6V92 question

[sanddollarII]

My port 6V92 engine is getting diesel pumped into the oil pan. Fuel lines have been checked and are ok. Return lines ok. Any suggestions?

[Boatsb]

The injectors are inside the valve covers. Any leaks in that area including their seats can do that.

[Will]

Not sure of the setup on 92s but, that usually results from problems with the crossover lines between the fuel manifold and injectors on 71s. As previously mentioned, look under the valve covers.
Will

[Genesis]

Yep - pull the valve cover.

If you've got a jumper line that doesn't have oil pooled on top of the nut, its leaking.

You may need to start the engine to identify the bad one, but usually not.

[REBrueckner]

Am I correct in saying that the only internal fuel lines in two cycle Detroits, that is the only way fuel can get into lube oil, is from the fuel lines under the valve covers?

Also, if you do need to run the engines at idle with the valve covers off, what's the procedure...remove the covers first and start/run at idle or vice versa? and does oil spray around at idle or remain contained???

[Will]

I usually pull the valve covers first then start. The leak may be identifiable even before you start the engine. You shouldn't have much problem with oil spraying unless you rev the engine. You will probable be able to spot the leak with the engine idling.

Have some rags handy just to keep things clean but try not to get them in with the machinery under the valve cover.

You should use new valve cover gaskets.

Will

[Genesis]

Yes.

The fuel goes into a built-in raceway in the cylinder head and then there are "towers" on each side of the injector that screw into the head and have the fitting for the jumper lines on them. The towers are almost never the problem unless improperly assembled when the head was made/rebuilt/installed, and if they DO leak they typically will do so immediately.

The jumper lines comes in two forms - a flare and an O-ring sealed one. The flare fitting was replaced in later engines by the O-ring sealed version. The reason for the change is that the flare fitting is very succeptable to overtightening; the torque specifications MUST be obeyed when installing them and the flare (both sides) must be clean of any debris or you can cause cracks in the flare, which will then of course leak.

The O-ring version does not depend on the tightness to make the seal (as with all O-rings); the torque on the nut is simply to insure that the nut does not back off and provide the preload on the O-ring for the initial seal. However, an overzealous tightening of it, while bad, doesn't break things (unless ridiculously overdone)

With the valve cover removed and the engine started at idle there will be some oil that comes out around the rocker shafts from the oil delivery up through the tower bolts and into the towers (this is how the rocker shafts get lubricated under pressure, along with the rest of what's under the valve cover by "splash") but on most of these engines there is very little "spit" at idle. Be scrupulously clean as anything that gets into there will immediately seek one of the return holes in the casting to head towards the oil pan (Murphy is a bastard) and there are moving parts (rockers, valve stems, the control tube and injector racks, etc) that can cause injury or do damage if they get obstructed.

The location of the leak is often obvious even without starting the engine. Diesel washes the oil that usually coats everything under the rocker cover off quite nicely. The jumper lines will normally have a small pool of oil on top of them where the nut is; if you have one that looks "too clean" (devoid of oil) that's probably the leaking one. Starting the engine should confirm it quite quickly. Its also possible that an injector body is leaking, although this is less common.

The jumper, if its defective, is inexpensive and easy to change; you need a split socket to properly torque the new one on installation and the proper torque is CRITICAL - "tight enough" is wrong on essentially everything under the rocker cover. If you have flare-style pipes inspect the tower and injector flare fittings carefully (using magnification if possible) to insure they're not damaged before replacing the line, as if the mating part is damaged it will just leak again.

If the leak is coming from an injector it needs to be replaced; one injector in an engine can be changed without doing a full tuneup if you know what you're doing.

If any of this makes you go "huh" call someone qualified, especially if an injector is leaking, as its very possible to cause significant trouble replacing an injector improperly.

[on the hook]

My port 6V92 engine is getting diesel pumped into the oil pan. Fuel lines have been checked and are ok. Return lines ok. Any suggestions?

check fuel pipe washers under fuel lines .this is the part that the fuel line connects to..also i would replace lines.only other part that can cause this is BAD INJECTER..you can put die in your fuel system and check it with a black light..contac det diesel about this die..

[captddis]

A leak may not show up running the engine at idle at the dock as fuel press is only about 10 lbs. Shutoff the return line and using a hand pump, pump the fuel press up to 70 lbs and the leak should be obvious. You will probably see an injector with a slow drip. Good luck.