Fountaining header tank

[Giggetty]

This is a recently overhauled Bukh DV20ME (1985).

 

ON revving up from cool idle coolant fountains out of the header tank.

 

Overheating when attempting normal rpm under load results in overheating. Colourless exhaust at alltime.

 

Engine cut is followed by bubbling up into header tank (no obvious smell of exhaust gas there).

 

Mechanic suggests a) airlock blown gasket c) sticking thermostat. However, is cracked block or head a possibility?

[Chris-B]

This is a recently overhauled Bukh DV20ME (1985).

 

ON revving up from cool idle coolant fountains out of the header tank.

 

Overheating when attempting normal rpm under load results in overheating. Colourless exhaust at alltime.

 

Engine cut is followed by bubbling up into header tank (no obvious smell of exhaust gas there).

 

Mechanic suggests a) airlock blown gasket c) sticking thermostat. However, is cracked block or head a possibility?

 

 

Purchase one of these Gasket Tester

 

That will assist in fault finding

 

Chris

[Guest]

This is a recently overhauled Bukh DV20ME (1985).

 

ON revving up from cool idle coolant fountains out of the header tank.

 

Overheating when attempting normal rpm under load results in overheating. Colourless exhaust at alltime.

 

Engine cut is followed by bubbling up into header tank (no obvious smell of exhaust gas there).

 

Mechanic suggests a) airlock blown gasket c) sticking thermostat. However, is cracked block or head a possibility?

Think I'd be looking at an airlock, especially as engine has been overhauled. Failing that it sounds like the system needs pressure testing.

 

Purchase one of these Gasket Tester

 

That will assist in fault finding

 

Chris

That looks a good bit of kit.

[blodger]

I am not familiar with your engine though I have had a similar problem with a Lister LPW3. However since your problem seems to have coincided with refurb/repairs I would think it relates to that work. How is the water pump driven; couldn't be as simple as a slack belt could it?

[Chris-B]

Think I'd be looking at an airlock, especially as engine has been overhauled. Failing that it sounds like the system needs pressure testing.

 

 

That looks a good bit of kit.

 

 

Been using them for ages mate, and how much work have they saved me ........

 

Also bit like doing the black magic bit ..........

 

 

Chris

[johnjo]

This is a recently overhauled Bukh DV20ME (1985).

 

ON revving up from cool idle coolant fountains out of the header tank.

 

Overheating when attempting normal rpm under load results in overheating. Colourless exhaust at alltime.

 

Engine cut is followed by bubbling up into header tank (no obvious smell of exhaust gas there).

 

Mechanic suggests a) airlock blown gasket c) sticking thermostat. However, is cracked block or head a possibility?

 

If it is then I'd expect to see signs of the water mixing with the oil, check inside the rocker cover for white smears and also the dipstick [after she's sat for a while], for signs of water.

[Big COL]

Been using them for ages mate, and how much work have they saved me ........

 

Also bit like doing the black magic bit ..........

 

 

Chris

 

Kept it quiet though It's bloody obvious, AFTER someone comes up with a simple test kit like this.

Must find out where I can buy some hindsight.

[Chris-B]

Kept it quiet though It's bloody obvious, AFTER someone comes up with a simple test kit like this.

Must find out where I can buy some hindsight.

 

edited due to too much wine and a beating from SWMBO !

Chris

Edited October 29, 2009 by Baldock

[Big COL]

edited due to too much wine and a beating from SWMBO !

Chris

 

 

Can one have too much wine? open for discussion. Beatings from SWMBO two a penny

[Roger Gunkel]

I'm with Catweasel on the airlock. Reason being that while driving my car a couple of weeks ago, a water pipe burst, loosing all the coolant and resulting in sudden overheating and massive increase in oil temperature. As it is an MG, after replacing the burst pipe, the mechanic was concerned that the head gasket may have also been damaged in the overheating. Inspite of extensive bleeding, the engine kept blowing hot water out of the header tank, and after a number of attempts we concluded gasket. Rather than a ridiculously expensive recovery and against the advice of the mechanic, I decided to try to get the car 40 miles home in short hops. After 5 miles I checked the water, and immediately got a blowback and water pouring out. Let it cool down, topped it up again and tried another five miles, surprise surprise, no drop in level! 500 miles later no problems, it was an airlock which finally cleared itself.

