Oil in my water pump

[Swanrad2]

Evening,

In my ongoing engine saga I reached the final part of stage one and went to change the pump impeller (before trying to re-start the big metal bugger). Stage two if this doesn't work means I have an issue with the governor, at which point I'm calling in the experts.

For now though there was oil in the gunk in the pumop and pump housing. It's a volvo MD11C, so I figure this must be something amiss with the seal to the water pump. There also seems to be a bit of play in the shaft of th impeller - so maybe a bearing? I can't think of any other any I'd end up with oil in the water pump (we have replaced the head gaskets and bits and bobs)

Tme to just swap out the water pump maybe?

Thoughts?

Ta, Tony

 

[Andrew G]

I'm not familiar with your specific engine (I have a Volvo 2002) but oil in the pump could mean water is also getting into the oil via a sick seal (or two). You can get kits to replace seals, bearings and the cam - or a new pump. (I recently got both and keep the rebuilt one as a spare). Andrew

 

[VicS]

Evening,

In my ongoing engine saga I reached the final part of stage one and went to change the pump impeller (before trying to re-start the big metal bugger). Stage two if this doesn't work means I have an issue with the governor, at which point I'm calling in the experts.

For now though there was oil in the gunk in the pumop and pump housing. It's a volvo MD11C, so I figure this must be something amiss with the seal to the water pump. There also seems to be a bit of play in the shaft of th impeller - so maybe a bearing? I can't think of any other any I'd end up with oil in the water pump (we have replaced the head gaskets and bits and bobs)

Tme to just swap out the water pump maybe?

Thoughts?

Ta, Tony

There are two seals. one to stop water getting out of the pump itself. the other to keep oil in the engine crankcase. There is a weep hole between them so that anything passing one of the seals should drain out.

Either seal could leak if it is worn , if the shaft is worn or there is play in the bearings. A big water leak could overwhelm the weep hole and force water into the crankcase.

Surprised though if oil would get through to the waterside without you seeing a lot of oil leakage from the weep hole.

but your pump is in need of an overhaul if there is much play in the shaft

Another possibility is a leak in the gearbox cooler, leading to oil from the gearbox finding its way into the pump ??????????

 

[Swanrad2]

There are two seals. one to stop water getting out of the pump itself. the other to keep oil in the engine crankcase. There is a weep hole between them so that anything passing one of the seals should drain out.

Either seal could leak if it is worn , if the shaft is worn or there is play in the bearings. A big water leak could overwhelm the weep hole and force water into the crankcase.

Surprised though if oil would get through to the waterside without you seeing a lot of oil leakage from the weep hole.

but your pump is in need of an overhaul if there is much play in the shaft

Another possibility is a leak in the gearbox cooler, leading to oil from the gearbox finding its way into the pump ??????????

This had occurred to me (the gearbox), but its a bit of a lift.

I suspect it is pump off to find out for sure, but maybe the seal, I think we had some kind of head/gasket fail a couple of years ago.. Never had one off before, so this will be next weekends challenge - I didn't have my reading glasses so couldn't consult the workshop manual today.

Cheers,

Tony

 

[VicS]

This had occurred to me (the gearbox), but its a bit of a lift.

I suspect it is pump off to find out for sure, but maybe the seal, I think we had some kind of head/gasket fail a couple of years ago.. Never had one off before, so this will be next weekends challenge - I didn't have my reading glasses so couldn't consult the workshop manual today.

Cheers,

Tony

I really find it difficult to belive that oil is getting into the waterside via the pump seals but it sounds as though the pump needs an overhaul anyway . There would be an obvious oil leak

Check the manual . There's one online at Bluemoment IIRC. Something in the back of my mind about the spacer between the seals.

Head gasket failure could get water into the engine oil but I don't think it would lead to oil getting in to the water pump.

Dont dismiss the gearbox oil cooler as a possible cause.

 

[Swanrad2]

Thanks Vic - I'm struggling as well, but an overhaul can't hurt. They sell new gasket kits on Keyparts so I'll give it a go.

Cheers

 

[VicS]

Thanks Vic - I'm struggling as well, but an overhaul can't hurt. They sell new gasket kits on Keyparts so I'll give it a go.

Cheers

No point in just fitting new seals if the shaft is worn or the bearings cream crackered.

 

[Bilgediver]

Thanks Vic - I'm struggling as well, but an overhaul can't hurt. They sell new gasket kits on Keyparts so I'll give it a go.

Cheers

If the boat has been left out ashore in freezing weather then possibly the cooling passage in the gearbox has cracked. Especially if you forgot to flush antifreeze through the sea water system at lift out.

This passage is more or less unnecessary in this country due to low temperatures and you can take the sea inlet direct to the pump from the hull inlet.

If this is the problem the oil in the water pump will be in the impeller cavity.

If the oil is in the seal cavity is is coming from the engine. remove the impeller and spindle and check the spindle for wear. If the wear is on the spindle then new ones are available. If the wear is in the body then the body is worn possibly due to a diet of mud or sand. Minor body wear is not a big problem. Where I have doubts about wear I have often fitted a double lipped seal . These are obtained from seal and bearing suppliers. Check your yellow pages. For each seal size there are about half a dozen different seals some with the seal towards the front some towards the back and some double. It can be possible to find a seal where the lip sits on the unworn part of a ridged shaft . Make sure any seal obtained with a spring has a stainless spring.

