Perkins T6.354 Best Practice

Regarding an oil change, has anyone has success with sucking the oil out through the turbo return line, where it meets the sump? I don't think I get enough old oil out from suctioning at the dipstick. I'm contemplating removing the oil return line and inserting a suction hose down into the sump there.

Thanks,
Robert

I don't see what you can lose by trying it. The service manual doesn't give much details about that, but I don't see what harm you could do by trying.

It also helps a lot to warm up the engine so the oil isn't cold - much easier to pump.

GOOD LUCK!

J.S.

Smitty,
Sounds like you have done your homework, which is the essential factor in "overpropping" your trawler. Most owners don't know what all those curvy lines on the graphs mean!
From there, it is up to the operator to keep the engine in it's happy spot, and not push up the throttle from there.
Exhaust gas temperature can tell you a lot about how the motor is liking being overpropped.
An occasional out of gear WOT test is also a good idea, the motor should always be able to redline easily.

"Smitty,
Sounds like you have done your homework, which is the essential factor in "overpropping" your trawler. Most owners don't know what all those curvy lines on the graphs mean!
From there, it is up to the operator to keep the engine in it's happy spot, and not push up the throttle from there.
Exhaust gas temperature can tell you a lot about how the motor is liking being overpropped.
An occasional out of gear WOT test is also a good idea, the motor should always be able to redline easily."


Between the 4 boats that we installed pyro and boost gages on and the many others which we have been able to help do the same you really begin to see the relevance of running within an engines designed parameters. Also learned a lot by keeping a strobe tach handy and using it to determine what the real rpms are to ensue all of your testing past that point has value - many were off by a bunch. We have seen a large number of owners have issues due to being overpropped over the years and many of them have graphed out their experiences with the data they collected on their own pyro ,boost and in some occasions their fuel burned ratios as well. In every case we have seen there was no (zero) fuel use advantage to being overpropped and in most cases measurable increases in fuel economy when returning the boat back to correct prop loads. On another forum there was a similar thought posted about purposely overpropping a diesel to achieve better nmpg at slower speeds - a couple of boats did add more than a couple inches to the props and ran into troubles within a year.
I believe that most of the problem with the entire concept comes from commonly known traits of gas engines which run within a fairly narrow fuel/air mixture and therefore could gain some fuel use margins at vary low speeds when overpropped. Diesels can run at vastly larger air/fuel mixtures and actually enjoy the benefits that larger amounts of air and turbulence bring. When helping other diesel owners which have run slow speeds overloaded consistently I have seen the build-ups of combustion by products in the valve and injector areas as well as in intakes and exhaust elbows (all were 4 stroke 6 cyl diesels).
If you really want to get much better mileage knowing your hull and key speeds sill most always yield a 2:1 reduction in fuel use by slowing down 1-1/2 to 2 knots (ie - say 9 knots to 7 knots)or so (dependent upon hull length). In boats with twin diesels you can also often gain a much smaller margin of fuel economy by running on one engine only if the transmission, electrical power demands and your patience can tolerate that method. But using that technique and raising the boats speed very little above your lowest rpms will then again begin to show signs of overload on the engine that is in use - as we saw when we tracked this data with the pyro and boost gages with a single engine test.
FWIW - this is what we have seen and I hope it helps

"On your Bayliner this would be the case, so I ask, can your twin turbo 310 Hinos pull full rated RPM plus about 50?"


No, not 50 - it is propped to reach rated WOT +3-5 % on a fully loaded boat on a hot a humid day - in my case that is over 100 rpms above the rated 3,000 (strobed)


"Smitty, on some small low HP boats being over propped is common provided one never runs the vessel above say a 60% load."


That can be true in some case of low hp engines with high slip angles and very high self control on the captains part. In my experience more than 90% of the owners I know will easily push past the safe level when the 7 knots they are accustomed to is challenged by a strong head current, inclement weather or a problem with their schedule. I have seen the most of that while heading up and own the Hudson river where the tides are stringer and they can last your entire trip.
Now instead of traveling at 7 knots you are at 5 or even lower and any normal person tends to push forward eventually. Not a problem with a correctly propped boat at all as it will just use more fuel for the most part.
In the context of this post the engine is unable to reach 2,400 and is used at 1,400 - turbo and aftercooled and not so low powered. When you do want to occasionally 'open it up' to help clean the fuel and combustion path you really can't.
Hoping that everyone has a good boating experience and does not face any unnecessary problems / expenses.

One could say that Overpropping is validated by the fact that we had OD transmissions in cars. They got better millage.

But any fool that knows how to drive properly knows that when you come to a hill you downshift. And a boat is always on a hill .. so to speak. In any engine application there is an ideal engine speed to road or prop speed. A car in OD on the highway on basically level ground benifits from OD. A boat using only 25% of it's power going very slow benifits from overpropping ...... as long as they don't over fuel the engine. And it's very easy to do when overpropped.

Running a diesel boat at 25% load is a bad thing to do. Trying to make it better by overpropping is also a bad thing to do. And two bads is worse than one .. or none.

