Anyone use a fuel cooler? What is a good fuel temperature? Ideas?

[rweis]

Going to put on a fuel cooler to help the VP44 stay cool. The H7B is a stacked cooler and certainly should be able to do the job. It works well with transmission fluid, will it work with fuel?



Maybe even put a temperature gauge on the fuel as well. What is a reasonable fuel temerature anuway?



Any ideas or inputs?



Bob Weis

 

[nickleinonen]

100°f ± 20°f

 

[Fishin Guide]

Bob, I would place the cooler on the return line to the tank. This will prevent overcooling of the fuel to the pump, but will help shed the heated fuel out of the VP. You could hook up a thermostat inline and run a fan over the cooler if the temps get hot.



There should be enough fuel moving to keep the temps down. Now, if you are running multiple lift pumps, most likely you are adding tons of heat to the fuel right there. Also, if there is not enough pressure to open the bypass in the VP, you will be heating the fuel on both ends. On the pressure side and on the return side by not having any.



Dave

 

[fox]

I read a story about a trucking company that did this testing a few years ago. I couldn't findout when it was done, and felt is was a decade old or so.



Their testing showed best performance was with the fuel at or below 160* , I would think the above spec is even better.

Their tests also showed the best mileage from the truck was with an exhaust temp of around 800*.

 

[tractorface]

160 is near the upper limit of what most engines want to see. I see lots of specs that say max inlet temperature to injector pump is 160. I gaurantee we would be better at a temperature quite a bit lower.

I have a nice big Caterpillar installation guide and it devotes a lot of print to fuel. One of the things it reminds the installer is that the viscosity of the fuel changes with the temperature. temperatures just above the cloud point would be ideal for keeping a healthy pump.



Ever notice how your pressure goes up in the winter when it is really cold. The fuel has a higher viscosity.

 

[tractorface]

I did a little more research and fox is right about the optimum temperature being 160 F for complete combustion and best performance. The problem is that that temperature is not the best for VP longevity. There is even a product on the market with a mixing valve that strives to maintain 160 F.



From the QSXK Cummins data sheet I have on my desk, it lists 160F as the MAX inlet temperature. Hope this helps.

 

[rweis]

What's the "cloud point"?



I'm thinking of running a fuel cooler in the summer or when pulling hard (heavy) for a long time (more than a couple of (2) hours?. Bypass the cooler in the winter (below 50*) with a ball valve or a manual bypass.



I like the idea of the return line because if anything breaks off from the internals of the cooler it would probably not be good for the VP if it were in the supply line.



Can the return line after the VP / engine drain T be change without detriment to an AN-6? (Easier to work with than the steel return line mounted to the frame). I found a Earl's coupling to fit the supply line to AN-6. Is the return line the same size steel line as the supply line? (ie the same coupling would fit)



I also started looking for a temp gauge that would measure 0* - 250*. Everything I have found so far seems to start at 100* which is too high a gauge start temp.



I stopped at a local truck stop and asked 10 different truckers (that knew yes or no) if they had a fuel cooler. 8 had a fuel cooler. I think I read in this or another thread that Duramax does a fuel cooler.



Finally something that might actually help the VP ($2000, parts and labor) live longer.



Bob Weis

 

[nickleinonen]

What's the "cloud point"?

depends on fuel grade... it is the point when the wax in the fuel begins to crystalize [fuel goes from clear to cloudy... it is before the gel point of fuel [goes from cloudy to near solid glob]



how about using an ambiant air temp gauge... ?? dakota digital has some gauges that read from 0-300 [trans/water] and some that go from -40 - 250... [air/amp]

 

[bmoeller]

I stopped at a local truck stop and asked 10 different truckers (that knew yes or no) if they had a fuel cooler. 8 had a fuel cooler.

Are you sure? They generally have fuel heaters, not coolers. All of the trucks we run have fuel heaters.





Cloud Point (CP)

A measure of the ability of a diesel fuel to operate under cold weather conditions. Defined as the temperature at which wax first becomes visible when diesel fuel is cooled under standardized test conditions (ASTM D2500).



http://www.dieselnet.com/gl-a.html

 

[rweis]

Westach has a 0* - 200* gauge (2c9-63 on page 8 with the 399s1 sensor on page 35) which should work. If 160* is max, the objective is down in the 100* range which is right in the middle of the range where a gauge should be.



