Overheating Engine (?) - where does coolant go, and what is our cooling system?

[Thomas C King]

We have recently found our engine getting rather hot (~100C) and the engine room rather steamy, which has caused coolant to splutter into the bilge, on account of a box with coolant missing a cap (no longer missing). The boat has a Mitsubishi K4E 33hp diesel engine and we are running it whilst moored but in reverse gear. There are two concerns:

 

1) Of three possible places to put coolant, we don't know the right one. In the images below, does anyone know what the boxes on the right and left in the third image do? They both seem connected to the cooling system, and coolant spluttered out of the rather hot box on the right. Secondly, should coolant instead go into the bit of the engine that looks like the typical place coolant goes into? (first image)

2) What could be causing the engine to get this hot and should we be worried? We are in shallow water (hull hits the bottom when boats whizz past). I am unsure how the water cooling on this boat works, but in the second image there is a pipe going into the bottom of the hull and another to the side, both seem to be part of the cooling system. Am I right in thinking that there is an external skin tank? If so, how can I check that the skin tank is doing its job and how can I release, for example, trapped air (if that's the problem)?

 

Quite a few questions, so any illumination is much appreciated

[Tracy D'arth]

Cooling water goes in the radiator cap [ with ears] on the exhaust manifold cum expansion tank which should have a pipe connected to the brass fitting below the cap to an auxiliary expansion bottle situated higher than the engine.

The stainless tank on the left of pic 3 is an expansion and fill tank foe a heating system, you have radiators?

The plastic tank is another expansion tank which may be the one that should be connected to the brass fitting mentioned above.

 

Moored on silt it is possible that it is restricting the flow of cold canal water over the outside of the skin tank. Does the engine overheat when you are on the move?

TD'

[Thomas C King]

2 minutes ago, Tracy D'arth said:

Cooling water goes in the radiator cap [ with ears] on the exhaust manifold cum expansion tank which should have a pipe connected to the brass fitting below the cap to an auxiliary expansion bottle situated higher than the engine.

The stainless tank on the left of pic 3 is an expansion and fill tank foe a heating system, you have radiators?

The plastic tank is another expansion tank which may be the one that should be connected to the brass fitting mentioned above.

 

Moored on silt it is possible that it is restricting the flow of cold canal water over the outside of the skin tank. Does the engine overheat when you are on the move?

TD'

One radiator, in the bathroom, but we've not tried to get it working yet. Thank you that helps a lot, I will try and determine if the plastic tank on the right is the right one (which we have suspected that it is). We have moved a bit and didn't seem to experience problems, but perhaps we have only just noticed now that we are stationary, we'll need to test things a bit more.

[Graham Davis]

24 minutes ago, Thomas C King said:

We have recently found our engine getting rather hot (~100C) and the engine room rather steamy, which has caused coolant to splutter into the bilge, on account of a box with coolant missing a cap (no longer missing). The boat has a Mitsubishi K4E 33hp diesel engine and we are running it whilst moored but in reverse gear. There are two concerns:

Please do NOT do this. It does nothing for your boat and potentially damages the canal.

[matty40s]

The problem with your engine bay installation from what I can make out from the photos, is that the battery bank has been built over your skin tank. The most common overheating issue on boats that have not been used for a  while is air in the skin tank causing the coolant to be expelled as the air bubble heats up and expands.

On the top of the skin tank will be a bleed valve,  a nut, or a tap, or an allen key plug. Find this and open carefully when engine runs, and you will be able to expel the air.

Edited July 7, 2020 by matty40s

[blackrose]

7 hours ago, matty40s said:

The problem with your engine bay installation from what I can make out from the photos, is that the battery bank has been built over your skin tank. 

 

You're obviously seeing something in those pictures which I can't, but I'm just looking at them on my phone.

 

Assuming it's a conventional curved skin tank built along one side of the swim what would be the problem with batteries located over the skin tank anyway - apart from the possibility of heating the batteries up? From an engine cooling perspective the vast majority of heat transfer from a skin tank is to the water on the outside of the hull, not to the air in the engine space so it doesn't really matter if you place anything over the tank.

