Volvo Penta MD7A - Water in oil problemns

[Abestea]

I seem to have encountered a myriad of problems on my engine.

1. There is water seeping somehow into the oil.
I have no idea why!!

2. There seems to be a slight leak at the sea pump.
Could this be the reason for the water getting into the engine oil?

3. When i took off the cylinder head. there appears to be a hole on the side which is next to the exaust manifold. The gasket does has a hole there, about the size of a tem pence piece. but the hole is not circular. should this be here?

I am just not sure where i need to go from here!! i am not sure if the cylinder head is knackered. Can someone help me please!!

Thanks.

 

[steve_cronin]

Could be a complex problem but it is hard to say, so let's just take it stage by stage otherwise one of us "old sages" will be giving you so many options probably neither you nor us will be any the wiser!

This "oil in the water", where exactly are you finding it? Also can you tell me if the oil, otherwise looks normal or is it an opaque, milky looking liquid or does it just look like you would expect oil to look?

Waiting for your reply to that first, before we go on.

Steve Cronin

 

[Abestea]

Thanks,

The problem is in the sump when i checked the oil level. The oil is milky. It turned milky initially when i put the boat back into the water after it had been laid up for a while. I thought it may have just been condensation but it is just as bad again. After i had replaced the initially used oil and filter, it seemed fine, even after about four hours of engine usage. After leaving it for a week, the oil is as bad as ever!

 

[freebird1]

I had this problem on a Bukh engine. In my case the oil was emulsified (milky grey) by being thoroughly mixed with sea water that had migrated along the shaft that drives the water impeller. The two rubber O rings that kept the oil in and water out of the engine had perished. Lots of hassle but not a major problem if if has not been left for months. Check for play in the shaft that drives the water pump. Check the drain hole in the pump assembly has not become blocked.
If shaft worn, replace and change O rings. Engine can be flushed through with lots of parafin - turn the engine over by hand with fuel shut off to get it all shifted. Drain and refill with oil.

 

[VicS]

The water pump has two seals fitted opposite ways round so that one prevents water leaking from the pump and the other prevents oil leaking from the crankcase. Normally, but I cannot say for sure if yours does, there is a drain hole in the under side of the pump between the two seals from which water will escape if the water side seal is leaking. If that drain does not exist or is blocked then a leaking water side seal will lead to water being forced past the oil seal and into the oil sump.

I cannot comment on the head but the exhaust manifold forms an integral part of the cooling system so in addition to the exhaust ports there are connections to the water passages in the head. I imagine that the hole you describe is one of them. Does it connect with the water passages in the manifold. Any leakage of water from the head into the oil is more likely to be via a defective head gasket. It is difficult to see how it could get into the oil sump via the joint with the exhaust manifold.

What concerns me most is what you say in your second post about things being OK after 4hours running but as bad as ever after standing for a week. That would point to two things. Firstly that you are not closing the cooling water intake seacock and secondly that the antisyphon valve in the "plumbing" between the engine and the water injection point is not operating correctly. Check that the inlet seacock is shut/shutting off properly and clean/service/replace the antisyphon valve.

I am not sure that I entirely agree with Kadeena's suggestion to flush the engine with paraffin. Don't do that unless you are sue you can drain it all out, that is very unlikely to be the case, there are usually too many places in a engine that do not drain including the oil filter. It would be better to use a cheap engine oil for the purpose, several times over, with short runs under little or no load, if necessary. Even if you do decide to flush with paraffin flush with a full charge of egine oil afterwards, giving it a short run under light load before draining that to get rid of the paraffin.

 

[joeh]

i had a similar problem on my md6a few years ago. the problem was the worn rubber seal in the fuel pump. replaced n i was ok.

 

[gandy]

Do you have the workshop manual? It's downloadable from somewhere, I can't remember where. I can email you a copy if it helps. For what its worth, the seawater pump looks pretty easy to check, and its probably worth replacing the seals and O rings as a precaution.

As Vic says there should be a drain behind the pump, in the space that shouldn't have either oil or water.

 

[VicS]

[ QUOTE ]
worn rubber seal in the fuel pump.

[/ QUOTE ] Fuel pump? Wouln't that lead to fuel in the oil rather than water.

 

[VicS]

[ QUOTE ]
workshop manual? It's downloadable from somewhere

[/ QUOTE ] If the manual is available for download then it is from here I have not checked though.


There are also schematic diagrams Here

 

[joeh]

hey you are rite
my mistake
it was diesel i found in the lube

 

[stevebirch2002]

The Albin Vega uses the MD6A as standard fit and had quite a few dealings with the engine problems.
1. Water pump seals are the first choice. There was a mod that had to be carried out which entailed taking the O RIng away as this blocked the drain hole. One seal stops sea wter getting into the engine and the other stops the oil getting into the seawater pump. You need two Oil Lipseals (1" x 0.5" x 0.25")
2. Sea water cooling leaking into the engine through a cooling channel, could be anywhere.

Hope that helps.

Cheers

Steve B

 

[Bilgediver]

There are various routes that water can leak into your engine and turn the oil milky.

