Fuel pump swap - Lucas to Bosch

This is the Forum for all your Peugeot Technical Questions, Problems or Advice.

Moderator: RichardW

Post Reply
User avatar
nametooshort
Posts: 146
Joined: 22 Mar 2012, 09:22
Location: Cali/Sometimes south UK
My Cars:

Fuel pump swap - Lucas to Bosch

Post by nametooshort »

I am sure this has been covered before, but does anybody know the exact details of 'de lucasing' the XUD engine?

I have two XUDs, one a XUD7 in mt pug 305 and one a XUD9 which is going into one of my old classic cars, however just my luck they both have the Lucas pump. Ideally, I would like to end up with Bosch pumps on both of them, mainly because I like using veg oil. Bosch injection pumps handle food-grade oil with no problems at all, and it seems the weaker Lucas pumps don't like it.

I know part of the problem is that in some Lucas pumps there is a component made of some kind of non-metal material which gets attacked by oil, and it is possible to retrofit a metal version of this component (but you also have to change the end-cap, which a lot of folks forget), BUT, having taken both apart often, I would rather have the Bosch version just because of it's superior construction anyways.

Also Bosch pumps work slightly differently and because of how they are designed, a side-effect is that they are somewhat self-cleaning, whereas Lucas pumps are not.

So, anyways, i have a few questions:

1) Has anybody here done this before?

2) Am I right in assuming that since the basic XUD engine is all identical, as long as I take ALL the fuel-pump associated parts off a Bosch-equipped engine, everything will bolt to my engine?

3)Are the injectors also different, or are they the same.

4) Is there a physical difference between XUD7 and XUD9 n/a pumps? Or are they they interchangeable, and only set up differently.

5) Iv never actually changed a fuel pump before. I took dead ones apart just to see how they work but never had to put one back on before. Is it hard to time/set up/tune etc it in a DIY environment?

Thanks!
Image
User avatar
spider
Posts: 3949
Joined: 05 Jan 2010, 14:28
Location: Derby.
My Cars: Soon, I hope...
x 77
Contact:

Re: Fuel pump swap - Lucas to Bosch

Post by spider »

1. Yes a few people have done this before. :)

2. Yes, you must take the injectors too and the fuel pump mounting cradle as well, I'm sure the cradle is different but I'm not 100% sure, better safe to take it too. Don't forget the pump sprocket. Might need a tool to remove it.

3. See (2) they are different, different opening pressure for one if I remember correctly.

4. XUD7 pumps are a bit rare now, only really on the (early) C15 / 205D / Visa and some early 405's, you are a lot more likely to find an XUD9 pump. I'd imagine that the only difference is how they are setup but I'm not 100% sure, Jim ?

5. Not really no, you should in theory have a dial gauge to set the initial 'basic' timing although to be honest if its fitted midway it won't usually be that far off, using the same cradle (see (2) above) will help as you will see where it was, a tiny tweak each way until it sounds correct although if you can borrow a DTI it will be a lot easier.

I'm no expert, just posting my thoughts.
Andy.

91 205D-Turbo, gone but still missed
02 106D, TUD5B, gone but not really missed apart from the MPG
User avatar
nametooshort
Posts: 146
Joined: 22 Mar 2012, 09:22
Location: Cali/Sometimes south UK
My Cars:

Re: Fuel pump swap - Lucas to Bosch

Post by nametooshort »

Sounds reasonably doable then!

Can anybody confirm whether a 1.8 and a 1.9 fuel pumps is interchangeable or not? I assume they are the same pump just set up differently or something?
Image
User avatar
spider
Posts: 3949
Joined: 05 Jan 2010, 14:28
Location: Derby.
My Cars: Soon, I hope...
x 77
Contact:

Re: Fuel pump swap - Lucas to Bosch

Post by spider »

I would suspect Jim would know (he'll no doubt see this topic on his travels anyway) although as above I cannot be 100% on this.

Out of interest is it because you have a 1.7 donor ? , 205D's (1,7) were more Bosch than Lucas thinking about it.
Andy.

