Changing Fuel Filter, Water Separator on CAT engine

[wolfe10]

Jim,

Is your coach set up so that the shore power (using your converter or charger) DOES charge the chassis battery? Many do NOT.

If you have a voltmeter, check voltage at chassis and house battery and let us know voltage of each while plugged in.

Also, as I mentioned, if you have a boost/combine switch, that allows you to "add" the house batteries to the chassis battery for operating the starter.

Brett

[jmgrigsby]

Brett,

I opened the inlet line to the filter - fuel flowed out, good stream, no air.

Tried to crank it 2 times - won't start.

I then unscrewed filter about 3 turns - no flow.

I put air into tank then it came out but stopped when I stopped putting air in.

Tried 2 more times - won't start.

Jim

[wolfe10]

Jim,

You are doing the right stuff. It is just that without a manual primer pump it is sometimes difficult to get all the air out of the system. Let it sit (and battery charge up) and crank it again.

As you are doing, do not overheat the starter.

It may help to have someone slightly pressurize the tank with compressed air while you crank-- this really helps of the lift pump has air in it or the line to it.

There are many of us who feel Freightliner made a poor decision to save a few bucks by deleting the secondary filter and manual primer pump. Evidently enough people felt that way that they went back to fitting the two filter/manual primer pumps on newer chassis.

Brett

[jmgrigsby]

Brett,

I'll let it sit a while.

And probably can get a buddy to come over tomorrow.

I'll report back later.

Thanks,

jim

[jmgrigsby]

Brett,

I'm not pumping the gas pedal - should I do that?

Jim

[jmgrigsby]

Brett,

If I can't get this thing started - I think I have 2 options.

1. Call Roadside Emergency Service and let them tow it to a CAT RV Service Center(I'm in east Texas).

2. Install that second filter with the primer.

My question is - Will the primer solve my problem?

And is this hard to install?

Its pretty cool outside today and the next few days, I probably wait for a warmer day to get back on this - but just doing some thinking now.

I guess I have a 3rd option - start over and get a buddy to help.

What do you think about the second option?

Jim

[wolfe10]

In order, I would do #3, then #1 and last #2. With calling a mobile diesel tech probably inserted as the second choice right after #3.

To fit the second filter and manual primer pump requires new fuel hoses be made. As stated in that post, fuel goes from tank to present filter (with 10 micron filter element instead of current 2 micron filter element) then to the lift pump, then to the new secondary filter (with 2 micron filter element), then to the engine. View this as a permenant solution, not a "get me back on the road the easiest way possible".

An observation for anyone changing filters-- fuel WILL flow if there is a difference in fuel level between tank and filter base. While it is messy for fuel to flow out of the filter housing when replacing a filter element, it is a LOT better to have some fuel flowing out than to have that 25'+ line siphon back to the tank and become filled only with AIR. Repriming with 25' feet of air in the line is really tough.

And sadly, very few coaches have a ball valve at the filter on the inlet line which would solve a lot of this "loss of prime" problem.

Changing the filter with a full fuel tank, raising the front of the coach and lowering the filter housing all aid in lessening the chance of draining all the fuel from the line.

As discussed yesterday be sure to keep the chassis batteries charged up-- some coaches charge the chassis battery from shore power, others do not.

Brett

[jmgrigsby]

Brett,

I have fuel flow from tank to filter. I think the air is trapped in the line from the filter to the injectors.

When my buddy comes - What do you think about bleeding the line at each injector? I guess I can get to all of them from the opening in the bedroom floor.

Jim

[wolfe10]

Jim,

You should not need to bleed each injector. If fuel rather than air is getting to the lift pump using the starter should clear the air from the lines.

Brett

[jmgrigsby]

Brett,

I don't recall seeing the lift pump. But I'll look again. I'll trace the line from the filter, I should find it ok. Does it split and go to the injectors after the lift pump?

Do you think that I can bleed the line just before it enters the lift pump?(assumimg that I can get to it from the bedroom floor access)

I noticed that this thread has quite a few views - must be a popular subject.

Jim

[wolfe10]

Jim,

The lift pump is driven off the back of the HEUI pump.

Freightliner installed the filter-- so they can tell you on which side of the lift pump the filter is installed.

Give them a call-- have your VIN handy: 800 385-4357

Normally, it is not necessary to access or bleed at the lift pump. If the line from tank to filter and the filter itself is primed, the lift pump should be able to prime the system.

