KATOOM

Try looking here. http://dodgeram.org/tech/dsl/troubleshooting/24v_trouble.htm

dripley, what gauge do you have?

I'm interested to see where this goes.

It is funny to watch the threads cycle back and forth from hot weather issues to cold weather issues. - - - Updated - - - JAG1 brought up a great point I forgot to talk about. And that being the fuel module. The only reason I feared re-routing my return line into the fill hose was because I remember hearing that by doing so can potentially cause an issue with low fuel level in the tank since no longer is that fuel feeding the fuel module basket, which the bottom acts like a "cup" for fuel to sit in, always feeding the engine. Not being completely sure if the return fuel was an issue, I wasn't willing to create a problem trying to solve another. And the way I look, I'm only hoping that with my fuel pressure running at 16-19 psi all the time (far more volume than OEM), the volume of return fuel is so great that its constantly overflowing the "cup" and keepeth my cuppeth full.....and overflowing.

No one look at the screen like I'm crazy but let me share something really really bizarre.....which I can only connect to what I did while trying to stop as much VP heat soak as possible. Like so many others, I live where summer heat can get in the triple digits. When the outside temps get over around 75*-80* is when the VP will begin to heat soak to uncomfortable levels. So when driving on days this hot and I'd come home, I'd pull the truck in the garage, open the hood and lay a smaller free standing house floor fan directly on the side of the engine blowing down on the VP. I'd just turn it on high and come back later to turn it off when everything was fully cooled down. Was it doing anything to aid in heat soak????? Not sure.....but something strange happened more than once while I used the fan. The next day or so, fan put away and hood closed, I started the truck and heard a crazy loud hissing noise coming from under the hood, the engine shook violently, and I had ZERO fuel pressure. Instantly I'd shut the truck off and look for the problem or anything standing out but finding nothing. The first time this happened I could have sworn the engine was running "backwards". It was that weird. Days or weeks later, it happened again but this time I let it ride out only to have it last for about 3-5 seconds and then it stopped making noise, engine stopped shaking, and the fuel pressure became normal. This crazy event happened to me a few times before I made the direct correlation that the VP was the source of the loud hissing noise, the engine shake must have been because of whacked out fuel timing, and the loss in fuel pressure was something to do with the VP telling the ECM to stop power to the fuel pump. Sounds strange and bizarre I know but when I stopped using the floor fan to cool the VP like I was, all this weird stuff stopped happening. So.......... I've come to the conclusion that my VP simply doesn't like to be rapidly cooled off or that possibly there is some internal programing in the FPCM to acknowledge the increase in heat after engine shutdown and by cooling the VP like I did caused something to go awry in the electronics. Now I know someone's going to post a rebuttal saying there's no connection but truly, this only happened (more than once or twice) when I cooled the VP with a fan. Now if its hot out, I simply open the hood and let all that hot air escape. Believe it or not, that does help.

Uh..........I was lost after the third sentence. But I elect you hired to complete the objected task you speak of.

Wonder how the ribbon cable problem could be rectified? It would seem to be the only real way to stop the excessive heat from affecting the FPCM. And good analogy too.....although not really as bad as taking the engine belt off but rather something like taking out the thermostat and replacing it with a plate which only has a 1/4" hole in it, and still expecting the cooling system to work on a hot day. Coolant will still flow through the engine.....but with little ability to keep temps under control. Now to take that analogy you've created a little further and say that adding a big HP timing/fueling box to the VP is exactly like adding huge injectors to the engine. The higher EGT's created by the additional fuel are even more work for the cooling system. Which is why big HP tuners can aggravate VP reliability.

There is some good "accurate" information going on here. I like it..... It seems the knowledge of the forums are working. :)If I may, can I throw my two cents in this topic.....The problem is this and this ONLY. The VP computer has lead free solder.....thats it. Lead free solder cant take extreme heat otherwise it deteriorates. Over time that deteriorating solder eventually leads to intermittent and/or no electrical connections. We could try to come up with all kinds of coolers but as Moparman mentioned, as long as fuel is passing through the VP somewhere between 14-20 psi at ALL times, the VP temp will stay plenty cool enough, running roughly between 110*-150*. Fuel temps over 160* are bad and will cause the fuel temp sender to de-tune the engine. The problem lies with shutting the engine off. Shutting the engine off stops fuel flow and causes the engine to heat soak the VP to approximately the same temp as the 190*-200* engine. This is when the solder deteriorates. So if the engine was continually running then the lead free would never be an issue. And if anyone doesnt know this, fuel passes "though" the VP and not just in the inlet and out the outlet. Which is why the engine must be running, turning the VP, for fuel to fully pass through the fuel lines.The best fix I can think if is to simply REMOVE the computer from the top of the VP and mount it somewhere less susceptible to direct heat contact from the hot engine. Sounds simple enough..... But no ones been able to successfully pull this off. Something to do with the surrounding electrical interference the farther the computer gets from the VP causing problems.

