calling all old school mechanics

[Mhannink]

well really i need anyone who has worked on the old detroit 2strokes we have a 4i-71 thats pucking white smoke bad we ran some ps to clean the fuel and some sort of additive in the oil seemed to help but came back and now its the worse it been in a while. this is white smoke which i always thought was just lots of fuel but this smells like oil which it has alot of on the stack and is real thick on the inside im at a loss for whats wrong i suspect oil leaking around the rings but that doesn't expalin the smoke any help is appreciated thanks in advanced.

 

[Cigar John]

On our old 8V-71 thats how we knew we had a bad piston. :{

Pull the exhaust manifold and start it,

if it smokes real heavy from one port you will know.

Could also be a bad injector.

 

[Mhannink]

On our old 8V-71 thats how we knew we had a bad piston. :{

Pull the exhaust manifold and start it,

if it smokes real heavy from one port you will know.

Could also be a bad injector.

2 questions if it where a bad injector would it run rough like most diesels i heard or would it be the same reason being this is one of the smoothest engines ive heard it just purrs when it idles and its rev just fine and never misses also how would you check the injectors im familar w/ craking the lines but havent found where they are just yet



on the bad piston part does this mean a rebuild and about how much would it cost and how long would it be down

 

[Nyoest]

I'm gonna say either a fuel or compression problem. All the fuel isn't getting

burned in the cylinder. Could be injector, piston, rings or the problem I've

had with a bent valve. The tolerance on the valves is really tight and they

can be bent with little trouble. Like mentioned pull the exhaust manifold and

watch for which jug it is. It's hard to keep wrenches out of the valve train

to loosen a fuel suply line while running on that engine imo.



When you find the problem cylinder swap the injector with another cylinder

and fire it up and see if the smoke follows the injector. If it does it's just an

injector.



Keep us informed.





Neal

 

[mhuggler]

If you have oil coming out the exhuast, I'd recommend checking the blower seals immediately! Once the seals start puking enough oil out that engine's gonna run away on ya'. It's neat but expensive!

 

[Skydiver]

Mhannink,

Did the engine ever run hot?

We had an 8v-71 run hot in a charter boat and it bent an exhaust valve. It smoked blue all the way back to the slip. 20 miles.

Tim

 

[Hoefler]

Check the blower box drains. If they are plugged, any oil from the blower or the cylinders fills up the box and will usually wind up in cyl. #4.

 

[PSchwering]

Bear with me here, I have not worked with a two Cycle DD since my college days - about 12 years ago. It seems to me that the injectors should be Camshaft actuated, Port & Helix metered Unit Injectors. If you want to deactivate in Injector, simply pull the rocker cover, Find the injectors, Start it up. If you take a big screwdriver or prybar, & hold the injector spring compressed, the cylinder will not fire. You can go through & test each cylinder very quickly. Note: The fuel control rack lays exposed in the rocker box! Be careful around it!



In general, the old 2 stroker is an odd animal - Detroit recommends installing the Pistons from The Bottom! There are several other oddities to it. I still have my DD factory service Manuals from school. If you need anything out of them, Send me a PM, & I will see what I can do. P.

 

[NLofton]

As stated above the screwdriver method is the easy way to isolate injector problems. But i'm putting my money on a cracked head, white smoke is usually antifreeze, Check your coolant level and make sure youre not loosing any. I have changed many of these heads because of cracks. The easy way to put the pistons in is to load it in the liner and then put in in from the top (after you have checked all the liner heights), but hopefully you wont have to go that far

 

[DavidBurt]

If the head is cracked and its burning anti-freeze you would get that sludge in the exhaust too. That stuff really makes a mess when you have a bad leak.

dave

 

