ZX Diesel pump swap: CAV to Bosch - How?

drabux · Post by **drabux** » 17 Nov 2004, 18:27

Hi all,
New here and new to diesels but quite experienced with petrol cars.
I’m about to replace my lucas pump and injectors for a Bosch pump and injectors in my non-turbo zx and I’d like some advice about how to do it including:
1. How far do I have to go in removing the cambelt in order to swap the pumps (it has a newish belt so I don’t want to replace this). Can I just get away with removing the tension from the belt and ‘slip’ the new pump in?
2. I’d like to avoid paying out for the diesel pump timing equipment to set the timing if possible and I feel that I can probably fine tune the timing competently by ear. However, I need some advice about the ball-park position for the pump timing so that I get the right tooth on the belt. In other words, is there some mark on the sprocket which aligns with something when the engine is at, say, TDC?
Thanks,
Alan

tomsheppard · Post by **tomsheppard** » 17 Nov 2004, 19:05

This engine "sets up" with three 8 mm bolts about 80mm long, one locking the crank at the flywheel, one locking the camshaft sprocket and the third locks the pump. Everything is now aligned. The pump pulley has a hole in it for this and the pulley fits with a Woodruff key so the timing isn't the least bit tricky.
Provided that you get this right on the new pump,the belt goes on and everything should be all right.

bxbodger · Post by **bxbodger** » 17 Nov 2004, 19:18

As above- you shouldn't need to touch the cambelt at all.
Use two 8mm bolts through the pump pulley- the backplate is tapped to accept them, and then remove the pump leaving the pulley in place.
The new pump should then fit in more or less as the old one was, leaving just a bit of fine tuning.
Are you doing this so you can run on veggie oil??
The reason I ask is because the Bosch pumps are happy on it and the Lucas ones are'nt!!!

beezer · Post by **beezer** » 17 Nov 2004, 20:17

Just something to bear in mind for all those who intend to do this.: Lucas pumps and Lucas injectors go together likewise Bosch pumps and Bosch injectors. In these days when smoke meters are used in MOT tests you have to be careful. Check that the opening pressures and calibration match. The engine will run but not necessarily as it should. I have been there. The poster has obviously thought about this.

Post by **RichardW** » 17 Nov 2004, 20:34

No, 'taint that easy....
Think of the injection pump like a distributor - you can put the drive shaft (ie the cam belt sprocket) back in the same position, but the distributor body (ie injection pump body)can swivel about to set the timing. You might get lucky and get the pump on in a position where the engine will run, but then again you might not! Some trial and error required to get it to run right if you don't have a dial test gauge to do it properly.

NiSk · Post by **NiSk** » 17 Nov 2004, 20:51

The amount of movement available on the pump mounting slots is marginal - I tried this timing adjustment when my timing belt was fitted one tooth out - the total movement on the adjustment slots made absolutely no difference at all.
//NiSk

Kowalski · Post by **Kowalski** » 17 Nov 2004, 20:53

If you got a Bosch pump with the electronic control it can adjust its timing a certain amount, so you don't need to worry about getting the timing spot on.

drabux · Post by **drabux** » 17 Nov 2004, 22:29

Thanks for the replies so far. Excellent forum!
Yes, I am swapping to Bosch so that I can run on veggie.
Now, there is a slight problem with the replies so far as I understand it: I've been told that the CAV and Bosch pumps have different sprockets and are not therefore interchangeable. If this is the case then I will have to change the sprockets and this will involve messing about with the cam belt and tensioner after all.
Please tell me I am totally wrong![^]
Thanks.
Alan
PS I will be using BOSCH injectors with the Bosch pump so hopefully no smoke issues.

beezer · Post by **beezer** » 17 Nov 2004, 22:45

As far as I know the sprockets are identical. I am going by XUD engine. The shaft is keyed which, if you have locked the sprockets, as suggested earlier, will set the pump in approximate position and you shouldn't be as much as a tooth out. You should check the bore of the injector pipes is same too. Bosch and CAV can differ. Lucas pump will run on 50/50 nae bother.

Dave Burns · Post by **Dave Burns** » 17 Nov 2004, 23:58

The pump pulleys don't have the same taper nor is the keyway in the same position relative to the timing holes so its a belt off job.
Also the pump mounting bracket has two sets of stud holes one for each type of pump, the lucas occupies the first set looking at them in a clockwise fashion from the near side, you must either remove and refit them in the next position or swop the complete pump mounting bracket for the Bosch type.
If the lucas is to be a standby pump or sold on, you must not strike the pulley nut in order to break the taper to get the pulley off, this is known to be the kiss of death to the bearings of this pump.
Dave

beezer · Post by **beezer** » 18 Nov 2004, 00:04

Well that seems to have cleared that up! I wouldn't use the same belt. I may well have a spare Lucas sprocket removing gizzmo if it is needed (older engines had them as original).

bernie · Post by **bernie** » 18 Nov 2004, 00:04

Don't forget also the 4 metal feed pipes from the Bosch system

drabux · Post by **drabux** » 18 Nov 2004, 03:08

Great and speedy information! Having hung around Saab forums for years, I'm not used to such quick & knowledgable responses.
So, it is a belt off job after all[V] The belt was definitely replaced just 6k ago but you still think I should put a new one on? If I didn't do this, could I just get away with locking the crankshaft and camshaft, releasing the belt tension from the tensioner and putting the pump in that way?
Finally, if I understand you right, because I have to lock the pump sprocket in place I will necessarily get the pump timing 'roughly' correct (i.e. on the right tooth) and then all I have to do is fine tune it by moving the pump backwards or fowards within the pump clamp bolt holes?
Final question: I haven't got the woodruff key for the Bosch pump so does anyone know off hand whether the Lucas one fits?
Thanks.
Alan

beezer · Post by **beezer** » 18 Nov 2004, 04:28

Yes, you should get the timing right enough to start it. The problem with not taking the belt right off is it will be in the way. There will be slight tension on the pump sprocket when you are trying to align it. You might as well just remove it. With the cost of a new belt being relatively small it would seem sensible to just change it. There is a very good chance the old one will be fine but is it worth the risk? A place to try is eBay: http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 45892&rd=1
I am unsure as to whether the woodruff key will swop over but a scrappie should have one as it is likely that other Bosch models have the same key.

Dave Burns · Post by **Dave Burns** » 19 Nov 2004, 03:03

Nope, the woodruff keys are pump specific aswell unfortunately.
Your belt is easily good for another 44,000 miles providing its a Dayco or Gates and not contaminated, at only 6000k I would put it back on, nobody would take a tenner out of their wallet and wang it, so why wang a tenners worth of belt.
Dave