Looking for Fuel Leak into Oil

Fred Mc · January 06, 2018, 03:07:19 PM

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

Geoff · January 06, 2018, 05:16:11 PM

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

luvrbus · January 06, 2018, 05:44:10 PM

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

Fred Mc · January 06, 2018, 06:03:58 PM

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.

Fred Mc · January 07, 2018, 04:03:13 PM

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

lostagain · January 07, 2018, 04:52:03 PM

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

Fred Mc · January 07, 2018, 05:00:52 PM

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

Fred Mc · January 08, 2018, 02:33:33 PM

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

luvrbus · January 08, 2018, 02:54:24 PM

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

Geoff · January 08, 2018, 03:07:26 PM

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".

Fred Mc · January 08, 2018, 03:24:04 PM

Thanks Geoff

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

Thks

Fred

buswarrior · January 08, 2018, 04:52:00 PM

luvrbus has the solution.

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

happy coaching!
buswarrior

Geoff · January 08, 2018, 04:59:52 PM

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.

luvrbus · January 08, 2018, 05:55:06 PM

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

Fred Mc · January 08, 2018, 06:58:56 PM

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