Brett

[chucknewman]

Brett,

Very interesting posts. Safari did it right with a Racor R90T 10 micron primary and a CAT 1R0751 2 micron secondary, plus a prime pump. But for information (and amazement) purposes, what micron sized single filter did Freightliner install in these single filter systems?

Also, you used the terms "transfer pump" and "lift pump" interchangeably in this thread. Am I correct you are referring to what CAT labels the engine "fuel transfer pump" in both references?

Thanks, Chuck

[wolfe10]

Brett,

Very interesting posts. Safari did it right with a Racor R90T 10 micron primary and a CAT 1R0751 2 micron secondary, plus a prime pump. But for information (and amazement) purposes, what micron sized single filter did Freightliner install in these single filter systems?

Also, you used the terms "transfer pump" and "lift pump" interchangeably in this thread. Am I correct you are referring to what CAT labels the engine "fuel transfer pump" in both references?

Thanks, Chuck

Chuck,

Since the fuel must be filtered (per Caterpillar requirements) to 2 microns, the single filters have just that, a single 2 micron filter. And yes, that will clog up a LOT quicker than a 10 followed by a 2.

Yes "transfer pump", "lift pump" and "fuel transfer pump" are all the same animal (kind of like thermostat and regulator). They are basically a fuel pump that "lifts/transfers" fuel from tank to engine/HEUI pump. If is unrelated to the manual primer pump that some ("properly equipped" IMO) systems have. So for your system, you have: fuel tank, primary filter, lift pump, secondary filter with primer pump, engine/HEUI pump.

And the secondary fuel filter housing with manual primer pump has been the same for decades. The one fit on our Foretravel in the fall of 1992 is the same design used today. So, for those on a strict budget, a truck wrecking yard followed by trip to a place that makes fuel hoses will get the job done.

There are also a few coach makers who speced a primary filter and secondary filter WITHOUT manual primer pump. Retrofitting the manual pump on these is really simple. The secondary filter housing will have a block-off plate held by two bolts. Remove the bolts/plate and with new gasket primer pump and two bolts, just bolt it in place. If there is not room for the pump to fit straight because of where the secondary filter is mounted, Caterpillar makes both 45 and 90 degree mounts that bolt right up.

I just hate to see the agony caused by trying to prime 30' of fuel hose and a filter when the alternative (as you and I have) is to just fit the filter on dry and use the manual pump to prime, then start the engine and drive away.

[jmgrigsby]

Brett,

I had a buddy here today and we started over. I have fuel flow to the filter. But the line from filter to lift pump must be full of air.

I have cranked it about 10 times today - then added a little air pressue to tank fill opening.

And cranked on it about 5 times more. No luck!

My buddy seems to think we should bleed the line from the filter to the lift pump - at the lift pump.

But, there is no way we can get to that connection.

Do you think cranking it will eventually push that air out of that line and it'll eventually start, if I keep trying to crank it 3 or 4 times a day.

Jim

[wolfe10]

Jim,

As I mentioned earlier, you would need to check with Freightliner to see if the filter is before or after the lift pump. If the filter is after the lift pump which is on the back (forward in the coach) of the HEUI injection pump, there is no reason to even consider bleeding at the lift pump. You may be able to trace the fuel lines to/from the filter and determine which side of the pump the filter is on-- don't know the access to the lines in your coach.

Yes, your best chance of success is to pressurize the tank and crank the engine.

Hopefully this will do it, if not look for a mobile diesel tech.

Brett

[fredkeen@ymail.com]

Jim,

Of course it's too late now, but don't feel alone, I first changed filters (marine Cummins) without filling the filter and filter bowl with diesel. Just to prove I'm human, did the same on our old Ford tractor. In BOTH cases, had to crack the injector fittings to allow the air out (only one on the 8.3 Cummins in the boat, but had to do all three on the Ford.)

As to the second filter if you don't have one, I added Baldwin 10 micron filters as they are relatively inexpensive and can be found most anywhere. Note, the Cummins already had a Racor external filter and 2 micron internal at the pump.

Sorry to hear about your probs, but am sure you'll get it worked out.

Fred

[jmgrigsby]

Brett,

Today, I had a mobile diesel mechanic come out.

He said "there is no air in the lines - and the transfer pump is out picking up fuel when it trys to start".

He said it is the "transfer pump on the back of the injector pump".

He made me nervous when he put ether in the intake.

So I guess next week I'll have to go to Dallas and buy a transfer pump. Guess I'll also get the parts to add a second filter with primer and have the mechanic add it while he is working on it.