 

[UncleAlbert]

+1 for stainless steel spring and make sure they are installed round the right way.

unfortunately cant remember any more to give guidance.

 

[Swanrad2]

If the boat has been left out ashore in freezing weather then possibly the cooling passage in the gearbox has cracked. Especially if you forgot to flush antifreeze through the sea water system at lift out.

This passage is more or less unnecessary in this country due to low temperatures and you can take the sea inlet direct to the pump from the hull inlet.

If this is the problem the oil in the water pump will be in the impeller cavity.

If the oil is in the seal cavity is is coming from the engine. remove the impeller and spindle and check the spindle for wear. If the wear is on the spindle then new ones are available. If the wear is in the body then the body is worn possibly due to a diet of mud or sand. Minor body wear is not a big problem. Where I have doubts about wear I have often fitted a double lipped seal . These are obtained from seal and bearing suppliers. Check your yellow pages. For each seal size there are about half a dozen different seals some with the seal towards the front some towards the back and some double. It can be possible to find a seal where the lip sits on the unworn part of a ridged shaft . Make sure any seal obtained with a spring has a stainless spring.

The ok was in the impeller cavity (coating rather than filling). So the an of action seems to be - overhaul the pump (JIC) and by-pass the gearbox cooling channel. I did notice that the gearbox oil was a little low during the initial engine service.

 

[Bilgediver]

The ok was in the impeller cavity (coating rather than filling). So the an of action seems to be - overhaul the pump (JIC) and by-pass the gearbox cooling channel. I did notice that the gearbox oil was a little low during the initial engine service.

Just keep an eye on the output shaft bearing temperature when you start using the boat. However I doubt if in the UK you will have a problem.

It is wise to flush the sea water system of MD 1 2 5 6 7 and 11 before layup as this cooling channel at the rear of the gearbox is difficult to drain and is liable to freeze and split inside the gear box.

I am surprised if there is NO indiction of water in the gearbox oil.

The shaft bearings in these pumps are machined into the body however you might be able to find a tame Model Engineer or machinist who will machine the body and fit a bronze bush if your body is excessively worn. Much cheaper than a new pump.

 

[VicS]

The shaft bearings in these pumps are machined into the body however you might be able to find a tame Model Engineer or machinist who will machine the body and fit a bronze bush if your body is excessively worn. Much cheaper than a new pump.

ITYWF that it depends on the age of the pump. Pumps on later model engines and replacement pumps on older engines have ball races.

 

[vyv_cox]

It does seem very surprising that oil at a nominal pressure of atmospheric or very little more could enter the pump with a pressure considerably more than that. Can we assume that the engine's crankcase breather is working OK?

I have known some oil from the engine to leak from the tell-tale holes in the pump body, possibly because the seal was fitted the wrong way around, but hard to understand how it could then get into the pump. I tend to prefer the alternative possibility, that the water entering the pump was already contaminated.

 

[Swanrad2]

It does seem very surprising that oil at a nominal pressure of atmospheric or very little more could enter the pump with a pressure considerably more than that. Can we assume that the engine's crankcase breather is working OK?

I have known some oil from the engine to leak from the tell-tale holes in the pump body, possibly because the seal was fitted the wrong way around, but hard to understand how it could then get into the pump. I tend to prefer the alternative possibility, that the water entering the pump was already contaminated.

I COMPLELTEY missed the bl***y obvious. The water flows through the gear box before entering the pump - I knew this, but in my mind think of the water pump forcing the water through the system, so think pump gearbox, engine block. Schoolboy error! Thanks guys for hammering the point home until I actually understood it.

The solution therefore is circumvent the gear box with fresh water. Run for a while, re-inspect for oil. If there is still oil then it must be the pump seal, not the other way around.

Cheers.

 

[Bilgediver]

I COMPLELTEY missed the bl***y obvious. The water flows through the gear box before entering the pump - I knew this, but in my mind think of the water pump forcing the water through the system, so think pump gearbox, engine block. Schoolboy error! Thanks guys for hammering the point home until I actually understood it.

The solution therefore is circumvent the gear box with fresh water. Run for a while, re-inspect for oil. If there is still oil then it must be the pump seal, not the other way around.

Cheers.

The sea water pump draws the water through the gearbox passage. This means
it is possibly under slight negative pressure if any throttling by the inlet filter so
oil can leak from the gear box via the freeze crack into the cooling passage .

This will be clean oil. If the oil is also in the seal space and is dirty then it is
engine oil however it is unusual for engine oil to migrate from the crank case into
the pump and the bleed hole would have to be blocked to allow this.

Inspection of the pump will tell the story.

There have been many threads over the years on the cracking of this cooling passage.

 

[Swanrad2]

The sea water pump draws the water through the gearbox passage. This means
it is possibly under slight negative pressure if any throttling by the inlet filter so
oil can leak from the gear box via the freeze crack into the cooling passage .

This will be clean oil. If the oil is also in the seal space and is dirty then it is
engine oil however it is unusual for engine oil to migrate from the crank case into
the pump and the bleed hole would have to be blocked to allow this.

Inspection of the pump will tell the story.

There have been many threads over the years on the cracking of this cooling passage.

Until recently I didn't understand ANY of this stuff - it's like a foreign language, only after you've lived in the diesel for a bit does it make any sense at all. I re-read some of the old threads now and they make (some) sense.