Engine/Transmission (1998.5 - 2002) Modifying fuel system so temperature input to VP44, 80* - 100*, your inputs.

[rweis]

I am in the process of installing a fuel cooler in the VP return line, VP return line will be to the tank filler line, fuel temp gauge just prior to the ff, so I can get the fuel feed to the VP in the 80* - 100* range primarily for cooling the VP properly and I hope to keep the VP electronics from overheating. Fuel cooler willl have a bypass valve for winter driving below 50*.



What problems do you see with the concept?



What I know:



Input fuel should not reach a maximum of 160* (Bosch limit)



Input fuel is used for cooling as well as lubrication. More cooling fuel seems to be bypassed at higher rpm's.



There is an internal Vp44 fuel temperature compensator (of some sort).



The VP electronics can and do get overheated with heat cycles over time. I am going to try to keep the whole VP mechanism cooler.



Do not go below the cloud point for fuel gel purposes.



Lubricate the fuel (low sulfer fuel?), (I use Stanadyne Performance).



Clean the free water out of the fuel, clean any particulates out of the fuel (I use a RACOR 690T).



All fuel lines are AN-6. All full flow fittings. No restrictions in any lines.



RASP mechanical pump being installed in this iteration.



I am asking for your inputs. Do you see anything wrong, not quite right?



Some of you have extensive diesel experience, please give your inputs and ideas.



Bob Weis

 

[GBobbitt]

We have a couple of Volvo VHD dump trucks that have frame mounted fuel coolers with temperature controlled fans. Both trucks have Cummins ISM engines but I don't know if the fuel cooler setup is a Cummins item or a Volvo item. The measurements are roughly 12-16" square and about 4" thick including the fan. You might be able to look at one and get some ideas for what you are building. Your project sounds like an excellent idea.

 

[Texas Diesel]

Just a thought but cooling the VP-44 return line may not solve the problem.



Somewhere on the back of the block the injector return fuel joins with the VP-44 excess fuel and they combine and return to the tank. Simply cooling the VP-44 excess fuel wont help the hot fuel coming from the injectors / cylnder head. Cooling the fuel between the filter and VP-44 might be a better approach. This is what I am gathering parts to do.



What do you think? I'd hate to do this incorrectly.

 

[ThrottleJockey]

Yeah, your'e gonna want to cool BOTH the input and the return fuel.



I'm looking for a dual circuit transmission cooler to mount next to the AC condenser, (the space in front of the radiator is on the VP side of the engine all ready and waitin'!).



From the FASS to the front cooler and back to the VP and the return from the back of the head BACK to the front cooler and back to the tank.



Brian

 

[Texas Diesel]

Like this:



http://www.perma-cool.com/Catalog/Cat_page12.html

 

[Lsfarm]

Cool at the hottest point

You will get the best cooling where the temp difference is the greatest. So I would cool the fuel when it is the hottest, which is when it has left the VP44 and is on it's way back to the tank. The greater the temperature difference across the hot fuel/cooling air interface the greater the temp drop from the cooler.



There is some temp rise after the lift pump, but with only a few PSI pressure rise I doubt if this is creating an issue for our VP44's. It would be very interesitng to put several temp probes in or on the fuel lines to monitor the temps and see what is really happening.



Just for heavy towing and high ambient temps I installed an air duct from the gap beside the radiator to the top of the VP44 to provide outside air cooling directly to the computer. I know this is not very effecient, but at least the air blowing over the top of the pump and computer board is not preheated by the radiator.



On a recent towing trip I stopped many times and used a laser thermometer to read the temp of the top of the VP44 and never had over 135*. The fuel tank temp stayed around 110-120* . I'm not sure if the duct was any help or not, I didn't try a run with the duct blocked to see if the pump temp would rise with out the cooling duct air or not. I was pulling a flat front box trailer [car hauler] weighing in at 8700# at 70-75 mph in 95*F ambient temps. I did not have any codes set for overheating fuel like I have had in the past without the duct. Not a true controlled-condition test but maybe it helped.



Just some ideas and experiences, Greg L

 

[BarryG]

I would agree with Greg the higher the heat going into the cooler the better it is going to be at shedding the heat or make the most difference.