91 205D-Turbo, gone but still missed
02 106D, TUD5B, gone but not really missed apart from the MPG
User avatar
nametooshort
Posts: 146
Joined: 22 Mar 2012, 09:22
Location: Cali/Sometimes south UK
My Cars:

Re: Fuel pump swap - Lucas to Bosch

Post by nametooshort »

I have two engines. One is a 1.8 in my daily driver Pug 305, which is a reasonably early one so has the 1.8.

The other is a 1.9 from a LDV van, which is going into one of my old cars as a conversion.

I want to eventually fit Bosch pumps to both.

I know with the 1.9 its reasonably easy, since they are common, I can just find one with a Bosch pump and swap them over, so that takes care of my project engine, but then there is still my daily driver.

I know in theory I could just find a 1.9 engine, which will give me a little more cc and more common parts, but I would like to keep the 1.8 engine in that car, since it's a little less hassle and also it's originally a 1.8, if I can just swap pumps in situ it would be easier. Since this car is my daily driver, I don't want to have it off the road for too long.
Image
User avatar
spider
Posts: 3949
Joined: 05 Jan 2010, 14:28
Location: Derby.
My Cars: Soon, I hope...
x 77
Contact:

Re: Fuel pump swap - Lucas to Bosch

Post by spider »

In that case if you wanted a 1.8 Bosch pump just hunt down a 205D, they are all (UK ones at least) 1.7 / 1.8 (same thing just named differently) and most are Bosch equipped. Note: TD1.8's are usually lucas, but there's a lot more N/A than TD 205's around.
Andy.

91 205D-Turbo, gone but still missed
02 106D, TUD5B, gone but not really missed apart from the MPG
User avatar
CitroJim
A very naughty boy
Posts: 49531
Joined: 30 Apr 2005, 23:33
Location: Paggers
My Cars: Bluebell the AX, Polly the C3 Picasso, Pix the Nissan Pixo, Propel the duathlon bike, TCR Pro the road bike and Fuji the TT bike...
x 6160
Contact:

Re: Fuel pump swap - Lucas to Bosch

Post by CitroJim »

spider wrote:
2. Yes, you must take the injectors too and the fuel pump mounting cradle as well, I'm sure the cradle is different but I'm not 100% sure, better safe to take it too. Don't forget the pump sprocket. Might need a tool to remove it.

3. See (2) they are different, different opening pressure for one if I remember correctly.

4. XUD7 pumps are a bit rare now, only really on the (early) C15 / 205D / Visa and some early 405's, you are a lot more likely to find an XUD9 pump. I'd imagine that the only difference is how they are setup but I'm not 100% sure, Jim ?

5. Not really no, you should in theory have a dial gauge to set the initial 'basic' timing although to be honest if its fitted midway it won't usually be that far off, using the same cradle (see (2) above) will help as you will see where it was, a tiny tweak each way until it sounds correct although if you can borrow a DTI it will be a lot easier.

I'm no expert, just posting my thoughts.
No expert? Come off it Andy :wink: That's a bit like Nick Clegg saying he's no politician :)

Right, in turn...

2. Yes, the pump sprockets are a little different between pumps so do take the correct one for the pump. The cradles are exactly the same and have tappings to put the studs in the right positions for both Lucas and Bosch pumps. You'll see three sets of tappings - when converting just move the studs to their alternatives.

3. yes, different operating pressures.

4. XUD7 Bosch pumps are as far as I've seen, all non-turbo ones so they have no LDA on the top as the 1,.9TD Bosch VP20 pumps have for turbo boost compensation. I have never seen a Bosch pump on a Turbo XUD7, only Lucas.

The XUD7 Bosch pump is different internally as it has a much smaller driveshaft diameter and again a good reason for using the right sprockets. Other internal components are pretty much the same though but I'd not swear on how swappable parts are between XUD7 and XUD9 Bosch pumps.

