Water spewing out of my Volvo 2040

[john_morris_uk]

We have developed a problem with our Volvo 2040 that has got me puzzled. When the engine heats up, the overflow pipe from the filler cap fitting on the heat exchanger spews water into the bilge. It gushes out - not just a trickle.

My initial reaction was that I had fitted the heat exchanger incorrectly. You have to fit the tube stack into the heat exchanger casting so its sticking out both ends evenly, and then you fit the rubber caps on the end etc. However a quick check showed that it was fitted OK. I then removed the heat exchanger stack and made a rig up at work with two metal plates and some rubber and pressurised the internal pipes to around 100 psi to see if there was a leak. There was no sign of any air escaping and it held its pressure remarkably well so I concluded that the heat exchanger stack is OK.

This leaves me stumped. I know that if I turn off the sea water cooling, the water stops coming out. I know that its salt water, but how is it getting from the raw water side to the fresh water side? Also, the fresh water side should be pressurised with a cut off of about 12 psi according to the engine handbook, and I am surprised that the raw water has enough pressure to overcome that and get back into the fresh water side and come out of the filler over flow pipe.

Any ideas please as I have to pump the engine bilge every few minutes whenever we motor at the moment. I suppose it did encourage me to sail off our anchor in Barn Pool yesterday instead of being lazy and turning the engine on.

 

[wotayottie]

my engine is a 2030 but from memory the only place where salt and fresh meet is in the heat exchanger so if they are mixing it has to be there.

 

[john_morris_uk]

my engine is a 2030 but from memory the only place where salt and fresh meet is in the heat exchanger so if they are mixing it has to be there.

That was my thought as well. I think one of the large jubilee clips might be slightly dodgy - it slips a thread now and again when you do it up - but I am not sure that it accounts for the amount of water thats leaking through.

I changed one of the rubber end caps last year, so I think I will replace the rear one as well and put a new jubilee clip on it. I am not confident that it will solve the problem, but I'm grasping at straws here.

I can just about imagine a split in a pipe that only opens up when the thing gets hot, but again I am grasping at straws, and I would have thought any leak would have shown up under 100 psi air pressure.

 

[pvb]

The 2040 manual contains a caution about getting the heat exchanger insert in the correct way up - guess you've done that? Other thing you could do is replace the pressure cap.

 

[vyv_cox]

Grasping at straws really, no obvious answer to me. The raw water pump is positive displacement, so in theory it will develop a pressure higher than the fresh water side if its discharge is blocked. In practice I suspect the blades will deform or break eventually, so there must be a limit. But checking the raw water discharge into the manifold could be worth while. Otherwise I can only think the same as the others, there's something wrong in the heat exchanger.

 

[blaggard]

I have had the same problem on my md2030b . It was caused by the rubber end caps slipping and allowing salt water into the fresh. refiiting end caps fixes it but is a real pain when it happens. someone on a previous thread reckoned a coked up exhaust elbow can also cause it. Its happened to me 3 times now and only when engine revs above 2200.

 

[john_morris_uk]

Grasping at straws really, no obvious answer to me. The raw water pump is positive displacement, so in theory it will develop a pressure higher than the fresh water side if its discharge is blocked. In practice I suspect the blades will deform or break eventually, so there must be a limit. But checking the raw water discharge into the manifold could be worth while. Otherwise I can only think the same as the others, there's something wrong in the heat exchanger.

My next plan was to remove the exhaust and check the outlet - since thinking about it, I guess a blocked or partially blocked exhaust mixer might cause the pressure to be such as it overcomes a minor weakness in the rubber caps and where they clamp onto the heat exchanged stack so:

1. I will order and fit a new rubber end cap and jubilee clip

2. I will remove the exhaust and check for free passage of raw cooling water.

I'd quite like to get it sorted as the main summer cruise is approaching and I have list of other jobs to do before we slip the lines.

 

[Bosun Higgs]

Would be worth checking the cooling system pressure cap too. I cant see the raw water pump developing mthe 10psi that typically is needed to blow off the pressure cap so maybe like mine its not doing a lot.

