Cat C7 secondary fuel filter

Randy A wrote:
A trick I've learned over the years is if your vehicle has two fuel filters don't change both at one time. I usually change the primary first, start the engine, change the secondary, start the engine. Using this procedure my C-7 starts easy both times.

Randy, do you prefill, too? Or do them dry?

jeff

A trick I've learned over the years is if your vehicle has two fuel filters don't change both at one time. I usually change the primary first, start the engine, change the secondary, start the engine. Using this procedure my C-7 starts easy both times.

Changing the fuel filter on the engine is no easy task. You will need a strap wrench and a lot of patience. The manual primer pump from CAT is the best and safest way to go. It cost me around $100 at CAT.

I found a trick to cleaning the radiator and CAC. I cut a hole on the top of the fan shroud approx. 6" X 6" and mounted a piece of thin metal, gasket with a gate hinge and lock. This allows me to open the hinge and clean the back side of the CAC and radiator. Freightliner wants in the neighborhood of $3000 to remove both of these components. Not necessary if you do it the way I did.

Good luck!;)

tinkerer wrote:
We deal with a lot of diesel engines on our farm and the new diesels seem to handle air in the system than the old diesels. If we have trouble priming an engine the quickest we to .....,,... It started immediately and at an idol for a while if never even run rough. I opened the opening under the rear bedroom and it's a big opening that I can stand right on the engine and the filter is a piece a cake as it's located at the top of the engine. It was the first time I opened the cover and setting the valve lash will be a piece of cake and cleaning the radiator will be easy. My radiator looked very clean.;)

Thanks, Tinkerer! Good info there.

Jeff

Sounds like you know your way around a diesel-- that's great.

First valve adjustment on your engine around 30,000 miles.

And in looking at the CAC (Charge Air Cooler) which is what you see from the bedroom, as it is in front of the radiator, be sure to look carefully with a strong flashlight around the perimeter, particularly lower perimeter for dirt buildup. The fan blades sling the dirt to the perimeter.

We deal with a lot of diesel engines on our farm and the new diesels seem to handle air in the system than the old diesels. If we have trouble priming an engine the quickest we to prime them is put a little air pressure in the fuel tank. That being said we have one piece of machinery that didn't want to prime after fuel filter changing and we put some air pressure on the tank and got it bled out. But later found out the fuel pump was weak. If the fuel pump was good it would have primed on it's own. The C7 is the 330 hp version. Evidently the fuel pump is good on this one. It started immediately and at an idol for a while if never even run rough. I opened the opening under the rear bedroom and it's a big opening that I can stand right on the engine and the filter is a piece a cake as it's located at the top of the engine. It was the first time I opened the cover and setting the valve lash will be a piece of cake and cleaning the radiator will be easy. My radiator looked very clean.;)

Jeff,

Just a little more information:

The manual primer pump was deleted by a few chassis makers (likely their bean counters) to save a few bucks).

One other critical issue when you don't have a manual pump is that the level of the fuel in the fuel tank needs to be at or above that of the primary fuel filter when you change it. If not, the fuel will siphon those 25+ feet of fuel line back to the tank when you remove the primary filter. And that 25+ feet of air is VERY hard to prime up. So, fuel tank full/park with nose up. Better a little fuel coming out when you remove the primary filter(that you catch) than an engine no-start issue. BTW, same issue for all brand engines, not just Caterpillar. Most fuel pumps are not designed to pump that much air.

Thanks Wolf and Scott for the additional I info.

Jeff

Caterpillar's official position (I know, I present the Caterpillar Maintenance Seminars at FMCA Conventions, Diesel RV Club Rallies, etc) is to install filters dry IF, repeat IF you have a manual primer pump. Done it probably 100 times over the years-- never a problem.

BUT, if you do not have a manual pump (or until you install one which just takes removing two bolts on the secondary filter head and installing the pump in the place of the block-off plate) DO NOT INSTALL THE FILTERS DRY.

Instead, slowly fill the small outer holes which are the filter inlets.

Spizzer wrote:
I'm looking at having to do the same thing. Cat says to not prefill, many say to do it. Is your c7 the 350 hp? Did you do it from below or above? What filter did you replace it with?

Thanks,

Jeff

Jeff,
Filling the fuel filters, prior to installation has been on this and other forums, several times. Based on my experience, and others, the OP did in fact, get real lucky in the "re-start" of his C-7 after the installation of an empty fuel filter. You see, and I think Brett will agree here, the "transfer pump" or, the one inside the HEUI pump, is not all that strong in terms of pulling fuel, THROUGH AIR. Once the line, filters and all, are completely void of air, that transfer pump does just fine. But, if air is introduced into the system and, depending on just how much air, it just doesn't have ability to "self prime".

So, whether it be the C-7 330HP or the 350HP version, (same exact engine, same specs, just tuned for 350HP instead of 330) if it's got either one, or two filters, the smart move is to fill the filters the way Brett stated and, there's waaaaaaay less chance of any mal-starting conditions occurring. The addition of the primer pump he's referring to is of course, nice but, in many engine bays, based on the normal installation area of that primer pump, it's almost impossible to actually use it. I know that would be the case in ours. Some may have more side clearance. Good luck.
Scott