First is to monitor the fuel feed temps into the VP to see what they really are. Cost is about $85 + shippping for the gauge and sensor. Seems to be a reasonable start point. I would assume the fuel temps need to be monitored for a fair amount of time under as many conditions as possible, unless they are at the high end of 160* early on, which they could be.



What are your thoughts?



Bob Weis

 

[Fishin Guide]

Bob,



you are on the right track to establish baselines. The next question will be at what temp does the cooler fuel become a negative to performance and emissions?



I don't know, but it will be interesting. I wil pester my dad and see if I can steal some of his schoolbus 5. 9 stuff.



And as far as fuel heaters not coolers, many of the OTR units run double duty. Some are plumbed into the coolant system in the order of a heat exchanger. While this serves to heat the fuel and improve combustion in very cold climates, it can also help pull some of the excess heat from the fuel system.



Dave

 

[rweis]

I could stand a little performance degradation to keep the VP alive.



150,000 miles @ 16 mpg = 9,375 gallons.



150,000 miles @ 15 mpg = 10,000 gallons.



625 gallons @ 2. 50 / gallon = $1563 or about the cost of a VP.



If I could get 150k (about 6 years of driving for me) out of a VP that would be good.



I am going to order the Westach gauge and see what actually the fuel temperatures are.



I have a RASP arriving tuesday so now is a good time to do some replumbing for the fuel temperature gauge also.



Bob Weis

 

[scotty1]

I ran into a glitch with my 3rd gen that may get a solution with what you are looking at doing with the fuel cooler.



A friend of mine bought an 03 and everytime he went to fuel up, steam would billow out of the tank and several stations refused to fill it. He had the truck back to the dealer until they bought it back and he drives an 04 now.



Recently I was encountering the same thing in 90 degree weather while towing with my 04.

It did not matter if I had a full tank or not. What started happening was a stumble, then fuel pressure would go up and I had no throttle then another stumble and it all returned to normal... and then cycled again and again. This happened for about 2 wks on and off. Then it went the other way... the stumble would occur and then the fuel pressure would drop below what it normally was and it kept falling over time with lost throttle. Then the stumble ceased and the fuel pressure kept falling.



The dealer was leaning towards the aftermarket fuel pump I had on the truck... so we switched to a Holley Blue I had... brand new... same low pressure. Then we put the in-tank pump that DC was doing and I had the same pressure at idle but not as much of a drop under empty driving conditions but hook up the trailer and poof... 0 PSI. The old in-tank assembly was all distorted and melted. The pick up tube was the worst looking part of it all. My Essex pump was fine and so was the Holley and even the old original lift pump that mounted on the back of the filter housing. Excess heated fuel was doing a number on all the components and was turning the pick up tube into a floppy melted mess. My fuel filter was getting messed up every 500 miles now.



What has been determined is the pressure relief valve is defective in the injector pump and dumping heated/pressurized fuel back to the tank. With the new in-tank pump and assembly I started getting the symptom again and the fuel was hot. 180F and higher. This was within 10 minutes of driving with 1/2 tank of fuel!



So now the injector pump will get changed and my plan is to take cool fuel from the 66 gallon in bed tank that has a steel pick up and supply the engine, then have fuel return to the stock tank as usual and lift/pump the fuel from there to the big tank to dissipate the heat more. I tried this on my 01 and I may have been hallucinating but I had better pressures [2-3 psi] and better mileage. I think that a cooler might be a good idea.



Does anybody have a link to a site or some pictures of what these look like? Do they look like a mini radiator?



Sorry for posting in the 2 gen on this about a 3 gen but the feedback you gave prompted me to let folks know what I encountered.



I wonder at what point a lift pump exceeds its productive side by adding more heat to the fuel that is being supplied to the engine? Afterall, all pumps are increasing pressure/supply and friction/heat, right? Only on a smaller scale then an injector pump.



A pressure box on a 3 gen truck will only make this worse, I would guess anyway.



Scotty



on edit:

http://www.dana.com/Automotive_Syst...Products/Fuel Coolers/fuelcooleroverview.aspx



I know a local company that builds stuff like this for bigger companies. I am going to check them out.



Each site I went to discussed the HOT fuel back to the tank and the more you run the fuel through something to increase pressure, the hotter the fuel.

 

[nickleinonen]

fuel temp was a major issue on larger cummins engines with the PT fuel system... i don't remember if any of them had fuel coolers on them, but maybe they did?



maybe a dmax fuel cooler retrofit?



or one of these?

 

[rweis]

I am ordering a temperature probe & gauge tommorrow and installing it in the supply line between the ff and the VP to see what is really going to the VP. The gauge temp range is 30* - 150* F.



