Changing Fuel Filters

Apr 17, 2013
153
Catalina 310 57 Pompano Beach, FL
I have changed the fuel filters on my catalina 310 numerous times. I am familiar with how to do it, but have a new issue. Normally I close both valves on the tank one would be for the supply to the engine and the other for the return. Since the engine is gravity fed from the fuel tank if the valve or valves are not closed fuel would continue to run if you did not close the valve or valves. My question is when looking at the tank, looking toward the stern there are two valves one to the right of the fuel sender and one to the left. The one to the right is easy to get to and turns very easily, the one to the left of the sender is harder to get to and does not turn very easily in fact I am afraid I will break the handle off if I continue to turn it off. The questions are do you have to turn off the return valve and is it the one to the left of the tank.

Thanks for any input,
Mark
 
Jan 5, 2017
2,263
Beneteau First 38 Lyall Harbour Saturna Island
I've never closed the return line on any diesel engine I've owned. Not sure which valve it is on your engine but it should be easy enough to follow the fuel line from your filter to the tank and see.
 
Nov 16, 2012
1,037
Catalina 310, 2000, #31 31 Santa Cruz
I'm pretty sure leaving the return valve open is fine, but I've got no idea which is which, or if Catalina did it the same on every C310 (probably not, given how many other differences there are in plumbing and electrical over the years). I think you'll have to trace the fuel lines your self.
 
Oct 22, 2014
20,995
CAL 35 Cruiser #21 moored EVERETT WA
Mark. Only way to know for certain is to trace the lines.
You may be able to start the engine and see fuel returning to the tank (if the tank is plastic and see thru).
You could tell if you start the engine. Close the easy to turn valve and see if 1. Fuel starts spraying out all over. Oops that is the return line. 2. The engine stops. That is the intake line.

Or you get some PB Blaster or penetrating oil and work the non functioning valve till it is free.
One clue, I would think the side with the internal long hose to the tank bottom is the intake and the short hose is the return side.
 
May 20, 2016
3,014
Catalina 36 MK1 94 Everett, WA
Like John said Put a shot of penetrating oil on the stem of the hard turning one.

You might also look at adding valves close to the filter intake and after the lift pump. See the article in the latest Mainsheet, but do it for a single filter

Mahalo
 
Jan 17, 2013
439
Catalina 310 St. Simons Island, GA
Just did this last week and only saw one valve on the top of the fuel tank. I am fairly sure it was the supply to the engine. I did not know there was a second valve but will look for it. Changed both fuel filters and did not have to bleed any lines...engine just started and ran like normal!
bob
 
May 20, 2016
3,014
Catalina 36 MK1 94 Everett, WA
The only second valve I had before mod is the bypass bleed valve (aka knurledknob). This is on the Universal diesel. I think the other valve is because the tank is mounted high and gravity can cause fuel to flow backwards.
Before my latest mod I had clamps that pinched the fuel line so didn’t worry about any other valves.

Mahalo
 

Tom J

.
Sep 30, 2008
2,301
Catalina 310 Quincy, MA
I normally close both valves, mainly because I'm not sure which is the supply line. Neither of them is easy too turn. In any case, the best way to keep any valve from freezing up is to exercise it regularly.
As Bob mentioned, the system in our C310's is self bleeding, so the engine should start with no problem after changing filters, especially if the filters are prefilled with fuel before installing them.
 
Oct 22, 2014
20,995
CAL 35 Cruiser #21 moored EVERETT WA
@paulj That is what I am talking about. Way to go. What a clear and easy to understand set up. Liked the way you resolved your issue.
:worship: you get a crew giving you adoration.
 
Apr 17, 2013
153
Catalina 310 57 Pompano Beach, FL
Thanks for the input, starting the engine after changing the filters has not been an issue and filling the filters with fuel before installing is the best way to do it. I guess not all tanks were setup the same way, I will close the valve which I believe is the supply line tomorrow and then drain the Racor filter. This will tell me if it is the valve is for the supply line.
 
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Nov 18, 2010
2,441
Catalina 310 Hingham, MA
Our boat, hull 65, has valves on both the supply and return. I never close either. For the most part it's a minimal flow and if you change the filter quickly there is no difference in the the amount of diesel that drips when doing the change.

I now have a valve in the engine compartment to stop flow there, that's part of a fuel polishing system I put in after Irma. Once I finish to tweaking the system I will put up a post.

Anyone here ever hear of putting transmission fluid in your fuel filter during changes? A lot of mechanics down here swear by it.
 
Apr 17, 2013
153
Catalina 310 57 Pompano Beach, FL
Our boat is Hull# 57 and it has valves on both the return and supply. I thought that if you didn't close the supply valve it would continue to run out at a fast pace. I have never tried to change the filter without closing both valves. That was my original problem was that one of the valves was getting very hard to close. I would close both valves because I did not know which one was the supply. Thanks for the advice.
 
Apr 17, 2013
153
Catalina 310 57 Pompano Beach, FL
Thanks again for everyone's advice. I finally did what I should have done in the beginning, I lubricated the valve and it now turns very easily in fact I may need to tie wrap it so it doesn't vibrate closed. It was the supply valve.
 
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Apr 17, 2013
153
Catalina 310 57 Pompano Beach, FL
That is my same setup, I worked on the valve today and it turns very easily so I have what ever option I want to do.
Thanks
 
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Nov 16, 2012
1,037
Catalina 310, 2000, #31 31 Santa Cruz
Our boat is Hull# 57 and it has valves on both the return and supply. I thought that if you didn't close the supply valve it would continue to run out at a fast pace. I have never tried to change the filter without closing both valves. That was my original problem was that one of the valves was getting very hard to close. I would close both valves because I did not know which one was the supply. Thanks for the advice.
Is yours the same color as PaulJ's? His looks painted; ours, hull #31, is bare aluminum. I'll have to check this weekend if we've got two valves, or just one.
 
Jan 17, 2013
439
Catalina 310 St. Simons Island, GA
Just checked my fuel tank and I only have one valve. No valve on the return. Hull #1 so maybe they forgot it...
bob