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Apr 1, 2019
Hello to all,

Ive been seriously searching for a trawler now for a few months and figured this would be the perfect place to get some good advice and share information. My first boat back in the 90's was a 34 CHB which my wife and I really liked but my kids thought was just too slow. So we sold it after a few years and purchased a 36 foot Silverton with twin 454's nice boat but VERY thirsty... Now the kids are gone and the wife and I are ready for another easy going, relaxing trawler.

SO, here is my first question to you all. We are seriously looking at and considering a really nicely restored (impeccably restored) 1974 36 foot Roughwater. The only thing "tormenting" me about this boat is that it has the original 45 year old Perkins 185HP Turbo engine with 1700 hours.
To me the hours is nothing to worry about but the fact that its been sitting in the bilge of a boat for 45 years worries me. The engine is spotlessly clean and the owner has maintained it very well for the last five years anyway. rebuilt the turbo and replaced the exhaust manifold etc.

He was happy to start it up for me and on the first start of the day in ambient temperatures it smoked ever so slightly but cleared up in a few minutes and ran very smoothly, he told me it burns about a quart of oil every 4 to 6 hours. So without rambling on here for too much longer. Anyone out there still motoring around on a 45 year old (single) Perkins boat?? Should I be expecting to replace this engine soon? or if the engine survey comes back clean is the age a none issue?
Appreciate any and all input, opinions and words of wisdom.
Thank you
Welcome aboard. I am not a Perkins expert because I have 32 year old Lehmans. Only experience with Perkins was a good friend that had one. Other than the manifolds were crazy expensive he loved his. If it has been maintained I would not be concerned about it. 1700 hours is low. Good luck.
My last boat had twin 1977 Perkins 6.354 Perkins MGT 185HP engine.

Those engines are rock solid and will last you a long time. Obviously maintenance is an important aspect of any engine. And, over 45 years there will have been variability in maintenance. But, those will take more abuse than the average engine and keep on ticking just fine.

I am actually shocked that it only smokes a little at the slip. The 185hp version needs to push a lot of fuel to drive the turbo at the top end the simple injection system doesn't really have as much flexibility as a modern system. They usually over fuel a good bit at the slip.

The usual "surprise" on that engine is the "breadbox" intercooler that is used because of the turbo. It is an expensive thing and, like any raw water cooler will rot over time. That one isn't more susceptible to it than any other -- it is just particularly expensive. Having said that, brand new aftermarket replacements are readily available from Orca. So, you won't have any trouble replacing it if you need to. The same is true of the oil/transmission cooler and heat exchanger (from Seakamp). They are all available from, among others. Another surprising thing about that engine is that the manifold also gets raw water running through it. So, it rots out eventually just like the coolers. It is also readily available.

I have no idea where in their life these coolers might be, or even how to measure their lifetime. But, as you can tell, I have a lot less concern that you'll end up needing to put money into the engine block than the cooling system.

None-the-less, I wouldn't sweat it. Just get a good survey so you know where they are in their lifecycle. Coolers can often be cleaned out. If necessary cores replaced and bad spots welded. There is a huge amount of space between bran new and news service/repair and even more between there and needs replaced.

Parts are readily available for any part of those engines and surrounding systems. Some are new-new OEM. Some are new-new aftermarket. Some are rebuilt. And, others are reconditioned used. But, places like TAD Diesel in Virginia and S&W in Los Angeles, and (England, but Internet) specialize in them.

Like any boat, the exhaust and turbo can be expensive. But, it sounds like the turbo has been done. The fuel injectors are easily and inexpensively rebuilt. The injector pump, like any pump with rubber seals, will need rebuilt eventually, but when I had one in my old boat pulled apart, it turned out to be in good shape, so I didn't do the other one. Rebuilding the one I did was several hundred dollars, iirc. Regardles, it hadn't been done before -- and after 40 years, still didn't need done.

1 liter of oil over 6 hours seems high for that engine. Most especially if you aren't seeing significant smoke. I guess I can say that I didn't burn that much. But, if you aren't seeing blue smoke -- I don't think you are burning it, at least all of it. I bet there is a leak that is getting cleaned up. Those engines are notorious for leaking around the valve cover. It doesn't have enough screws to keep it down flush. And, people over-tightening it, make it worse, not better. It can also end up flowing in weird places and looking like other things, e.g. side plate gaskets, etc. There are also a few other seals that tend to leak. I spent a lot of time getting those tied down perfectly in my last boat -- and only the new owner knows if I ever did! (I've been afraid to ask).

