Fuel Filter Change

I have not changed my fuel filters in almost 2 years; no problems, no water seen in the Racor, the gauge on the filter bracket shows below 10" when running. I would like to change them just to be on the safe side, but will I have to crack the injector lines while cranking? Or is this no big deal. Since I've never done it befor I need a little advise. Engine is a Perkins 4-236, pics of the filter setup below. The bracket I built has*Wix & Racor filters, and there is a Cav on the side of the engine block. Thanks.
Mike
Baton Rouge

Does fuel gravity-feed to the primary filters? It does on our boat so there is no need at all to bleed anything when changing the primary Racor filter elements. I just leave the top off the Racor, open a valve on the closest saddle tank, and the filter fills up by gravity. When it gets to the top I close the tank valve and put the top on the filter. Engine starts right up and keeps running with no hiccups. There has to be a little air trapped in the top of the filter when I do this but I don't know where it goes--- the engines never miss or stumble.

The secondary filters on the engine itself are a different story--- when I change them the engine's fuel system (FL120) needs to be bled but only as far as the two injection pump bleed screws. There is no need to bleed the injector lines on these engines after a secondary fuel filter change.

If you can't gravity-fill your primary fuel filters then I suppose you'll need to bleed the whole system. I don't know if you'll need to bleed the injectors themselves, though. Bleeding through the injection pump may be as far as you need to go. But that's just speculation on my part--- I'd check with a mechanic familiar with your engine or, as an absolutely last resort, read the engine operations manual

Marin:
The Wix/Racor set up is above the engine, thus above the fuel tank, no gravity flow into it. However, I installed one of those bulb primers (like an outboard uses) in between the 2 clear lines next to the Wix filter, just cant see it in the pic. So, I guess I could replace both filters and prime them w/ the bulb and see what happens. The Cav is lower than the Wix/Racor so it should remain full, I don't plan to change the Cav unless the other 2 are dirty. The fuel I am seeing in the Racor is clean, with no water.
Mike

If you can fill your primary filter setup with fuel after changing the elements and you're not going to be changing the CAV secondary filter, which will remain full of fuel along with the line from it to the injection pump, you may not have to bleed anything, same as us when we change only our primary filter elements. But every engine is different so I wouldn't make any assumptions based on what our experience has been.

Yeah, your last post got me thinking; the line to the Cav and the Cav should remain full. But, there's got to be a little air left between the Racor & Cav after I prime both Wix & Racor, maybe not enough to stop the engine.

When filling either of my Racors, I just fill them with clean diesel as much as possible. The 900's I just fill to the top; the final spin-on I fill to the top as well. When I restart the engine after doing the latter, as soon as I crank it up I increase the RPMS to maybe 1500. The engine will die, then start up again after 3-4 seconds of cranking, then run fine. It's a Lehman 135 though, so I don't know how picky yours would be.

Agree with the other comments on the final CAV filters. You will have to bleed.

Ditto what Walt said.

I have to carry a gallon of diesel.
To change the racor.
Open the top pull out the filter slip a new one in. Top it off with diesel and go.
Cat 3208 n.a.
If I do get some air there is a priming pump on the fuel pump.
I pump that up, close it and I'm done.

How do you know when to change the racor. I have the guage and a little light to tell me when to drain the bowl.

I Like it.

SD

That's a big part of my question SD: the racor looks clean, no dirt visible on the bottom or floating around, no water visible, vacuum gauge shows under 10". Maybe leave well enough alone, but we're going on 2 years w/ these filters. Appreciate all the comments.
Mike

The Racor filter elements lose their ability to reject water after about one year.

OK, the change is coming Keith. I've always been one to fix things that ain't broke.

That's one of the problems with doing good PM. You don't have any failures to report! With my razor knife on the prop shaft, I've never had a problem. So do you report it works? I found a loop of PP line there one time, so it worked once, but if it worked other times, how would I know? If you change your filters or RW impellers often, and you don't have a problem, how would you report that? Better to report no problems than if you had them.

Keith wrote:



That's one of the problems with doing good PM. You don't have any failures to report! With my razor knife on the prop shaft, I've never had a problem. So do you report it works? I found a loop of PP line there one time, so it worked once, but if it worked other times, how would I know? If you change your filters or RW impellers often, and you don't have a problem, how would you report that? Better to report no problems than if you had them.

Click to expand...

Absolutely correct.* The best prevention is PM.* Works almost every time.* Not fool proof but damn near.

*

Good PM, as pointed out, may prevent problems that you won't even be aware of.

You do need to do this regularily as filter element can deteriorate. The guage is a good idea although one with a telltale pointer that remains at the highest vacuum reached is better. That way you don't have to read it while running but just check it and see where the telltale needle is.

