740 vacuum pump

It might be because it is made by Pierburg, of equally horrible carburretor fame. Inside there are about six valves. The central pushrod is encased in a large spring held in place with collets (essentially a very big cylinder head valve). The spring sometimes breaks and sometimes fractures without a complete break. This has the effect of weakening the spring and increasing the clearance on the extension pushrod and the eccentric in the middle of the camshaft. The seal around the periphery of the diaphragm is another weak point, although not quite as bad as the spring. I would have been happier with a vacuum pump, either belt driven or gear driven, of a different pattern. Most commercial designs are belt driven from the power take-off and are known as exhausters. Unfortunately Pierburg have almost cornered the market. As well as that they make a different pattern for the 850 diesels and the VW ones. The only thing you can do is keep a check on eBay or ask around the purveyors of parts to Volvo owners. There are quite a few advertising in the Driver. All the best, Peter. :car-smiley-031:

Thanks for this Peter. Having spent many hours overhauling Pierburg carburettors I begin to understand the problem! Overhaul kits for carbs weren't cheap either but at least there were independent carburettor specialists which kept the price down. I will look out for a cheap new one - the car is worth it. Failing that, I just might try a belt drive unit on from a similar capacity diesel, just out of curiosity to see how this does. Land Rovers 2.4 diesel unit from a 110 might work. The only problem is that in Insurance terms this is probably a modification, and so will cost me. Regards John D

As you would be only replacing one vacuum pump with another there should not be an insurance problem. Do you have details of the Land-Rover unit? It might be worth my doing as well. All the best, Peter. :car-smiley-031:

Found a decent second hand one (looks overhauled) for peanuts so the pressure is off, but will keep an eye out in the scrappies for a remote unit which will fit.

You couldn't really use a late Transit pump as it has an oil feed coming up from below. I'd say try a Peugeot XUD early pump which has its own oil reservior and is driven by a v-belt off the end of the cam and mounted on the back of the head(not the later ones which are directly mounted to the cam). Something like a Peugeot 205 or 309 would be acceptable, also when they used this engine in the Rover 218 they all used this type of pump but here mounted on top of the gearbox. This engine in the LDV 200/Pilot has another belt drievn one driven off the front crank pulley. Or another (bulkier) choice would be that from an LDV 400 series (or early Convoy) with the Peugeot 2.5 engine.