[pentapenta]

Hi, ill write in English (I'm Danish) so I understand a bit of written swedish.

I have an old B20 boat engine (Volvo Penta AQ115A) that I was gifted. It's still attached to the boat. We're in the process of seeing if it's worth spending time on, or if it will be too expensive (we are students).

There is water on the oil stick when I pull it up.

We are not sure if the engine is stuck or not, and we would like to manually try and turn the engine crankshaft, but we are unsure if it's a bad idea to do when there is water in the oil.

Questions:

1) Should we replace the oil first, before trying to manually turn the crankshaft with a socket wrench (Nyckel?) or is it OK to try and see if the engine is stuck or not, and if it's not stuck, then we change the oil?
2) Do I need to remove the starter engine before turning the crank manually?
3) Should I remove all the spark plugs before trying to turn to crank manually?

If the engine is not stuck, we need to find out where the water came from - if its from the boat having being sunk or if its just condensation.

4) What would be the best way to check if the engine is leaking, would it be a air pressure test? and can you do an air pressure test without the engine running?

Thank you! any advice is welcome, I hope it's OK that the post is in English.

[rid54]

To check if the engine is stuck, just try to turn it. Use a wrench or a socket on the crankshaft front end (the nut at the drive belt pulley). You don't nee to do any preparations, just try to turn it. Removing the plugs is of course a good idea anyway. If it is stuck, you'll notice... If it turns, remove old oil, fill new and try cranking with the starter motor. If that works OK, do a compression test. Remove plugs, open throttle fully and crank with the starter (you'll need a good battery). Attach a compression test instrument to all cylinders in turn and note the measurements. If there are big deviations from 10 bar (kg/cm²) values, more investigations are needed.

Unless the engine block is shot (frozen/cracked) water can enter the oil only from the cooling system and through leaks in the head gasket. A compression test is a help, but if there is a leak ONLY between oil and water systems, that test will not help you, so you may have to remove the cylinder head at some point.

Depending on the situation, that is, what has happened to the boat/engine, other possible events may have caused water to enter the engine (has the engine been submerged?), so don't start fixing things unless you know what problem you are trying to solve.

[lennarte]

Is it realy water or is it cream in the crankcase? Is it cream is "inside" leak, is it water it must came in after the engine has run last time
Är det verkligen vatten eller är det vispgrädde (piskeflöde) i vevhuset? Är det "vispgrädde" är det en "inre" läcka, är det vatten måste komit in efter att motorn har kördes förra gången

[pentapenta]

Good news, the engine turns. What is our next move? Replace the oil and oil filter and see if it runs? or can you do a compression test before that, to see if the block is cracked?

[rid54]

Replace oil and filter. Fill with coolant, try to start. Run for a few minutes, then check engine oil level and notice how it looks. If it looks good (no traces of coolant), run engine until it warms up, taking care not to run it at high speed. Check oil again.

A compression test will not give any conclusive information regarding leaks between oil and coolant channels (how water gets into the oil). If the oil gets contaminated again, you will need to take the head off to check the head and the gasket.

A worst case scenario is if the engine has been standing with no anti-freeze in the coolant, and the temp has been below zero C. If the coolant freezes, there may be cracks in the water jackets in the engine block. The coolant will then run into the sump about as fast as you can fill the system.

[pentapenta]

OK, thank you.

Question:

1) Which coolant should I get (from Biltema) and where do I fill the coolant?
2) When checking engine oil, I still just use the oil gauge stick, that I pull up out of the engine - right?

[rid54]

Any normal, cheap ethylene-glycol-based coolant will do for the testing. I don't know where to fill, unless there is a normal radiator in the boat... But I'd guess it is something else in a boat. The hoses from the engine may give a clue.

Checking oil could be done with the dipstick, yes. You will see the level and the oil will look very odd if there is water in it (opaque, creamy, perhaps even coloured by the coolant).

[norings]

Hej hoppas du fårstår på svenska, har haft en båt med likadan motor med aquamatic 100 drev som var saltvattenkyld, det är ganska vanligt att avgaslimpan och avgaskröken rostar sönder på dessa när dom blir gammla och då suger motorn i sig kylvatten om man drar av på gasen snabbt, råkade själv ut för detta när min avgaskrök rostade sönder. Om motorn har stått utan att man tappat ur vattnet ur den kan den frusit sönder, är motorn sötvattenkyld eller saltvattenkyld? Är motorn saltvattenkyld så är risk att topplockspackningen har gått sönder för att kylkanelerna rostar och blir så stora att packningen inte kan hålla tätt längra.

[lennarte]

Utan att veta vad han har för installation, alla B20 marinmotorer är från fabrik sjövattenkylda om inte installationen av färskvattenkylning beställdes i samband med nymontering, alltså saltvatten om båten körs i havet. När Volvo började marin konvertera B21 motorerna är alla färskvattenkylda (värmeväxlare), alltså omkring -75.

[LarsBd]

För att felsöka ett eventuellt vattenläckage använd rent vatten om möjligt, med tanke på frysrisken. Lite rent vatten i motoroljan är ingen katastrof och man kan låta motorn gå en stund utan skador.
Glykol däremot gör att oljefilmen brister och ger snabbt metallkontakt med stort slitage i alla lagerytor, det brukar sluta med lagerbyte.
Med rent vatten i kylsystemet är det dessutom bara att släppa ut på marken om systemet behöver tömmas för någon åtgärd.