Do I need to bleed to fuel line when changing a Racor prefilter?

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asteven221

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Normally I change the Racor primary filter element and the two engine fuel filters at the same time which means I always bleed the system. However I have just changed the Racor elements, without changing the engine filters and am wondering if I need to bleed the system. My gut feeling is that I won't have to, but I am hoping one of the experts on here will be able to confirm if I correct in my thinking. I have not run the engines yet since changing the filters. They will obviously start but I am conscious they could conk out before I get out the marina if there is air in the system.

The engines are VP TAMD63p, but I am not sure the model of the Racor filter housing. What I can say they are about 12" in height with a glass bowl at the bottom and tap for water/sediment draining. There is also what I can only describe as a upturned metal bowl under the glass bowl for I assume catching drips when changing the filter element. There is a T bar on the top that is undone to remove the cover so the element can be replaced. If I knew how to attach a photo it would be a bit easier!

Thanks for any advice given.
 
asteven221 said:
Normally I change the Racor primary filter element and the two engine fuel filters at the same time which means I always bleed the system. However I have just changed the Racor elements, without changing the engine filters and am wondering if I need to bleed the system. My gut feeling is that I won't have to, but I am hoping one of the experts on here will be able to confirm if I correct in my thinking. I have not run the engines yet since changing the filters. They will obviously start but I am conscious they could conk out before I get out the marina if there is air in the system.

The engines are VP TAMD63p, but I am not sure the model of the Racor filter housing. What I can say they are about 12" in height with a glass bowl at the bottom and tap for water/sediment draining. There is also what I can only describe as a upturned metal bowl under the glass bowl for I assume catching drips when changing the filter element. There is a T bar on the top that is undone to remove the cover so the element can be replaced. If I knew how to attach a photo it would be a bit easier!

Thanks for any advice given.
Click to expand...

You will need to bleed after changing the elements, sounds like you have Racor 500 size, the metal bowl is a heat shield.
 
aquapower said:
You will need to bleed after changing the elements, sounds like you have Racor 500 size, the metal bowl is a heat shield.
Click to expand...

Why? If you keep the diesel level above the outlets, as in change the element "wet". Then top up the element bowl to the brim before replacing the lid there is no need to bleed.
 
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If your racor is level with the fuel tanks this might depend on fuel level in the tank. But if you fill the space above the filter to the brim before you put the lid back on you should be ok. As a precaution run the engine for at least 10 minutes to allow the engine to purge any small qtys of air through to the spill line, before you slip your mooring.

I use my polishing pump to pre fill the Racor and engine filters, with plenty of tissue wrapped around to catch any spillage as they prime.
 
Close the fuel shutoff cocks on the tanks if you have them as when you open the Racor filter there is a strong possibility that the fuel in the lines will drain back to the tank giving you lots of air just waiting to be pulled up to the engine. If the level doesn't go down in the filter housing apart from when you remove the old element, then fit the new element and top off the filter housing to get rid of the air pocket that you will now have when you replace the top, alternatively just bleed it at the engine to be sure, and always run the engines at high idle 1200-1500 rpm for a few mins to make sure they won't die when you set off. Don't forget to open the stop cocks again.
 
Thanks everyone for your advice which has saved me from an embarrassing situation. I am sure I would not have made it to the marina exit before the engines would have conked out!! I just thought that the small airpocket above the elements was normal, hence bleeding wasn't required. Now I know.
 
I never have. My engine is gravity fed but there is no siphon once you take the top off the racor anyway. I turn off the fuel to the filter, change it, open the fuel line and let it fill back up. I have a bulb to speed it along. When it is just about to overflow I turn the fuel off, put the lid on, fuel back on and away I go. It doesn't need to bleed because air never gets in the fuel line. Quite a bit of air can gather in the filter before it becomes a problem.
 
Thanks for your input pmagowan, but now I am a bit confused. Should I do nothing further, or do as spannerman has advised/suggested. Being around these forums for a long time now, I have a sneaky suspicion that spannerman is a pro (something in that name :) ) so for that obvious reason when he speaks - I tend to listen!

Would it be sensible to simply run the engines for a while and if they don't conk out then I am good to go. If so how long is long enough on a fast idle to prove whether the air is going to be a problem or not? If they do conk out then I guess I would then just bleed them as normal.

