Airlock Isuzu 55

[blackrose]

My calorifier isn't getting hot when I run the engine. I'm assuming it's an airlock in the cooling system, but I suppose it could be a physical blockage. The coolant reservoir pressure cap doesn't seem to activate even though when I slowly open the cap there's a lot of pressure in the reservoir - even when the engine has cooled. I also replaced the thermostat recently.

 

What's the best way of bleeding any airlock? I just ran the engine with the pressure cap removed. Should I try to bleed air out from engine hose connections to/from the calorifier while the engine is running? I bled the skin tanks so it's not that.

Edited April 8, 2023 by blackrose

[Tracy D'arth]

51 minutes ago, blackrose said:

My calorifier isn't getting hot when I run the engine. I'm assuming it's an airlock in the cooling system, but I suppose it could be a physical blockage. The coolant reservoir pressure cap doesn't seem to activate even though when I slowly open the cap there's a lot of pressure in the reservoir - even when the engine has cooled. I also replaced the thermostat recently.

 

What's the best way of bleeding any airlock? I just ran the engine with the pressure cap removed. Should I try to bleed air out from engine hose connections to/from the calorifier while the engine is running? I bled the skin tanks so it's not that.

Yes.

[blackrose]

It seems to me like the thermostat isn't opening because with the engine up to temperature the pipe from the coolant reservoir to the thermostat and the pipe below the reservoir to the port side skin tank are hot, however the pipes to the right of the thermostat to the gearbox oil cooler and starboard skin tank are stone cold.

 

I'll try running it in gear for a while...

32 minutes ago, Tracy D'arth said:

Yes.

 

Ok I'll try that next...

 

For anyone else who has a similar issue - DON'T try to bleed air by removing coolant pipes from a hot running engine. It's a BAD idea.

 

I was trying to introduce a small crack between one of the coolant pipes and engine to bleed any air when suddenly the pipe came adrift and the engine scalded me with hot antifreeze all over my chest and arm. Entirely my own fault -it's just a stupid thing to do. I've just stepped out from a cold shower. I'm ok but my arm is already blistering. Just lucky it wasn't my face!

Edited April 8, 2023 by blackrose

[Tony Brooks]

2 hours ago, blackrose said:

however the pipes to the right of the thermostat to the gearbox oil cooler and starboard skin tank are stone cold.

 

That sounds as if it is a bypass thermostat (two thermostat connection) but once hot you have found what would be expected. The return from the skin tank is far colder than the thermostat outlet to the skin tank pipe. You want cold or cool water through the oil cooler, and Beta had problems when their design fed hot water through the oil cooler - that was soon changed.

[blackrose]

Ok thanks. I need to work out what's preventing the calorifier heating up. Today's efforts were curtailed prematurely but the pain has subsided now thanks to some emergency burn gel from Boots - it's good stuff. I'll carry on trying to figure it out tomorrow. 

[Mike Adams]

I have found with this engine and my set up (with the calorifier higher than the engine) that even after the engine cools down it maintains some pressure in the system and you can bleed the calorifier from the highest point in the loop even when cold. I fitted a central heating type bleed screw. As you have probably read these engines are often subject to head gasket failure caused by over heating on skin tank cooled models so you really don’t want any air or air locked in the system or you could end up in big trouble. By squeezing the hose From the header tank to the thermostat you can help to get any air out. Make sure you have the correct thermostat installed correctly some can be put in upside down.

[ditchcrawler]

1 hour ago, Mike Adams said:

I have found with this engine and my set up (with the calorifier higher than the engine) that even after the engine cools down it maintains some pressure in the system and you can bleed the calorifier from the highest point in the loop even when cold. I fitted a central heating type bleed screw. As you have probably read these engines are often subject to head gasket failure caused by over heating on skin tank cooled models so you really don’t want any air or air locked in the system or you could end up in big trouble. By squeezing the hose From the header tank to the thermostat you can help to get any air out. Make sure you have the correct thermostat installed correctly some can be put in upside down.

Same here

[blackrose]

15 hours ago, Mike Adams said:

I have found with this engine and my set up (with the calorifier higher than the engine) that even after the engine cools down it maintains some pressure in the system and you can bleed the calorifier from the highest point in the loop even when cold. I fitted a central heating type bleed screw. As you have probably read these engines are often subject to head gasket failure caused by over heating on skin tank cooled models so you really don’t want any air or air locked in the system or you could end up in big trouble. By squeezing the hose From the header tank to the thermostat you can help to get any air out. Make sure you have the correct thermostat installed correctly some can be put in upside down.