Yes water can leak along the pump shaft but this is not normally possible as there is a drain hole between the two seals about half way along the round portion of the pump casing on the bottom to release leakage to the bilges. This hole is sometimes missing or can be blocked with paint. Check you can find this hole and that is is clear.

You seem to have the head off and are asking about the port on the exhaust side in the gasket face. This port in the head is a cored port so might not be round. In the block it is also a cored depression with a SMALLER hole drilled through at the bottom. This hole must me clear as it regulates the thermionic flow between the block and the head.

Some of the later engines have wet liners. If you have wet liner(s) then it is possible the liner seals are leaking. However another fault that developes is that a hole developes in the liner opposite the drain cock and this is invisible as always covered by the piston. It is usually an easy task to jack the block up enough to see if this hole exists. This only happens in the wet liner engines.

I am puzzled as are others that you say the engine was fine after running...are you saying the oil was fine when you stopped the engine but was white next time you went to the boat. This is confusing because if the engine was NOT run between times then the oil would not emulsify but the sump level would rise and only emulsify on restart.

A volvo engine in a boat here had this problem a few years ago and after draining the engines a few times I heard about the probllem and we found the hole in the liner.

SOmetimes there is a shadow on the cylinder wall above this hole caused by the different lubrication of the wet oil /forums/images/graemlins/smile.gif

This engine did not suffer in any way after swallowing large quantities of water and after replacing the liner and turning the other 90 degrees and fitting new rings it ran perfectly.

The other place water can get into the engine is via the exhaust. Either by leakage past the water pump to the mixing elbow or due to there being either no water trap in the exhaust or the water trap being too small for the volume of the exhaust.

If you suspect the exhaust system try turning off the sea cock before stopping the engine and then turning on only after the engine is running.

If this stops the problem then the exhaust setup needs to be improved.


John

 

[VicS]

[ QUOTE ]
You need two Oil Lipseals (1" x 0.5" x 0.25")


[/ QUOTE ] I think you will find that there were several different pumps fitted to the MD6 and 7. They may not all be the same.

 

[Abestea]

There does not seem to be a clear indication of a drain hole in the sea water pump housing. I can only suspect that it has been blocked up over the years. The lower attaching bolt is very corroded and will need to be replaced. I shall try and remove it and recondition it anyway. May as well eliminate a potential problem.

I had turned off the sea cock after i was finished sailing but I am unsure where the anti syphon valve is on the engine and I cant see it in the manual. But i did see the mating surface of the cylinder head that i was wondering about. and the hole is exactly the size i thought it should be. (section 5 page 11) There is an alarming build up of something on my cylinder head. Is there something i can do to remove it?

The milky oil is confusing myself as well. I can only assume that i checked the oil too quickly after use and the bad stuff had not flowed back into the sump. I know i am fetching here but i am just as confused as everyone else!

 

[thalassa]

[ QUOTE ]
. Normally, but I cannot say for sure if yours does, there is a drain hole in the under side of the pump between the two seals from which water will escape if the water side seal is leaking. If that drain does not exist or is blocked then a leaking water side seal will lead to water being forced past the oil seal and into the oil sump.

[/ QUOTE ]
From the experience I had with the MD7A, this is the most likely scenario. As long as the engine is running, the cooling water will keep flowing out. Once the engine stops, water will drain past by the worn shaft bearing into the engine.

 

[gandy]

[ QUOTE ]
1. Water pump seals are the first choice. There was a mod that had to be carried out which entailed taking the O RIng away as this blocked the drain hole. One seal stops sea wter getting into the engine and the other stops the oil getting into the seawater pump. ...

[/ QUOTE ] Ahh. That explains the bit in the manual that says "NOTE! A new 0-ring must not be fitted. " I thought that must be a misprint.

 

[VicS]

[ QUOTE ]
I am unsure where the anti syphon valve is on the engine and I cant see it in the manual

[/ QUOTE ] If the cooling water injection into the exhaust is not well above the water line an antisyphon vent should be fitted in a loop of the final cooling water outlet pipe and located a minimum of 30cm above the WL. It is similar to the vented loop(s) on your toilet plumbing unless you have a Lavac. There are in fact two types one of which incorporates a mechanical relief valve, the other has small diameter outlet that discharges over board or somewhere handily visible, like into a cockpit drain. The former type is shown in this diagram

It is parts numbered 60 to 65.

 

[Frankklose]

If the water comes through a leakage on the water pump there should be some water flowing out of the pilot hole which is located between the two seal in pump.
If there is a leakage in the cylinder head it means a NEW ENGINE.
No parts are available from Volvo for the older MD11 MD7 etc since a number of year..
The Volvo Repair Center manger fraised it in a German forum for a few weeks ago like this .
„Eine sachgerechte Reparatur am Zylinderkopf ist für die alten Modelle nicht mehr möglich"

Translation " A proper repair on the cylinder head is not possible anymore for the older models"
They published also some photos which were self-explanatory.
No Parts no repair. The head was corroded.

 

[Catamaranlove]

Water in oil

I have an older penta and stern leg,2.0L same problem, the guy got it off said the engine was running great, we even went for a quick run in the harbour, but then noticed the water pump leaking. The sump us oil is greyish colour. Is this a common problem in inboard sea motors? I've only ever had outboards in the past.