Hit by cavitation last Sunday

[Waldi]

The small fan it a good idea Chris, it will also cool the tank a bit. Do you note the difference in boot temperature with and without the fan?

Waldi

[chrismitchell]

21 hours ago, Waldi said:

The small fan it a good idea Chris, it will also cool the tank a bit. Do you note the difference in boot temperature with and without the fan?

Waldi

Sorry no, it was all done in a hurry to try to eliminate cavitation with Lucas pump on long hot runs.

Someone above mentions heat from the exhaust.   This is very good point, possibly the major culprit on long runs. Not much space for a heat shield though?

Edited July 24, 2021 by chrismitchell
Typo

[Waldi]

The effect of dissipated energy by the pump is another factor:

Example:
A tank with 20 liter is circulating over the pump and prv (which it does with most of the fuel pumped around).

The theoretical increase in temperature then is 14.7 degrees C. So if you start with 20 C, after one hr of running the fuel temperature will rise by some 10-15 degrees, just by dissipated pump energy. The heat from the exhaust/engine can be added to that.
Off course, initially the tank will cool down and warm up the boot area but once the boot temperature increases, the cooling reduces proportionally and fuel temperature will rise. 

So “cooling” the tank with an extractor fan for the boot area back to ambient could be a good idea. It will not only cool the tank, but also the pump, if installed in the boot.

Waldi

[Mike C]

8 hours ago, Waldi said:

The effect of dissipated energy by the pump is another factor:

Example:
A tank with 20 liter is circulating over the pump and prv (which it does with most of the fuel pumped around).

The theoretical increase in temperature then is 14.7 degrees C. So if you start with 20 C, after one hr of running the fuel temperature will rise by some 10-15 degrees, just by dissipated pump energy. The heat from the exhaust/engine can be added to that.
Off course, initially the tank will cool down and warm up the boot area but once the boot temperature increases, the cooling reduces proportionally and fuel temperature will rise. 

So “cooling” the tank with an extractor fan for the boot area back to ambient could be a good idea. It will not only cool the tank, but also the pump, if installed in the boot.

Waldi

+1

[John L]

From a hydraulic point of view, I think the spill off/return from the regulator valve with the Bosch pump should be twice the size as the pressure into the regulator valve, the Bosch pump produces far more flow than the Lucas one, and now the fuel is more volatile I'm sure it would help.  If we were to run the engine at full throttle most of the time there wouldn't be so much heat generated by the regulator valve, the engine would be using it, and not returning very much to the tank.

I also like the idea of a fuel cooler rad in the overflow line from the regulator valve before going back to the tank, but this would need to be under the car somewhere to get the air flow over it, which car can we salvage one of these from, any ideas?

John

[Waldi]

21 minutes ago, John L said:

 which car can we salvage one of these from, any ideas?

John

I’ve heard of someone who uses a VW fuel cooler.

I ordered the SKV002 (100 ltr/hr) pump, but a different make arrived; will order again from another shop, and plan to install it as a test.

Waldi

[Mike C]

2 hours ago, John L said:

From a hydraulic point of view, I think the spill off/return from the regulator valve with the Bosch pump should be twice the size as the pressure into the regulator valve, the Bosch pump produces far more flow than the Lucas one, and now the fuel is more volatile I'm sure it would help.  If we were to run the engine at full throttle most of the time there wouldn't be so much heat generated by the regulator valve, the engine would be using it, and not returning very much to the tank.

I also like the idea of a fuel cooler rad in the overflow line from the regulator valve before going back to the tank, but this would need to be under the car somewhere to get the air flow over it, which car can we salvage one of these from, any ideas?

John

Isuzu Dmax's have fuel coolers in the diesel common rail return line, but an auxiliary auto transmission cooler should also work- you'd just need to confirm the WP is over 100psi or so.

I'm glad the Australian BP Ultimate that I use can maintain it's thermal stability at high ambients and I don't have the problems you blokes are having.

[John L]

This one looks promising, but don't know how to connect it, does anybody know how I could connect a push on hose connection to the existing stubs?

https://www.ebay.ie/itm/123498948294?hash=item1cc11c66c6:g:Rc0AAOSwRfxb8cu5

John

[Mike C]

Maybe you would have room to cut the ends of and fit compression to hose barb fittings like this:

https://www.wholesalebeerparts.com/draft-parts/hose-clamps-and-fittings/compression-to-barb-fitting-38-tube-size-to-38-barb

If you're planning to fit the HE in the return line from the PRV to the tank, assuming that you can find a location exposed to an air stream, the WP would be minimal.This would cool most of the fuel not burned in the engine.