My view is that a VP20 from a Turbo XUD9 should be fine on an N/A XUD7. Just leave the LDA inlet open to the air but you may need to adjust the maximum fuel delivery screw with the greatest caution to ensure the pump governs correctly to just on the red-line. You many need to set the idle and Max-speed screws a little to get it all right. The maximum Delivery adjustment is heavily critical and take great case unless you want your engine rapidly disassembled to kit-form.

None of these adjustments should be attempted until the timing is correct. A DTI is good but what do you set a 'foreign' pump to? Best to do it by ear. It takes a bit of practice but basically advance the pump on idle until the idle sounds just a tiny tad 'tinkly' If all is good, at this setting on revving smartly the tinkle should immediately clear, the engine should pick up revs very quickly and cleanly and sound sweet in a diesel kind of a way. Over-advanced and it'll knock on acceleration and if under-advanced it'll sound quiet, flat and might be smoky. Your ears will tell you.

One last word on pumps. Later XUD9 Turbos used the AS3 Bosch which was semi-electronic. It looks like the VP20 but the timing is under ECU control. The ECU and wiring is hard to retro-fit (although possible) and if you try to use this pump without the ECU the engine will run horribly as the pump will not auto-advance with increasing revs.

The only justification for Bosch'ing is if you want to run on veg. Otherwise the Lucas is an excellent pump. It can't tolerate veg. because of the design of the distributor does not allow it to receive adequate lubrication when running the more viscous veg.

EDIT: Whenever you adjust the timing by moving the pump body relative to the cradle ALWAYS loosen all injector delivery pipes at both ends and then re-tighten them to relieve them of any torsional stresses the timing change might have caused.
Jim

Runner, cyclist, time triallist, duathlete, Citroen AX fan and the CCC Citroenian 'From A to Z' Columnist...
User avatar
nametooshort
Posts: 146
Joined: 22 Mar 2012, 09:22
Location: Cali/Sometimes south UK
My Cars:

Re: Fuel pump swap - Lucas to Bosch

Post by nametooshort »

Thanks very much for that info!

I do run veg oil, which is why I need a Bosch pump.

So, by the sounds of it, I can use pretty much *any* XUD pump, as long as 1) I take the whole thing including the cam belt sprocket, and 2) it's a mechanically advanced model and not a ECU advanced model?

What's the 'DTI' that people keep referring to? Would that happen to mean a dial gage?

Its just taking me a while to get used to diesel tuning, since it's a different philosophy to tuning gas engines, since there is no throttle.

I get that I can use a turbo pump with the boost can disconnected, since it will basically think it's running under no boost and therefore dose the fuel correctly for a n/a engine, but the other two settings, I am not too sure about.

-Timing. That sounds like it has to be done 'by ear' like you said, I guess it just takes some practice. I also understand that if you have the 'wrong' pump, physically timing it with a dial gage to 'book value' may not work since the pump will be incorrect for the engine.

Is there any diagnostics equipment available that can turn it into a process that doesn't rely on my brain for analytical purposes? I see there are adapters on Ebay like item 370488424205. Is it possible to (maybe after marking the crank pulley in degrees) just use something like that to time it to the correct 'book value' for that engine?

-The whole high speed thing. Do I understand correctly that since diesels are 'throttled' by the amount of fuel administered into the engine, then the only major difference between a 1.8 and a 1.9 is that on wide-open throttle the 1.9 pump doses more fuel? So in a 1.8, it will make it run rich when pulling hard, and more importantly make it go past it's red-line when it can? And that's what causes engine failure, over-revving? So, the acute danger, to put it in simple terms, is that the engine gets too much fuel which makes it spin too fast which makes it fall apart? And that's it? Or is it more complex then that?

Is the 'max speed' screw and 'maximum delivery' screw the same thing?

So is it just simply the case of hooking the engine up to a tacho, once the timing etc is done, and setting the correct idle speed (which will in theory be slightly lower, since in a 1.9 it needs a little more fuel to maintain idle rpm), and then just flooring the throttle and adjusting the max delivery so that at wide-open throttle it spins at not above the maximum RPM? So, presumably, you would intentionally wind the max delivery screw in a bit (to create an artificially low top speed), then connect a tacho, push the throttle to the stop, and then just wind the max delivery screw out until the tacho is showing the engine's redline RPM, and then you are done?

