3306 PC truck engine

[12v92]

hi all!

was wondering if someone could help me with a part #. i'm looking for the part # for the constant bleed valve that comes out of the injection pump with the return line attached to it.

the engine serial number is 76r5965. I have the cat parts book for this engine but it does not list or show this fitting. its a 90 degree elbow that is 1/8 male pipe on one side and #4 male jic

on the other side. i'm hoping someone has a parts book for something else that shows this elbow. thanks for any help!! this is a sleeve metering pump

 

[tool_king]

Check a local hydraulic fitting supplier .like a parker dealer hose shop .they should have them on stock.

 

[12v92]

this is not a regular elbow.......its a special fitting made by cat. definitely NOT available at a parker store

 

[Jonas302]

#49 ? 1p-4001

 

[DoyleX]

It goes on the sleeve cover. In between the filter housing and the pump at the top. Meters something like 3 gal per hr return and helps bleed air out.

Did some digging in SIS and cant find it either.

 

[12v92]

that is correct doylex.

according to the service manual it spills approx. 9gph @ max pressure. this is a picture of it that is in the service manual

 

[12v92]

and to reply to jonas302. that item 49 i believe is just the drain line fitting on the transfer pump housing. thanks for trying though.....sooner or later someone will figure out the part#!!

 

[d9gdon]

Pretty sure it's that #16 which is 4N7572:



It does call out in SIS that it's an "ELBOW FUEL RETURN" and it's under the SN that you provided. And at about $55 I'd really think it'd be the right one. Let us know if that's the right part. There's a lot of talk in Google search for a constant bleed valve, but a part number is nowhere to be found.

That SN in SIS shows to be a 1673C but it wouldn't be the first time that it was wrong. Looks like a 76R started out life as a 1673 but morphed into a 3306 after SN 370 so that's prolly where the error is coming from. Engine shows to be originally installed in 1985 Peterbilt.

 

[12v92]

item # 16 i think is the aluminum elbow that bolts onto the top of the fuel filter housing....not the fitting i'm looking for. thanks for trying !!!

 

[Delmer]

Are you missing the part? or is it missing the insides? I'd bet that those are common carb parts stuffed into a bored out hydraulic fitting...

 

[d9gdon]

There's lots of combinations on the sleeve metering system, some with and some without constant bleed valve and/or return line. Did it come with the valve and a return line?

I cannot find either with your SN.

 

[12v92]

yes, it does have a return line with the constant bleed valve. i took it off and cleaned it off real well hoping the part # might be on it but no luck

 

[Cmark]

It's 4N1828.

 

[12v92]

cmark........ i'm speechless!! you are the man!! thank you very much!!

by the way, where or how did you come up with the part number? just curious .

 

[Cmark]

I'm actually a black-belt parts ninja!



But seriously, I knew I'd seen one on an old D6D so I did an advanced full text search for parts only on the 4N7572 elbow. That gave a list of machines which contained the elbow, I browsed a couple of D6Ds until I found one that also had the valve.

 

[d9gdon]

A curve ball from Cat. It's not a return line, it's a drain line. But it has no line attached to it.

And it's not a constant bleed valve, it's a fitting. Just a 90 deg elbow fitting in NPR.

 

[Cmark]

It's called an elbow in NPR but it is a bleed valve:


"All 3304 and 3306 Engines equipped with a sleeve metering fuel system and a return-to-tank fuel line have a 4N1828 Elbow in the fuel injection pump housing. The 4N1828 Elbow has a check valve inside which controls the rate at which fuel flows back to the fuel tank. When the check valve adjustment screw is installed too far into the elbow, the force of the spring will not let the plunger come off the seat. When the plunger is against the seat, fuel can not flow to the fuel tank. This will cause air to become trapped (held) in the fuel injection pump housing. This restriction can make the fuel become hot and cause a loss of power.


The fuel must flow by the check valve at an approximate rate of 9 gallons per hour (34 liters per hour), when the engine is at normal operation rpm. If the flow rate is less than the rate given, back the adjustment screw out until the fuel flow rate is correct.


NOTE: To check the flow disconnect the return line to the tank and let the fuel flow into a separate container. A nine gallon per hour flow rate will fill a quart or liter container in less than two minutes."

 

[d9gdon]

Yeah, I wasn't saying it wasn't a constant bleed valve. I'm just saying that Cat could have actually called it a constant bleed valve in the parts book and instead of calling it a drain line, they could have called it a return line like we do.

 

[12v92]

unfortunately, the parts book for the engine doesnt show either! anyway... thanks again to cmark for figuring this out for me!!

 

[d9gdon]

I can see it from 76R4658 and down in the parts book, but not above that SN.

I'd say that either your complete engine has been replaced at some point with that higher SN engine or the fuel system has been replaced or altered.

Or it could be that it was omitted from the parts book.

It could be that Cat used a different fuel system combination above that SN. Like I say, there were different combinations that did not use the constant bleed valve on the sleeve metering system.

You could see if the engine matched the build date of the truck.
76R5965 built Aug 26, 1985 shipped Nov 14, 1985