[Mhannink]

wow thats alot of reponses this will help ok to help the subject its useing oil or at least it did till the additive mentioned, haven't checked it latly. coolant is fine never uses any plus i would think the exhaust would smell kinda funny not like what i smell. to me it smells like oil or possibly diesel. as for running hot i don't know what the egts are since it doesn't have a gauge but coolant never gets hot, one thing i should mention is this is in an old hay squeez and the other to guys that are allowed to run it make the thing scream. sounds good but everytime they get on it i expect to see the head fly through the hood. also this thing will idle for hours at a time be use a little and idle some more ive seen it used 2 maybe 3 times in a day and idle the rest of the 8 to 12 hours thats its in use it does have alot of oil buildup around the blower (biggest concentration) and some spots all over. one thing to note is the smoke is only when you hammer on it maintained speed at any speed is fine but when accelerating it smokes. last thing i talked to the boss today about it he said the head and injectors are realitivly new and should not be a problem yet, this is why i think its something to do w/ oil. thanks again for all the replies and keep them coming ill keep ya'll informed

 

[Speedo]

Do an injector cancellation test (hold the spring on injector compressed) to locate the responsible cylinder. Pull the air box covers on that cylinder and take a look at the piston/cylinder to see if you have any stuck rings or a scored liner. You will be looking inside the cylinder through the liner ports.



Gus

 

[nickleinonen]

low compression will make a 2 cycle diesel smoke white very badly [most of my experience is on the much larger emd 567/645/710 engines] with the air box covers off you can see the rings and with a screwdriver you can give them a push to see if they spring back or are stuck in/broken. a broken/damaged injector nozzle tip can make for white smoke too as the fuel won't be atomized properly

 

[Mhannink]

lol ok this is getting to be alot more info then what i thought i would get and my feble little brain is having a hard time handleing it all since im not real familar w/ the dd i need some help w/ some of the parts that ya'll speak of such as the air box covers i only know of the air filter before the blower also i need some idea of dificulty i would like to start w/ the easiest and work my way to the hardest diagnostics also these things that i remove to look at stuff some sound like i would need to replace a gasket after looking what all do i need for this stuff.

 

[NIsaacs]

Might be a combination of fuel and oil build up from constant idling, also low engine water temperature. It sounds like it runs fine at all RPM. Will it smoke if you drive it down the road at normal water temp? Does it have an oil bath or dry type air cleaner? If oil bath, does it have a rain cover over the intake stack? It might be over full of oil or water. If dry type, check to see if it is clean. Make sure the emergency air shut off is wide open or it can suck oil past the blower seals. Like others have said, it might be bad blower seals.





"NICK"

 

[Mhannink]

Might be a combination of fuel and oil build up from constant idling, also low engine water temperature. It sounds like it runs fine at all RPM. Will it smoke if you drive it down the road at normal water temp? Does it have an oil bath or dry type air cleaner? If oil bath, does it have a rain cover over the intake stack? It might be over full of oil or water. If dry type, check to see if it is clean. Make sure the emergency air shut off is wide open or it can suck oil past the blower seals. Like others have said, it might be bad blower seals.





"NICK"

well the squeez is not road legal it used to be steetable but its not anymore it has a dry type filter that was changed not all that long ago i know that because i did it. whats this emergency air shut off im not familar w/ it. as for water temp it does get properly warmed when we use it for extended periods say unloading a truck or moving blocks around to make room for a load and when it does get that warm the smoke is the same. other then the smoke though it runs fine no missing or rough spots at all.

 

[Speedo]

well the squeez is not road legal it used to be steetable but its not anymore it has a dry type filter that was changed not all that long ago i know that because i did it. whats this emergency air shut off im not familar w/ it. as for water temp it does get properly warmed when we use it for extended periods say unloading a truck or moving blocks around to make room for a load and when it does get that warm the smoke is the same. other then the smoke though it runs fine no missing or rough spots at all.

Emergency Shut Down

If it uses twin screw racks it will have a flapper in the air horn on the blower inlet, the flapper is used to shut down the air flow to stop the engine in case of a stuck injector. If it has the later spring loaded rack it likely won't have a flapper.



Gus

 

[Mhannink]

i havent seen anything like what your speaking of on there

 

[J DeMaio]

It would be down on the supercharger behind the aluminum cover (6 or 8 bolts hold it on). Where your emergency shutoff cable goes to. It is used to suffocate the engine if a runaway would occur.



Hope this helps

 

[nickleinonen]

some of the parts that ya'll speak of such as the air box covers

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the little doors below the exhaust outlets are the air box covers. .