I don't know if you recall but what led me to change the fuel filter - was coming back from Branson it had a tremendous loss of power, only go 40 mph on gentle hills with the pedal to the floor. We first suspected the fuel filter - could it have been the "transfer pump" all along?

What caused it to go out?

Jim

[wolfe10]

Jim,

First, do NOT allow ether to be used on your engine. Your engine has an electric grid intake manifold heater like the vast majority of other modern diesels. Hitting a red hot wire grid with an explosive is just not done. Yes, on older engines, it could be done if done in real moderation.

And, sure, if the lift pump is not functioning, all the priming in the world will not get fuel to the engine. I was not aware that you facing any issue other than just replacing the filter.

As to what kills lift pumps (any diesel) being starved for fuel really pushes them hard (they are pulling fuel under high vacuum load). So a clogged filter(s) WILL shorten their life.

Also, any dirt or water will affect it, though the injector pump/HEUI pump is more susceptible to damage from these contaminants because of the much higher pressure they work under.

Cummins also had a problem with seals in some of their lift pumps being damaged by ULSD, causing the lift pump to leak. To my knowledge, Caterpillar did not have this issue.

Please keep us posted.

Brett

[jmgrigsby]

Brett,

It seems to me that the fuel pump was working fine before changing the filter - I guess that when it was sucking air I damaged it.

Don't know what this will cost but hindsight is 20/20. Next time I need to change filters I think I'll hire it done. I was thinking about changing the oil myself but may not now.

Jim

[wolfe10]

Jim,

While all any of us can do at this point is speculate, but improperly priming the lift pump once should not kill it if it was healthy to start with.

And if you fit/have fit the proper secondary fuel filter with manual primer pump, changing filters is extremely easy.

Changing oil is not difficult-- you just need the proper size bucket-- I use an old Rubbermade tub. Because of higher ground clearance, I would rather change the oil on the motorhome than on my automobiles.

I suggest using the engine manufacturer's filters (Caterpillar in your case) and verify the correct oil capacity. To verify, call the Caterpillar RV Hotline with your engine serial number: 877 777-3126. Then VERIFY that your oil dipstick is correctly calibrated.

Brett

[jmgrigsby]

Brett,

When adding a secondary fuel filter, where do you get a 10 micron filter element?

Can I get it at CAT?

Jim

[wolfe10]

Jim,

While Caterpillar may certainly have one, Freightliner speced your current filter housing and will have 10 micron elements to fit it.

Brett

[jmgrigsby]

Brett,

With regard to changing oil, the oil capacity for my 3126( from the CATRV Club files) states 22 quarts.

However, when I recently talked to the CAT rep - I mentioned that my toad had oil spots on it - he suggested filling my engine with 19 quarts.

Which is right - 22 or 19?

Jim

[wolfe10]

PM 1 Recommended Change Intervals*

Serial # Prefix Oil Pan Capacity Sump Change interval--Miles/Years

1WM 19 Qts (18L) Shallow 6,000 Miles / 1 Year

1WM 29 Qts (27L) Deep 10,000 Miles / 1 Year

7AS, 8YL, CKM, HEP 22 Qts (21L) Shallow 11,000 Miles / 1 Year

7AS, 8YL, CKM, HEP 30 Qts (28L) Deep 15,000 Miles / 1 Year

KAL, SAP, WAX** 19 Qts (18L) Shallow 11,000 Miles / 1 Year

KAL, SAP, WAX** 27 Qts (25L) Deep 15,000 Miles / 1 Year

* Fill volumes changed due to side mounted breather

** Refer to the O & M manual for S•O•S and storage

recommendations.

If any question, call the Caterpillar RV Hotline with your engine serial number: 877 777-3126.

[wolfe10]

PM 1 Recommended Change Intervals*

Serial # Prefix Oil Pan Capacity Sump Change interval--Miles/Years

1WM 19 Qts (18L) Shallow 6,000 Miles / 1 Year

1WM 29 Qts (27L) Deep 10,000 Miles / 1 Year

7AS, 8YL, CKM, HEP 22 Qts (21L) Shallow 11,000 Miles / 1 Year

7AS, 8YL, CKM, HEP 30 Qts (28L) Deep 15,000 Miles / 1 Year

KAL, SAP, WAX** 19 Qts (18L) Shallow 11,000 Miles / 1 Year

KAL, SAP, WAX** 27 Qts (25L) Deep 15,000 Miles / 1 Year

* Fill volumes changed due to side mounted breather

** Refer to the O & M manual for S•O•S and storage

recommendations.

If any question, call the Caterpillar RV Hotline with your engine serial number: 877 777-3126.