I'd recommend making sure everything is spotless before your sea trial. Check it yourself. And, I'd recommend checking the levels and exactly noting them. Then, after the sea trial going back down there and looking for leaks and checking the levels again yourself. Make it clear that you understand engines can leak some. But, you need to see where and how much -- no one cleans up a drop. Also make sure all engine tray diapers and diapers near the engines are white --- not grey. No oil absorbing carpeting under the engines. Bring your own diapers, if needed. If oil leaks, you want to see it.

I don't think you have anything to worry about with those engines. I loved them. The new owner of that boat does, too.

I liked the Perkins enough that I got them in my new boat, too. They are the naturally aspirated version of the same 6.354 from the same era.

Many of these old school industrial/agricultural diesel engines are just outstanding w.r.t. longevity. The Perkins 6.354 is among them.

I've collected a bunch of documentation for them. You can find it here:

Look in both the Main folder and the CAPDPAMechanicalInjectorPump folder

Hope this helps.

Thanks Greg for taking the time to write such a detailed reply, I really appreciate it. There is no better teacher than experience and it sounds like you've had plenty with these engines.

The owner of the boat in question is very meticulous about everything on it, and it shows, anything that even looks suspect has been repaired or replaced and like I said the engine was spotless and I don't think he was trying to cover anything up,that's just his nature, and I'm totally okay with that.

The boat is immaculate/spotless.
My biggest (only) concern here is the age of the motor and the fact that he was honest enough to tell me its burning some oil, but I agree that a good engine survey and sea trial should uncover any issues.
Thanks again
Hi Gene,

My only concern with the theory that it is burning 1 liter of oil per 6hrs is that you should be able to see it in the exhaust. That is half a coke can per hour in a single engine.

Even if you can't see the characteristic blue, I'd expext you to see at least seem grey. Motor oil has plenty of energy, but doesn't burn cleanly. Maybe you'll see it underway.

One thing you can do to get some sense of the age of the engine is to remove the valve cocer cap (oil fill) while it is idling, maybe fast idling, and feel for air moving out. The more gas coming out, the older the engine is, in some ways.

But, again, this oil thing doesnt sound like a big deal. As long as they start quick and run well, they are good.

I wouldn't assume the current owners replaced the coolers just to do it. At $3k+ for that intercooler, no one replaces it until nearing EOL (and some tempt problems and stretch further).

Dont think of big ticket items like that in a boolean way. They arent good or bad. They are somewhere in their lifecycle. The goal is just to do your best to learn where, so you can plan ahead.

An inspector could tell you it is good today -- and you have a $3k bill in 1 - 10 years. The survey and inspection is a great chance to get an estimate of that timeline from the surveyor and engine inspector.

It might not affect the value of the boat at sale. But, it might give you confidence to spend more or less on other things now or later. Boat maintenance is much less painful financially when it is planned, routine, and anticipated.

I think. :)

And, again,
Hi Gene,

My only concern with the theory that it is burning 1 liter of oil per 6hrs is that you should be able to see it in the exhaust. That is half a coke can per hour in a single engine.

Even if you can't see the characteristic blue, I'd expext you to see at least seem grey. Motor oil has plenty of energy, but doesn't burn cleanly. Maybe you'll see it underway.

One thing you can do to get some sense of the age of the engine is to remove the valve cocer cap (oil fill) while it is idling, maybe fast idling, and feel for air moving out. The more gas coming out, the older the engine is, in some ways.
The OP said it burns 2 pints (= 1L approx) in 4-6 hours. I had a well used T6354 185hp(turbo+aftercooler) in my previous boat, it had some blow-by, but did not burn anything like that much oil. If the oil burn is correct, it is a concern.But the general engine maintenance, and the hours,seem fine,and it will probably be good for years and years. They are tough agricultural motors, similar to Lehman 120s,but with turbo added.
Perkins, I no not, rumors only and rumors are good, I run a pair of DD's over 22000 hours over 53 years old still running great, good luck see you on the water.
Thanks guys for the advise,

I know for sure the exhaust manifold was replaced do to pin holes and the turbo was rebuilt, all age related wear. I cant remember if anything else was replaced or not and I have asked the owner, I will also have the engine inspected. But I do understand that there are normal wear items that need to be replaced every so often and I'm okay with that, and coming from an aviation background I firmly believe in preventative maintenance and NOT waiting for something to wear out completely before replacing it.
My concern is the age of the motor and weather or not I should be figuring on replacing it soon or maybe maybe even just walk away now.

I know there are certain precautions one can take, like a very thorough inspection, but that there is no right answer here.
Thanks to all
The age of the motor, by itself, is not a concern (.)

Diesel engines are all about compression. Makebsure your inspection happens on a completely cold motor. Walk away and reachedule if it is at all warm. Verify with owner, broker, and captain, and check with IR thermometer. If it starts quickly -- compression is good.