 

Ok, I'm not quite sure how to bleed the calorifier? Mine is vertical and at about the same base level as the engine.  Since the coils inside probably extend higher than the pipes feeding the calorifier how can they be bled?

 

I'll try squeezing that header tank - thermostat hose with the engine running. I replaced the thermostat recently and it's definitely the right way up.

 

I've never had this problem before and I've owned this boat since 2005 so I'm not sure why this has happened now? I flushed the system out when I replaced the coolant last autumn so I'm wondering if I've dislodged some crud and it's causing a blockage somewhere?

 

The other thing is that if there was any overheating happening surely I'd see that on the temperature gauge? I'm not seeing that even if I push the engine hard.

 

 

Edited April 9, 2023 by blackrose

[BWM]

If any of the areas you scalded aren't painful you'll be wise to seek medical attention, as this means the burn has penetrated far enough to require looking at. 

[Mike Adams]

The calorifier should have two fittings,inlet and outlet, vertically above each other with the coil in between so the highest point is the higher of the two connections unless any pipe connecting to the engine is at a higher level so I would loosen the higher connection to release any air. I think that the temperature sensor is in the thermostat housing as shown in your picture and not on the cylinder head which means it might not be reading correctly the actual engine head temperature. I am not at the boat so I might be wrong on this there may be two switches one for the overheat warning lamp and one for the gauge sensor depending if you have a temperature gauge or not. I think it is unlikely but possible that calorifier loop is blocked but can be checked by disconnecting the engine connections and running a hose though it.

hope this helps.

 

[blackrose]

37 minutes ago, BWM said:

If any of the areas you scalded aren't painful you'll be wise to seek medical attention, as this means the burn has penetrated far enough to require looking at. 

 

Thanks. It was painful for a few hours afterwards but it's fine today, just superficial burns. 

11 minutes ago, Mike Adams said:

The calorifier should have two fittings,inlet and outlet, vertically above each other with the coil in between so the highest point is the higher of the two connections unless any pipe connecting to the engine is at a higher level so I would loosen the higher connection to release any air. I think that the temperature sensor is in the thermostat housing as shown in your picture and not on the cylinder head which means it might not be reading correctly the actual engine head temperature. I am not at the boat so I might be wrong on this there may be two switches one for the overheat warning lamp and one for the gauge sensor depending if you have a temperature gauge or not. I think it is unlikely but possible that calorifier loop is blocked but can be checked by disconnecting the engine connections and running a hose though it.

hope this helps.

 

 

Thanks. The connections to my calorifier are at the bottom of the tank which is lower than the connections to the engine. 

 

I cleaned an electrical connection near the thermostat today as it looked a bit corroded. I think it's for the temp gauge bit I'm not sure. I'm now getting hot water going to the calorifier but the odd thing is that after running the engine for an hour the water from the calorifier is just warm, not hot. Normally it would be really hot. 

[Tracy D'arth]

Give it time.  Or a duff thermostat?

[blackrose]

13 minutes ago, Tracy D'arth said:

Give it time.  Or a duff thermostat?

 

It would normally give me a full tank of hot water in half an hour. As I said above, the thermostat was replaced recently.

[Mike Adams]

Classic example of a stuck open thermostat or damaged water pump impeller. Did you use a genuine part? There is a lot of dodgy Chinese stuff out there.

[ditchcrawler]

2 hours ago, blackrose said:

 

Thanks. It was painful for a few hours afterwards but it's fine today, just superficial burns. 

 

Thanks. The connections to my calorifier are at the bottom of the tank which is lower than the connections to the engine. 

 

I cleaned an electrical connection near the thermostat today as it looked a bit corroded. I think it's for the temp gauge bit I'm not sure. I'm now getting hot water going to the calorifier but the odd thing is that after running the engine for an hour the water from the calorifier is just warm, not hot. Normally it would be really hot. 

Sounds like some of the air has moves and you have some flow going through. how hot are the pipes where they leave the engine for the calorifier?

[blackrose]

3 hours ago, Mike Adams said:

Classic example of a stuck open thermostat or damaged water pump impeller. Did you use a genuine part? There is a lot of dodgy Chinese stuff out there.

 

No I didn't. I found an equivalent thermostat (dimensions & temp). I think I'll take the thermostat out and run it again and see what happens.

 

Next weekend... I'm not in any hurry to fix it.

 

2 hours ago, ditchcrawler said:

Sounds like some of the air has moves and you have some flow going through. how hot are the pipes where they leave the engine for the calorifier?

 

Pretty hot, as was the antifreeze that shot out of that port all over me yesterday! 🤣

 

Edited April 9, 2023 by blackrose

[Tracy D'arth]

I would guess that the flow from the engine top connection is going to the top connection on the calorifier.

