Hard starting and Davco 382 leak down issue

your back check in the davco has trash or the spring is bad in it, holding it open. but the only way it would drain back is if there is a leak to begin with.

 

I don't think their is a check valve to prevent back flow as their wouldn't need to be one as an air vacuum should keep it primed (example, put a piece of paper on a glass of water and turn it upside down and the vacum inside the glass keeps the paper in place which prevents water from pouring out) which tells me that you have air intruding some where in your fuel system. If you haven't noticed any leakage I would suggest that it probably is a non pressurized fuel line. Since it is only happening while it's cold makes me think that it's an o-ring on one of the joints in the non pressurized fuel lines, either suction or return. When it warms up the O-ring expands preventing the air from intrueding but when it's off for the night, it cools down, and the crack lets air in but it's small enough not to have much fuel, if any fuel leak over the night. I had a fuel transfer pump gasket that had a small leack on my cummins ISX in my 06 volvo 780 that made it harder to start. never noticed anything leaking for a long time cos when the engine was hot, the fuel was evaporating faster than when it was leaking, and when it was cold, not enough was leaking for me to notice. Eventually it got worse to where it started dripping one cold morning and I found it that way. In my senario, my fuel processor never lost its prime and your's shouldn't either, I'm suspecting it's an o-ring on one of connectors, or the glass filter bowl gaskets, or that little plastic top might have a small crack, or it's o-ring cracked but my guess is that it's right their on that 382 where you'll find your problem. I don't think those cost much so long as you don't go to the volvo dealer, might just be easier and cheaper to replace the 382.

 

Yes there is a Check Valve Spring and Ball, it's in the Inlet Side of the Fitting that connects to the Davco 382, it is probably dirty and staying open causing it to suck air.

You do not need to replace your Davco, they are pretty much Maintenance Free but like anything, things wear out or need a good cleaning.

 

Gotta have a leak somewhere for it to suck air, right?

Their isn't much to clean/repair in a fuel processor, and it's probably just as cheap to replace a bad unit as it is to rebuild one when you look at the time involve in doing one. Besides I think everyone agrees the problem is not the unit it self but a leak somewhere, and I'm still gonna say it's an o-ring because volvo loves using orings and O-rings like to dry out and crack overtime.

with the check valve stuck open, I still don't see how it's going to suck air without a leak in one of the fuel lines, unless his volvo's fuel plumbing is different from mine. My vovlo's fuel plumbing is on the bottom side of the tanks and I would have to assume the the fuel return from the engine is a wet return, meaning that I don't believe they some how route it to the top of the tank internally where air could infiltrate the return side, which is what would have to happen for a "bad check valve" to have a leak down right? as for replacing the Davco, you have two choices, rebuild it or replace it and you can do it or you can pay someone to do it. I'm assuming that it is cheaper to replace a faulty unit than rebuild it just like an air dryer assembly is about the same price to replace as it is to rebuild. Still, I think everyone agrees, replacing or rebuilding the unit probably won't fix the hard starting problems as I think everyone can agree their's a leak some where causing it to suck air while it's parked over night. Right?

 

The Check Valve Service Kit is Davco Part# 101132, which Volvo should stock it or try Freightliner, Paccar or International Dealer.

The clips should be stocked by Volvo.

 

I didn't know you could get volvo specific parts from anything but a volvo dealer, sounds to me like it's a non volvo specific part that the just want to make it hard on you to find without them.
amazon has that kit: http://www.amazon.com/Davco-101132-Check-Valve-Service/dp/B008VC77RS

I was thinking you were talking different check valve, I didn't know realize they had those valves in the lid.

You do realize you can get the whole lid for less than $20 at any truck stop garage worth a darn. I had to replace one last year on one of my trucks because all the fins broke off and I was tired of trying to find a large pliars to use on it (which for the record was why all the fins broke off it in the first place)

 

If you have the older Davco 382 which has a collared bottom plate with a threaded hex plug on there it contains a small O-Ring which will need to be replaced. It is not shown as a Serviceable Part but you can call Davco and get the Part# for the O-Ring which you will need to source it out yourself from a Supplier.

 

http://www.davco.com/diagnostics.html

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