[Martin Nicholas]

8 hours ago, Graham Davis said:

Please do NOT do this. It does nothing for your boat and potentially damages the canal.

...and is against the General Canal Bye-Laws:

 

Quote

 

38.
No person shall unless so authorised by the Board turn or cause
to be turned the propeller or propellers of any vessel while such
vessel is moored alongside any wharf, wall, bank or other work of
the Board except as may be necessary for the proper navigation

of the vessel.

 

 

[WotEver]

1 hour ago, blackrose said:

what would be the problem with batteries located over the skin tank

I believe that Matty is suggesting that the battery box is obscuring the bleed screw. 
 

Edited July 8, 2020 by WotEver
Wrong name

[Tony Brooks]

2 hours ago, blackrose said:

 

You're obviously seeing something in those pictures which I can't, but I'm just looking at them on my phone.

 

Assuming it's a conventional curved skin tank built along one side of the swim what would be the problem with batteries located over the skin tank anyway - apart from the possibility of heating the batteries up? From an engine cooling perspective the vast majority of heat transfer from a skin tank is to the water on the outside of the hull, not to the air in the engine space so it doesn't really matter if you place anything over the tank.

If the base of the battery "box" covers or hides the skin tank bleed points you will not be able to access them to bleed it - or even know they arr there.

 

 

More points;

 

In my view  Tracy was a bit dogmatic because he really has no idea exactly how the system is plumbed. The brass fitting on the filler neck looks like a blanking plug to me and if so it implies at some time in the past or present the pressure cap was faulty AND/OR there is another expansion tank with its own overflow. I suspect it may be that plastic one but as its inside the accommodation by the look of it that seems very odd. An expansion tank of coolant can be fed from any point in the cooling system pipe work but into the highest point is often best/ I suspect that plastic tank has its feed into the bottom. We cant see from the photos.

 

I also think that the skin tank may be a bit small with off pipework but again I can't see enough.

 

I think the OP would do well to trace all the cooling pipes and draw out what he has, then we may be better able to give help. Definitely try to bleed the skin tank if it has bleed points.

 

Edited July 8, 2020 by Tony Brooks

[Jen-in-Wellies]

I don't think there is enough information yet to determine what the open topped aluminium tank, or the plastic pressurised expansion tank are, or were for. Either could at one time have been part of a central heating system. As @Tony Brooks says, that it appears to be in the accommodation cabin isn't usual if it is for the engine. Some pipework tracing and more photos from different angles and taking in more of the engine bay would help.

Jen

[blackrose]

22 minutes ago, WotEver said:

I believe that Tony is suggesting that the battery box is obscuring the bleed screw. 

I was originally responding to Matty's post, not Tony's. I guess the question might be, is it just obscuring the bleed screw in the pictures or obstructing a small spanner from accessing it?

17 minutes ago, Tony Brooks said:

If the base of the battery "box" covers or hides the skin tank bleed points you will not be able to access them to bleed it - or even know they arr there.

 

 

"If"

 

There may be a difference in what we can see from a badly taken picture and what is actually accessible. 

Edited July 8, 2020 by blackrose

[Tony Brooks]

13 minutes ago, blackrose said:

I was originally responding to Matty's post, not Tony's. I guess the question might be, is it just obscuring the bleed screw in the pictures or obstructing a small spanner from accessing it?

 

"If"

 

There may be a difference in what we can see from a badly taken picture and what is actually accessible. 

 

I agree, the whole topic is based on two or three photos that do not show sufficient details in respect of pipe runs and connections etc. Its not the OP's fault because I get the impression of a degree of lack of knowledge but that does not assist in giving help.

 

Here is a diagram that may help the OP sort out his system. The diagram does not show any expansion tank because thee are so many ways of installing them.

 

[WotEver]

26 minutes ago, blackrose said:

I was originally responding to Matty's post, not Tony's

Yeah, I’ve edited my post to correctly attribute the comment. 

[Alan de Enfield]

1 hour ago, Tony Brooks said:

In my view Alan was a bit dogmatic because he really has no idea exactly how the system is plumbed.

I cannot see a post from 'Alan' ?

