Minimum Cetane 45?

[VanIslandGuy]

Do the new rail-diesels run on lower cetane levels than the old mechanical injection pump diesels?

Our 1998 Yanmar 4jh2e has slowly been developing a problem with exhaust smoke. Generally white with occasionally a blueish tint to it.

After going through the engine, with a fine tooth comb, (injectors were machine polished, replaced two clean fuel filters, checked fuel tank for sediment, replaced the thermostat and impeller), yet I couldn't stop this stinky smoke completely. I have the smoothest running stinky engine in the area.

I re-read the operators manual and it states that fuels with a cetane rating below 45 may result in a blueish white exhaust. Hmmm....

I brought the boat back from Seattle in 2016 with zero smoke or stink. Since then I've only bought fuel locally on Vancouver Island. I decided to phone the two places I've purchased 90% of my diesel from and to my surprise their diesel pump's says cetane index of 40, while the manual calls for minimum 45. Foolish me, I assumed all diesel sold at big marine retailers would be fine. I have always added Startron and have had zero water or algae issues. However I hadn't considered that the minimum cetane level from the pump would be below what the manual states.

Looks like I will be buying some cetane booster. Anyone have good recommendations?

[a64pilot]

In the Diesel pickup hot rodding world Stanadyne is very popular, although I had real good luck with Diesel Kleen, and it’s widely available
https://powerservice.com/psp_product...-cetane-boost/

Odd your getting only 40, that is the min allowed.
Is this Valvtect fuel? It’s seems that is sometimes a better grade of fuel.
Oddly I believe California requires a Cetane rating of over 50, and sometimes, rarely you can find Premium Diesel with higher Cetane.

But yes, lower Cetane burns slower and may require more injection advance, and in high speed Diesels, which we all are isn’t a good fuel.

You are likely correct, and I’m wondering now just how many Yanmars that smoke, do so due to low Cetane. I have always just accepted that Yanmars are a smoky engine and gone with that, but now I’m likely to go buy some Diesel Kleen at Walmart. It came in white jugs and silver ones, and I believe the silver ones boosted Cetane higher and maybe the white jug was for low temps?

[a64pilot]

This also has an excellent rep, but I’ve not seen it for sale locally, I guess you have to order it.
https://fppf.com/product/8-cetane-improver/

[Compass790]

That's interesting, never thought to check cetane rating, just assumed it would be above minimum at a place like B.C. anyway. Let us know if cetane booster cures your engines symptoms please.

[VanIslandGuy]

Originally Posted by a64pilot

In the Diesel pickup hot rodding world Stanadyne is very popular, although I had real good luck with Diesel Kleen, and it’s widely available
https://powerservice.com/psp_product...-cetane-boost/

Odd your getting only 40, that is the min allowed.
Is this Valvtect fuel? It’s seems that is sometimes a better grade of fuel.
Oddly I believe California requires a Cetane rating of over 50, and sometimes, rarely you can find Premium Diesel with higher Cetane.

But yes, lower Cetane burns slower and may require more injection advance, and in high speed Diesels, which we all are isn’t a good fuel.

You are likely correct, and I’m wondering now just how many Yanmars that smoke, do so due to low Cetane. I have always just accepted that Yanmars are a smoky engine and gone with that, but now I’m likely to go buy some Diesel Kleen at Walmart. It came in white jugs and silver ones, and I believe the silver ones boosted Cetane higher and maybe the white jug was for low temps?

Thanks for the recommends. The FPPF 8+ wasn't sold locally, but I found and picked up two bottles of the PS Diesel Kleen+ cetane tonight. I have around 30 gallons in the tank, so I'll add the 16 oz bottle and see if things improve.

[a64pilot]

Let me know, I’m interested in your results.
I don’t think it will be an instant improvement, may take a few hours?

[VanIslandGuy]

We're leaving on a two week cruise tomorrow. I plan on giving the diesel 'an Italian tune-up' for the first few days and run it about 4 hours a day at 3200 rpm. Hoping that by day 3 we will start seeing a difference.

