Benjamin

I agree, the black chunks possibly came from the fuel line. I'd remove the hose from the tank, if you can get to it. Remove at the fuel separator and blow back toward the tank into a clean bucket, if you find more chunks of rubber there's your answer. I've heard fuel breakdown products described as fried chicken skin, that's the best way I can describe the harder stuff that fuel makes. The slime is common also, neither should be a problem if you use many full tanks of fuel a year. But with a hundred gallon tank, if you top it off before it goes below 1/2, then you end up with old fuel if you only go a few thousand miles a year.

I don't have enough or consistent experience with 31T to confirm or deny the difference between the 750 and 950CCA types, especially in any particular application. I would say that RVs typically suffer more abuse from neglect and deep discharge than trucks or other equipment. In my limited experience, it's not uncommon to get ten years out a pair of batteries in a medium duty truck. The difference between 3, 5 or 10 years would be mostly abuse, or random failures. In the case of those interstate models, the 750 has less reserve capacity as well as CCA, so it could be a lighter battery, and not fewer thicker plates. The heavier duty 750CCA story was told to me in response to a question about poor life (5-7years). I was not a hard sell as I'd heard that before, it was from a battery representative, but still a salesman, so who knows.

Tell me more about the black stuff, is it slimy or chunky? "Algae" is a common fuel issue if the fuel isn't turned over like an RV sitting all winter. You'll want to add some biocide to the tank, and carry spare filters. Or flush the tank if it persists. I'd try another water separator, don't have to throw the old one out, you can swish it around and dump the garbage out, AS LONG as you have a secondary filter. If the engine is starved for fuel, it can't make boost.

And in two types, threaded terminals, and post terminals. 700,750, 950CCA are all interchangeable. Most RVs will start fine with one in typical temps. Two or three batteries makes them last longer, maybe helps the starter last longer, but the 950CCA is not critical if you can't find it. The 750 are often a heavier duty battery as the case and weight are the same size as the 950, so the 950 is built with more and thinner plates to get more amps, resulting in a less durable battery. If you don't need to start below zero, without plugging in, then 750 are a better choice in my opinion.

Sorry, that wasn't clear about a one way cylinder. I was trying to refer to a two way cylinder with the piston hypothetically removed as operating like a one way cylinder. And using the "spring return" reference to Ivan's post. Clear as mud. edit: on these you fill with rods retracted, "otherwise" there's no room and the fluid overflows when you retract them.

Most cylinders have a rod on only one side, so the base has a larger volume than the rod side. If you remove the piston entirely, the cylinder will still function as a one way cylinder (spring return) with the displacement of the rod. So the volume is not the same, which is why you fill with the cylinders retracted to avoid overfilling in this case.

That sure looks like a C8.3 used up to 1998.5, after 1998.5 it became the ISC that had a flat valve cover without those notches. The ISC has a rotary injection pump that's harder to "decipher", the C8.3 uses a large inline injection pump with the six injector lines obvious in a row off the top. The hp will give it away also, C8.3 will be 325, maybe 300hp in that era, the ISC will be 330 or more. https://www.irv2.com/forums/f123/visual-difference-between-c-and-isc-8-3-a-153329-2.html On second thought, that link is not all that helpful, the pics show a later common rail ISC, not the CAPS pump that would be on a 99. Search "cummins c8.3 vs isc valve cover" to see the difference.

For maximum contrast, as Tom said, do it early morning when it's as cool as it will be, before the sun comes up to start heating everything up, and turn the heat on inside to get some conduction through the roof. I don't know what's going on with those pictures, if the longitudinal lines are gaps in the insulation, or what? Like Bob said, if there's foam over the top of the framing then it makes the FLIR much less useful, but the foam much more effective, we're reading the thermal bridging, which the foam will greatly reduce if done right, outside metal framing.

Above I mistakenly referred to the 37MT as gear reduction. The DELCO 37MT is the old direct drive starter that came on many engines originally. The 8200433 is a DELCO 39MT substitute. DENSO (as in Nippon Denso) is good also, either gear reduction starter is a big improvement. Take your chances with a copy if you want.

Pay the extra for a genuine Denso if you're going that route, even if you're carrying a spare and the tools to change it. The Delco 37MT is also an excellent gear reduction starter and a similar reduction in weight from a direct drive. The 8200433 is a common replacement starter that is indexable as mentioned to adjust to different clearances. Not all 37MT are indexable, there are many part numbers that are "new equipment" that have a one piece instead of two piece adjustable base, because they are meant for new installation on a particular engine in a particular application. The "replacement" number will fit many "new equipment" part numbers, but may need to be clocked/indexed to fit. The "new equipment" will not fit all the applications that the "replacement" number will fit.

Summit racing has an excellent search function for radiator hoses (and other stuff like brake hoses) based on size, length etc. You can check your numbers against what's on there currently, may need to cross reference your numbers to gates first. That will give you a confirmation of the sizes of the numbers you have, or the search can find a hose that matches, or one you can cut your needed hose out of. If you're replacing proactively, go with gates or other top names, don't go replacing OEM hoses with no name china hoses.

Any codes?

I removed a pair of valves from my engine. I had two pairs of heater hoses, one had valves threaded into the engine, and the other was the heater hoses to the front heater core. I didn't trust the valves to stand the engine vibration, so plugged those holes and will tee into the other heater hoses for other uses. I will probably not add shut off valves either, as I can cut the hose and loop back to the engine at any point with a knife and screwdriver to keep going in an emergency. On mine, the heater hoses to the front have a bypass crossover "H" just before valve, in order to keep hot coolant circulating and provide quicker response I assume. Useful for defrost also. The downside of that is heat added to the basement anytime the engine is running.