Bob: The RASP pump return line also can be plumbed into the tank vent. If you use the tank vent line for the RASP return and the vp return will that cause a backflow to the RASP? At idle the RASP return line will have none to very minimal flow but the VP definitely will. Obviously not a problem if you dont use the vent line for the RASP return. Also one other thing if I recall the orignal FASS users were having problems filling up with fuel while the truck was running due to fuel being returned via the vent line. Again not a problem if you dont fuel while running which I dont usually but have on occassion.

Just food for thought.

 

[Texas Diesel]

Definately the greater the temperature the greater the heat rejection. But what about the injector return fuel? It is bound to be hotter than the VP-44 return. If that heat is allowed to get into the fuel tank than it will be pumped right back to the VP-44.

 

[rweis]

I am going to put the fuel cooler in the tank return line back by the tank so I will get the VP return fuel and the injector return fuel (ie hottest temperature differential) going through the cooler. The cooler is also a 1/2" female input / output so there might be some pressure drop cooling as well. I am mounting the H7B cooler 11"x11"x1 1/2" flat plate type cooler up under the bed vertically with a 1000 cfm fan. I have an ignition on circuit to the fan with a switch in the cab.



I am also going to cut the OEM tank return line and return spring / summer / fall (above 50* outside) fuel to the tank vent tube. I am going to return winter fuel (below 50* outside) to the tank cannister unless working the engine hard, then return to the vent line also. I have the lines designed so I can easily route the return fuel where I want it depending on what I see as the fuel input temp to the VP.



I live in florida so I probably will leave the cooler in line all the time unless the fuel temp gauge shows less than 50* fuel temp going into the VP. You colder climate guys would want to bypass the cooler as well as dump the fuel into the OEM fuel cannister so you don't gel the fuel.



I like the idea of ducting frontal air at the VP and electronics area also. Good simple solution. There will be a combination of ideas that will get the job of cooling the VP done.



My temp sensor is going to be in the line between the ff and the VP. Gauges will not be here for 3 weeks, but I am going to install the RASP and the fuel cooler this wed & thur. To insure the temp probe does not interfere with the fuel flow at all, I am using a 3/8" female T with 3/8" AN-6 males on the straight through and a 3/8" to 1/4" male bushing in the T where the temp probe goes that will lift the temp probe out of the main fuel flow but will still allow it to sample the fuel temp.



All the plumbing T's etc have the straight through as the primary fuel path so the fuel does not get turbulent and stays as smooth as possible. All the fittings are full flow type.



I do not know what temp the VP will be with 80* - 100* input fuel temp. I am thinking somewhere around 125* is a reasonable temperature. I will have to get a infarred temp gun so I can measure over a long period of time.



Just some ideas and experimenting,



Bob Weis

 

[Hohn]

Definately the greater the temperature the greater the heat rejection. But what about the injector return fuel? It is bound to be hotter than the VP-44 return. If that heat is allowed to get into the fuel tank than it will be pumped right back to the VP-44.

Well, if the cooler were plumbed into the return side AFTER the tee where the two meet, wouldn't that solve the problem?



I say plumb it in after the tee on the return side-- no need for anything else.



jlh

 

[Gary - K7GLD]

I thought Bob was pretty clear from the first post that the cooler was going in back near the tank AFTER fuel/lines had fully exited all engine/VP-44 functions, at least that's what I understood him to mean, and it would be lots harder mechanically cut lines and mount a cooler closer to the engine anyway...



"I like the idea of ducting frontal air at the VP and electronics area also. Good simple solution. There will be a combination of ideas that will get the job of cooling the VP done. "



In another thread, a member mentioned work he was doing to develop an actual solid-state refrigeration module (looked to be adapted from those small 12 volt portable cooler units) to install on the top of the VP-44 for cooling of the electronics - looks like a better idea than the air ducting approach, and I'm very interested in that approach if it works out.

 

[rweis]

I have a question.



Exactely where (under the electronics cover I would imagine), exactely how are the electronics mounted (on a heat sink, just screwed onto the frame, floating,,,), is one end of the electronics more suseptable to heat than the other end (is one end the processor and the other end the connector terminals?), someone that works with electronics - what is a normal electronics board temperature range?



I would like a little more info on exactely the characteristics of the part (electronics) we are dealing with.



