and it opened. But still have my suspicions!

 

[bobgarrett]

Is the engine vented i.e. a fan to draw air through the compartment? Has the fan failed and the environment very hot?

 

[jlavery]

Is the engine vented i.e. a fan to draw air through the compartment? Has the fan failed and the environment very hot?

No, no vent or fan. 1989 Sweden 36 with no fan or vent as part of design.

 

[westernman]

Is the sea water exiting warm?

The fact that the calorifier is heating the domestic water, points to the fact that that particular heat exchanger is working!

It all points to a heat exchanger issue. Is it connected up right? Some times there are two possible input connections and two possible output connections.
Any chance you have connected input to input or output to output??

Looks like no heat being exchanged.
I suspect that the sea water coming out is the same temperature as that which when in.

 

[jlavery]

Is the sea water exiting warm?

The fact that the calorifier is heating the domestic water, points to the fact that that particular heat exchanger is working!

It all points to a heat exchanger issue. Is it connected up right? Some times there are two possible input connections and two possible output connections.
Any chance you have connected input to input or output to output??

Looks like no heat being exchanged.
I suspect that the sea water coming out is the same temperature as that which when in.

When alarm came on, checking shortly afterwards showed the seawater was slightly warm. Not as warm as I'd expect.

No way to connect HE incorrectly, due to design. Good suggestion though!

My feeling is that, as you say, the HE is not Exchanging the Heat! Hence my thought that the thermostat isn't opening and allowing the fresh water through it.

 

[westernman]

When alarm came on, checking shortly afterwards showed the seawater was slightly warm. Not as warm as I'd expect.

No way to connect HE incorrectly, due to design. Good suggestion though!

My feeling is that, as you say, the HE is not Exchanging the Heat! Hence my thought that the thermostat isn't opening and allowing the fresh water through it.

Is the engine hot water circulating through the heat exchange and not just the calorifier. May be some value somewhere deep down in the bowels and out of sight? Or a hose is quashed, or blocked??

 

[sawduster]

I changed the coolant on my D1-30 earlier in the year as we had no history of when it was last done by the previous owner. It took four flushes to get the rusty silt and sludge to come out before we re-filled with coolant. Doing a freshwater flush along with something like Rydlyme may help.

Also if you have access to a laser thermometer or a thermal imaging camera that might help to pinpoint hot and cold spots in the engine.

 

[jlavery]

Is the engine hot water circulating through the heat exchange and not just the calorifier. May be some value somewhere deep down in the bowels and out of sight? Or a hose is quashed, or blocked??

The calorifier is plumbed in inline with the fresh water side, so can't be taking flow away from HE. So thinking either something in bowels or thermostat.

 

[jlavery]

I changed the coolant on my D1-30 earlier in the year as we had no history of when it was last done by the previous owner. It took four flushes to get the rusty silt and sludge to come out before we re-filled with coolant. Doing a freshwater flush along with something like Rydlyme may help.

Also if you have access to a laser thermometer or a thermal imaging camera that might help to pinpoint hot and cold spots in the engine.

Fresh water side is clean, thanks for suggestion though. Don't have access to thermal imaging.

 

[jlavery]

Workshop manual lists stuff I've investigated as causes, and also "incorrectly set injection advance in the injection pump".

Need to pursue this avenue too, I think. Hopefully got an engineer coming to boat tomorrow

 

[foxinsox8]

Workshop manual lists stuff I've investigated as causes, and also "incorrectly set injection advance in the injection pump".

Need to pursue this avenue too, I think. Hopefully got an engineer coming to boat tomorrow

Any joy?

 

[jlavery]

Very knowledgeable marine engineer friend has got back to me.

If starting and otherwise running OK , then advance timing won't be the cause.

He's checked the HE and thermostat design on the D1-30. Crucially, the thermostat, when fully open the thermostat shuts a coolant bypass while opening the HE. So removing the thermostat wouldn't have helped - the bypass would also be open. This also means that a partially open thermostat would leave the bypass open - meaning no or negligible coolant flow through HE. This would be in line with my observation that the raw water is cold or only just warm when engine is up to/over temperature. Jamming the thermostat fully open would be one way to test.