I am going to drive a full tank to an empty tank a couple of times around town unloaded. Then a full tank to an empty tank of continuous 60+ mph a couple of times unloaded. Then go hook up the 5er (13k) and run a full tank to an empty tank at 60+ mph a couple of times (loaded). I will report temperature characteristics of each tank as I drive it out.



IF the data collection is so skewed to prevent further test ie somewhere along the test the fuel gets hot and stays hot then I am going to put a fuel cooler like an H7B on the return line. H7B Large?, yes, but then it should keep fuel from going beyond 120* feed temperature. If it is too large I will put a bypass on the H7B so only a portion of the fuel goes through it.



Based on what the test shows it may be that you bypass the cooler except when you know you are going to run continuously above 60 mph or tow heavy for more than a couple of hours and the outside air is more than xx* temperature.



I was reading about the VP today on the internet and it said the VP has an internal fuel temperature sensor so it can work with the correct fuel density. Anyone know anything about that?



I am aiming for about 120* max feed temperature to the VP. I thought 120* would be a good maximum since the absolute maximum temp of 160* - 20% (safety margin) of 160* = 120* (approximately). It would also allow a 40* rise of the fuel temp within the VP for cooling the VP before it gets back to the 160* maximum.



I would think a full tank can dissipate heat better than an empty tank so the 120* will probably be determined by an almost empty tank, and maybe only with ambiant outside temperatures above xx*. And maybe only with a heavy load or continuous high speed driving. Time will tell.



This should be interesting. I like the 2002, I think the DC fuel engineers should be dipped in boiling oil. We basically are doing the proof testing of the fuel system of an already in production vehicle, and that is assinine.



One of the comments about the fuel pickup and the fuel return being in the same "cannister" in the tank may obviate how much fuel the tank has in it. If the tank only makes up the difference the injectors use, the actual amount of fuel the fuel tank may have in it may be a really small factor. Do all 2nd gen tanks have the same fuel cannister / pickup cell system?



If 70% of the fuel going through the VP is used for cooling (and if this is right) then the return cooling fuel gets mixed with SOME whatever temperature tank fuel and sent back to the VP. Some threads have said the mesh filter screen on the bottom of the fuel cannister is super fine mesh, so is there any real heat transfer to the tank anyway? Some have said the tank actually gets HOT to the touch.



How would hot fuel effect the internal clearances of the VP? It would seem like a cooler VP frame & internal systems would be better. But how cool? So far 160* maximum is the only target suggested. What about a "normal" operating temperature? One post in this thread suggested 100* +- 20*. Should that be the target range?



MUCH to be learned,



Bob Weis

 

[rbattelle]

I'm not sure about the 2nd gen trucks, but on my third gen the return line is a solid stainless tube (8mm OD). What if it were used as the cooler? This could be accomplished by "wrapping" it with fins (like on a radiator) along its entire length, thereby increasing its surface area significantly.



Not sure where to source such a thing from...



-Ryan

 

[Fishin Guide]

I'm not sure about the 2nd gen trucks, but on my third gen the return line is a solid stainless tube (8mm OD). What if it were used as the cooler? This could be accomplished by "wrapping" it with fins (like on a radiator) along its entire length, thereby increasing its surface area significantly.



Not sure where to source such a thing from...



-Ryan

Easiest thing with stainless would be to cut a chunk out and install a cooler with compression fittings.



Dave

 

[nickleinonen]

I was reading about the VP today on the internet and it said the VP has an internal fuel temperature sensor so it can work with the correct fuel density. Anyone know anything about that?

i think i have heard something similar too, but over on the VW forums. . the pre PD tdi's had a vp pump on them i believe, and you could wire in a trim pot to trick the ecm fuel temprature to get more power... i can't remember the name of their mod though... maybe a trip to the tdiclub.com forums might find it?

 

[rweis]

FYI



I ordered the Westach 30-150 temp gauge and temp probe today. They are out of stock and the next production run is 3 weeks (mid aug) when it will be shipped.



Soooooooo, will be a couple of weeks before fuel temperature data collection starts. :{



Bob Weis

 

[scotty1]

Its official as of today that my CP3 injector pump is on its way out. The specs for what it should be doing compared to what kind of pressures its putting out are WAY OFF.



I will see if this helps the fuel temps. If not, a fuel cooler is going on the truck asap.



Looking forward to your temperature reports.



Scotty