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So I finally got around to searching for the fuel leak into my oil. I have attached an air line to the fuel line coming out of the filter and plugged the return fuel line so I can pressurize the fuel system in the heads. I pressurized the line to about 10 lbs and looked for leaks.Only done the one head so far (the easy one to get to on a GM 4106) There doesn't appear to be a leak on any of the crossover tubes but I can hear an air hiss coming from the bottom of one of the injecters where it seats on to the head.

Im not sure how injectors work so I am wondering if perhaps its a leaking injector allthough I presume it would then leak into a cylinder. Both the rockers have some clearance .

Any words of wisdom for me?

Thx.

Fred

Spray some soapy water like window cleaner around where it is  hissing air.  This will narrow down the problem.

There is a O-ring between the injector body and nut you can change those without any special equipment once the injector is removed if it is leaking there,
The injector seals against the tubes so fuel cannot leak into the cylinder if not the compression would blow by the injector,if one is leaking you may think about replacing all what injector do have N's    

Not sure what injectors.I presume they are stock.Ive had the bus 30 years and havent changed anything myself. And when I got the bus it had just come out of scheduled service.

So I have determined there is a leak where the injector meets with the head. Clifford mentioned an o-ring.   Are replacement o-rings avaiable or will I need a new injector. Are there any special tools/precautions  needed to remove the injector? Also did you mean replacing all the injectors or all the o-rings.
How do I tell what injectors I have?

Thanks

Fred

Fred, Western Bus Parts in Vancouver. 604-980-4844. Also a Detroit dealer would have the orings: look up Wajax Power Systems in Vancouver. I would replace all the orings. There is a tag on the injector body with a model number. Then do a tune up (run the rack). You need a Detroit service manual to do it right. Or have it done by a good mechanic.

JC

Thanks. Actually I bought the bus 30 years ago from Western Bus Parts.Wonder if they remember me? ;D

So I found my leak(s) of diesel into the oil.

I bought a mechanics stetascope and pulled the tubes coming from each ear piece off and put a smaller plastic tube into one of the tubes.I was then able to insert that tube down around the injectors(where the injector body seats onto the head) and found air leaks(I pressurized the fuel systemwith air  thru the heads)at 4 of the 8 injectors. There were NO leaks at the crossover tubes.

Is this simply a matter or replacing the "o" rings on the injector body or might there be other problems with the injectors. I have N60 injectors. I understand  I will have to "run the rack" after removing the injectors. I think I will try and find a local shop that can do that.

Regards

Fred

Me I would buy a set of rebuilt injectors you can buy a set for around 400 bucks from Don at Quality Fuel Injectors in Ca (209-863-8810) 30+years you got your money from those

The seals for the injector tube body use a special O ring that is impervious to diesel fuel.  The problem may be as simple as removing the injectors one at a time and tightening the tubes.  If they loosened up, you will know right away.  If you are care full you can pull an injector one at a time without loosening the rack, and put it back together without the hassle of "running the rack".

Thanks Geoff

Is there a special tool for tightening the tubes or are the located by the o-ring?

Thks

Fred

luvrbus has the solution.

fresh set of injectors, or you'll be back in there again...

happy coaching!
buswarrior

Okay, if you pull the injector out, you put the top into a vice upside down on the flat spots provided.  The tube has a couple of flat spots that you use to tighten the body to the top.  Absolutely do not take the tube off!  The whole injector will fall apart if you do. 

There is no reason to buy injectors if all they need is a little tightening.

I use the six point Kent/Moore socket 1-1/8 J-4983 but if you can find a extra deep 1-1/8 6 point socket they work you really need a socket and a torque wrench, torque the nut to 85 ft lbs.If the follower(the round plunger on top of the injector) on the injectors show a lot of wear just replace the injectors and be done with   

Okay. After downloading a service manual and familiarizing myself with some terms I think I understand how this works now. I am going to remove one injector(the easy one to get to) and re-torque the injector tube  and test it for leaking.If that fixes the problem I will do the rest and if the injectors appear worn I will order a new set.