 

Hope your problem is as simple,

 

Roger

[Giggetty]

I'm with Catweasel on the airlock. Reason being that while driving my car a couple of weeks ago, a water pipe burst, loosing all the coolant and resulting in sudden overheating and massive increase in oil temperature. As it is an MG, after replacing the burst pipe, the mechanic was concerned that the head gasket may have also been damaged in the overheating. Inspite of extensive bleeding, the engine kept blowing hot water out of the header tank, and after a number of attempts we concluded gasket. Rather than a ridiculously expensive recovery and against the advice of the mechanic, I decided to try to get the car 40 miles home in short hops. After 5 miles I checked the water, and immediately got a blowback and water pouring out. Let it cool down, topped it up again and tried another five miles, surprise surprise, no drop in level! 500 miles later no problems, it was an airlock which finally cleared itself.

 

Hope your problem is as simple,

 

Roger

 

A happy conclusion. I also got home in short hops at 1 mph, topping up at intervals, and negotiating two 10' locks single-handed in the dark (a new thread on here?)

 

As far as I can tell, there is no water in the oil and no oil in the water.

 

Also, the mechanic has commented on anomalous skin tank connections (top entry being 2" below the top). He proposes tapping in an airbleed screw.

 

I have to say that tapping the skin tank sounds a bit hollow.

The problem with sampling the header tank for exhaust gases seems on my reading to give false positives, and a compression test means removing injectors, replacing gaskets etc and hiring the kit.

 

 

 

I'm with Catweasel on the airlock. Reason being that while driving my car a couple of weeks ago, a water pipe burst, loosing all the coolant and resulting in sudden overheating and massive increase in oil temperature. As it is an MG, after replacing the burst pipe, the mechanic was concerned that the head gasket may have also been damaged in the overheating. Inspite of extensive bleeding, the engine kept blowing hot water out of the header tank, and after a number of attempts we concluded gasket. Rather than a ridiculously expensive recovery and against the advice of the mechanic, I decided to try to get the car 40 miles home in short hops. After 5 miles I checked the water, and immediately got a blowback and water pouring out. Let it cool down, topped it up again and tried another five miles, surprise surprise, no drop in level! 500 miles later no problems, it was an airlock which finally cleared itself.

 

Hope your problem is as simple,

 

Roger

 

A happy conclusion. I also got home in short hops at 1 mph, topping up at intervals, and negotiating two 10' locks single-handed in the dark (a new thread on here?)

 

As far as I can tell, there is no water in the oil and no oil in the water.

 

Also, the mechanic has commented on anomalous skin tank connections (top entry being 2" below the top). He proposes tapping in an airbleed screw.

 

I have to say that tapping the skin tank sounds a bit hollow.

The problem with sampling the header tank for exhaust gases seems on my reading to give false positives, and a compression test means removing injectors, replacing gaskets etc and hiring the kit.

[Chris-B]

A happy conclusion. I also got home in short hops at 1 mph, topping up at intervals, and negotiating two 10' locks single-handed in the dark (a new thread on here?) Good

 

As far as I can tell, there is no water in the oil and no oil in the water. And ?

 

Also, the mechanic has commented on anomalous skin tank connections (top entry being 2" below the top). He proposes tapping in an airbleed screw. Sensible but the air bleed will need to be 12" higher than the highest point of the system

 

I have to say that tapping the skin tank sounds a bit hollow. NFC

 

The problem with sampling the header tank for exhaust gases seems on my reading to give false positives, and a compression test means removing injectors, replacing gaskets etc and hiring the kit. Do the job once and do the job properly

 

Answers given off to look sole fully into a glass of Scotland's finest export

 

C

Edited October 30, 2009 by Baldock

[Giggetty]

I am not familiar with your engine though I have had a similar problem with a Lister LPW3. However since your problem seems to have coincided with refurb/repairs I would think it relates to that work. How is the water pump driven; couldn't be as simple as a slack belt could it?