Well this may be your original VP simply wearing out. The older OEM VP's were subject to poor quality control and inferior materials and there was really nothing you could do to keep them wearing out. Fro example, over time those components, like the timing piston, would wear out the bronze timing sleeve and you'd end up with poor fuel timing. If you're experiencing loss in power and loss in fuel mileage then maybe thats the problem. But I would certainly explore all options before running out and replacing the VP.

A heat soaked VP wont cause the engine to shut down but rather cause a hard start or no start when the engine is warm. Did you ever check the ideas suggested?

I pull this same trick when in dusty conditions. Leaves all that junk out of the vent system until the air clears up. I like to run in the normal A/C selection though since the MAX setting seems stuffy and not fresh.

Good info so far. I see you have a long bed too so I'm guessing you thoroughly inspected the carrier bearing as well. Also, just because a u-joint isn't obviously flopping around doesn't mean there isnt a dry or rusted cap making noise. Exploring all variables is sometimes the only way to track such issues. Like decelerating in all gears, in and out of 4wd, turning, forward/backwards, etc. Having someone listen with you helps.

John, I'm not downplaying your intelligence since I like your analytical point of views. But.....you cant ignore the fact that there is plenty of people with engine temps which hardly swing at all. Like me. My engine temps lay solid at 190* unless idling in the cooler weather for long periods whereby I might see 185*. And when pulling hill or driving "faster" on the freeway I may see 195*(ish). When towing the temp will consistently maintain 195* until I stop and then it will settle back at 190* again. My truck has ALWAYS run this way, even when I had the OEM thermostat. So why with my cheap NAPA thermostat will I not get the wild swinging engine temps but another guy will? As I mentioned, I think there's other reasons this issue is as rampant as it is. I've never had an engine that would swing engine temps 30*+. - - - Updated - - - My bad guys..... This is what the FSM says about "diesel" engine coolant system. I would have edited my post but you already quoted me. TEMPERATURE GAUGE READING INCONSISTENT ( ERRATIC, CYCLES OR FLUCTUATES) 1. Heavy duty cooling system, extream cold ambient (outside) temperature or heater blower motor in high position. 1. None. System operating normaly. 2. Temperature gauge or gauge sensor defective. 2. Check gauge. (Refer to 8 - ELECTRICAL/INSTRUMENT CLUSTER - DIAGNOSIS AND TESTING) 3. Temporary heavy usage or load. 3. None. Normal condition. 4. Air traped in cooling system. 4. Fill cooling system (Refer to 7 - COOLING - STANDARD PROCEDURE). 5. Water pump 5. Replace water pump. 6. Air leak on suction side of water pump. 6. Check for leak. (Refer to 7 - COOLING - DIAGNOSIS AND TESTING) ___________________________________ And to answer your question dripley. TEMPERATURE GAUGE READS LOW 1. Vehicle is equipped with a heavy duty cooling system. 1. None. System operating normaly. 2. Temperature gauge not connected 2. Connect gauge. 3. Temperature gauge connected but not operating. 3. Check gauge. Refer (Refer to 8 - ELECTRICAL/INSTRUMENT CLUSTER - DIAGNOSIS AND TESTING) 4. Coolant level low. 4. Fill cooling system. (Refer to 7 - COOLING - STANDARD PROCEDURE)

