Volvo MD2B - water in the oil after winterising

[WotSandbank]

I have water in my oil after winterising the engine.

I have recently bought a boat with an old (1976) Volvo MD2B. The previous owner had not used the boat much for 4-5 years but had maintained the engine and ran it up regularly as the boat was on a mooring.

The boat is ashore now so I winterised the engine yesterday. I ran the engine for 30 mins and drained the old oil using a vacuum extractor via the dipstick. I also drained the MS reduction gear. I noticed that as the last drops of oil were being extracted I saw what looked like a small amount of water running through the extractor pipe. I put the dipstick back in to check the oil had been fully extracted and again noticed a few droplets of water. I then added the new oil and changed the oil filter (oil was black in the filter as expected). I ran the engine for half an hour recycling the exhauste water to get it up to temp so the thermostat could open. Added the antifreeze. Stopped the engine and checked the dip stick which had a creamy oil on it. (as did the oil filler caps). So I now have fresh water mixed with my new oil.

Does anyone have an idea on how this could happen?

I am thinking 3 possible routes:
a) Water seals on the water pump allowing water into the sump.
b) head gasket (the engine certainly didn't run that hot to blow it though)
c) some sort of back syphon of water from the exhaust pipe into the cylinders

Any thought gratefully received!

 

[pyrojames]

Unlikely to be number one. The housing for the pump has drain holes between the pump and the casing which should allow water to drain out before gettingto the oil seal.

Could be 2 or 3. I had head gasket problems with both heads at different times on mine. Not a big repair job if you catch it early enough.

Also had back syphoning problems. You need to check the valves/water levels. If you have a back syphoning problems then it usually ends up with lots of water in the sump, not a just a little.

 

[WotSandbank]

Thanks pyrojames. Did you have any noticeable overheating when the head gasket went? Or change in exhaust?

 

[bedouin]

Surely if the boat is on the hard, and you are recirculating the cooling water, then there wouldn't be any water in the exhaust anyway so hard to see how that can be the cause.

Had you run the engine before draining the old oil?

PyroJames makes a good point about those drain holes - it is worth knowing about those and checking occasionally, if the water pump seal goes it has the habit of dripping warm salt water over the engine that you might not normally notice and that can cause corrosion problems.

 

[vyv_cox]

Sorry, I have to disagree with pyrojames. It is very common for water to enter the crankcase via the water pump seals. This may very well be accompanied by water leaks outside the engine from the tell-tale holes but it is possible for this not to happen. There is a spectacular example on the water pumps page of my website. In this case the engine had seized completely due to rusting of the piston rings to their bores. Not a Volvo, obviously, but the mechanism and sealing is identical.

 

[WotSandbank]

bedouin: in recycling the water you must collect it from the exhaust in a bucket and then have your water input hose sucking it out from the same bucket. So water still goes through the exhaust but gets progressively hotter to enable the thermostat to open around 60-70c.

On the oil seals - if they have ben wrongly fitted and are blocking the drain hole (or gunge has blocked it) then it is possible that water can be forced back into the sump. I had this on an old engine previously.

 

[WotSandbank]

thanks vye_cox - useful link to your site.

the previous owner tells me he did the water pump seals around 10 years ago so might be very worthwhile checking this out..

one extra question: does it take quite a lot of water to emulsify new oil or could it be a small amount from the beginnings of water seal failure? I ask because from having no water when I drained the old oil to having creamy oil I am wondering how much and how quickly water is ingested into the engine to cause this? Many thanks.

 

[bedouin]

bedouin: in recycling the water you must collect it from the exhaust in a bucket and then have your water input hose sucking it out from the same bucket. So water still goes through the exhaust but gets progressively hotter to enable the thermostat to open around 60-70c.

Ah - I hadn't thought of that - it would be very difficult to achieve on my boat. For winterising I have always just let the engine suck fresh water from a bucket once through, it still gets up to temperature, but probably takes much longer. I have been wondering about trying to set up a closed loop but I had been thinking about intercepting it from the point of injection into the exhaust.

 

[WotSandbank]

Ah - I hadn't thought of that - it would be very difficult to achieve on my boat. For winterising I have always just let the engine suck fresh water from a bucket once through, it still gets up to temperature, but probably takes much longer. I have been wondering about trying to set up a closed loop but I had been thinking about intercepting it from the point of injection into the exhaust.

Can you not hang a bucket over the stern and gather the sputtering water and then stick a longer hose in that as I did? (You do get gassed by fumes a fair bit though so watch out!)

 

[pampas]

WatSandBank

Could you explain exactly how you coupled up the water supply for testing please, then a more definative answer may be given.

 

[WotSandbank]

Could you explain exactly how you coupled up the water supply for testing please, then a more definative answer may be given.

yes, I hung a bucket over the stern to collect the exhaust water and used a long pipe to feed it back to the engine sea cock. So the cooling water was recycling and getting hotter slowly, so the thermostat would open up. I kept a careful check on the temp guage but it still hardly moved much.

