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My port engine smokes at idle and it looks like a mini exxon valdez in the water behind my exhaust. I checked the oil after yesterdays run and it is over full. I think there is fuel getting into the oil system. Anybody have thoughts on where diesel can get into the oil system? I have Perkins 250HP. 6 cyl. Thanks, Kurt

Not really sure but I would think by the rings.

My guess would be a broken injector tip. Happened to me on Detroit and about 10 minutes of idling put a lot of fuel into the pan.

For starters, if you're smoking at idle, one or more of your injectors are not functioning to specs. Pull them all and have them tested. The anwer might be right there.

I had a local diesel shop reman all of the injectors this summer. I suspect that oil is dripping down through aged valve seals that may be causing smoke. I'm having the head done this winter. My worry is the oil sump filling with diesel. Could this be a pump issue? My Lucas Cav pumps are due for service as well.

Don't trust the local diesel shop. Just because they're new doesn't mean they're good. I had three of the six injectors I bought from Cummins not meet specs right out of the box last year. Fortunately for me, my mechanic had the test equipment and the spec sheets or I'd still be smoking and rough idling. Yes, the other things you mentioned are possibilities, but the injectors are the least expensive place to start looking. The injector pump shoots the fuel through the lines coming out of it, directly to the injectors. I don't see where/how that unit could be causing your problem. Good luck and please keep us informed. Walter

I am pretty sure that your engine has a camshaft driven fuel transfer pump that supplies fuel to the CAV injector pump.

Its possible that the "Transfer Pump" could be leaking fuel internally into the engine oil pan.

Then the injector pumps may be leaking fuel into the engine base also.

Question here......when you removed the injectors did you make sure that the copper washer came out with the injector or if it did not come out with the injector did you remove it before installing the rebuilt injector.

If there happens to be 2 copper washers in the injector bore then the injector is out of ideal position........to my knowledge that will cause some smoking......and low power.

hb

Same thing happened to my 2 6.354 perkins. Either the manual priming pump is bad (the inside gasket cracks)or the injection pump is leaking from one of the internal seals. The manual pumps cost like $28 each.

Send an email to this guy qbano12155@aol.com, his name is Armando, tell him that Micky sent you. He sold me the re manufactured injection pumps and he's a Perkins dealer.

Not saying related at all but yrs ago mechanic told me at prolonged idle kick it up to 750 RPMs to avoid fuel dump into oil and we idle alot, of course. Manual says to avoid prolong idle too.

i know nothing about it but i thought prolonged idling was something diesels were really good at. years ago i went skiing in vermont with a friend who had a diesel mercedes. he never turned it off for three days. just let it idle all night. ran fine on the way home.

kevin,
The detroit used a high pressure pump to deliver fuel to a common feed to all injectors at all times. Those injectors then fired by a rocker arm just like on the valve.

This opened the internal valve and delivered the fuel. If the internal mechanism breaks, fuel will continue to flow since the injector is being fed with continous pressure despite the rocker opening it or not.

Conventional injection pump diesels use a pump that pumps a predetermined amount to each injector at a specific timed event much like a spark on a gas engine. The pressure from the pump opens the injector and squirts the fuel into a cylinder.

Pretty hard to wash out a cylinder with this type of system.

Newer common rail diesels operate much like the detroits did with those injectors firing etiher mechanicaly usualy thru a rocker arm or electricaly for electric injectors.

Since injector pumps are gear driven for the most part, bad seals will allow fuel to leak in to the gear cover area dumping into the pan.
Some injection pumps have a line from the oil gallery to lube them. This could be another source of fuel contamination into the pan.

Another would be real bad rings, but it would take some time to over fill the pan given the small amount of fuel delivered to that cylinder on each firing cycle.

Of course a hole in the piston would account for it also.

Btw on detroits if you had a weak hole and the engine smoked at idle, you could easily back off that cylinders injection timing so it wouldn't fire at idle thus reducing or eliminating the smoke. Did it many times during the hey day of Hatteras ladden detroits at docks where people complained of engine smoke.

At about 900 or 1000 the cylinder would kick in. the caviat was that you'd lose rpm off the top end.

This was a trick for cheap sons a bitches, Pat you know who I am talking about, who didn't want to spend the money on redoing weak holes.

Had a 53' tub that had 3 cylinders on one engine backed off to keep the smoke down due to bad compression.

Micky is also correct in that the primary fuel pumps on many engines are driven off the cam or crank and opened to the block.

This is where I personaly would check first and would deliver the most fuel quickly on those Perkins.

Bruce,
Darn good explanation. It makes sense but now I am not even sure what type of system I have with out looking at the manual. One electric pump which I believe pulls fuel from tank. Then it goes to mechanical pump?

I always enjoy reading these threads because I get to learn so much. Hopefully Kurt is able to get dialed in with all the good information.

Kevin,
Steyers operate the same as the 2 cycle detroit, common rail rocker activated.

BTW pm me your address. I got a pair of oil and fuel filters, new that I won't use. They're yours free. BTW do you have the service manuals?

randall, had a chance to get my Cummins manual (1993) and on General Info page 1-2 it has a triangle (warning) and says;



"Caution; Do not idle the engine for excessively long periods. Long periods of idling (more than 10 minutes) can damage an engine because combustion chamber temps drop so low the fuel will not burn completely. This will cause carbon to clog the injector spray holes and piston rings, and can cause the valves to stick. If the engine coolant temp becomes too low (60 C (140 F)), raw fuel will wash the lube oil off the cyl walls and dilute the crankcase oil; therefore, all moving parts of the engine will not receive the correct amt of lubrication."

The lift pump seems to have solved the oil overfill problem. It still smokes at idle but clears under load. I'm going to follow up by sending the inj. pumps to Armondo and have the head done. Thanks for all of the advice. This site is priceless. Happy Holidays to everyone, Kurt :-D

[quote] Harry is rite. Perkins engines have a lift pump that fills a cavity in CAV injector pump if u indeed have a cav pump fuel sits there till its pumped into injectors. Excess fuel returns to tank lift pump has diaphragm and one pin hole will dump fuel into crankcase Gear driven injector pump

r has seal in front and when worn will give same results Valve seals don't have anything to do with black smoke , that is white smoke till it Burns off Oil on pistons In my opinion don't rebuild head it will put too much compression on rod and main bearings I would think those two spots is where ur prob is BR Goober

Wow, Andre brought up a really interesting point for me with my 6BTA reman repower.

We do a lot of salmon fishing where trolling at 1.5-3 knots is the norm - in other words, trolling at idle speed. I planned on transmissions with trolling valves to ensure that I could keep Shambala below 3 knots with bigger wheels, but now I'm wondering if I will be able to keep the RPM's up high enough for proper cylinder temps at what is usually idle speed trolling.

Is it possible to change the thermostats on a 6BTA to keep the engines warmer at idle?

Is there a different injector size that I should be inquiring about?