There's plenty of guys with swinging temps running Cummins thermostats which would rule that variable out. This whole topic perplexes me and trying to chalk up all these similar engine temp issues as cheap garbage thermostats just doesn't add up. I'm not saying that getting a bogus thermostat isn't possible but I think there's other reasons this is happening to so many people. Here's what the service manual has to say about it: TEMPERATURE GAUGE READING IS INCONSISTENT (FLUCTUATES, CYCLES OR IS ERRATIC) 1. During cold weather operation, with the heater blower in the high position, the gauge reading may drop slightly. 1. A normal condition. No correction is necessary. 2. Temperature gauge or engine mounted gauge sensor defective or shorted. Also, corroded or loose wiring in this circuit. 2. Check operation of gauge and repair if necessary. (Refer to 8 - ELECTRICAL/ INSTRUMENT CLUSTER - DIAGNOSIS AND TESTING). 3. Gauge reading rises when vehicle is brought to a stop after heavy use (engine still running) 3. A normal condition. No correction is necessary. Gauge should return to normal range after vehicle is driven. 4. Gauge reading high after re-starting a warmed up (hot) engine. 4. A normal condition. No correction is necessary. The gauge should return to normal range after a few minutes of engine operation. 5. Coolant level low in radiator (air will build up in the cooling system causing the thermostat to open late). 5. Check and correct coolant leaks. (Refer to 7 - COOLING - DIAGNOSIS AND TESTING). 6. Cylinder head gasket leaking allowing exhaust gas to enter cooling system causing a thermostat to open late. 6. (a) Check for cylinder head gasket leaks. (Refer to 7 - COOLING - DIAGNOSIS AND TESTING). (b) Check for coolant in the engine oil. Inspect for white steam emitting from the exhaust system. Repair as necessary. 7. Water pump impeller loose on shaft. 7. Check water pump and replace as necessary. (Refer to 7 - COOLING/ ENGINE/WATER PUMP - REMOVAL). 8. Loose accessory drive belt. (water pump slipping) 8. (Refer to 7 - COOLING/ACCESSORY DRIVE/DRIVE BELTS - DIAGNOSIS AND TESTING). Check and correct as necessary. 9. Air leak on the suction side of the water pump allows air to build up in cooling system causing thermostat to open late. 9. Locate leak and repair as necessary

The right Cummins replacement thermostats have "jiggle pins" on the sides of the plate. Dont get the wrong type.

Will they work?..... Well the question should be, for how long. Because yes, they will work but understand that all batteries are not the same. If you try to run a parked and disconnected RV off of auto batteries, they wont last long at all. Not only do automotive not have a very long reserve but automotive batteries are made with thin grid type plate for quick maximum amperage draw for starting. Deep cell batteries contain thick solid cell plates which are for long term low amperage draw. And marine batteries are a combination of the two with thicker grid type cell plates so that they can offer a longer lower amp draw for things like trolling but yet still allow enough amperage draw to start an engine. Every time any battery runs below a certain level of discharge, the cells are deteriorated. That level is different from auto to deep cell. Thats why deep cell batteries are thick and solid which can sustain more discharges and lower discharges. When you discharge an automotive battery, they quickly fall apart and the cells can and will easily short out from the debris. Thats why a few times of leaving the lights on overnight will cause you to replace the battery that wont hold a charge anymore or is shorted out. Point being is yes, you can use them in your RV but its not right and you'll destroy them if you aren't constantly plugged in.

While you're at it, use your temp gun to shoot the VP, VP computer, and the intake and outlet fuel lines. That would be interesting. I need one of those little tools.

Thats not cheap but it is cool looking. Especially if they did all the prep.

$400 is a steal of a deal. And, I havent seen retreads in forever. Are they decent quality? I only know from running trucks that retreads can be good like Bandag's, or not.

I couldn't comment on anything but.....how freaking expensive tires have gotten.

Yes, the fan clutch is viscous. The coil is the clutch's thermostat.

I agree. How much prep is required?

I dont care what anyone says..... That is NOT normal, and I agree with you there must be some underlying issue causing this besides chalking it up as poor thermostat construction. Maybe there's a air lock which is cycling the thermostat in and out of coolant causing the temp to swing. And I'm not sure why the thermostat you had did not have jiggle pins since I understand the jiggle pins are there to help stop air locks.

I've wanted to do the rocker panels for years. Just haven't had the spare cash nor the time. I thought about doing it in the color red since I have a red truck but after hearing from numerous people that the stuff can fade, I thought pink wouldn't look so cool.

I just dont get what could be the reason why there is so many people having thermostat issues. There has to be a logical answer.