9 Jul 2014 | Author: | Comments Off on ROVER 75 MGZT SERVICING






The BMW M47R 16v chain driven DOHC engine. Made by BMW in Steyr, Austria, it superior to most other diesels, being smooth and quiet, but not as quick to rev as some diesels probably due to having a heavier flywheel. This improves the smoothness but hinders the throttle response somewhat.

It can also be found in the Freelander TD4 ’99-’06 and BMW owners will recognise the engine in longitudinally mounted form in their cars.

Unlike the version fitted to the 136bhp BMW 320d, it has Bosch common rail fuel injection and was the first passenger vehicle in Europe to have this.

With the cover removed the engine is barely any noisier. The inlet manifold is plastic and the air filter is at the back to the right of and behind the oil filler cap.

I’m not overly impressed by that air duct supplying the air filter in the Rover 75/ MG ZT. Those corrugated bellows are best removed and this also reduces the chances of spray ingestion which damages the maf. (see tuning page)

The turbo is hard to see, let alone get at except from below.


The Maf sensor shown opposite, is a Bosch one but has a Pierburgh style connector. So a Pierburgh one will fit straight in, though you will need a Mafam Mf75p or RonBox 2 since the Pierburgh maf is a Merc one.

You have to remove the air filter cover to get to it.

If the Bosch sensor is only mildy out of spec, a Mafam MF75p or preferably, a RonBox 2 can be fitted to boost its signal. Then when needed, a Pierburgh maf can be fitted when needed at minimal cost (Ј63)

Hi Ron got the Mf 75 first thing this morning (excellent service) took 15 minutes to fit and all I can say is WOW. The cold sweat that I used to get at busy islands has disapeared.

The CAM SENSOR can be seen in front of the oil filler (to the right of it in the photo above, opposite.

The Exhaust Gas Recirculation valve feeds cooled exhaust gas into the inlet manifold on light throttle and steady speed conditions. This reduces NOx emissions, reduces particulates and minimises fuel consumption.

The ecu uses the MAF signal to control it, since if exhaust gas replaces ‘fresh air’ the maf signal will drop. The valve is operated by vacuum from the brake servo line and the ecu modulates this via a solenoid valve to regulate the amount of exhaust gas being drawn in.

When the throttle is opened it closes and so in theory it should not affect power delivery.

However, as with the L series, disabling it by simply disconnecting the vacuum tube ( plugging this with a bolt) often improves the throttle response below 2000rpm, giving a bit more torque and quicker response.

It seems to be due to the ecu not closing it immediately when the throttle is opened gradually.

A faulty maf sensor will affect egr operation and can cause flat spots, vibration and hesitation when first opening the throttle, especially around 17-1800rpm.

Removing that 8mm braided tube visible in the bottom of the photo disables it.

I have left mine disconnected for the past 5k miles with no detriment.

EGR BYPASS PIPE. You can now obtain a straight through egr replacement. This just bolts on in place of the EGR valve, giving improved unobstructed airflow into the inlet manifold and eliminating the need ever to clean it.

Contact Dave for price and delivery. More details here

I cannot emphasise enough that this engine will never perform properly if neglected and money spent tuning it may give disappointing results. The oil and all filters should be changed every 10-15k miles max: change the oil and filter twice as often if you’ve tuned it. (Tuning it will increase the sooting up of the oil) Don’t waste money on fancy oils – nothing can turn carbon into a lubricant so if the oil is like sludge it matters not whether it was Ј10 /Lor 10p /L, it should not be allowed to get that bad. I recommend Millers XFD or XFE – see for your local stockist and buy some Ecomax diesel fuel additive at the same time and use it all the time.

In addition, I do not recommend supermarket fuels, but prefer Shell Extra or V Power. Many a rough noisy engine is due to cheap fuel. There’s whisky and there’s a 12year old malt.

These are the items that MUST be attended to if the mileage is over about 75k or age is over 5years. Ignore any service history, the majority of dealers can’t be trusted to replace a bulb and the previous owner may have been a skinflint!!


By 100k miles you can expect to have replaced the low pressure fuel pumps, eventually have the injectors serviced due to leakback, and may need new intercooler hoses due to leaks.

* Hopefully you will have fitted one of my RonBox 2 and Pierburgh maf combinations so won’t have any maf problems!

^ One of Dave Lyon’s (wingspeed / evotomturbo) egr bypasses makes a massive difference, especially on a tuned engine.

¬ Viton seals are available from

I find it sad when such superb vehicles are neglected by owners who won’t spend the modest sums required to properly maintain the car. They will have spent less than half the money buying it, of anything comparable. However, those who cannot do the work themselves are unfortunately, at the mercy of the dealers, the majority of whom are in it purely for the money.