Open valve cover cap. Feel for air moving out. The more gas coming through the crank case. "Blow by" here is an indicator of effective age of the motor. The more blow by gas is coming out, the worse the ring and pistons are sealing. Common culprits are wear and fouling. Basically, aging.too much is a problem. Some isn't. Your inspector can help you calibrate.

You wont be in a position to disassemble the coolers to check them, but look at the end plates of the intercooler, around the zincs, fittings, and welds, and at their general condition. Check the zincs. They should be good -- but brand new can go either way.

Run the boat. Does it get up to WOT RPM or close? Probably about 2400. If not, ask survey about prop match. It can be tested by rpm curve and speed during sea trial.

Once back at slip, after the engine has cooled off to 180 or so, with proper PPE, and if the overflow allows it, open coolant cap on header tank. You should see water movement and maybe bubbles from agitation, but not exhaust gasses coming through. Do it above 175 or a closed thermostat can fool you. If you dont see wayer,moving thermostat is closed and you may not learn much without it being hotter. But, be careful with this one. Opening a hot tank is very dangerous. Also, check level while cold to make sure it is safe. Skip if anything isnt right. You'd likely see this type of problem also in exhaust or cooling.

Figure out where that oil is going and when. It is glong somewhere. Moat likely, you'll see it in exhaust or bilge. If not, check in coolant. Look around. It is going somewhere.

A good inspector can do all,these things and many more.

Really, you have plwnty to learn about the boat and want to start now. But, I suspect it is all good. My last boat had probably been idle close to 10 years. All coolers were shot. Manifolds shot. Turbos shot. Exhaust **** -- and a rata nest.

I reolaced the whole cooling loop, manifolds, exhaust elbows, hoses, and turbos -- and it ran like a champ.

As for what if motor goes bad internally -- they are fully rebuildable or you can buy a rebuilt one. But, in a recreational boat, that just never (very rarely) seems to be needed, except for some weird special cases.
Thank you for the great advise.
From what I know and can visibly see the boat has been meticulously maintained and regularly used for at least the last five years by its current owner and he is only selling in order to buy a bigger boat, so any major issues should have popped up already if the boat had sat around a lot, 1700 hours for a 45 year old boat is not a lot of usage.
So my main concern are things like internal corrosion, leaks etc.
This has been a salt water boat probably most of its life so when I hear stories of oil pans turning to 'dust' it worries me, especially on a single engine boat, I just dont want this thing to crap out on me with the wife and kids on board.
But I understand that there are no absolute guaranties with anything, so a thorough inspection is the only coarse of action to take.
Thanks again
On the older Perkins the crankcase breather is simply a hose from the rocker cover to the intake. My first suspect if no leaks or smoke would be the breather. I have a 4-236 that if filled to the high mark on the dipstick blows 1/2 quart out in a few hours, then 10 or more hours for the second 1/2 quart. My oil consumption is drastically reduced by adding a bit of oil at a time, keeping keeping the oil level in the bottom quarter of the range on the dipstick.
Great advice here. I have nothing to add except that I have twin 1977 4.236 Perkins naturals approaching 4000 hrs. 42 years old and still running strong.

The accessories hanging on the engine are normally where the issues lie with old Perkins. Over 12 years of ownership, I've repaired/rebuilt/replaced the FW pump, oil/tranny cooler stack, heat exchanger, manifold, exhaust elbow, and alternator in addition to normal wear items like belts, hoses and filters. (No turbo/mani cooler installed.) Only the manifold was pricey at over $2K.

They always fire right up and smoke a little on start until warm. My normal oil consumption rate is about 15 hrs per qt of oil. If you see droplets of oil in the exhaust water, check your oil cooler. When my oil consumption rose on one engine, that was my culprit. Replaced the oil/tranny cooler stack for under $300. Had another leak due to a broken bracket and ended up bypassing the cooler to get home. Even without the cooler, the oil temp never rose above 240*F.

I love these engines!
While it all sounds good, you do now have one key thing for your engine surveyor to look for with your sea trial and that is burning or leaking oil. I would want to run the boat at least 3 hours in the sea trial to check the oil. I see three possibilities:

1. It's burning as the owner said, in which case I'd expect to see some in the exhaust.
2. There's a leak and you may or may not see any signs of it.
3. The current owner is so meticulous that he's overestimated it's usage. Yes, every few hours, it's requiring oil to be added but maybe it's 6 hours or maybe 8 and maybe it's a liter or maybe it's not really that much but he's only got liter containers of oil. Unless one times and measures, estimates are rarely accurate and most would estimate on the low side, but this owner sounds like one who might go the other way.

If it runs great but uses oil as he says, I might want some pricing consideration, but would otherwise go for it. I knew one very good mechanic say the ones he was concerned about were 40 year old engines that claimed to use no oil.
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