Cummins Engine Blowby

[Ron222]

Tomorrow, I have my diesel mechanic scheduled to pull the fuel injectors on my 1986 -210hp Cummins 6BT5.9M engine (1500 hrs) and have them tested. At the same time he will do a compression test on each cylinder. It is highly unlikely anything has been done with the fuel injectors since the engine was new and the engine is showing some white smoke. My mechanic felt doing a "blowby test" is a waste of time and money. What he did instead was (1) took off the oil fill cap and looked with a flashlight across the air stream raising from the valve cover for white smoke (a faint white smoke could be seen)and (2) looked at the exhaust for white and blue smoke (some, yes). However, there was no presence of oil in the water around the exhaust pipe which was good. Both observations still suggested to both of us that performing the compression test and removing and inspecting the injectors is a good idea. I want to have a better understanding of the engine integrity given the long trips planned in the future. Does anyone know if replacing the fuel injectors will increase cylinder compression to the point where this could cause more problems with oil being pushed past the cylinder rings. I don't want to solve one problem to add to another.
Ron
A34 Paumanok

[jleonard]

Compression test is pretty meaningless. If he is good he can get something from the "seat of the pants" blowby test he did by removing the oil ca.
However sinnce he wants to do a compression test I question the above.
Who is the mechanic? Is he from Cummins Rocky Hill?
Replacing injectors won't cause what you are thinking. They have zero to do with compression unless the copper washers are leaking. If they were you would know it. They are probably still servicable. 1500 hours ain't much in injector life really.
Getting them all re-set to be close to the same pop-off pressure might make the engine idle smoother. If they are not shutting off perfectly they may make some start up smoke, which really doesn't hurt much.

BTW new Cummins injectors are cheap. (I bought a new set for a 210 for $100, including the washers). Ebay sells sets for $300 to $400. All the truck guys buy them for HP upgrades.
So be careful of spending too much to get them rebuilt.

[Panhdjoe]

Hi Just wanted to confirm that as the above post says, replacing the injectors will not affect the compression pressure at all. White smoke from the exhaust is usually engine coolant entering the combustion chamber. Head gasket, cracked head, cracked block. These problems are usually the result of overheating. Did it ever run hot?

[Tuxedo]

White smoke from the exhaust is usually engine coolant entering the combustion chamber. Head gasket, cracked head, cracked block. These problems are usually the result of overheating. Did it ever run hot?

Also oil cooler leaking. This happened on an Albin 49 that was shuffled from dealer to dealer for about 8 years, with little regard for maintenance. I ended up with it at my dealership, and the problem showed up during an engine survey. The mechanic knew something was wrong when he stuck his hand under the blowby hose. $3,000 or 4,000 later, problem fixed.

Moral - change your coolant every two years.

[Ron222]

Just wanted to provide an update to those who offered great feedback on the blowby issue. First, I have owned the boat for less than one year so I wouldn't know if it ever overheated. My mechanic removed the injectors. On visual inspection each injector showed no pitting or corrosion. They are now being tested. It is my understanding the test looks at the spray pattern. If any one or two injectors have a problem then all will be replaced. If they all check out to be fine then I have to decide if it makes sense to replace with new injectors and use the old ones as spares. While the injectors are out was the perfect time to check the compression. The psi results (based on three strokes) were 375, 350, 375, 400, 375 and 400. Given the age of the engine I am told these are great results. I engine when new was probably 375 to 400 psi. When the injectors are replaced the valves will then be checked and adjusted. Cummins recommends adjusting the valves every 1000 hrs. I am at 1525 hrs. Last, Cummins also recommends checking the timing of the fuel pump. I hope I have this right. The compression stroke and pump injection can be off a few degrees which is common over time. When this happens it leads to smokey exhaust.

I thought I would pass this update along for your information. Another interesting piece of information new to me is that my 210 hp Cummins block (6BT5.9-m) is pretty much the same block and head that Cummins now uses for their 400+ h.p. diesel engines. For us Cummins 210 diesel owners we have an engine that can run extremely efficiently for many hours without much wear and tear.

More to come later.
Ron

[DougSea]

Sounds like you're making good progress Ron. Good luck and keep us posted.

[JeffM]

A 6B at 210 hp is about as bullet proof of an engine as you can get. 1,500 hours on that motor is nothing. You need to remember the engine is a early 6B which is fully mechanical. That engine will smoke, especially when cold. It is hard for that engine to completely burn its fuel when cold. Does the smoke deminish when engine gets warm? If it does, you can clean it up a bit on start up by adding a block heater or pan heater. That will raise the temperature at startup and help with the smoke. Have you noticed the smoke being worse than when you first got the boat? Are you sure some of the white smoke you see is not steam? You are correct in that the base engine is essentially the same as current 6B, but the new ones are not mechanical. The fuel injection system on the new engines is completely different.