[a64pilot]

I’d watch her close initially at high RPM, if you have any cooling issues etc., they will likely surface.
Me I cruise at lower RPM and hold my foot on the throttle to hold it wide open for a few minutes once or twice a day if motoring all day. Mine won’t stay wide open, and as how I never run it that way anyhow I haven’t bothered cranking in enough throttle cable friction so that it will.

I think if it’s low Cetane and assuming the fuel additive really increases Cetane, I think you’ll see a difference pretty quick, after blowing all the junk out.

[Compass790]

Sorry if this is stating the obvious but is there anywhere on the island you can get a higher cetane no. fuel? I imagine it will be cheaper than cetane booster even if it's more than 40 cetane.
Here in NZ bio diesel min cetane is 51 & HSD diesel is 47 min but standard is 50. Do you get biodiesel on the island? Maybe that works if you are allowed to run it by Yanmar.

[VanIslandGuy]

Originally Posted by Compass790

Sorry if this is stating the obvious but is there anywhere on the island you can get a higher cetane no. fuel? I imagine it will be cheaper than cetane booster even if it's more than 40 cetane.
Here in NZ bio diesel min cetane is 51 & HSD diesel is 47 min but standard is 50. Do you get biodiesel on the island? Maybe that works if you are allowed to run it by Yanmar.

Unfortunately I haven't found a place. Most pumps here don't even display the cetane number, but the service stations will provide the number when asked. If it were like octane where it was always displayed it would be so much better for consumer.

[VanIslandGuy]

Originally Posted by a64pilot

I’d watch her close initially at high RPM, if you have any cooling issues etc., they will likely surface.
Me I cruise at lower RPM and hold my foot on the throttle to hold it wide open for a few minutes once or twice a day if motoring all day. Mine won’t stay wide open, and as how I never run it that way anyhow I haven’t bothered cranking in enough throttle cable friction so that it will.

I think if it’s low Cetane and assuming the fuel additive really increases Cetane, I think you’ll see a difference pretty quick, after blowing all the junk out.

The cetane did help a little with the smoke, and did get the engine running a little warmer. However there is still a smell of unburned diesel in the exhaust even when the engine is fully warmed up. I've run the engine around 15 hours since starting this thread, mostly after a proper warm up at higher rpms (2800-3100), with occasional (every 2+ hours) runs to 3500 rpm for 5 minutes.

We took an IR heat read gun to the engine and it appears to be running around 170-180'F which is great. I'm replacing the sender for the coolant temperature gauge as it was reading 40'F cooler. There is a new thermostat installed as well.

Trying to resolve this issue we've verified we have clean fuel, clean fuel filters, we've bench tested the fuel injectors, clean air intake silencer, no air in the lines, clean water separator with good raw water flow, and no visible diesel leaks in the engine room anywhere. Low cetane number was the last 'easy' fix, and while it removed some of the smoke, (20-40% better), it's not running clean out the exhaust without the smell of raw diesel.

Lastly we're going to check valve lash, and fuel injector timing. The engine runs strong and smooth, doesn't burn oil, starts on the first half crank, and is otherwise perfect. I just need to solve this smelly unburned diesel exhaust issue once and for all. Anything else people would look at to solve this issue that I've missed?

[Compass790]

Yea definitely do the valve lash & timing. How much was the cetane booster supposed to raise yr tanks cetane no.?

[Compass790]

Forgot to add :No exhaust restrictions?

[VanIslandGuy]

Originally Posted by Compass790

Forgot to add :No exhaust restrictions?

Zero soot issues, and strong water flow out the exhaust so I'm reluctant to pull the elbow. No black smoke either, only white.

[a64pilot]

I hope you fix it, but I don’t think you can really, I think it’s inherent in the design unfortunately.
I’m sure you have smelled a Detroit Diesel idling? Same thing, they seem to reek of unburned fuel.
I’ve been on big Sportfishing boats and backing down on a fish can make you gag at times.

I pulled my Yanmar elbow the other day, zero deposits either in the water side and exhaust side.
Now sometime soon, I get to helicoil the heat exchanger where one of the bolts stripped. Bolts? Why in the world did they use bolts and not studs?