I was a little alarmed  for a while because I was confusing the "tube" on the injector with the "injector tube" installed into the head which would have required removing the heads.

Thanks for now.
Regards

Fred

Regards

Fred

Don't assume more than one is loose. Probably just that one. I'd recheck after fixing that one, and if no more leaks, leave the rest alone.

I have 4 that I think are leaking so I will do the first one and if it corrects the problem on that one I will then tackle the other 3.

Regards

Fred

Wow, if you have that many leaking, the set must have not been rebuilt properly in the past. Better do them all then. Course, you could upgrade one injector size for more power.

Dunno. Ive had the bus for 30 years and haven't done anything to it.
What are the downsides to increasing injector size? Dioes it involve any other adjustments.Timing etc.?

Fred

Geoff back--. The reason you have N60's is because your engine came with standard timing in the gear train.  If you put N65's your engine will start smoking under load.  You need to advance the timing for bigger injectors, and that is a big job.  Just try to tighten up one injector body and if that doesn't stop the leak then get a rebuilt set of injectors.  You can change them without removing the rack, you just have to wiggle them out and back in.  Then you can have everything adjusted when you find a 2-stroke Detroit mechanic.

Thanks Geoff. Thats what I figured.

Just need to use an injector with the advance timing built in to it. 7c65 or something like that. This was discussed some time back.If you've been happy with it for that long, then just fix what you have.

You can upgrade to 7G65 injectors without A timing on a 8v71 I do it all the time and people love it.Talk to Don and have him build a set of low calibration 7G65, the atomization is so much better than the N series and spray pattern is better so you get more HP from the cleaner burn it dosen't add much of any heat increase or smoke from the higher HP .He can use the 7E65 also without A timing,but I prefer the 7G65   

I talked to my injector rebuilder and he said 7G65 injectors won't work without updating the cams.  I know the later 8V71's used the newer injectors but they also used the smog cams with different timing built in.  So I don't know what to say other than the old school of thought.

Geoff

I don't know what to tell you but I have a engineering bulletin that say different Don Fairchild and my self have been doing it for years I just done Tom's old dry block 8v71 and he is very happy,then TomC has 7G85's in his 8v71 non A timed turbo engine but Fred can use what he likes if he wants to stay with the C-60's it ok by me   

Cliff-- you are braver than me.  I might try it on a new style block but not a dry block.  I didn't think there were even any dry blocks left!  They crack at the lower bore from heat, while the new style blocks have coolant around the lower bore. (This is not news to Cliff, but for the other people on this board).

That is what he wanted Geoff so I did it his is defiantly a old dry block 8v71 lol I see quite a few of those blocks still running in 4106 GM buses.I had to remove a set of 7G65's a bus guy installed in place of N65's on A timed engine it was a dog with the 7G65's 

CA  EPA used to put 7G75's in the 277HP 6V92TA transit engines, for what it's worth.

Sio I remnoved the first injecotr and tested it on the bench for leaks and it definetely leaks around the o-ring. Tommorrow I will get the proper socket and re-torque it. Is replacing the o-ring doable or will all the parts fly all over the place if I remove it to replace the o-ring? The cam follower shows little wear.

Fred,
I had these people install my Jakes. 8N70S injectors (aug.2011)
24V Jake Soleniods,Buffer switch , Run rack and tune up.
Very good mechanic and high on details.
Cost at time OK. Would use again if needed. No problems to date.

Gary Woods Pres.
K.N.W. Diesel Inc.
Unit C-1 19325 94 Ave
Surrey BC  604-888-3440

Thanks Taibob.Im off to see them this afternoon. Only about 15 min from me.

Bingo!!
Not only do these guys specialize in 2 strokes but are only 15 minutes away and do "house calls".

Thanks again for the recomendation.

Regards

Fred