BMW E38 7 Series Trouble-shooter

BMW E38 7 Series Trouble-shooter

BMW E38 7 Series Trouble-shooter: Practical pointers and tips for owners. It’s now 24 years since the first E38 7 Series arrived to replace the much-loved E32. With similar 3.0- and 4.0-litre M60 V8 engines, a bigger 5.4-litre V12 750i was also included in the range.


The E38 might have looked vaguely similar to the older model, but it was completely new. Notable features included multi-link rear suspension replacing the E32’s semi-trailing arm set-up and new suspension at the front. CanBus electrics were featured, as were standard 16in wheels.

The 730i V8 was effectively replaced in 1995 by the 2.8-litre straight-six 728i, fitted with the all-alloy M52 engine. Five-speed automatic gearboxes were used again, with no more manual option for the UK market. In 1996, the 735i and 740i 4.4 replaced the old 4.0 740i, and the E38 was facelifted in late 1998, with slimmer headlights, new wheels, double Vanos for the 728i and single Vanos for the V8s. Production ended in early 2001, in readiness for the all new and shocking E65. The E38 is an old car now, and many (most?) are in a parlous state.

Consequently, really good examples – low owners, low mileage, no rust and everything working – are starting to appreciate.

The best E38 7 Series models are at last starting to appreciate, but finding good ones with low miles and no rust can be a real struggle.

NIKASIL ISSUES?

The 2.8-litre M52 engine used Nikasil up until March/April 1998. This was a nickel-silicon coating that was as hard as nails, but which proved vulnerable to attack from the sulphur content in UK fuels. BMW solved this by pressing steel liners into the block, and loads of engines were replaced under warranty and as goodwill gestures. The 3.0 and 4.0 V8s also used Nikasil, as did very early M62 units.

However, the coating technology was replaced by Alusil, a special silicon-impregnated alloy in mid-1996. Again, BMW replaced many engines under warranty so you’ll be unlucky to find one now.

This is the sort of bore wear experienced by engines that lost their Nikasil cylinder coating.

FUEL TANK RUST

Oddly, BMW decided to make the E38’s fuel tank from mild steel rather than the plastic used on the E36 3 Series and E39 5 Series. This was OK but, after 10 years or so, rust finally got the better of them, and many tanks started leaking from the seams, as a result of wet mud lodging and leading to corrosion.

Tanks that leak when they’re more than half-full are suffering with this problem. Unfortunately, new tanks are a fortune from BMW, and are available as and when they’re in stock. The 728i tank is unique, and costs an astonishing £1,350! Other tanks cost about the same, but you can buy an aftermarket version for about £750 – still pricey but realistic, given the value of an E38.

THE DREADED RUST

The E38 comes from an era when BMW was having a few issues with the old ferrous oxide. While not as bad as many other cars from the period (including Mercedes-Benz), the E38 – like the E39 – is prone to scabby rust if neglected. Rust can affect the rear arches, the boot lid, lower door corners and so on. However, the corrosion is very rarely structural although things can look pretty ugly if problem areas are left untreated. New panels are available at a price, but are generally BMW-only and, with the E38 now really getting on in years, the supply of good, rust-free secondhand panels is drying-up.

Rusting bodywork is likely to be an issue for most E38s nowadays.

BROKEN SPRINGS

All cars break coil springs, but the E38 can break a front coil. Being of the ‘barrel’ design, this can lead to a bit of spring spearing the tyre sidewall, never a good thing. If your springs look rusty and tired, it’s not a bad plan to fit new ones, and something like an Eibach or H&R spring kit to lower the car about an inch, and sharpen-up the handling, is a good option. Being of a similar design to the E39, the front struts can be a bit of a swine to get out due to the dampers being so long, so expect a fair bit of swearing if you fancy going ‘DIY’ on this one.

Broken springs are quite common on the E38 7 Series.