 

This makes it much more difficult to bleed the air out, as you are trying to force water down into the trapped air which is trying to rise.

Remember the engine does not have a positive displacement pump but a circulator.

 

Connect the flow to the bottom connection and the air will rise to the top of the coil and be pushed back to the engine.

[blackrose]

As the connections to the calorifier are right at the bottom I always imagined the coil would extend up vertically or up at an angle into the calorifier, in which case how could it ever be bled?

 

Or doesn't it go up into the calorifier?

Edited April 10, 2023 by blackrose

[ditchcrawler]

56 minutes ago, blackrose said:

As the connections to the calorifier are right at the bottom I always imagined the coil would extend up vertically or up at an angle into the calorifier, in which case how could it ever be bled?

 

Or doesn't it go up into the calorifier?

 

56 minutes ago, blackrose said:

As the connections to the calorifier are right at the bottom I always imagined the coil would extend up vertically or up at an angle into the calorifier, in which case how could it ever be bled?

 

Or doesn't it go up into the calorifier?

Round in a loop

[Tracy D'arth]

No, its an horizontal coil between the 2 connections so it bleeds from the top connection.  We are talking vertical calorifier.

Horizontal are the same really, the coil is a big loop which is why it is vital to orientate properly

[Mike Adams]

On 09/04/2023 at 18:36, blackrose said:

No I didn't. I found an equivalent thermostat (dimensions & temp). I think I'll take the thermostat out and run it again and see what happens.

If you run it without a thermostat nothing will get hot. If you are going to take the current one out just bung in a new one whilst you  are at it. For some reason the thermostats for the 4LE1 are very expensive which makes me think they are slightly different. Try contacting Engines Plus who still supply the industrial version of the engine. I have attached the page of the manual in case you don't have it

[blackrose]

On 10/04/2023 at 17:09, ditchcrawler said:

 

Round in a loop

 

Yes I know the coil runs around in a loop. My question was what direction or orientation that loop runs.

On 10/04/2023 at 17:10, Tracy D'arth said:

No, its an horizontal coil between the 2 connections so it bleeds from the top connection.  We are talking vertical calorifier.

Horizontal are the same really, the coil is a big loop which is why it is vital to orientate properly

 

Ok thanks.

21 hours ago, Mike Adams said:

If you run it without a thermostat nothing will get hot. If you are going to take the current one out just bung in a new one whilst you  are at it. For some reason the thermostats for the 4LE1 are very expensive which makes me think they are slightly different. Try contacting Engines Plus who still supply the industrial version of the engine. I have attached the page of the manual in case you don't have it

 

Thanks I do have an engine manual but I'm not sure I've seen that page.

 

You're telling me they're expensive, I think I had a quote of around 90 quid last time I looked which is why I found the alternative one - same temp and dimensions. A boat engineer who works around here seemed to think it would be fine.

 

Nothing will get hot without a thermostat? So where would the engine combustion heat go? My knowledge of diesel engines is limited but I thought the thermostat allowed the engine to heat up quickly by restricting coolant flow to local parts of the cooling system around the engine. Once that was all up to temp then the thermostat opened and dissipated heat to the rest of the cooling system?

 

So surely eventually the whole system would heat up without a thermostat? If so then wouldn't that tell me if my thermostat was working in the engine and whether there is an airlock or blockage in the cooling system? I'll also test the thermostat with hot water in a cup while it's out.

Edited April 11, 2023 by blackrose

[Mike Adams]

I have a spare engine and will have a look at its thermostat and the weekend but I have a feeling it different to a standard automotive one in that it seals in two places.
The cooling system (skin tank)is designed to dissipate at least the maximum waste energy of the engine which is approximately equal to the power output of the engine 40kw. At say tickover  the skin tank will take all the waste heat away as it is produced and the engine should only get slightly warm and it will maintain this equilibrium indefinitely. It is extremely important to have the correct thermostat on a modern engine as it is designed both to reach and maintain the correct temperature and maintain thermal balance across the engine and avoid any thermal stress. Running without a thermostat in my opinion could cause head gasket failure and worse. Do you still have the old thermostat ? if so check if it has a rubber ring seal at the base.

 

[blackrose]

Yes I've still got the old thermostat. From memory there was no rubber ring seal, but I'll check it again as soon as I can.

[Mike Adams]

Just one thing I forgot to mention and that is there were 2 different versions of the engine and I believe HMI may have used both one is the 4LE1 and the other 4LE2 ,one is direct injection and the other is indirect and although the same capacity use different cylinder heads and May use a different thermostat.