You cannot always tell, by looking, if a filter is dirty. This has fooled many including me. Lots of dirt won't show up visually but can still clog the filter pores. Yes the guage will tell you if you check it.

The other thing is you need to know what your engine/system needs to change the filters and reprime if needed. The best way is at the dock when YOU have control, not when they do plug and shut you down somewhere nasty.

When I looked at the photo again I see the vac guage shows ~*10" Hg.* Is that correct?** It should be lower when running, ideally less than 5" Hg when the filters are new with 10" Hg or so the time to change

-- Edited by C lectric on Thursday 16th of September 2010 11:08:27 AM

C:
Yes, its a tiny bit less than 10 when running. Going to the boat tomorrow to change them.

Hey Gulf,Don't wait for them to clog up * * ..change them. Of course the other side of the coin says
wait for the other side of the vacuum to go up * * ..why throw away something performing flawlessly. *If the filter gets old will it rot? How does a filter fail to perform. The gasket could get old hard and leak or suck air. The screen could break down and change the filter into a holding tank. How many tanks to you have and how old or gummy and gooey are they?
The question is how often should they be changed * *..right? Well * ..if you changed them every time you went out in the boat that would probably be hazardous. If you changed them every time the engine quit for lack of fuel * * ..... I guess it's completely up to you but the fact that you asked the question speaks volumes about what you think. By the way I'm in the same boat but I've got new fuel tanks, engine and everything else. I pump the bottom of my fuel tanks every 3 months (or so) and everything looks totally clean. I'm going to change mine later.
One thing I would get rid of though is the OB squeeze bulb. I'm surprised you've got one of them in your diesel fuel system. The rubber is not that reliable. They give lot's of trouble on outboards.
Keith,
What on earth does this mean??
"The Racor filter elements lose their ability to reject water after about one year."
Does the water drain valve cease to turn??

I've not yet installed an OB primer bulb but it's on my list.


Eric, the photo shows his bulb is isolated from the system with two ball valves and a third one between the other two.* The middle one* is closed when priming to force the fuel to go to the filters.

The bulb is not 'IN' the main line, only valved in when needed. And it does work. Not all engines need it but for some it is invaluable.

-- Edited by C lectric on Thursday 16th of September 2010 11:24:51 PM

That's correct, the bulb is isolated from the main line. I'll let you know how well it works after I change the filters. Got the plans for that filter setup from Boat Diesel.

GC, I have had a 4236 and they DO NOT like air at all. Perkins are probably the most picky about this. If you can change the on engine filters and fill them with as much fuel as possible that would help. I would then open the gizzy on top of the fuel filter fixture and use the manual pump and try to pump out any air you can. If you start it and then she dies, then you are gonna have to go thru the bleeding process.

Filter change for the Wix and Racor were no problem at all except for the 94 degree outside temp and high humidity thus lots of sweat stinging the eyes. The pump bulb worked like a charm, just as advertised. Has to be easier than manually filling the filters then trying to spin them on without spilling diesel. Left the Cav on the engine alone, will tackle that one another day. Engine started right up and didn't miss a beat. Vacuum gauge showed about 6" Hg after the change.

Well done Capn'!

Steve:
Went down the Tickfaw at first light this morning with one of my buds; talk about pretty and quiet. No fast boats, just bass fishermen.
Mike

I love the rivers leading into the lakes here Mike- all those cypress trees. Early mornings are the best. I been working on my tub today but hope to get out to the lake tomorrow

Steve Where is your boat now?
Steve W.

Hey Steve
We are on the the North Shore of Lake Ponchatrain up the Tchefuncte River. We were able to get a permanent slip at Beau Chêne.

Nice area!
Steve W.

I have to carry a gallon of diesel.
To change the racor.

Many boat or truck shops do not have diesel handy.

Auto ATF works just fine , and many folks believe it is a great protection as injector lube.

I was curious as to why filters fail, other than the obvious (dirty fuel, water, cracked gasket). So I looked on the internet and could not find an answer. What if you keep your tank clean, polish your fuel to the nth degree, and run it through several 2 micron filters? Would the last filter in the series fail at some point? Why? Does the filtering part (paper, cotton, whatever) grow old and just fall apart? Seems to me that diesel fuel would act as a preservative. Just curious.
Mike
Baton Rouge

Mike,

According to the Mack Boring school that I attended the Yanmar engine final*filter is impregnated with some* chemical that aids in*the lubrication of the injection pump.* It is*dissipated by time*as well as by*the amount of fuel that is*passed through the filter.* So it will have all been dissipated by 12 -14 months if the engine has run 100 hours or not.

Can't speak to other filters.