Sorry for the dumb questions, but going from tuning gas engines to tuning diesels is a little confusing at first.

Thanks
Image
User avatar
CitroJim
A very naughty boy
Posts: 49531
Joined: 30 Apr 2005, 23:33
Location: Paggers
My Cars: Bluebell the AX, Polly the C3 Picasso, Pix the Nissan Pixo, Propel the duathlon bike, TCR Pro the road bike and Fuji the TT bike...
x 6160
Contact:

Re: Fuel pump swap - Lucas to Bosch

Post by CitroJim »

I'll be back later with a proper response to all those questions! Bit busy sprucing up my fleet in this lovely weather right now. V6 has a special weekend ahead of her so she must look her best...
Jim

Runner, cyclist, time triallist, duathlete, Citroen AX fan and the CCC Citroenian 'From A to Z' Columnist...
User avatar
nametooshort
Posts: 146
Joined: 22 Mar 2012, 09:22
Location: Cali/Sometimes south UK
My Cars:

Re: Fuel pump swap - Lucas to Bosch

Post by nametooshort »

Yeah, I hear you. I am just off to carry on with the effort to crowbar a XUD9 into my 1960s car. That thing has a very small engine bay for such a big stationwagon, the XUD is just a liiiiiitle too long, and slants too much. Problems after problems, this is gonna be a fun one.

Thanks very much for all your help so far!
Image
User avatar
CitroJim
A very naughty boy
Posts: 49531
Joined: 30 Apr 2005, 23:33
Location: Paggers
My Cars: Bluebell the AX, Polly the C3 Picasso, Pix the Nissan Pixo, Propel the duathlon bike, TCR Pro the road bike and Fuji the TT bike...
x 6160
Contact:

Re: Fuel pump swap - Lucas to Bosch

Post by CitroJim »

Right 'ere we go :-D
So, by the sounds of it, I can use pretty much *any* XUD pump, as long as 1) I take the whole thing including the cam belt sprocket, and 2) it's a mechanically advanced model and not a ECU advanced model?
Yes, any mechanical VP20 should be absolutely fine.
What's the 'DTI' that people keep referring to? Would that happen to mean a dial gage?
Yes, a dial gauge. Great for timing a Lucas and I have the kit but not easy on a Bosch pump. Best to learn to do by ear. It does not take a lot of practice. You know what a diesel sounds like when running right and you'll soon hear what over and under advanced sounds like. Timing on a diesel is amazingly critical. And absolutely, using a 'foreign' pump you have no timing reference except that it should start out timed a few degrees before TDC.
since there is no throttle.
Absolutely. The speed of a diesel is controlled entirely by how much fuel the pump delivers to the injector on each stroke. The maximum deliver screw, the one that pokes out of the rear of the pump just adjacent to the stop solenoid sets the maximum stroke of the pump and hence the maximum delivery to any injector per pump stroke. mechanically it sets the maximum excursion of the mechanical governor and in doing so sets the maximum off-load speed. Some performance gain can be attained by setting this to deliver more fuel per stroke but the risk is that a missed gearchange can cause the engine to overspeed dangerously and at MOT time it will fail due to the snap-acceleration smoke test causing the engine to overspeed. Set this adjustment to just touching redline with the engine running off-load and the load (throttle) lever pulled to maximum.

The idle and maximum speed screws set the upper and lower limits of travel on the load lever. The idle screw also has an effect on anti-stall. A characteristic of all pumps is that if the load lever is smartly returned to the idle stop the engine may falter. Many Bosch pumps have a hydraulic damper to slow the return of the load lever back to the idle position and this component is absolutely essential.

The maximum travel of the load lever is set to ensure the engine can reach full speed as set by the governor via the maximum delivery screw so to adjust the maximum delivery screw properly you need to wind off the maximum speed screw and then reset it so that the engine reaches the same revs when the load lever hits the maximum speed stop.