I also like the idea of cooling the electronics compartment with a solid state cooler chip. I wonder if it will try to cool the entire VP though. Good idea that it will cool after shutdown which maybe is where the real problem focus might be / should be. Or a combination of both internal cooler temperatures and cooler electronics compartment.



Bob Weis



I might get a chance to do some VP infarred gun samples this afternoon Oo.



Bob Weis

 

[Gary - K7GLD]

I wondered the same thing about the VP-44 electronics mounting method, but dunno. The guy doing the mod I mentioned further above stated he will use a heat-transfer putty to provide maximum heat transfer to the refrigerent chip, and it WILL be thermostatically controlled to provide temp protection even after the engine is shut down - looked REAL cool (pun!) - the thread is here on TDR...

 

[darkhorse]

What would be involved in removing the electronics completly from the pump body & mounting them in a cooler spot?

 

[Gary - K7GLD]

Here's the thread I mentioned with the "VP-44 cooler"



https://www.turbodieselregister.com/forums/showthread.php?t=135126&highlight=cooling+VP44



And here's a pointer to a pic of the added unit - hope it comes out:



#ad

 

[rweis]

I saw that, different approach, good idea, as many different ideas as we can generate and test. I especially like the after shutdown remain cooling. Something fuel cooling will not do.



I hope that fuel cooling will cool the entire mass of the VP and therefore have less latent heat to dissipate after engine shutdown.



On the surface sounds like a good combination. Less latent heat to start with, and a way to rid even that for the electronics bay.



On the Blue Chip Diesel site (I think) they had a different cover for the electronics bay on the VP. The point was to be able to tap the electronic component that you would tap with the pump wire, but do it through a different cover and would be removable if need be. BCD used a pheonlic cover with a set screw (attached to a wire) to touch the electronic component or trace to make the connection.



Now this seems that if BCD can get to the electronics bay other possibilities open up. The set screw was not very long, ie the electronic board was not burried very far under the cover. If you used their cover (not for the purpose of tapping the electronics board) and powered ventilated it and protected it from debris and water getting to it, an idea? Maybe something that would pickup clean cool air (sounds like a Scotty II commercial ) and forced the cool air through a duct attached to the electronics bay. Much like one of the members had devised a front grill duct to the VP electronics bay. There are lots of fan assemblies in the computer case markets that take relatively little power, are 12 volt, and could run continuously (shutoff timer like the "turbo cool down timers") taking very little battery amperage well after the engine is shutoff.



Maybe a more heat efficient cover, copper?, maybe even the whole cover and heat sink be intergral. Unscrew one, screw the other one on, duct it or like the picture you had of the refrigerator unit. Or run the duct fan for x hours, or maybe even run it permanently on.



Ok, guys, ideas, inputs, threats, admonishments, "give her he. . ", whatever. This $2500 for a VP every 50k miles is going to stop.



Bob Weis



BTW just checked one of my servers motherboard circuit temperature zones #1 97*, zone #2 93*, zone #3 101*, cpu#1 105*, cpu #2 101*

 

[Texas Diesel]

When I worked for AlliedSignal, we would test and certify circuit boards to function @ 155F.





Mission accomplished! As Hohn suggested (thanks) I changed my plans and hooked the cooler just past the return T. Even after just a 6 mile run you could feel the heat in the fuel.

 

[rweis]

How full was your tank during the run? Any estimate of the fuel temp (SOP is fine).



Bob Weis

 

[Texas Diesel]

Tank was 7/8 full. Guess it was 110F.

 

[Gary - K7GLD]

Just thinking out loud, but as dandy as the "refrigeration unit" looks, there IS the issue of significant modification to the VP-44 to get it properly installed as shown.



The fuel cooler setups look fine, but I sorta wonder if proper or substantial cooling of fuel and the VP-44 *MIGHT* be accomplished by a billet-type of aluminum block that itself has as many of the solid-state cooling chips attached as needed, that then attaches to the fuel input port of the VP-44 for fuel to flow thru by way of a longer attaching bolt. Thus, the fuel flowing THRU that block would cool incoming fuel, and the heatsink effect of the cool block would provide conduction cooling of the VP-44 case after the engine is shut down...



Hopefully, that method would also provide a substantially reduced temperature rise for the pump's electronics as well.