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I was in the engine room early yesterday, working to clean away the oil that had leaked out of the engine in the hope of determining the source of the problem(s?). Even though, when compared to many other boats, the access to our Perkins engine is great, it’s still a tight fit to get down beside it. This made the job a tiny bit claustrophobic at times.

Once most of the surfaces of the engine were a bit more clean, it didn’t take too long for me to notice this leak…

Knowledgeable friends, both in person and online, assure me that if this is the only problem, the valve cover gasket, we’re golden. I am not quite so optimistic to believe that is the case, but we’ll start with the relatively easy and obvious issues first. Fortunately, the boat came with a complete set of gaskets so hopefully, I have all that I need on hand to complete the job. I say hopefully because with J’ouvert beginning early tomorrow morning, the nearby boat chandlery is all boarded up. Yes, they do that as less than 24 hours from now, the streets will be filled with oil and paint covered revelers!


  1. My ’83 Irwin has the original Perkins 4-108. It’s in excellent condition. When I bought it, you could tell it was well taken care of After 10 hours of engine time, it was obvious it had an oil leak – but mine was down around the crank case. I spent $1300 on a mechanic trying to get rid of that oil leak. It was greatly lessened. Being the perfectionist that I am, I did lots more research.

    Finally I ran across a Perkins guru in my travels who told me that I will always have a small oil leak of some sort. He said that the crankcase pressure is too high in those engines and he recommended an Air-Sep which reduces the crankcase pressure. I couldn’t find anyone else who had heard of it. I purchased one (I think it was around $500) and installed it on the engine (about 8 years ago). It almost did away with the leak completely. Still, as I have conversations with marine mechanics, almost none have heard of it.

    It might not apply to your current leak problem, but put this little data nugget into your quiver for the future.

  2. A surveyor years ago told me, if you have a Perkins and it doesn’t leak oil, it’s out of oil!

  3. If take the valvecover off, make sure to check the valve clearance at the same time. If you don’t have the gauges for that, have a mechanic check it for you.

  4. Just for grins and giggles I once timed a “5 minute job.” It took 2.5 hours, some bad words and bloody knuckles.

    I’m off to do some boat shopping later today. The boats I’m looking at are supposed to be in great shape, but I know there’s always something to deal with. This is the time of year in New England when the good boat deals start to pop up. I wasn’t really in the market this year, but the prices are too good to resist.

  5. While the valve cover is off, make sure it is straight, or a new gasket will be for naught.


  6. I’ve just replaced the rocker cover gasket on a Ford Lehman. I noticed the old one was ‘glued’ to the cover – a memory recall from years ago told me that one of the difficulties of replacement is keeping the gasket in it’s rightful place when you re-install.
    So I scraped it all clean, applied a thin layer of contact adhesive to both ‘lid’ and the correct gasket face with an artists brush and applied the gasket to the ‘lid’.
    Refitting was a breeze with no leaks and I’ve taken it off one more time to re-torque the head bolts. It came off with the gasket still securely fixed and back on with again no leaks.

    ps – I’ve been ‘stalking your website from Day 1 and it’s given me no end of useful information – stay lucky – Mick

  7. Years ago I replaced my old engine for a new 4-108 and put about 500 hours on it before selling the boat. Based on others comments I guess I may have been lucky, but no leaks.

  8. Before reading GW’s comment, I was going to ask about the crankcase breather. I wonder if one could be installed either in the oil pan or the valve cover. The valve cover would be optimal if the oil drain holes are big enough to prevent blowby from preventing the oil from returning to the crankcase.

    For the valves, always adjust them to the outermost spec. As the engine wears, the valves will recede into the valve seats and close the gap.

  9. From the top view picture, it seem like the engine already has a crank case vent into the engine breather . As you will have the valve cover off, you can easily check the hose and see if its blocked in any way.

  10. Hey Mike, I hope your oil leak turns out to be an easy fix. When I bought my Maramu it had the same engine but I repowered with a 75hp yanmar. The original had a wood step mounted on it so you didn’t need to step on the valve cover to get down into the engine room. Maybe the leak is from foot traffic?

  11. Well…I see that there is an other Ross here so I’ll be rossny here. I saved the wood step to mount on the new engine. Didn’t get to that yet, if you like I will dig it out and get a picture to you.

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