[Tony Brooks]

1 minute ago, Alan de Enfield said:

I cannot see a post from 'Alan' ?

Ta, edited.

[Thomas C King]

Thanks everyone, I'll take more photos today and trace the pipes as well later on. The battery bank isn't actually near what I have photographed, which is a good indication that more photos are required. I am a bit confused about where the bleed valve might be, I'll poke around but it looks like you have pipes going into the side of the hull and that's it, I can't see anything internal relating to the skin tank. Thanks again for all of the responses!

 

Oh, and I'll run the engine in neutral next time.

[Tony Brooks]

49 minutes ago, Thomas C King said:

Thanks everyone, I'll take more photos today and trace the pipes as well later on. The battery bank isn't actually near what I have photographed, which is a good indication that more photos are required. I am a bit confused about where the bleed valve might be, I'll poke around but it looks like you have pipes going into the side of the hull and that's it, I can't see anything internal relating to the skin tank. Thanks again for all of the responses!

 

Oh, and I'll run the engine in neutral next time.

 

The "side of the hull" is almost certainly the inner skin of  a hopefully very slim skin tank. If you were able to look down on the top of it and compare it to the other side the tank normally obvious.

 

The wooden structure on the right of the frost photo may well be obscuring the bleed point(s) they will be right on the top of the tank or at the top but in the side.

 

 

[Captain Fizz]

Maybe the ideal solution would be to ascertain where the OP is situated and, if possible, just go and have a look.

[Thomas C King]

3 minutes ago, Captain Fizz said:

Maybe the ideal solution would be to ascertain where the OP is situated and, if possible, just go and have a look.

Thanks, but I think that's a bit of an ask, although if we can't figure it out we will call someone out (somehow).

[Tony Brooks]

Just now, Thomas C King said:

Thanks, but I think that's a bit of an ask, although if we can't figure it out we will call someone out (somehow).

No one will respond if they are unwilling to come and have a look. If you can get a more knowledgable member to visit I am sure they will tell you a lot more about your boat.

 

Until this virus required me to shield due to age I was always happy to visit a boater with problems within about 30 miles of Reading to help them out. Several other are younger and do the same in their own areas.

 

Even if no one is able to visit juts keep a dialogue going with the forum and answer questions that get asked, even if you can't see the point of them at the time. I am sure we can work it out.

[Eeyore]

Is it my imagination, or is it plumbed “upside down”? I’m sure I can see the gearbox cooler connected to the top of the keel tank, and the other hose to the bottom of the tank.

 

 

[Detling]

15 minutes ago, Eeyore said:

Is it my imagination, or is it plumbed “upside down”? I’m sure I can see the gearbox cooler connected to the top of the keel tank, and the other hose to the bottom of the tank.

 

 

Mine is that way you put the hot coolant into the bottom of the skin tank which ten makes it's way throught the baffles and comes out of the top cooler.

 

The other reservoir and expansion tank look to me as though they are part of a sealed central heating system, although why you put one on a boat beats me.

[pearley]

25 minutes ago, Detling said:

Mine is that way you put the hot coolant into the bottom of the skin tank which ten makes it's way throught the baffles and comes out of the top cooler.

 

The other reservoir and expansion tank look to me as though they are part of a sealed central heating system, although why you put one on a boat beats me.

Surely the other way. Heat rises so hot in the top and cooler out the bottom. 

[Alan de Enfield]

3 minutes ago, pearley said:

Surely the other way. Heat rises so hot in the top and cooler out the bottom. 

Hot in the bottom and as it rises it cools meaning the cooler water is taken from the top.

[Tony Brooks]

6 minutes ago, Alan de Enfield said:

Hot in the bottom and as it rises it cools meaning the cooler water is taken from the top.

So no assistance of circulation by gravity.  suspect horizontal or  vertical baffling may alter how important it is.

57 minutes ago, Eeyore said:

Is it my imagination, or is it plumbed “upside down”? I’m sure I can see the gearbox cooler connected to the top of the keel tank, and the other hose to the bottom of the tank.

 

 

Its why we need better photos. I thought that at first bout I think the oil cooler is connected to the bottom tank fitment shown in another photo - the one with a black pipe in it.