But usually I think overpropping burns less fuel only if the boat and engine are very lightly loaded. But if your running a good load (like 50 to 70%) overpropping won't help and probably will result in higher fuel consumption. I think Marin went fro overpropped to correctly propped and either found the fuel burn stayed the same or became less. But Marin dosn't underload his engines and I don't think he ever has.

So (IMO) overpropping can be of benefit but usually is not. Most people overprop for reduced noise. Some think that's justifiable .. I do not.

I also do not believe in over propping. A diesel is a very precise machine and uses fuel based on horsepower used not based on rpm.
By the way my ex boat had a turbocharged diesel and actually made less noise once the rpm got up enough to start producing boost

In a gas engine the amount of air AND fuel is regulated. The amount of fuel is regulated by the velocity of air through the cab venturi. The amount of fuel in a diesel is regulated by the injector pump in any given rpm and the throttle position. The amount of air in a gas engine is regulated by the butterfly valve in the carb. But in the diesel full air is always availible. That's basically why it's so lean at lower loads.

So if you prop to anything but rated rpm at WOT there will be lots of mismatch and over fueling beyond a certian point. Ironically though there will be only one rpm that will be matched wether or not it's overpropped. Rated rpm or some rpm below rated that is frequently not known or not known specifically. Some of what I've just posted may not be true of electronically controled emgines.

Excuse me if this is too far astray from the original thread topic, but:

Has anyone ever put a block heater in one of these engines? If so, which freeze plug did you put it in? Pictures would be awesome.

-Gabe

I bought a 1979 34 Californian three years ago with twin T6.354mgt's at 185hp. The motors then had, as far as I could tell, about 3000 hours. I bought the boat because I could afford it and it was in reasonable condition. I worried about the motors in part because if their age and also because of what I had read in some of the forums. There is no way I could have afforded rebuilds, let alone a complete re power if this had not gone well. It should be noted that my motors have the conventional exhaust manifolds and not the mani coolers. Three years later I have put just under 600 hours on the boat and am glad to report that all is well. The engines start right up, hardly smoke and I see no reason now that I won't get a lot more life from them. My boat is plumbed for flushing the engines, so after every trip I flush the motors with Salt Away or plain fresh water. I also always run two stroke oil in the fuel at a 200/1 ratio. My maintenance schedule is oil at 100 hours, zincs twice a year, and fuel filters twice a year. This winter I plan on cleaning my intercooler and turbos. As far as upgrading the fuel filters to canisters all I do is use electrical tape to tape the cup to the standard filter. It holds well enough that I can fill it with fuel and install it without having to bleed the system. If The engine rpm's start wandering it is a sign that your Racor is getting plugged! Change it or them then and you will be ok. I recommend that you install a pyrometer if one isn't installed already. I know these motors are "old" technology but their simplicity and ease of working on them are a huge benefit. I routinely run 40-60 miles out of San Diego looking for fish and I have complete faith in my boat and motors.

Sweet marie said:

I also always run two stroke oil in the fuel at a 200/1 ratio. My maintenance schedule is oil at 100 hours, zincs twice a year, and fuel filters twice a year. .

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Sounds like you are top of things. Two questions:
-Why add oil to fuel?
-Why change fuel filters twice per year?

I add the oil as a precaution against the low or no sulphur fuel that we get in California. I read a study comparing additives designed to improve lubricity and the two stroke oil scored very high. For me it is cheap insurance. Not wanting to open a can of worms but I can tell the difference, the motors seem to run better with a smoother exhaust note. Maybe it is my imagination. I change the filters twice a year because I got a load of dirty fuel a while back and I had to change the filter(s) on the fly a few times, not fun in rough seas. I could probably cut back to once a year now, but at 8 dollars a pop for the Racor filters, again it is cheap insurance. By the way SW Diesel in Wilmington, California has any part imaginable for Perkins diesels at pretty reasonable pricing. They are also generous with advice and tips.

Sweet marie said:

By the way SW Diesel in Wilmington, California has any part imaginable for Perkins diesels at pretty reasonable pricing. They are also generous with advice and tips.

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That is good to know, thanks. They have a counterpart I believe in the Phoenix area.

Sunchaser where do you keep your boat?

Sweet marie said:

Sunchaser where do you keep your boat?

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Sidney, British Columbia

Gabe n Em said:

Excuse me if this is too far astray from the original thread topic, but:

Has anyone ever put a block heater in one of these engines? If so, which freeze plug did you put it in? Pictures would be awesome.

-Gabe

Click to expand...

You should probably start a new thread on this subject

What's the best way to do a blowby test on the t6.354?
Also, I have a pyrometer and at WOT for thirty minutes it will approach 900f. At 1800 rpm cruise it's around 450f. Does that seem normal? At WOT I experience stream but have checked all temps with an infra red and everything is normal. I had stream before and after replacing the wet elbow, adding a muffler, replacing impellor, and cleaning out the raw water circuit. There is plenty of raw water flow out the exhaust and I'm not losing coolant. I'm concerned the exhaust manifold may be corroded and leaking into the exhaust since it's raw water cooled, however I would think the exhaust pressure in the manifold is high enough to prevent that.