 

The water pump is integral with the engine and I think driven by the camshaft (the workshop manual is silent on this and the exploded view is unhelpful). However, the impeller is said to be liable to wear and tear, so we shall look at this as well.

 

I would have thought though that a faulty impeller would result in steam locks rather than air bubbles.

[macc]

im having the same problem as you but i know my skin tank has got a small hole in it check all your hose conection are tight and the cooling system hasnt got any leeks

[Giggetty]

A double explanation, in the end. The thermostat and compression tested OK.

 

Firstly, a large airlock dealt with by tapping an airbleed into the top of the swim tank and topping up. Secondly-obstructions:

 

On opening the waterpump cover a fairly new and intact rubber impeller was found. The inlet and outlet however were blocked by two very obvious and very old impeller blade fragments. On removing these and replacing with an even newer impeller the engine ran perfectly with no evidence of overheating.

 

The recent engine overhaul seems to have been rather incomplete.

[Giggetty]

A double explanation, in the end. The thermostat and compression tested OK.

 

Firstly, a large airlock dealt with by tapping an airbleed into the top of the swim tank and topping up. Secondly-obstructions:

 

On opening the waterpump cover a fairly new and intact rubber impeller was found. The inlet and outlet however were blocked by two very obvious and very old impeller blade fragments. On removing these and replacing with an even newer impeller the engine ran perfectly with no evidence of overheating.

 

The recent engine overhaul seems to have been rather incomplete.

 

After the impeller repair I took Giggetty out for an uneventful league down to Stourton Junction & back. I then revised the coolant hose set up. This was necessary as the header tank was corroded, and the connections to the skin tank were copper. I was concerned about vibration-induced work-hardening and eventual fracture, so these were replaced completely with flexible hose and new ball-valves and a new plastic header tank put in. I ran the engine in the marina under load for two one hour sessions-no overheating.

 

However, on routine checking before a third session water emulsion appeared on the oil dipstick. The ever available Blackhands appeared like a genie from a bottle immediately to take the cylinder head off. It appears that there now is a blown gasket. I've had it sent it away to be skimmed and tested.

 

What concerns me is that the leak track between a single waterway and the no 2 cylinder bore seemed to me very small. Is this enough to account for events? There are wet liners. What are the chances that the O-rings at the bottom of the liners have gone? Can you get the liners out without removing the engine block? (the visible portion of the liners seem intact with no pinholes).

 

I guess that this engine has had a chronic overheating problem, perhaps dating from early in its history and due to the impeller fragmentation. That is why the boat was apparently abandoned by a disheartened owner in the past. I doubt that a freeze fracture of the engine block has occurred as for some of its history the engine bay was deep under water.

[Albion]

snipped

What concerns me is that the leak track between a single waterway and the no 2 cylinder bore seemed to me very small. Is this enough to account for events? There are wet liners. What are the chances that the O-rings at the bottom of the liners have gone? Can you get the liners out without removing the engine block? (the visible portion of the liners seem intact with no pinholes).

 

Yes, the leak path only needs to be tiny to give the problems that you describe. If you imagine the massive pressures generated during the combustion process then a small path is quite sufficient. As to whether there is a possibilty of the lower liner seals having failed, that's difficult to say. It is one of the extra fun bits of a wet liner engine I'm afraid. To remove the liners you should first remove the pistons and rods, can you do that with the engine in place? If you can't then I think you've answered your own question.

Roger

[RLWP]

Yes, the leak path only needs to be tiny to give the problems that you describe. If you imagine the massive pressures generated during the combustion process then a small path is quite sufficient.<snip>

Roger

 

If you think about it, all the air in the cylinder gets squeezed into a very small combustion chamber. Some of this very compressed air goes through the tiny gap, then expands back to the size it was before it was squeezed in the first place. So you can pass a lot of air at atmospheric pressure through quite a small gap in a gasket!

 

Richard

 

Just expanding on what Roger said.