Note that the load lever is connected to the governor via a stiff spring so that the governor can over-ride the setting of the load lever to guard against overspeeding.
Do I understand correctly that since diesels are 'throttled' by the amount of fuel administered into the engine, then the only major difference between a 1.8 and a 1.9 is that on wide-open throttle the 1.9 pump doses more fuel? So in a 1.8, it will make it run rich when pulling hard, and more importantly make it go past it's red-line when it can? And that's what causes engine failure, over-revving? So, the acute danger, to put it in simple terms, is that the engine gets too much fuel which makes it spin too fast which makes it fall apart? And that's it? Or is it more complex then that?
Spot-on :) Absolutely correct!

Diesels don't run rich as you'd understand it in a petrol or gas context. Diesels actually run apparently very weak and always in excess oxygen conditions to ensure as much fuel as possible burns with least smoke. The excess oxygen is always in excess of 50%. Diesel combustion is an entirely different process to petrol combustion. Diesel is injected as a finely atomised spray just before TDC and the increasing temperature and pressure as the piston compresses the air charge is enough to make small areas of the diesel spray start to spontaneously combust which in turn starts more and more of the injected diesel burning. This causes an initial avalanche of burning that causes a big pressure spoke that slowly tails off as the fuel is burned. It is this big pressure spike that gives a diesel it's characteristic knock.
Is the 'max speed' screw and 'maximum delivery' screw the same thing?
No, as already explained but they achieve the same thing in the end.
So is it just simply the case of hooking the engine up to a tacho, once the timing etc is done, and setting the correct idle speed (which will in theory be slightly lower, since in a 1.9 it needs a little more fuel to maintain idle rpm), and then just flooring the throttle and adjusting the max delivery so that at wide-open throttle it spins at not above the maximum RPM? So, presumably, you would intentionally wind the max delivery screw in a bit (to create an artificially low top speed), then connect a tacho, push the throttle to the stop, and then just wind the max delivery screw out until the tacho is showing the engine's redline RPM, and then you are done?
Absolutely! Correct in every way. I reiterate that you must never adjust the maximum delivery screw to above the redline.

Tuning a diesel follows much the same as a petrol engine. Your goal is to get as much air into the engine as possible so that more fuel can be burned effectively without excess smoke but in such a way that you don't compromise the governor's role of limiting maximum speed. This is done by subtle pump mods that allow a given amount of fuel to be injected for a longer period of time. Also, just like a petrol, the exhaust is critical too. You want it very free-flowing.

There's no advantage in trying to make a diesel spin faster anyway. Diesel pistons are very heavy (they must be to be able to withstand the huge pressure spikes) and over about 4,000 rpm on an XUD the pumping losses caused both by the heavy pistons and the high compression ratio outweigh any small gains that may come about from upping the rev limit.

Diesel combustion is a very heavy subject and if you're interested I'm happy to go deeper into it...
Jim

Runner, cyclist, time triallist, duathlete, Citroen AX fan and the CCC Citroenian 'From A to Z' Columnist...
User avatar
nametooshort
Posts: 146
Joined: 22 Mar 2012, 09:22
Location: Cali/Sometimes south UK
My Cars:

Re: Fuel pump swap - Lucas to Bosch

Post by nametooshort »

Thanks for the very informative post!

I sort of half-understand how diesel combustion works, but unfortunately I have never actually tuned diesel engines, or ever seen anybody do it, iv always treated them as 'sealed units' in a way, because most of the time I pulled them out of junk cars and they were already running fine and were set up correctly, and I never needed to modify their fueling system.

I have done plenty of work on gas motors tho, swapping carbs and distributors, and converting to using after-market ECUs to retrofit digital injection/ignition to old style engines (and me any my buddy even made a set of pistons once from scratch using some 1970s vintage machines), so I am reasonably used to putting 'foreign' parts on engines, but, you know how it is, this is my first real encounter with diesels in this detail, and there is a lot of new things to learn, and a lot of re training to do, because my brain is too used to spark-ignition engines. While i can visualize fuel/air/spark curves and maps in my head, it's going to take some time to gain the same ability with diesels. So I really appreciate the help!