It was related to using old tires in certain positions beyond manufacturers recommendations, if I remember right.

I'd try it with the thickest cords you have, I bet it works fine. You might consider trenching in a 12/2 or 12/3 UF to a pedestal to keep the rig plugged in if this is going to be a permanent parking place. I'm not a fan of damprid for the quantity of moisture you want to remove. Plus you have the air movement and heating you get from the dehumidifier. And the risk of spilling salt brine with damprid (calcium chloride).

If I had to guess, that's a 3/8" hex head with a 3/16" thread. If that's 3/8" threads, then the hex is 3/4"??? I'd agree that is the appropriate fastener for a metal framed roof if that's what you have (not the 3/4" hex head, the smaller size that I think it is)

Thank you for a well run and helpful site. We could argue forever about different interpretations of advice or rules. I appreciate a transparent "lock" and "editorial notice" when threads have ventured past the comfort zone like that one.

Exactly. The plumbing is always connected, there is one pressure water system, that supplies the cold and hot sides that go to the bath and kitchen. The pump comes on, that will flow out the city water connection if it can, the check valve is the only thing keeping the water from running backwards out the city water connection unless there's a manual valve or plug that you use in addition to the check valve. Even IF you bought the RV new, it could be different from the next one on the assembly line. I purchased a very well used RV from a very meticulous owner, and still find obvious mistakes from the factory that were never identified in 100k miles and who knows how many hundreds or thousands of hours of working on the various systems. Quality control and reliability on RV's are not even in the same universe as cars and most other consumer products these days.

So the Remco RV55 will flow water backwards when shut off? every diaphragm pump I've had apart has a rubber flapper inlet and outlet valve on each of the three pump chambers. That's common across RV's and sprayers, but I've never worked on variable speed or 5 diaphragm pumps, just the old three chamber single speed.

Good point, diaphragm pumps will suck air and self prime eventually. A dry centrifugal pump will never pump the air out and will burn out the seals. A diaphragm pump includes the check valves in the pump. Also, a centrifugal pump is typically a higher speed so won't produce full output until it reaches full speed, and will keep producing some output as it slows, the diaphragm pump works ok turning on for a couple seconds at a time. As far as I know, RV's and small yard/farm sprayers are the two main uses of these style diaphragm pumps, and diaphragm pumps make up the majority of water pumps in these markets.

The roofs are typically insulated, but poorly, as in very little attention is given to eliminate thermal bridging. So a metal framed wall will perform terribly, especially if it's aluminum with aluminum skin. Even with above average insulation, the thermal conductivity shows through dew as it dries at different rates. I've seen the nails under vinyl siding with dew, rafters and finished attics on roofs with snow, even purlins under metal roofing from the paint fading, still don't know how that one works. You don't need a cool moist morning either, if it's cool outside, then have the heat on inside and mist down the roof before dawn, or in the shade on a still day. If it's hot outside, you can try it with the AC on inside. I'd reconsider the 1/2" lag bolts, that would take at least 1" of plywood plates to hold a bolt that big. More and smaller fasteners is more appropriate.

Accumulator tanks (bladder tanks/pressure tanks) were used with RV pumps in some cases simply to get enough flow from small single speed pumps, at least for several seconds of use. A larger variable speed pump doesn't need the same storage, and as noted in Tom's first post, a tank can cause issues with the variable speed controls. In most cases, a water hammer arrestor, or a small vertical dead end for an air chamber will absorb the pump output pulse which is a fraction of an ounce and smoothed between three "cylinders". A water hammer arrestor won't let you flush the toilet while the dishwasher is running and someone is in the shower without noticing the pressure drop, the pump will sink or swim on it's own in that case, but a gallon or half gallon of stored water in the pressure tank is not going to make much difference there either.

The basic cause of most pump noise is the pulsating output. These pumps are positive displacement pumps with a pulsating output, not a centrifugal pump like a well pump. Any bit of accumulator near the pump output will help dampen that pulse. The softer vinyl hose absorbs some of that pressure pulse. A tee with a section of pipe going up and capped so it holds air will help also, that would be a tiny accumulator commonly called a water hammer arrestor.

I agree, I would not replace the diode isolator with another one. Upgrade to a modern replacement as noted, if it tests bad. I don't think we can say that yet, the voltage could have been normal expected operation as the result of whatever the failure was, either a battery or wiring issue. Obviously could have been the isolator also. The Duvac system basically means the alternator is reading ("remote sense") the chassis battery voltage after the isolator, and NOT it's own output directly. That gives a very rough division of the control between chassis and house batteries that could lead to this from a simple failure.

Unless you're in a rush, I wouldn't jump to any conclusions on the isolator. Test the batteries first, if the chassis was 10V and the house was 17, which ones were hot? if it was the chassis batteries then some cells shorted internally, if the house batteries were hot, that's to be expected at that voltage and I doubt 30 minutes at 17V hurt them. Get the chassis charged 24 hours, then sit 24 hours and then see what's functioning and not. If the chassis batteries are shorted, then they might heat up unevenly while charging. I don't know what you have in that compartment, but I'd hose the whole thing out, water can't be as bad sulfuric acid.