Fixing what ain't broke

[Snotter]

I have an old Perkins 4-154 with about 250 hours on it since its last rebuild (1984). It is running pretty good except for some soot build up on the transom. Though I usually run my engine ~2500 rpm, Roger Long's thread has got me convinced I should probably up that to about 2700-2800 rpm (it tops out at about 3200 rpm under full load (7.2kts with a dirty bottom)).

The 4-154s are no longer being supported by Perkins. For this reason I always keep an eye on ebay for spare parts. I just snagged myself four rebuilt fuel injectors. The question I have for y'all is should I put these babies into storage or should I put them in now? In other words, should I leave well enough alone?

 

[Ross]

The engine needs to be used! leave the sails furled and go motor boating for a couple of days and then study the exhaust at 2000 rpm if it is smokey then the new injectors are indicated. Last spring I had to motor all day for four days because of a dead flat calm. The engine purred like a kitten and there was zero smoke at full throttle after the boat speed matched the engine speed. Diesels will smoke when they are running slower than the throttle setting calls for.

 

[RichH]

Injectors of all configurations, etc. are fairly common. Engine manufacturers usually dont MAKE injectors, they BUY them from common sources. Injectors can usually be obtained from 'specialty injector shops' - and every town over pop. 20,000 in the USA has at least one injector shop.
I'd save them and not install them.

Most 'older' internal combustion engines were designed to be run 'overfueled' ... the 'extra' fuel needed to help cool the combustion chamber and therefore its was OK for these older engines to have a 'wee bit of smoke'.

 

[sailaway78]

I think it's pretty normal

I think getting some dark soot stain around the exhaust is pretty normal, depending on where the exhaust is located. If you don't notice it smoking, and it runs good, I would just leave it alone.

 

[bobtigar]

I have an old Perkins 4-154 with about 250 hours on it since its last rebuild (1984). It is running pretty good except for some soot build up on the transom. Though I usually run my engine ~2500 rpm, Roger Long's thread has got me convinced I should probably up that to about 2700-2800 rpm (it tops out at about 3200 rpm under full load (7.2kts with a dirty bottom)).

The 4-154s are no longer being supported by Perkins. For this reason I always keep an eye on ebay for spare parts. I just snagged myself four rebuilt fuel injectors. The question I have for y'all is should I put these babies into storage or should I put them in now? In other words, should I leave well enough alone?

There are a couple of things that cause soot that are not related to engine problems:
1. Use of road diesel rather than marine (red). This is a 80/20 or 90/10 blend and the cetane rating is lower. You can use it and if you add a booster, you will minimize the soot.
2. Check the prop for barnicles. If its built up that can affect engine preformance, cause overheating and soot. Bob

 

[Roger Long]

1. Use of road diesel rather than marine (red). This is a 80/20 or 90/10 blend and the cetane rating is lower.

I use road diesel as much as possible per Rich H's suggestion that the higher turnover of a truck stop means cleaner fuel. I get the proper light gray smoke and a little bit of sooting around the exhaust outlet but nothing I would call soot build up. I don't normally use a cetane booster and my Yanmar seems quite happy.

How much lower is the cetane level of road fuel than marine?

 

[Snotter]

There are a couple of things that cause soot that are not related to engine problems:
1. Use of road diesel rather than marine (red). This is a 80/20 or 90/10 blend and the cetane rating is lower. You can use it and if you add a booster, you will minimize the soot.
2. Check the prop for barnicles. If its built up that can affect engine preformance, cause overheating and soot. Bob

I always get my fuel from marinas; and, my boat is used in fresh water only.

I can't see soot coming out of the exhaust when motoring. However, after a few hours of motoring (2500 rpm, which may not be high enough according to Roger Long's thread) soot will appear once again after I've cleaned the transom. Perhaps it would be worthwhile to clean the transom and power for a few hours at 2800 rpm to determine if the soot is as noticable.

 

[RichH]

How much lower is the cetane level of road fuel than marine?

Should be the same cetane rating ... only difference is the dye thats added to signify that the 'road use taxes' were not applied.

Then you have to ask: how come 'marina fuel' is always 20-25% more expensive than 'truckstop' fuel ... especially if marina fuel has less tax applied, same fuel but has dye added? Answer: Captive audience.

 

[Roger Long]

Then you have to ask: how come 'marina fuel' is always 20-25% more expensive than 'truckstop' fuel?

Actually, they are exactly the same price in Portland Maine right now, at least at the marina with a web cam that I can zoom in on the pump. The gas station I buy at usually has the lowest gas prices in town or within a few pennies.

 

[Steve Dion]

Do you know your prop specs? If you do, have a prop shop calculate what prop you should have on your boat and compare it to what you currently have. This is a very common problem, assuming you have a clean underbody.

 

[Steve Dion]

Rich:

There is also the volume factor when it comes to marina fuel prices. These truck stops use hundreds of thousands of gallons of fuel a month. I doubt that any marina see anywhere near this sort of volume.

 

[Don12364]

4-154s were designed for London Taxis and you don't think that cabbies gave a fig for the correct RPM. They go for 1/2 million miles.
If it ain't broke it never will be so just leave it.

Actually its probably just waiting for you to die rather than the other way round!

 

[RAD]

I have an old Westerbeke W30 in my old girl and I'm always looking out for spare parts on EBay and I run mine at WOT when ever I have to motor

 

[Ken13559]

4-154s were designed for London Taxis and you don't think that cabbies gave a fig for the correct RPM. They go for 1/2 million miles.
If it ain't broke it never will be so just leave it.

Actually its probably just waiting for you to die rather than the other way round!

So are you suggesting Snotter buys spare parts for himself rather than for the Perkin ?

 

[Snotter]

Do you know your prop specs? If you do, have a prop shop calculate what prop you should have on your boat and compare it to what you currently have. This is a very common problem, assuming you have a clean underbody.

I plan on replacing my current prop with a Cambell Sailor (sp?) when the boat is next hauled in about a year. I will plan on one or two iterations.

 

[Bill1565]

The folks at northwest (Campbell retail) are very knowledgeable and very helpful. I would be surprised if there were more than one iteration

 

[jibes138]

If it is fixed don't break it

 

[Snotter]

I appreciate the advice I've received here. The fuel injectors are going to go into the spare-parts locker.

 

[ffaubert]

Interesting.

I would have thought the consensus to have been to put the injectors in. That way you would know that they fit and work and positive knowledge that your spares (the old injectors) work as well.

If they didn't work, you could always put the others back in, buy new ones and again know that everything was going to work when you needed it to.

Maybe I just have too much time on my hands. I'll have to buy a wooden boat next.