 

[ianat182]

You might also check the core plugs in the engine block for corrosion while you're at it, did you winterize the cooling system?
I think I would also check impellor and inlet pipes /filter for any weed blockages in the raw water side which may be causing overheating, of the exchanger and the ejection of water through the vent on the pressure cap.
You'll have checked the whole cooling system then.

ianat182

 

[john_morris_uk]

You might also check the core plugs in the engine block for corrosion while you're at it, did you winterize the cooling system?
I think I would also check impellor and inlet pipes /filter for any weed blockages in the raw water side which may be causing overheating, of the exchanger and the ejection of water through the vent on the pressure cap.
You'll have checked the whole cooling system then.

ianat182

Yes I did winterize the engine cooling system inasmuch as I flushed it through and topped it up with antifreeze. Not sure what you mean by check the core plugs except that they are there and not leaking.

Regarding blockage/weed on the raw water inlet side, the usual tell tale of water from the anti-siphon valve is running as normal and there appears to be the normal amount of water coming out of the exhaust - except that its impossible to judge that very accurately...

However what concerns me is that if it was a simple matter of overheating, then it would only be a bit of water and the whole engine would get very hot etc as the engine boiled off the coolant in the heat exchanger. My problem is a matter of water pouring out in a continuous stream. Its like turning a tap on as the engine heats up and it will run very happily in this condition so long as I keep pumping the bilge.

 

[Bilgediver]

Yes I did winterize the engine cooling system inasmuch as I flushed it through and topped it up with antifreeze. Not sure what you mean by check the core plugs except that they are there and not leaking.

Regarding blockage/weed on the raw water inlet side, the usual tell tale of water from the anti-siphon valve is running as normal and there appears to be the normal amount of water coming out of the exhaust - except that its impossible to judge that very accurately...

However what concerns me is that if it was a simple matter of overheating, then it would only be a bit of water and the whole engine would get very hot etc as the engine boiled off the coolant in the heat exchanger. My problem is a matter of water pouring out in a continuous stream. Its like turning a tap on as the engine heats up and it will run very happily in this condition so long as I keep pumping the bilge.

I second the motion that you check the rubber end caps as leakage at the big jubilee clip position allows sea water into freshwater internally These clips must be tight!!!!!!!!!!!!!!!!!!!! If slipping then replace.

 

[ianat182]

Regarding checks of the core plugs,had you not winterized and the engine coolant froze they would have popped out hopefully before cracking the engine block.I had this happen on an old MD1B where the block had frozen water within(no heat exchanger here)and a corroded core-plug popped- and I was afloat then!.
I now have a VP2010 and also cannot understand any pressure in the heat exchanger that could vent the FW coolant; may be a perforated tube within the H/E then.

 

[Bosun Higgs]

The OP explains that the water is coming out of the pressure cap overflow so the only possibility is that the pressure within the engine is greater than the pressure cap resistance. Which suggests a duff cap given that the raw water pump is only a rubber vaned one.

Either way, salt water is getting in from the heat exchanger. Given that the OP has already pressure tested the tubes it seems likely that the problem is the fit of the rubber muffs. Can't see where core plugs come into the issue.

 

[Ruffles]

I can confirm that the sea water pump will produce enough pressure to bypass the pressure cap on the fresh system. At least it will on our 2030

If a restriction in the exhaust is the problem there are two ways to prove it. Re-seal the rubber caps on the exchanger and refill. Now run the engine. Put your hand on the input rubber end cap and rev the engine. You'll feel the rubber balloon out. It's the movement of the rubber that allows the clip to shift. The other way is to loosen the opposite rubber where it's attached to the exhaust. But you'll get sea water everywhere!

Chances are there's corrosion inside the water passage of the exhaust manifold. The only way to prove this to yourself is to take it to a VP dealer and compare it with a new one. You'll notice the difference when you blow into the water inlet. We've replaced two in 11 years for this reason.

One last thing. The last time we replaced it they'd forgotten to drill the hole that injects the water. So check it before you leave the shop!

Anyone know if you can sandblast inside a casting?

 

[Bosun Higgs]

I've got to correct myself. The max pressure generated by such a pump in new condition is about 30 psi according to Jabsco which is definitely more than the pressure cap will be set at. So a blockage where the sea water is injected into the exhaust together with a badly fitting rubber muff on the heat exchanger could do just what the OP says.

 

[VicS]

So a blockage where the sea water is injected into the exhaust together with a badly fitting rubber muff on the heat exchanger could do just what the OP says.