[super6al]

Hi All

Thought I would give some feedback after experimenting with some computer/electronic cooling material fitted to my Lucas pump. 

I used a heat pipe & a heat sink fixed from the pump to the wheel arch as per the photos attached. The heat pipe is aluminium with hollow tubes inside filled with acetone, its designed to evaporate heat away from cpu chips etc. I then did 10 mile back to back runs to compare temperatures. I measured the temp at the pump (2 points top & bottom), fuel tank & heat sink. The ambient was 22 deg & there was about 7.5 gallon in the tank. With this ambient & amount of fuel I have never had a problem but its serves as a reference. 

1st run with no heat pipe installed

Top of pump = 62 deg C

Bottom of pump = 51 

Heat sink = 27 

Fuel tank = 24.7 

2nd run with heat pipe

Top of pump = 52

Bottom of pump = 42

Heat sink = 28.4 

Fuel tank = 26.2 

Conclusion

I was doubtful the heat pipe would do anything but it does appear to move heat from the pump. There were small rises at the heat sink & fuel tank of 1.4 & 1.5 deg resp. I'm not sure if the fuel tank temp increase was due to the heat dissipating from the pump & heat pipe or would increase anyway due to 10 miles less fuel & the additional 30 minutes running with the 2nd run.

I still need to do a permanent fixing method to the pump that will allow some flex & may install heat sinks on both sides of the heat pipe. I could also install a couple of pipes either side of the fuel tank to the body. These could be glued using thermal glue. I paid about £25 for materials, however since I purchased the pipe a year ago they have more than doubled in price. Farnell now quoting £45.

      Alan

    

[Mike C]

Interesting solution. To get rid of the pump generated heat you need to remove something like 100Watts.

[Kenrow]

Maybe you could try something like this with 6AN fittings:

https://www.ebay.com/b/Derale-Cooling-Products-Car-and-Truck-Suspension-and-Steering-Parts/33579/bn_23266184

Edited July 28, 2021 by Kenrow
added info

[super6al]

10 hours ago, Mike C said:

Interesting solution. To get rid of the pump generated heat you need to remove something like 100Watts.

The heat pipe I fitted quotes a specification of up to 300W. I'm not sure its a final cure but I'll see how it performs. I did consider a small computer fan but I'm not keen on anything that has moving parts & my experience with cheaper fans is they don't last. Its a pity Lucas didn't use a pump motor with an impeller fan it would have probably never been an issue otherwise.  I quite like the idea of a fuel cooler but where to mount it? I wouldn't  want to mount it anywhere theres a risk of damage from debris thrown up from the road. Its one thing having a leaking radiator but fuel is another matter. Has anyone fitted a fuel cooler?

Alan     

[HSM]

I have fitted a small oil cooler in the return pipe from P.R.V. to tank, mounted outside

by the side of the boot floor.

                                              Harvey

[Mike C]

1 hour ago, super6al said:

The heat pipe I fitted quotes a specification of up to 300W. I'm not sure its a final cure but I'll see how it performs. I did consider a small computer fan but I'm not keen on anything that has moving parts & my experience with cheaper fans is they don't last. Its a pity Lucas didn't use a pump motor with an impeller fan it would have probably never been an issue otherwise.  I quite like the idea of a fuel cooler but where to mount it? I wouldn't  want to mount it anywhere theres a risk of damage from debris thrown up from the road. Its one thing having a leaking radiator but fuel is another matter. Has anyone fitted a fuel cooler?

Alan     

For what it's worth , my Isuzu has the fuel cooler mounted high between the chassis rails. Never heard of any problems with  a Dmax  fuel cooler being damaged in this location, even under extreme 4X4 driving conditions.

[trchris]

What about cavitation in the lines from the metering unit across the engine to injectors? using a bosch pump fitted outside of the boot seems to help most 6s 

Chris

[Waldi]

Chris,

cavitation will not occur once the fuel is pressurized in our cars.

It could theoretically occur in the inlet line from tank to pump, but mainly in the pump itself. Past the pump, cavitation does not occur.