[Giggetty]

If you think about it, all the air in the cylinder gets squeezed into a very small combustion chamber. Some of this very compressed air goes through the tiny gap, then expands back to the size it was before it was squeezed in the first place. So you can pass a lot of air at atmospheric pressure through quite a small gap in a gasket!

 

Richard

 

Just expanding on what Roger said.

It seems to have been just that! After £500 (skimming the head, lapping the valves, changing the head gasket and two oil changes) all now seems to be well). This has been a three month's saga for an engine which was clearly the object of a very negligent overhaul in the recent past. However, I've learned a lot of diesel anatomy.

 

One thing which puzzled me and Blackhands was the appearance of the original oil filter. This seems to have undergone total internal disintegration and was clearly not doing its stuff. What could have done that, I wonder?

[Keeping Up]

It seems to have been just that! After £500 (skimming the head, lapping the valves, changing the head gasket and two oil changes) all now seems to be well). This has been a three month's saga for an engine which was clearly the object of a very negligent overhaul in the recent past. However, I've learned a lot of diesel anatomy.

 

One thing which puzzled me and Blackhands was the appearance of the original oil filter. This seems to have undergone total internal disintegration and was clearly not doing its stuff. What could have done that, I wonder?

If you were getting water in the oil, maybe the filter material disintegrated in the water?

[Guest]

If you were getting water in the oil, maybe the filter material disintegrated in the water?

Sounds likely. Alternatively was it a genuine filter? I understand some pattern oil filters are unreliable.

[Giggetty]

Sounds likely. Alternatively was it a genuine filter? I understand some pattern oil filters are unreliable.

 

The old one was an orange one with indecipherable numbers on it. Giggetty now has a genuine Bukh filter (only £*******).

[John Orentas]

This is a recently overhauled Bukh DV20ME (1985).

 

ON revving up from cool idle coolant fountains out of the header tank.

 

 

 

I would suspect that you are simply over-filling your header-tank or that the tank is not big enough, it should be at least 2 pints.. The free space in the top of the tank is, or should be proportional to the amount of coolant in your system, the expansion of all that water can be considerable, when I installed my engine I couldn't find a tank large enough and had to make one..

 

You see so many boats that are fitted with those little plastic bottles that are to be seen in the windows of car-spares shops, ideally too the pipe connecting the tank to the engine should be quite large, at least 15mm bore to allow any air in the system to bubble up to the tank otherwise you might get a cylinder head-full of air..

 

Find a pressure cap with the lowest pressure rating, ideally 1 or 2 psi.

Edited December 4, 2009 by John Orentas

[Giggetty]

I would suspect that you are simply over-filling your header-tank or that the tank is not big enough, it should be at least 2 pints.. The free space in the top of the tank is, or should be proportional to the amount of coolant in your system, the expansion of all that water can be considerable, when I installed my engine I couldn't find a tank large enough and had to make one..

 

You see so many boats that are fitted with those little plastic bottles that are to be seen in the windows of car-spares shops, ideally too the pipe connecting the tank to the engine should be quite large, at least 15mm bore to allow any air in the system to bubble up to the tank otherwise you might get a cylinder head-full of air..

 

Find a pressure cap with the lowest pressure rating, ideally 1 or 2 psi.

The new pressure tank is about 2 pts.

 

The Bukh workshop manual says 4lb header tank top pressure (and specifies a certain Delco pressure cap). However, my mechanic says that this is unnecessary and that with the hydrostatic pressure from a header tank about 9" above the water jacket things are about right.

Edited December 4, 2009 by Giggetty

[Giggetty]

If you were getting water in the oil, maybe the filter material disintegrated in the water?

 

After all that, water persisted in the lubricating oil. So the engine had to come out. The double O ring system at the bottom of the wet liners of both cylinders was flattened, presumably from heat damage, thus allowing coolant to leak into the sump. I took the opportunity to replace the crankshaft shells, which showed early wear, and to renew all gaskets. Cost of parts £900, I await Blackhand's bill.

Edited March 26, 2010 by Giggetty