oil leak on mermaid engine

[gerry27]

Can anyone advise please, I have oil leak in both 17 year old mermaid melody engines on my kempala 38. I have reconditioned cylinder heads - new valve guides etc, and new seals on oil coolers. They were OK until coming back from Paris last year. Running out of ideas!

 

[essexboy]

A bit more info needed with pics if poss ?

 

[volvopaul]

Hi it could be the valve cover gaskets as they are prone to this, the engines sit down angle so the oil runs to the back and runs down over the rear of the engine.

If oil is passing between the exhaust and inlet manifold then its more serious, also the injector pipes pass through a rubber circular seal, oil can pass between them and the head, answer is to tighten the big nut with suitable grips as its difficult to fit the correct size spanner in sometimes.

PS my boats called steelaway!!

 

[gerry27]

Many thanks, will check those points, - it;s a great name for a boat isn't it!

 

[omega2]

I have much older Sabre's/Ford in our boat, as Paul has suggested the rocker cover gasket could be the problem, or even the cylinder head gasket look in the area above the bell housing, for these. Also prone to leaks on the crankcase pulley due to the seal hardening and grooving the pulley boss. If you cannot find oil traces then you are burning it, and this is a design feature just keep topping up, they will go for ever probably see you off!!

 

[gerry27]

Thank you, I'm sure you're right, only problem is that it's coming out of the exhaust and we travel the inland waterways of France! They get very cross if you leak any oil into their waters, especially in the locks. We're waiting to go back and can't until problem solved.

 

[omega2]

Sounds like the damage has already been done, not suitable engines for meandering inland water ways, they need a good thrashing, regular, I would not be surprised if the cylinder linings/pistons are glazed, only way to is to check compressions, take first set of readings, then add oil into the bore and recheck, if they are better then a rebore will be on the cards, if no better then the valves are not seating properly, and if you are turbo'd it could be seals. Why not strap a four stroke outboard on the transom? and use that for the inland bit. Make sure you have tester for diesel engines, petrol engine testers will be destroyed if used.

 

[longjohnsilver]

Just as likely to be unburnt fuel, common with older Mermaids. Does they actually use oil? I'd be surprised if they do. As Omega says, a good thrashing will help. They certainly don't like being run at low revs for extended periods of time.
I've had 2 Mermaids in the past and rate them very highly. Butnthey both left a trail of oily water from the exhaust when running slowly.

 

[LittleShip]

Oil from the exhaust can be two things.

1. As already stated .... cylinders pistons ect but this normally shows as blue smoke!

2. It maybe a sheen which is caused by the engine not reaching temperature and unburned diesel

3. Did I say three......... you may have a leak on the oil cooler, whilst the engine is running oil could be pushed into the coolant water and show as oil from the exhaust. This is normally followed by emulsified oil in the engine.

Check to see if the engine is reaching temperature and the gauge reading doesn't mean the cylinders are upto temperature.
Check if you have any water in the engine oil.
Check if you have any signs of emulsification inside the rocker box.

Dont go stripping down until you have exhausted these points first.

I agree with the Volvo Paul The rubber grommets on the injectors are very prone to leaking after any head work, this normally shows as a drip at the rear starbord side of the head. It is often thought to be the head gasket and or the rocker cover as it runs down the sharp edge on the head.

Hope this helps out

Tom

 

[NorthUp]

4. it may be gearbox oil from the gearbox oil cooler.. as littleship says, dipstick will show cream, not oil.

 

[NigelChattin]

It would be interesting to know what grade of oil you are using. The more modern and expensive fully synthetic oils are not always appropriate and simply changing to thicker oil may resolve the issue.

 

[gerry27]

Great Idea - have found old outboard in the shed, am about to tie it on with a bit of string....will let you know the result!

 

[gerry27]

Thank you, checking out all the points you mention, fingers crossed. We're not 'turbo' so hope all will turn out OK.

 

[gerry27]

Thank you, will check oil.