Caterpillar Engine Adjustments
I have a 2003 Alfa See Ya diesel pusher with a 7.2-liter Caterpillar 3126 engine with 26,000 miles on it. Is there any way to test a turbocharger, or is there any kit out there to check the boost or performance? The reason I ask is that the coach seems underpowered for the first hour of driving but after that it feels better. I recently had a new fuel filter, water separator, and air filter (it’s been less then 3,000 miles) installed. If you have any ideas, I would appreciate the help.
Another question regards valve adjustment on this engine. Are the specs on the valve cover for warm or cold adjustment? Finally, there is a vacuum valve by the radiator that indicates whether the air filter needs to be replaced. Is that accurate, or should I go by miles?
Efrain Bustos, F336913
Palmdale, California
The following comment is in reference to more than 12 years of experience, travel, and use of my personal motorhome. It’s powered by a Cummins 5.9-liter diesel engine with a six-speed transmission.
Yes, there is a way to continuously monitor a diesel engine’s turbocharger output efficiency from the driver’s seat. This efficiency factor is relative to the load on the engine, the gear the vehicle is in, as well as the throttle blade position.
A specialized 2-inch-diameter dash-mounted air pressure gauge is connected via a 1/8-inch, high-quality vacuum line directly to the turbocharger output, which connects into the engine intake manifold. For my particular installation, the name DW PRODUCTS appears on the face of the gauge. The numerical psi (pressure) value on the face of the gauge starts at the number 2 and ends at the number 30, in single (psi) graduated marks. I assume a similar product is available at many diesel engine specialty service shops.
In reference to your valve adjustment question, on my Cummins the valve clearance check/adjust should be done strictly on a totally cold engine. I suggest you reference a Caterpillar engine authority for your 3126 engine.
As for the air filter minder, I would consider that device only an indicator. Also, the number of miles traveled is not necessarily a “guidepost.” Just for fun, you might want to try this little experiment. If you have access to a precision scale, buy a new OEM-quality air filter and weigh it, then weigh the old filter and compare the results. The difference in weight will tell you how much dirt the filter has trapped. We’re only concerned with how much dirt is in the filter, right? Considering the cost of a new filter, I make the final decision to replace the filter only after up-close inspection for contamination and whether there is any damage or deterioration of the filter.
For more information about service recommendations on your Caterpillar engine, call the company’s Caterpillar RV Hotline at (877) 777-3126.
Brake Problem
I have a 36-foot 1997 Pace Arrow on a Ford chassis. The brakes always run hot. One time in very heavy stop-and-go traffic they actually faded. I have bled the system; changed the front and rear pads; replaced three of the four calipers; and removed all four calipers and cleaned the slides and lubed them. They seem to run hotter on the left side. The brakes on the tag axle seem to be working fine. I have a BrakePro supplemental braking system on my towed vehicle and it seems to be working as it should. I have been told that the problem could be the hoses or the master cylinder, but I have no way to check these parts. Any help you can give would be appreciated.
Kenneth V. Hansen, F336105
Zephyrhills, Florida
There are several possibilities to consider here. Since I don’t know all the actual specs of your chassis, I’ll list a few conditions that I’ve found cause this type of problem and some possible solutions.
1. A complete brake fluid purge may be needed. If so, this should be done by a certified technician.
2. A brake fluid test strip is the best way to determine whether your brake fluid has water in it. Verify that the strip is the correct one and is not out-of-date. Also verify that the correct type of brake fluid is present in your system.
3. Your chassis brake system may well have an antilock braking system (ABS) controller unit. Many ABS brake systems require that the controller be commanded OPEN with the proper scan tool to achieve a 100 percent flush. Otherwise, water-laden brake fluid may be trapped in the system.
4. Considering the possibility of more heat on the left side, only an infrared temperature device (gun) can verify this condition. I applaud your efforts so far to rid the demons from your brakes. Have you eliminated any and all possible rolling resistance issues?
5. The flexible brake fluid hose that connects a caliper to a stationary steel brake fluid line has been known to deteriorate on the inside, restricting brake fluid flow. Take the hose off; hold it straight; point one end at a bright light and look through the other end for restrictions inside. Squeeze the hose as hard as you can between a finger and thumb in several spots, checking for interior weakness.
6. Should the brake fluid really be nasty looking, consider the presence of sludge.
I also recall an additional comment about a brake fluid bleeding procedure that may or may not affect your motorhome, but I’ll share it in case.
Many of today’s highway vehicle brakes are equipped with an ABS controller unit. Steel (and flexible) brake fluid lines interconnect the ABS unit, if equipped, to all wheel cylinders and to a master cylinder. Certain heavy-duty vehicle chassis with hydraulic brakes may have additional brake system components. An electrical sensor at each wheel position continually informs the vehicle body computer as to the rpm of each wheel. If road surface conditions contribute to a varied degree of traction during braking, the ABS module instantly adjusts brake fluid pressure as required to all wheels. A motorhome chassis that is equipped with a tag axle with DC-powered electric brakes may not be affected, as this may be vehicle-brand-specific.
Hydraulic brake fluid, being hygroscopic (taking up and retaining moisture) in design, may become water-logged over time. This is due to atmospheric pressure, which is always present in the master cylinder. A total brake fluid purge is required when the presence of water becomes apparent in the brake fluid. Water in your brake fluid actually can boil and become steam when enough heat is generated by a hard stop, especially on a warm day. The brake pedal goes to the floor while very little stopping action of the vehicle is achieved. If this occurs, only partial braking pressure to one or more wheels may be applied.
Many years ago, the automotive tool/repair industry developed a universal and very effective hand-operated vacuum pump that simplifies replacing brake fluid. One person connects the vacuum pump to one of the wheel cylinder bleed valves. While an assistant keeps the master cylinder topped off with new brake fluid, the old brake fluid is withdrawn by vacuum into a clear reservoir, part of the vacuum pump. Continue to flush the old fluid until you see new, clean brake fluid. Again, I do not know if a scan tool is needed to open the ABS unit in your particular motorhome.