900F should be ok. I have not seen a spec for this engine, but that temp is good for other turbocharged engines in that general size.
NO black smoke is a good thing. That means no or little excess fuel and not building too much heat.
What is your WOT rpm? Should be 2400/2450 (or a little more is ok).

Please do not kid yourself regarding the raw water exhaust manifold. If it leaks externally its a warning sign.
If it leaks internally it can take the engine out in seconds. I know several who have had that happen.

Seems crazy there's not even a zinc on that manifold. If I add it to the freshwater circuit should I flush it with acid?

RP

Why would you want to flush. Many Perkins do not have zincs. not unusual. Do you have an Owner's manual you can use for service work and checks? Just read about Dude's engine flush travails on another thread. You're not overheating and the EGTs sound OK, what is the issue you are trying to fix?

I didn't mean flush the whole circuit, I just meant the exhaust manifold. Seems like there could be a corrosion issue with the salt water. I'll look for the thread you mention.

I flushed my exhaust manifold once. Did it while at anchor using the raw water washdown system.
Put on new end pieces, then painted it with regular engine paint, not the high temp stuff. The theory being that when the manifold overheated it would discolor or burn off the paint.
The flushing made a difference in operating temperature. It wasn't overheating prior, but it was cooler afterward.

My Perkins are plumbed to be flushed with fresh water after each use. Takes less than ten minutes and it flushes the heat exchanger, the intercooler and exhaust manifold. My components stay cleaner and it extends the life of the cast iron exhaust manifolds. Easy to do, just cut in antee after the main strainer/ through hull and put a ball valve on. The hose is then tied to a hose connection somewhere convenient on the outside of the boat. I have one connector for both engines but open one valve at a time while flushing.

Does anyone have the specs for a blow by test or compression test of the T6.354? I have blue smoke and want to rule out the rings and valves.

Thanks,
Robert

I'd like to put my exhaust manifold in the fresh water circuit. I've seen a post at the yahoo group with some of the technical details but I don't know if anybody else has done it or if it's a good modification in the long run. https://groups.yahoo.com/neo/groups/mainship/conversations/messages/31029

I'm wondering if a beefier heat exchanger would be needed in the long run, or possibly adding a second smaller universal one to take out the excess heat from the manifold, which I would think is enormous.

Thanks,
Robert

Rp,
I made the mod, but it's been quite a few years back, don't remember the details.
Seems like there was some McGyvering involved, nothing that you cant work out between the hardware store and NAPA. I would do a MAJOR cleaning of the exhaust manifold first.
I think the 6-354 comes with cast iron exhaust elbow as well, so it will be in the same condition as the exhaust manifold--ready for a good cleanup.
The heat exchanger on mine was adequate to handle the manifold, even with a big water cooled remote V-drive, and running the crap out of the motor, as the boat was woefully underpowered.
All in all, my Perkins ownership was not a wonderful experience, plagued by problems, finally resolved it all by replacing with a good used Cummins.
I bought the Cummins for the same price as a new Pekins heat exchanger, and have done nothing but change oil ever since!

Well, I would have lots of concerns: sufficient coolant flow, too much load on the coolant system, etc. But I read Jay Leonard's Yahoo post that you referenced and at least the water flow turns out ok.

The too much load issue is a serious one. It sounded like he overheated until he increased the size of the main heat exchanger. I wouldn't do it unless I also did that.

And if you decide to do it, take IR gun measurements all over the engine block at wot before, so you can compare it to after. You are robbing some of the coolant flow to satisfy the parallel path through the manifold and that may be marginal for cooling even with the bigger heat exchanger. If you see any spots with temps 5 degrees higher than before, watch out. You may be boiling coolant in a particular area and when you do the steam will block the flow and then .....

The best way would be to increase the coolant pump capacity and the raw water pump capacity as well. Then you are essentially redesigning the entire cooling system.

Thinking this through a little more, Jay increased the port on the coolant pump from 1/2" to 3/4". I am not sure I would do that. Increasing the size just means less for the main block and head. I wonder if 1/2" with 3/4" hose wouldn't allow enough coolant flow to keep the manifold at reasonable temps. Again before and after IR shots will tell the story.

David

Sounds like too much to justify it. What about a generic SS heat exchanger and a separate freshwater circuit for the exhaust manifold? Would SS hold up to hot saltwater? I can get a generic electric hot water pump used in automotive heater systems.

Could I just add a zinc to the manifold?

R_p_ryan said:

Sounds like too much to justify it. What about a generic SS heat exchanger and a separate freshwater circuit for the exhaust manifold? Would SS hold up to hot saltwater? I can get a generic electric hot water pump used in automotive heater systems.

Could I just add a zinc to the manifold?

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That sounds worse. Where are your going to pick up suction for your new fresh water circulating pump? Anyplace you do this you will be robbing flow from the main block. And where will you return the flow to? Sounds like all you are doing is paralleling the main pump.

That generic pump won't be anywhere near as reliable as the main loop and you won't have anyway of knowing if it is ok until it fails.

You can add a zinc but it may not do much good on the other end of the manifold.

David