 

[bedouin]

Can you not hang a bucket over the stern and gather the sputtering water and then stick a longer hose in that as I did? (You do get gassed by fumes a fair bit though so watch out!)

In my case physically that would be very difficult because the exhaust actually exits from the bottom of the boat so it would be very difficult to arrange the bucket securely. Even if I did the water level in the bucket would be below the normal waterline, and that coupled with the long hose means I would doubt the ability of the water pump to prime or achieve adequate flow.

 

[WotSandbank]

In my case physically that would be very difficult because the exhaust actually exits from the bottom of the boat so it would be very difficult to arrange the bucket securely. Even if I did the water level in the bucket would be below the normal waterline, and that coupled with the long hose means I would doubt the ability of the water pump to prime or achieve adequate flow.

yes it is a bit tricky. My exhaust also exits from the bottom (out of the water though) and I was able to hang the bucket from the pushpit on the transom. Then I filled the hose with water and plugged it with my thumb and put the end under water in the bucket. Seemed to to do the job.

 

[pyrojames]

Sorry, I have to disagree with pyrojames. It is very common for water to enter the crankcase via the water pump seals. This may very well be accompanied by water leaks outside the engine from the tell-tale holes but it is possible for this not to happen. There is a spectacular example on the water pumps page of my website. In this case the engine had seized completely due to rusting of the piston rings to their bores. Not a Volvo, obviously, but the mechanism and sealing is identical.

The example you give on your webiste shows the water seal and oil seal abutting one another for a Bukh engine? The MD2B does not have this arrangement. There is a significant gap between the seals with drain holes in the housing between the seals to let the water drain away before pressurising the oil seal. I stand behind my comment for the OP's MD2B. (but maybe not for long!)

Note, just looked at the exploded view of the MD2B water pump, and Vyv maybe correct it appears to be the same as the Bukh. Not as I remember it but...

 

[pyrojames]

Thanks pyrojames. Did you have any noticeable overheating when the head gasket went? Or change in exhaust?

None that I noticed.

 

[theoldsalt]

..... but I had been thinking about intercepting it from the point of injection into the exhaust.

Be careful, as denying the exhaust water can cause serious overheating of the exhaust including melting. The exhaust relies on the water for cooling.

 

[VicS]

Waterpump seals is one thing to consider esp if 10 years old.
For the reasons above you should/may notice water leaking from the pump before the water seal becomes so badly worn that water is forced into the engine via the oil seal.

If the water injection into the exhaust is not several inches above the water line you should have a raised loop in the hose leading to the injection point with an antisyphon valve at the highest point.
Check the valve for correct operation. A defective valve might explain water in the oil initially even if not how it may be getting in while recirculating.

The head gaskets are a possibility. Dont rush in to change these. They cost an arm and a leg so check cheaper things first.

If your engine has brass drain cocks ( or plugs) on the cylinder blocks perforation of the cylinder wall due to electrolytic action may be a possibility. It can happen, I understand, to the liners in an MD11 but I do not know if it happens to an MD2B

You may not have got rid of all the water when you drained the old oil. What you are seeing now may be water that remained after draining the oil esp if you sucked it out via the dipstick fitting rather than via the sump drain plug.
I'd feel inclined to flush the engine with the cheapest engine oil that you can find . ( Asda ?)

You dont say if you have the manuals. If not you can find the Owners manual on VP's website http://www.volvopenta.com/volvopent...lication_search/pages/publication_search.aspx
and the workshop manual at http://www.bluemoment.com/downloads.html

_______________________

 

[vyv_cox]

Note, just looked at the exploded view of the MD2B water pump, and Vyv maybe correct it appears to be the same as the Bukh. Not as I remember it but...

I looked at it before posting on http://www.marinepartseurope.com/en/e-volvo-penta-645-MD2B.aspx The pump dimensions looked pretty similar to my old Bukh ones.

I first came across this problem when I bought my Sadler. The previous owner told me that the design of the aft end of the cockpit allowed water aboard when heeled, thus accounting for the large amount in the bilge. I believed this at first but later realised that water was pouring out of the tell-tale holes. It had evidently been like this for a long time as the whole engine compartment was soaked by water flung outwards by the flywheel. When I took the engine out there was considerable corrosion of the lower parts, which made undoing bolts very difficult. Fortunately there was not too much water in the engine (the photo on the website is not of mine).

 

[Jcorstorphine]

Water pumps seals

My MD2B had the water pump seals changed by previous owner some months before I bought the boat. One month after buying the boat I found the engine full to the brim with emulsified oil.

Problem was previous owner had damaged the seals when replacing them and put them back to back so he had blocked the drain hole. Sometimes the drain hole gets blocked up and you would have same problem.

Easy fix for the water pump but i opened the crankcase plates and dried out all the water. Bad news was that the engine was never the same again but it was rubbish in the first place.

John

 

[WotSandbank]

Be careful, as denying the exhaust water can cause serious overheating of the exhaust including melting. The exhaust relies on the water for cooling.

I agree but I am not denying the exhaust water as the recylced water is passed through the engine in the normal way, still passing thru the exhaust hose. Good to point out though.