Just remember that the very expensive items such as turbo, injection pump and ecu rarely fail and should ONLY be changed as a last resort.


For servicing and repairs try: (Coventry) f or Injectors, injector overhaul and injection parts (Wokingham) Intercooler seals, radiator fan resistors etc

The first thing I do having bought a used car is to give it a service, regardless of any ‘service history’.

So all the filters are changed, the oil replaced with Millers XFD or XFE, Millers Diesel Power Plus is added to the fuel to clean and lubricate the entire fuel system (and added continuously thereafter), the brake pads are checked, tyres pressures checked and the entire car inspected. If the mileage is over 50k I recommend cleaning the egr valve and replacing the pcv assembly. (see below)

Next Waxoyl is applied to the underside where there are any signs of rust.

Rimmer Bros are one of the official parts suppliers and you can order online or download a pdf pricelist. (Their online ordering is cronky but the parts came 2days later so it works once you’ve figured how to actually use it – its somewhat non-intuitive. )

Now that factory warranties are no more, I will be progressively adding pages covering routine servicing, though Haynes have now published a manual for the 75 ZT its manual no. 4292.

Most of it is straightforward and amounts to simply oil. oil and air filters, with less frequent fuel filter and brake pad replacement.

Oil air filters cost about Ј45inc vat pp from Rimmerbros and 6.75L of Millers XFE semi-synthetic oil costs about Ј20 so you can do it yourself for well under Ј70 or under Ј100 including fuel filter change.

Air, oil and fuel filters

Front pads are Ј65 a set delivered, the pollen filter is Ј42 delivered.

The air, oil fuel filters.


Slacken the 10mm nut which clamps the fixing strap – its around the other side. Undo it until the filter is moveable – there is no need to remove the nut completely.

Detach the fuel lines by squeezing the pale blue retaining clips – place a rag under the filter to catch any small spillages.

Disconnect the fuel pressure sensor – shown opposite.

Now withdraw the filter vertically.

Next unscrew the canister from the top part and screw on the new one. Do NOT use excessive force.

Finally, reverse the above steps to refit it.

Turn on the ignition but do not start the engine. The electric pump will be heard making uneven noises as it primes the filter. After about 30seconds it will settle down to a steady note.

Check for any leaks on the filter’s seal and both fuel connections and if all is okay, start the engine.

REPLACING THE OIL FILTER. (do it whilst the engine is warm)

TIP: When checking the oil, the dipstick will show empty when first withdrawn – don’t panic! Reinsert it!

You will need to remove the under tray after jacking up the front of the car an supporting it on stands.

Then you will see the sump drain plug – a large container is needed as the sump hold 6 litres.

After draining the oil off the filter can be replaced..

The filter is not the usual screw on metal canister type, but is a bare paper element type that lives in the housing under the large cap shown opposite.

Wipe around the housing and cap first.

You will need a 37-38mm socket to undo the cap.

Once removed you will see the element and it can be withdrawn from the housing.

Insert the new one, making sure it is pushed right down onto the spigot. It will be a firm fit.

Fit the replacement ‘o’ ring to the cap and screw it down. If the other 2 seals are supplied with the filter, replace those as well – they are located on the central tapered core attached to the cap.

Tighten it little more than hand tight.(24nm)

Once the engine has been refilled, start the engine but do NOT rev it. The oil pressure light should turn off after a few seconds. Now check for leaks and then recheck the level as it will have dropped when the oil filter was primed.

REPLACING THE AIR FILTER. NB a dirty filter can lead to maf sensor contamination which will damage it and also invalidate any remaining maf warranty.

You will need to remove the oil filler cap and then: –

a) 3 x 8mm bolts holding the engine cover on.

b) 5 x 5mm hex bolts holding the air filter cover on. There are three at the front top edge, and 2 at the rear, lower down. See photo below.

Once the bolts have been loosened as they are captive bolts, do not try to remove them from the filter cover.

c) 2 screws holding the air duct to the inlet manifold. Then pull the duct towards you, against the bellows so it detaches from the air filter cover.

Finally, lift the cover vertically to reveal the air filter.

It lifts out right hand end first as it is just a push fit over the spigot at the left hand end.

Clean out any debris from inside the air box before fitting the new filter in.

TIP: If you cannot get the bolts to ‘take’, you have not refitted the cover properly. The left hand end has a narrow slot in it and you will probably have missed the slot when replacing the cover.

4 ) SPECIALISED (non service schedule) SERVICING ITEMS a and b SHOULD NOT BE OVERLOOKED – BOTH CAN SERIOUSLY AFFECT THE PERFORMANCE AND FUEL CONSUMPTION. A clogged PCV valve can cause major problems by causing a pressurised crankcase.