I'll second that.
The leak must be occurring where the rubber end caps are clamped to the heat exchanger tube nest.
There is probably a restriction at the injection point into the exhaust creating a higher than normal pressure in the seawater cooling circuit. Or a collapsed hose betwixt heat exchanger and injection point

 

[atlowers]

I have the exact same problem as op on a ford 2715e. I also checked stack and replaced end caps and still filled bilges at 2000rpm and above. Noticed 2 other symptoms hose pressurised between pump and heat exchanger and when I start the engine there is a jet ski style plume of water from exhaust. I have been told it is probably cracked head causing back pressure. Not sure if this correct as still to resolve but alledgedly a cause.

 

[john_morris_uk]

I cured the problem with my engine and cleaning the exhaust water injection manifold seemed to be part of the cure. This is what I fed back on my post about agents for cleaning exhaust elbows - but its pertinent to the water spewing out problem:

For those who read my plea for guidance on cleaning an exhaust elbow here is the final installment. Thank you to all who offered encouragement and advice

Patio and brick cleaner did the job on the whole. I tried caustic soda and phosphoric acid based cleaner as well. The phosphoric acid is very good for treating rust, but it didn't touch the carbon and other build up in the exhaust.

Lesson: use the right cleaner and don't allow bronze bits or copper bits of the elbow to be in the solution at the same time as the cast iron.

I removed the exhaust manifold and cleaned it all up, put it back on with a new gasket and some black sticky gasket compound from volvo (small tin with built in brush £8.00) I also removed the drain plugs in the heat exchanger and cleaned them and refitted them with gasket compound as there were traces of rust around them where they may have been seeping very slowly..

While I was at it I fitted all new rubber pipes and some new hose clips on rest of the cooling system of the engine and a new rubber end cover on the hear exchanger and all rust treated and painted.

On first start up, I realised I forgotten to tighten the exhaust hose clamp as it was spraying water, so quick turn off and sort it out.

Once that was tightened I ran the engine on load (in reverse - pulling the boats in the trot against the tide on their moorings) for over half an hour and until the whole thing was nice and hot.

NO SIGN of any leak anywhere. I'll post a picture of it all when I get a chance. Hurrah I have a boat again...

I then spent two hours cleaning the bilge and sponging out all the spaces where the engine had sprayed water when it developed its leak.

Now we have a clean bilge, a clean and working engine, and I just have to sort out the radio fit and the faulty aft shower pump and stern light. None of these stops us going sailing though!

I believe the essential parts to solving the problem were a new rubber end cap on the heat exchanger with new jubilee clips, and cleaning the coked up exhaust injection high rise elbow out which contributed to the back pressure.

 

[Ruffles]

This happened to us years ago mid channel coming back from Alderney on a windless day. Scared the life out of me - I thought we were sinking until I noticed the water was warm.

It didn't seem to harm the engine though. So if it happens again when you need power you can carry on for a while. Enough water gets through to cool the heat exchanger and the exhaust. Just need to drain and flush the fresh water system when you get back.

I might have a go at cleaning out my old exhaust so I can keep it as a spare. Is brick cleaner hydrochloric acid? I have some in the garage somewhere. Thing is though I'll need some way of proving that it's fixed . Perhaps by measuring the volume of the water labyrinth or filling a funnel and timing how long it takes to drain.

 

[john_morris_uk]

This happened to us years ago mid channel coming back from Alderney on a windless day. Scared the life out of me - I thought we were sinking until I noticed the water was warm.

It didn't seem to harm the engine though. So if it happens again when you need power you can carry on for a while. Enough water gets through to cool the heat exchanger and the exhaust. Just need to drain and flush the fresh water system when you get back.

I might have a go at cleaning out my old exhaust so I can keep it as a spare. Is brick cleaner hydrochloric acid? I have some in the garage somewhere. Thing is though I'll need some way of proving that it's fixed . Perhaps by measuring the volume of the water labyrinth or filling a funnel and timing how long it takes to drain.

Yes - Patio and Brick cleaner contains Hydrochloric Acid. I would have used plain hydrochloric acid but I couldn't think of how to buy some, and the 5 litre containers of No Nonsense Patio and Brick cleaner were £6.98 from B&Q. I agree that the engine doesn't overheat when run with this fault - you just have to keep pumping the bilge!