[jleonard]

Yes the early 210s had an overfuelling "issue" that was not formally addressed by Cummins. Common for them to have white smoke on startup and exhibit traces even when warm.
It will require re-calibratin of the pump. Not worth the cost for the perceived benefit.
Testing injectors really addresses the pop off pressure. They shim the springs to get them all within specs. Different specs for different era engine/pump combinations.
Injectors are way down on the troubleshooting list for smoke. . They last a very long time, 1500 hours is nothing.

[Ron222]

Just wanted to let the group know that my injectors were all tested yesterday and all injectors were in good shape except one. The spray pattern for this one was "off" and needed to be readjusted. Also, the pressure in each injector was tested and found to be within specs but not consistent within the range. Kind of all over the place within the range. The recommendations given to me were: (1) no need to spend money unnecessarily for new ones (2) have the old ones cleaned and readjusted using shims for the springs inside the injectors ($35 per injector) (3) adjust the fuel pump timing and then (4) go for a test ride and see what improvements we made. This should be on Monday or Tuesday. Will let you know.
Ron

[ScubaPete]

We will be waiting for the results............. hope these fixes do the trick for you.

[Panhdjoe]

I believe you are on the right track, and rember "If it anit broke....."

[Ron222]

In keeping with my promise to keep everyone up to date, all the fuel injectors were installed yesterday in Paumanok. The injectors sure look great and new after they are properly cleaned. The valves were then adjusted and it was a good idea since all the intake and outlet valves had some play and were off around 5-10 thousandths. This was described as normal wear but something I would not have wanted to wait too much longer....good preventive maintenance. According to my mechanic the top of the engine and valves also looked excellent (clean, no soot, no dirt, etc). He said Cummins had a reason for recommending valve adjustments every 1000 hrs. After everything was put back together the engine was cranked a few times and then started right up without bleeding the lines. She sounds great. The big question is has the smoke from the exhaust improved. Despite the fact that it was a bit windy yesterday I say it has but can't be sure. Cummins always are smokey at the start. As the engine warmed up it definitely seems less. The big test will now come this weekend as my wife and I head to Mattituck Inlet, join up with friends on their boat, go to dinner and travel around the north shore looking for vineyards on our Dahon folding bikes. BTW, there is a vineyard called Paumanok Vineyard which we will searching for. Oh!...and did I mention it is our 40th wedding anniversary this weekend. Can't get much better.
Ron

[Ron222]

Just wanted to post a quick final chapter to the smokey exhaust/oil in bilge/blowby issues I have been dealing with on Paumanok this summer. As posted earlier, all fuel injectors were cleaned, reset and reinstalled. All valves were adjusted. Six new valve cover gaskets were also installed. This past weekend we had a great trip to Mattituck Inlet, LI from Westbrook, CT and the engine ran perfectly and the smoke is really not smoke but steam. This is quite normal on a diesel as I am told. The steam goes away as the engine heats up. No longer is there evidence of sooty smoke. Unfortunately, this is the end of the story. We continued to find oil in the bilge and with the help of our mechanic found two problems. One, the rear main oil seal is definitely leaking. There is a drain hole under the bell housing and oil can be seen and felt from this hole. The rear seal is the only culprit. And, while feeling around under the turbo, engine coolant was detected dripping from the turbo seal which explains the need for coolant during the summer. Question: Do any of the A34 owners out there know if there is enough access to the rear of the engine (Cummins, 6cyl) by removing the drive shaft, turbo and transmission in order to get to the bell housing and seal or does the engine have to be lifted out. This will be a winter project for people that know what they are doing (which doesn't include me). With these problems solved over the winter it will be time to get really excited about next summers trip from CT to NH.
Ron

[jleonard]

If you can slide the tranny back and off the rear seal will be easy to replace. Cummins seals are easy.
Steam is NOT normal for a diesel in water temps as they are now in LI Sound.
White smoke when cold is normal esp for the older mechanical diesels. Cummins 210/220 with the CAV pump which is probably what you have, had a issue with calibration of that pump. Not too many know about it. It can be recalibrated to get rid of the smoke but it doesn't hurt anything

[Ron222]

Thanks for the CAV advice. My mechanic said the same thing. Also, will check with Cummins about the steam issue. I don't think this is a concern because it pretty much goes away as the engine warms up. I had the same exhaust "appearance" with my 1985 Westerbeke100 in the Albin 27 sold last year.
Ron