Water in engine oil – Volvo AQ171c

moresparks

moresparks

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Hi guys looking for suggestions please.
Boat has been fine all season, nice and reliable and no problems. The week before it was lifted for the winter one engine was hard to start. On close examination the carbs had a lot of condensation inside the flame shield lids and the accelerator pump was rusted solid within a week. Cleaned all this up and eventually started and ran.
Come to winterise and I have the same problem again. I managed to run the engine with the SternDrive in a tank so completed the winterisation and fogg the cylinders etc.
However, on changing the oil and filter I have the tell tale signs of water in the oil. The level has not changed but normally the oil is clean just like new and not coffee coloured.
The other engine is fine.
So where to start? The exhaust manifold is quite old so that’s one possibility. We have not had a frost yet so I don’t think it would be a cracked block or manifold. Maybe a head gasket?
Hoping somebody may know of similar problems and point me in the right direction; at least I have all winter to sort it out.
 
it sounds like the engine may not be operating at a hot enough temperature, which causes mayonnaise/ emulsification.

If the engine coolant level remains the same, and the oil level doesn't increase then just change the oil more regularly, and consider changing the thermostat!
 
moresparks said:
Hi guys looking for suggestions please.
Boat has been fine all season, nice and reliable and no problems. The week before it was lifted for the winter one engine was hard to start. On close examination the carbs had a lot of condensation inside the flame shield lids and the accelerator pump was rusted solid within a week. Cleaned all this up and eventually started and ran.
Come to winterise and I have the same problem again. I managed to run the engine with the SternDrive in a tank so completed the winterisation and fogg the cylinders etc.
However, on changing the oil and filter I have the tell tale signs of water in the oil. The level has not changed but normally the oil is clean just like new and not coffee coloured.
The other engine is fine.
So where to start? The exhaust manifold is quite old so that’s one possibility. We have not had a frost yet so I don’t think it would be a cracked block or manifold. Maybe a head gasket?
Hoping somebody may know of similar problems and point me in the right direction; at least I have all winter to sort it out.
Click to expand...

Start with the exhaust manifold a def problem on the 151/171 petrols, check the elbow as well.
 
Take the manifolds off and look inside the exhaust ports of them. I've seen these corrode and flake and allow small amounts of water into the bore. Rear most port is prone to corroding through, if I remember correctly.
 
Thanks guys – at least I have a plan now and a major strip down. My first thought was the exhaust manifold but kind of hoping it wasn’t, seeing as they are now quite rare to obtain and expensive. Interestingly; I replaced the water pump shaft seal at the beginning of the season!
 
moresparks said:
Thanks guys – at least I have a plan now and a major strip down. My first thought was the exhaust manifold but kind of hoping it wasn’t, seeing as they are now quite rare to obtain and expensive. Interestingly; I replaced the water pump shaft seal at the beginning of the season!
Click to expand...

If the wp seal has gone you will see water dripping from below the shaft when the engine is running,if it's that bad it will leak the contents of the pump body when its stationary .
 
If the water pump seal is gone it wil leak from the back of the pump and spray on to the cam belt on a 171, this will corrode the belly pulleys and the belt adjuster bearing, both these are potential causes of belt failure which on a 171 is terminal, ask me how I know...

If your exhaust manifold is corroded then you may well get salt water in sitting in the exhaust ports and running back into the cylinders, again not good

Neither of the above are causes of emulsified oil, which could be caused by head gasket failure, a leaky oil cooler ( there are o-rings either end of the tube stack that could fail iirc) or as someone else has suggested oil can can get damp and absorb condensation if the engine operating temperature is not high enough (thermostat stuck open) to sweat it out.

If you need any bits I still have half a 171 lying around (no manifold or serviceable head I am afraid)
 
hi , hope its not manifold related as very difficult to find, we get offered them occasionally. Likely to be a much simpler and inexpensive fault, check the oil cooler,
could be the insert heat exchanger , cooler element , or even just old, misplaced or perished o ring seals in the oil cooler. if nothing obvious pressure test to insert, readily available secondhand around £120.
hope this helps Paul
 
Just an update.
I have removed the manifolds and had a quick check of the exhaust manifold and it looks in pretty good condition for its age. I will do a full test over the next week or so but the culprit looks like it could be the oil cooler. The cooler is easier to inspect after the exhaust manifold has been removed and there is some distinct emulsified oil at the end cap. I will remove this at the weekend for a full check.
Thank you for your suggestions.
 
How definitive is a compression check in regard to the head gasket?
I have undertaken a compression test albeit on a cold engine and all cylinders are around 160 which looks o/k. My dilemma is do I persevere and strip down or leave well alone. The original symptoms were evident fairly quickly without the engine being up to normal operating temperature.
Whilst the manifolds are off I will change the timing belt etc, but I don’t want to put it all back together only to find a problem with the head gasket later on. Ideally a leak down test would be advisable but I do not have access to the tools. Changing the head gasket is a pain especially if I don’t have to?
Decisions ... decisions!
 
A coolant pressure test is the best way to check for leaks but if you are worried that it maybe a head gasket, remove the rad cap, start the engine and look for air bubbles coming up to the header tank. Air bubbles will be seen if the head gasket has gone. Removing the stat will allow water to circulate easier.

Not the best way to check but a simple and easy one.

Good luck

Tom.
 
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