I will go do some retail therapy next time I have some time off (and my version of that is walking around junkyards covered in oil looking for a Bosch-setup engine), and see if I find a whole Bosch setup, and will take things from there.

You don't happen to know off the top of your head exactly what the redline for this engine would be? Do all the XUDs have the same redline, or does it vary from spec to spec? You mentioned 4krpm in your post, is that the exact redline to aim for? I am not interested in performance gains or anything, I just want it to run 'on spec' and reliably.

I had no idea these engines were governed! Also, that thing you said about the throttle damper, I noticed on quiet a few old diesels, when you snap the throttle to idle really quickly, they hesitate for a few seconds and almost stall. Is that just a normal side effect of how the pump works, and thats what the damper prevents?

Will see how I get on when I found a new fuel pump!

Oh, by the way, you happen to know what the correct idle speed is for these things?

I have a feeling my current 305 is way out of tune anyways, but since I hope I can find a pump in the next few days, I will wait till then.
Image
User avatar
CitroJim
A very naughty boy
Posts: 49531
Joined: 30 Apr 2005, 23:33
Location: Paggers
My Cars: Bluebell the AX, Polly the C3 Picasso, Pix the Nissan Pixo, Propel the duathlon bike, TCR Pro the road bike and Fuji the TT bike...
x 6160
Contact:

Re: Fuel pump swap - Lucas to Bosch

Post by CitroJim »

Sorry for the delay in responding. I've been in 'forum read-only' mode for a while :twisted: I can grab a look when at my travails but not reply :(

Anyway...
While i can visualize fuel/air/spark curves and maps in my head, it's going to take some time to gain the same ability with diesels.
Same applies. Diesels have an advance curve just like petrols do. The spark is replaced by the start of injection. The curve is necessary for the same reason as in a petrol. Diesel takes a finite time to get burning - termed 'ignition delay' - and this is relatively independent of temperature once above a certain point so the injection has to start earlier as the revs rise. Diesels too need more advance when they're stone-cold to ease starting as under these conditions the ignition delay is a bit longer. You might have seen diesel fuels have a 'Cetane rating'; this has almost nothing to do with running performance as the petrol Octane rating is and relates only to the fuel's keenness to spontaneously ignite. A higher Cetane rating mainly assists cold starting although it does shorten the ignition delay slightly and thus a very little performance boost may be seen from using a fuel with a high Cetane rating. Some say veg has a higher intrinsic Cetane rating than pump diesel.

Bosch mechanical pumps have a cold advance control and often this is electrically operated. When volts are applied the cold advance is in operation to assist starting and initial running. It should not be used when the engine is at normal running temperature. Likewise Bosch pumps also have a cold idle increase lever to help cold running. Both these controls are usually in operation when the coolant is below 60 degrees.
You don't happen to know off the top of your head exactly what the redline for this engine would be? Do all the XUDs have the same redline, or does it vary from spec to spec? You mentioned 4krpm in your post, is that the exact redline to aim for? I am not interested in performance gains or anything, I just want it to run 'on spec' and reliably.
It varies between engines but 4,750 rpm is a good ball-park. Really then NA is stone-dead above about 3,500 anyway for the reason I've stated. It runs out of puff and pumping losses kill it. The Turbos will rev a bit better on account of forced induction but these sill redline at 4,750 and are then well on the way to running out of puff as well. All produce their best around 2,250 - 2,500 rpm.
Oh, by the way, you happen to know what the correct idle speed is for these things?
1000-1050 when cold and 900-950 at normal running temperature.

Looking forward to reading news of your pump swaps :-D
Jim

Runner, cyclist, time triallist, duathlete, Citroen AX fan and the CCC Citroenian 'From A to Z' Columnist...
User avatar
nametooshort
Posts: 146
Joined: 22 Mar 2012, 09:22
Location: Cali/Sometimes south UK
My Cars:

Re: Fuel pump swap - Lucas to Bosch

Post by nametooshort »

Thanks very much, makes things much clearer.

Will post when I get around to finding a pump and trying to fit it.
Image
Post Reply