Heat exchanger repair

[rogerthebodger]

you can also spray the joints you are testing with water to see where the leak is Just like looking for a leak in a car type.

I also do the same with leaking fenders for repair

 

[MagicalArmchair]

Thanks both. I pressurised it up, and the only bit air is escaping is from my Heath Robinson pressure testing affair. Air is getting down the reinforcement of the water hoses I think where one is 'nested' in the other.

I sprayed the rest of the exchanger with water and no air is escaping anywhere else.

Any tips on how I can make this more 'air' tight? Or do I just fit and go?

 

[Bobc]

Thanks both. I pressurised it up, and the only bit air is escaping is from my Heath Robinson pressure testing affair. Air is getting down the reinforcement of the water hoses I think where one is 'nested' in the other.

I sprayed the rest of the exchanger with water and no air is escaping anywhere else.

Any tips on how I can make this more 'air' tight? Or do I just fit and go?

I would say that if you can't see or hear any air escaping elsewhere, then you're probably good to go. You've been very thorough and not bodged anything together, so can't see that there should be a problem.

 

[MagicalArmchair]

Nope, it looks (sounds?) good.

For filling the coolant once its all back together, any tips for this to prevent air locks? (first indirectly cooled boat!) Pour in v slowly?

 

[Bobc]

Nope, it looks (sounds?) good.

For filling the coolant once its all back together, any tips for this to prevent air locks? (first indirectly cooled boat!) Pour in v slowly?

Your biggest potential for an air lock is at the calorifier. Fill the coolant tank, start her up, and then loosen the clamp from the top coolant pipe at the calorifier. You should hear air escaping. Continue to bleed here until there is no more air.

 

[dankilb]

For filling the coolant once its all back together, any tips for this to prevent air locks? (first indirectly cooled boat!) Pour in v slowly?

In addition to the calorifier... just expect it to need a bit of 'burping' (the level will drop as it heats, thermostat opens, air is purged, etc.). I don't know whether this would work on the Volvo (it certainly does on the Beta and stops it needing to 'puke' as much into a separate bottle or the bilges...) - it basically allows you to fill above the level of the tank and add a bit of extra 'head' while purging:
LISLE Spill Free (burp) Funnel Radiator Cooling Coolant Fluid System P/N:24680 5056044329770 | eBay

These are great on car engines when re-filling the entire system. Or you can fashion your own from a water bottle, using some amalgamating tape or such to seal to the filler, and even a basic 'plug' for the bottle so that - if it's still full once the system has purged - you can remove the remainder without it spilling everywhere!

 

[MagicalArmchair]

Thank you, any way of knowing all air is purged from the system? I do have a header tank, so hopefully that will drive air out of the system too.

 

[dankilb]

Thank you, any way of knowing all air is purged from the system? I do have a header tank, so hopefully that will drive air out of the system too.

Coolant level and engine temp ‘stable’ for, say, 10-15 minutes under load?

Didn’t realise there’s a header tank... ?? That should help a lot and circumvent the need for a bottle/funnel arrangement to add to the ‘head’ (which helps on the Betas, as they only need a tank if part of the system is above the level of the top of the engine).

 

[MagicalArmchair]

Coolant level and engine temp ‘stable’ for, say, 10-15 minutes under load?

Didn’t realise there’s a header tank... ?? That should help a lot and circumvent the need for a bottle/funnel arrangement to add to the ‘head’ (which helps on the Betas, as they only need a tank if part of the system is above the level of the top of the engine).

Alas the VP control panel I have doesn't have a gauge - all I have is the below. I guess with the header tank, its make sure that doesn't drop, top up if it does, and run the engine out of gear for an hour and make sure the alarm doesn't come on?

 

[PaulRainbow]

Alas the VP control panel I have doesn't have a gauge - all I have is the below. I guess with the header tank, its make sure that doesn't drop, top up if it does, and run the engine out of gear for an hour and make sure the alarm doesn't come on?

You run the engine in gear, so it's under load. No need to run it for an hour.

 

[rogerthebodger]

Alas the VP control panel I have doesn't have a gauge - all I have is the below. I guess with the header tank, its make sure that doesn't drop, top up if it does, and run the engine out of gear for an hour and make sure the alarm doesn't come on?

I use the non contact thermometer that is used these days to check your temperature for covid 19 testing.

using that you can check for hotspots around the engine and exhaust,

 

[MagicalArmchair]

You run the engine in gear, so it's under load. No need to run it for an hour.

Thanks Paul, how long is sufficient?

I use the non contact thermometer that is used these days to check your temperature for covid 19 testing.

using that you can check for hotspots around the engine and exhaust,

I do have one of those. What temperature should I start to worry about? The issue being the non contact thermometer will only measure the external temperature, which will be far less than the internal and dependant on the casting where the measurement is taken? Or am I just overthinking this and I should just fill it up nice and slowly, make sure the levels don't drop and the alarm doesn't go off and move on with my life?

 

[rogerthebodger]

I do have one of those. What temperature should I start to worry about? The issue being the non contact thermometer will only measure the external temperature, which will be far less than the internal and dependant on the casting where the measurement is taken? Or am I just overthinking this and I should just fill it up nice and slowly, make sure the levels don't drop and the alarm doesn't go off and move on with my life?

I generally fill up and run the engine for a while (half an hour) until the level stops dropping.

Unless the is any insulation on the metal parts of the engine that you are taking the temperature then outside surface temperature should not be too different from the water inside.

When I measure the temperature on he head close to the thermostat housing I get close to the thermostat setting once warmed up

 

[PaulRainbow]

Thanks Paul, how long is sufficient?

Once the thermostat is open and the calorifier is warming the water up, 10 minutes should be fine..

 

[dankilb]

Or am I just overthinking this and I should just fill it up nice and slowly, make sure the levels don't drop and the alarm doesn't go off and move on with my life?

Basically, yes! But you’re also running for the first time after a major-ish repair to that part of the system. And seeing as you have the thermometer already - no harm in closely monitoring it.

If nothing else, you’ll get a very good impression of how the system behaves during/after refilling. If it ever spews through a split hose or some such at sea, you’ll be confident in recommissioning it.

In reality, ‘modern’ water pumps - as of last 30 years or so - seem pretty efficient and will normally sort themselves out in terms of purging any air.

 

[PaulRainbow]

Basically, yes! But you’re also running for the first time after a major-ish repair to that part of the system. And seeing as you have the thermometer already - no harm in closely monitoring it.

If nothing else, you’ll get a very good impression of how the system behaves during/after refilling. If it ever spews through a split hose or some such at sea, you’ll be confident in recommissioning it.

In reality, ‘modern’ water pumps - as of last 30 years or so - seem pretty efficient and will normally sort themselves out in terms of purging any air.

That's very true Dan. I look after several of those small D-xx engines like the OPs and when i change the coolant during a servic, they all purge the air with no issues. Just start them up, keep them topped up, run until up to running temp, in gear, then another 10 mins.

 

[jwfrary]

That's very true Dan. I look after several of those small D-xx engines like the OPs and when i change the coolant during a servic, they all purge the air with no issues. Just start them up, keep them topped up, run until up to running temp, in gear, then another 10 mins.

agree totally. These small engines are usually pretty good. Except if the callorifier is a bit far away or piped with lots of air pockerlt potential as others have said.

it’s the water cooled turbos that usually give issues on the larger units and the heater matrix in cars.