I am not so keen on bleeding them right now as I will have to pull through quite a lot of fuel to get to the air in the primary filter. But if that's what I need to do then so be it. If you are correct and I don't actually need to do any of this, I could be pumping for a long time!!!

Thanks.
 
I have Racors for our primary fuel filters, engines are Tamd61a.
To change them, I switch off the fuel supply. Undo the drain cock at the bottom of the filter housing to empty the bowl slightly so that when you remove the top you don't get fuel spilling over the top. Remove filter element. Having checked the filter bowl/housing is all clean inside, fit new filter in position. Then using a fuel can (black 5 litre type from garage as an example), I pour clean fuel into the filter housing to the brim, and then refit the top to the filter housing. That way you've eliminated the air pocket. Reopen the fuel supply valve. Fire the engine up and as mentioned by others above, run high idle for 5 mins just to confirm alls well. I always keep a 5 litre can of fuel on board, so if an unplanned filter change had to be done, then I'm prepared.

Obviously, if changing the secondary filters (two off mounted on the engine) then you have to bleed these in the normal way your used too with the lift pump.
 
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Life is so much easier with a gravity feed. Shut cock, drain filter, remove element, clean filter body, fit new element, re-fill using fuel cock, stop when full, re-fit lid, open fuel cock. Job done, no mess, no worries.
 
Thanks for the compliment asteven221, I don't claim to have all of the answers, but I have changed a fair few filters in my 37 years on cars, aircraft, and boats. I am still picking up tips from various forums and more than happy to share my knowledge if it will help others. I have been a foreman with VP/Mercruiser/Mercury for some years now, but there is always something new happening in this industry to remind me that I am still learning and don't know it all!
 
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sharpness said:
I have Racors for our primary fuel filters, engines are Tamd61a.
To change them, I switch off the fuel supply. Undo the drain cock at the bottom of the filter housing to empty the bowl slightly so that when you remove the top you don't get fuel spilling over the top. Remove filter element. Having checked the filter bowl/housing is all clean inside, fit new filter in position. Then using a fuel can (black 5 litre type from garage as an example), I pour clean fuel into the filter housing to the brim, and then refit the top to the filter housing. That way you've eliminated the air pocket. Reopen the fuel supply valve. Fire the engine up and as mentioned by others above, run high idle for 5 mins just to confirm alls well. I always keep a 5 litre can of fuel on board, so if an unplanned filter change had to be done, then I'm prepared.

Obviously, if changing the secondary filters (two off mounted on the engine) then you have to bleed these in the normal way your used too with the lift pump.
Click to expand...

+1 exactly what I do.

Www.solocoastalsailing.co.uk
 
asteven221 said:
Thanks for your input pmagowan, but now I am a bit confused. Should I do nothing further, or do as spannerman has advised/suggested. Being around these forums for a long time now, I have a sneaky suspicion that spannerman is a pro (something in that name :) ) so for that obvious reason when he speaks - I tend to listen!

Would it be sensible to simply run the engines for a while and if they don't conk out then I am good to go. If so how long is long enough on a fast idle to prove whether the air is going to be a problem or not? If they do conk out then I guess I would then just bleed them as normal.

I am not so keen on bleeding them right now as I will have to pull through quite a lot of fuel to get to the air in the primary filter. But if that's what I need to do then so be it. If you are correct and I don't actually need to do any of this, I could be pumping for a long time!!!

Thanks.
Click to expand...

I don't see where the problem could come from. Gravity feed makes it easier but as others have said you can fill from a can or use a bulb pump. You don't get air in the system changing the filter because there is always plenty of fuel in the housing. There is an 'air bubble' at the top of the filter that needs topped up but that air certainly doesn't enter the system on my boat. I could leave an inch of air and it would have no effect. Perhaps an engine that sucks fuel really hard might be able to mobilise the bubble and cause problems. If you do it right there should be no air when you screw the top back on. I don't worry about a bit of spilt fuel so I am not that precise and often just have the top loose with the fuel running in under gravity until I see it start to overflow then I tighten the top. I might lose 10 ml! The one time my engine gave up by sucking air it had sloshing fuel in the tank and was ducking bubbles into the filter. It only sucked it further when the filter was completely empty of fuel.

Of course you should do what makes you happy, stress is for other people! Run the engine during your final roundup of stuff and last minute organising for departure. I don't think you will have a problem and hand bleeding a system that doesn't need it is a PITA! Good luck
 
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