I've got a new thermostat (as well as coolant pump) being delivered, should be here in Mallaig Wednesday.

Meanwhile managed to get to Isle Ornsay, Inverie and Rum with minimal engine use last week. And good walking/running nearby to entertain us so not a complete spoiler. Would be good to have it sorted though.

 

[jlavery]

Engine finally fixed.

Looks like it was air in the system. Exacerbated by potentially marginal design where the expansion tank isn't higher than the highest point in the heat exchanger, the pipe for the calorifier being lead over the top of the engine, and maybe the water heater pipe also being larger diameter than it needs to be, so robbing coolant from the heat exchanger.

Actions to rectify:
1. Remount expansion tank higher (I may be able to put back in designed location now I've got all air out of the system)
2. Re-route water heater pipe to be lower
3. Add valve to the water heater pipe so we can reduce its flow rate
4. Carefully bleed the system

After a day of changing things and then running engine with 10 minute observations using a borrowed laser thermometer, it's finally fixed!

I'm on 1st name terms with the Mallaig petrol station owner, the chandlery owner, the laundry lady, the boatyard staff and many more, who have all helped me.

A slab of beer and biscuits have been delivered to Mallaig Boatyard - they lent me their laser thermometer and also refused any payment for the bits they gave me to fit the valve. Absolute stars. Apart from continually calling my D1-30 a "wee little engine" - you'll understand if you look at their website and normal projects!

Other findings:
1. On a D1-30, removing the thermostat does not work. The thermostat is designed to shut off a coolant heat exchanger bypass as it opens, so removing the thermostat may open the passage to the heat exchange, but also leaves the bypass open. If you want to run "without" a thermostat, insert one which has been wired open. This is what I did, by removing the spring, and then wiring it fully open.

2. A laser thermometer is very useful if not vital when diagnosing cooling problems. I would not have been able to properly monitor the effects (or not) of my changes without it.

 

[pretzelpie]

I am experiencing the exact same issue as you are on the exact same engine. Engine had 20 hours when we bought the boat, we put on 80 hours delivering the boat, and all of a sudden on the last leg of the trip it started to overheat over 2200 rpm. Changed impeller, changed thermostat was not opening all the way, but the problem still persists. I think as you mention its a air in the coolant. I do have water heater and it is higher than expension tank. Any suggestion how to bleed this system is appreciated?

 

[jlavery]

Try unclipped expansion tank, taking lid off, and running engine. Then lift tank so it's above the engine and calorifier.

I found that this allowed air to rise above everything and bleed out of the reservoir.

However, depending on the layout of the calorifier and pipes, this may not be enough. If there are pipe loops with high points, you may still get air trapped - maybe put a bleeding valve at high points?

 

[Thresher]

I am experiencing the exact same issue as you are on the exact same engine. Engine had 20 hours when we bought the boat, we put on 80 hours delivering the boat, and all of a sudden on the last leg of the trip it started to overheat over 2200 rpm. Changed impeller, changed thermostat was not opening all the way, but the problem still persists. I think as you mention its a air in the coolant. I do have water heater and it is higher than expension tank. Any suggestion how to bleed this system is appreciated?

I had the expansion tank on my new D1-13 raised after 12 months of intermittent problems. I found that motorsailing on a port tack will definitely make it overheat, motorsailing on a starboard tack will definitely clear the overheat and on the flat, anything could happen. Try that and you will know whether you need to raise the tank.

 

[jlavery]

I had the expansion tank on my new D1-13 raised after 12 months of intermittent problems. I found that motorsailing on a port tack will definitely make it overheat, motorsailing on a starboard tack will definitely clear the overheat and on the flat, anything could happen. Try that and you will know whether you need to raise the tank.

Good point - I'm definitely raising the expansion tank on Arpeggio this winter.

I put together a blog page about my investigations here, which people might find useful. I think I've got the permissions correct on the page so that it's publicly readable!

 

[jamie N]

Great report, with a good outcome.