Cheers,

Waldi

[Mike C]

Waldi's right. For the fuel to vapourize , its absolute pressure  has to fall to below the pressure at which that particular blend of fuel boils at given it's temperature. Once the fuel goes through the pump its pressure is increased to way above the boiling pressure.

The injection lines may develop pockets  vapour due to heat soak when the engine is stopped, but these pockets of vapour will quickly collapse when the pump pressure pulses hits them.

For persistent pump cavitation problems you need to look at the suction lines of the pump and the tank venting/fill level.

to solve the fuel vapourization problem I've installed a Carter GP pump under the tank . This boosts the fuel pressure to far above the vapour  pressure before it's delivered to the Bosch pump. Bosch pumps need relatively high suction pressures (NPSH) or they vapour lock. Carter GP  pumps are much better at  "sucking " (low inlet pressure) and manage to keep my system operating at ambients up to around 40 deg C on Australian fuel blends.

 

Edited July 28, 2021 by Mike C

[John McCormack]

On 7/25/2021 at 9:01 PM, Mike C said:

Isuzu Dmax's have fuel coolers in the diesel common rail return line, but an auxiliary auto transmission cooler should also work- you'd just need to confirm the WP is over 100psi or so.

I'm glad the Australian BP Ultimate that I use can maintain it's thermal stability at high ambients and I don't have the problems you blokes are having.

Same. With a low fuel level on a hot day my Bosch pump cavitates but the car runs OK. Turn it off when I stop, restart and all is good.

 

[marting]

I had a bit of a radical solution to this wanting to sort it properly as in normal times the car normally does 2 or 3 trips round Europe each year. I cut a hole in the boot floor behind the wheel arch and fitted a large swirl pot. This contains two Bosch style pumps. One is duty, the other is backup. I then attached cooling fins to the outside of the swirl pot so heat is removed from the fuel as you drive. If you then run into severe traffic on a hot day with low fuel as we did a few years ago in Strasbourg, you have coolish fuel in the tank to keep your pump happy. If you do cook a pump. A flick of a switch brings the back up on line. I also have a PI dash where the radio used to be. This has a fuel air ratio gauge, vacuum gauge and electronic fuel pressure gauge. There are some pics on my website under long distance touring upgrades heading https://fredmillturnparts.com/upgrades-and-conversion-kits/

[Mike C]

1 hour ago, marting said:

I had a bit of a radical solution to this wanting to sort it properly as in normal times the car normally does 2 or 3 trips round Europe each year. I cut a hole in the boot floor behind the wheel arch and fitted a large swirl pot. This contains two Bosch style pumps. One is duty, the other is backup. I then attached cooling fins to the outside of the swirl pot so heat is removed from the fuel as you drive. If you then run into severe traffic on a hot day with low fuel as we did a few years ago in Strasbourg, you have coolish fuel in the tank to keep your pump happy. If you do cook a pump. A flick of a switch brings the back up on line. I also have a PI dash where the radio used to be. This has a fuel air ratio gauge, vacuum gauge and electronic fuel pressure gauge. There are some pics on my website under long distance touring upgrades heading https://fredmillturnparts.com/upgrades-and-conversion-kits/

Good idea. Had a look at your website and the bottom of the swirlpot is acting as a petrol/air HE in the airstream below the car and is protected by the chassis leg. I suspect a straight finned petrol/air HE mounted in the same position would work as well at rejecting heat- but the swirlpot  would help the Bosch suction conditions a lot when cornering.

[John L]

I've now got this cooler, https://www.ebay.ie/itm/123498948294?hash=item1cc11c66c6:g:Rc0AAOSwRfxb8cu5  the one I got is the same but with the pipes so just a matter of trimming the length of the pipes and fit it to the inside of the l/h chassis rail, my regulator is just there so should be an easy fit up.  Will do some tests for temperature when able to get out again.

John

Edited August 4, 2021 by John L

[Gary Flinn]

On 8/4/2021 at 12:50 PM, John L said:

I've now got this cooler, https://www.ebay.ie/itm/123498948294?hash=item1cc11c66c6:g:Rc0AAOSwRfxb8cu5  the one I got is the same but with the pipes so just a matter of trimming the length of the pipes and fit it to the inside of the l/h chassis rail, my regulator is just there so should be an easy fit up.  Will do some tests for temperature when able to get out again.

John

John

That should help if not solve the problem, keep us posted?

Gary