This section covers things which are not routine but which make a significant difference, particularly on higher mileage engines. Most dealers won’t have a clue about them.

a) CLEANING THE EGR VALVE (best replaced with a bypass one)

This is what it looks like after 99k miles! Why?

This condition is due to the crankcase ventilation system which requires that crankcase fumes be burnt rather than vented into the atmosphere.

So oil laden fumes are drawn into the intake duct on the inlet side of the turbo and pass through this, then through the intercooler and finally through the egr valve to the inlet manifold. You will find the interior of the intercooler and its hoses very oily as a result. As the cylinder bores wear, more combustion gases escape past the piston rings and the volume of crankcase fumes increases.

So the accumulation of ‘crud’ can be considerable – as you can see from my 99k mile car.

This the mounting flange :

Its removal is obvious, just 4 nuts and a hose clip and another similar type of fastening on the exhaust supply pipe.

I don’t think it does anything for the airflow in this condition!

I snapped a hacksaw blade in two to use a scraper and then plenty of swarfega and a toothbrush (swafega is good because being a gel, it can be left to soak in and can be rinsed off with warm water)

I also took off the inlet manifold to clean the mating flange. Ideally I should have used new rubber seals when refitting it and it would have been preferable to soak it in degreaser overnight as the interior was as gunged up as the egr valve. Otherwise there isn’t really any way of getting the insides clean.

I have heard of owners putting it in the dish washer or blasting the insides with a pressure washer. The former idea could lead to a divorce proceedings!

I am not overly impressed with the egr valve assembly. As you can see, even when clean, there is quite an obstruction to the airflow due to the exhaust gas inlet and the brass valve stem boss. If I was going to leave it disconnected, I might be tempted to get out my die grinder, but now there’s no need – another owner manufacturers a low cost bypass pipe.

EGR BYPASS PIPE. You can now obtain a straight through egr replacement. This just bolts on in place of the EGR valve, giving improved unobstructed airflow into the inlet manifold and eliminating the need ever to clean it.

Checkout EVOTOMTURBO on Ebay for them. Beware, another ebayer (kazet273 – read his feeback..) is selling his version – ITS NOT the same.

NB I ONLY ENDORSE THE ONES FROM EVOTOMTURBO (Dave Lyon) but have no control over delivery and do not stock them. I’m told by Dave that these are now cnc machined for grater accuracy and feature a boost gauge take off as well.

b) CLEANING THE PCV – The crankcase ventilation valve assembly.

If oil pumps out of the dipstick and the engine produces blueish smoke the PCV vale has failed and must be changed asap or the excessive crankcase pressure will damage the engine’s oil seals.

I have heard of owners being told they need a new turbo or even a new engine due to mis diagnosing the blue smoke caused by a clogged pcv valve.

If clogged, this has been shown to contribute to black exhaust smoke and a somewhat rougher engine so is worthwhile cleaning or replacing it especially on higher mileage engines. It is to be found just behind the injector wiring and is easily accessible with just the engine cover removed.

It is also possible for a large excess of crankcase fumes to enter the induction system, and since they do this after the maf, the maf signal drops causing erratic idle and possible stalling, as well as bluish smoke from the exhaust.

This is the assembly and it’s held on with 4, 5mm hex (allen) screws.

You will need to remove the injector wiring support screws (a 5mm socket fits) and lift it aside, then disconnect the return pipes from injectors 2 and 3. Carefully remove the retaining clips and gently prise out the tee pieces.

Then once the assembly has been removed, pull off the filter retaining clip and remove the filter, don’t lose the ‘o’ ring.

The felt filter can then washed in white spirit and then detergent and left to try in a warm place if its not to be replaced. Do NOT be tempted to omit it – its more of an oil separator than an air filter.

The part no. for the whole assembly is LLJ000060 Valve assembly-depression control

and the cost is about Ј50. but is cheaper from a BMW dealer and a new design is supplied which does not use a filter.

If the valve side (on the right in the adjacent photo) is very dirty, rinse it with white spirit as well.

Here’s a related thread on the 75and ZT club forum:

I advise replacing it every 36K miles and more frequently on high mileage engines.

It is now a service item – every 2years on BMW vehicles.


When using my ACR4 diagnostic tool I noticed that the pedal demand readings were not reaching 100% even if I stomped on the pedal as hard as possible. (96% was as high as they went – the sensor has two outputs, one half the other, 1.8volts and 3.6volts at full throttle equal 99%)

So I adjusted the ‘stop’ under the pedal. Its locked in place with a 13mm locknut on the underside of the plastic mushroom head. It took a few turns to get it to read 99%.


The editor has kindly sent me several recent issues which I can recommend to all 75 / ZT owners. In the absence of a Haynes manual, these will prove invaluable and should be added to your arsenal of servicing tools.








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