THE M52 ENGINE

The 728i quickly became a very good seller because, with 193hp, it had enough power to offer decent performance. The original, single-Vanos unit had Nikasil problems as already mentioned but, that apart, it’s a good, reliable engine capable of big, six-figure mileages. I’ve seen plenty with 200,000+ on their clocks.

The twin-Vanos M52TU – as launched with the facelift cars in September 1998 – is also good, but the Vanos seals can wear out leading to lacklustre performance. Any sign of head gasket trouble and your best bet by far is to put another engine in – the threads for the head bolts will just strip on retightening, so save your time, effort and aggravation.

The M52, though a popular seller (728i) can suffer with some serious problems.

UNUSUAL IMPORTS

Because all UK cars have endured around 20 British winters, most are horrid old teabags with rusty undersides that will have had brake pipes, fuel tank problems and so on. But look for Japanese imports if you want a really clean one – some I’ve seen are like two-year-old cars underneath.

But bear in mind that the radio and Sat Nav will be useless. It’s still worth buying one in my view, though. Rare Euro models include the torpid 725tds that will just about get out of its own way, the staggering 740d with its V8 turbo diesel, V8 manuals and the 730d with the M57 engine. The 740d is rare because only about 1,500 were built (simply to wave two fingers at Mercedes!) and, with 245hp and 560Nm of torque, they’re certainly not shy. Sadly, though, they’re also very hard to find…

Remember, one of the prices you pay for a rust-free E38 from Japan is useless sat nav and radio equipment. Nevertheless, these cars are still well worth considering, if you can find one.

COOLING SYSTEM

The original 728i and the 3.0/4.0 V8s used a very conventional cooling system – a radiator with a built-in header tank on the 2.8, and standard Jubilee-type hose clips for the hoses. Nothing ever really went wrong, although   728i water pumps could shed the plastic impellers. However, a new replacement only costs £30 and is easy to fit.

The M62 V8s, though, used clip-fit hoses and a mapped thermostat that made the engine run very hot under light and part-load for emissions. So, the thermostat should be replaced with an 85°C version from a Middle East market 840Ci, to take the strain off what is now a 20-yearold cooling system. The part numbers you need are 11531742964, or 11512248542 for a post-9/98 car.

AUTOMATIC GEARBOXES

Up until 1996, these were regular, five-speed automatics made by ZF, and pretty good, too. Much is said about oil changes and so on, but there are thousands of them still going with well over 150,000 miles on the original oil. A filter change, new sump gasket and top-up with the correct oil is about all you need to do.

Gearbox rebuilds are expensive and by the time a ‘box is playing-up and flaring on changes, it’s generally game over. Also, be aware that low battery voltage, or an electrical issue elsewhere such as a faulty cam sensor or ABS fault, can put the transmission into ‘limp home’ mode, so always do a complete check on everything before biting the bullet.

Early five-speed, ZF auto transmissions were reliable performers.

THE V8 MOTORS

The M60 – Nikasil issues apart – is a very good and reliable engine. It uses Duplex timing chains and, as long as maintenance levels are up to scratch, it’ll run indefinitely. Low oil pressure can be the oil pump bolts working loose – very easy to remedy with the front sump pan unbolted after you’ve drained the oil. But the picture regarding the later M62 isn’t quite as rosy. Simplex chains were used and while these don’t fail, the revised guide rails can break up.

Most will need a strip-down to replace them by now. After 9/98, Vanos was used but this is very reliable in general. But, replace the chains and guides, fit that ‘cooler’ ‘stat and the M62 should prove to be a brilliant engine.

While the M60 V8 would run and run if maintained properly, the M62 does typically require more attention.

V12 ENGINES

In all honesty, the 5.4-litre M73 V12 was a bit of a technological dinosaur, even when new in 1994. Producing just 300hp and with only two valves per cylinder, it was hardly cuttingedge. Nevertheless, it was a marvellous motor – smooth, eerily quiet, decently powerful, although it liked a drink, too!

As an engine, it’s a very robust unit in general terms. But there are characteristic problems to be aware of. Water pump bearings can fail, and this is a mission to deal with as the crank pulley needs to come off first.

But this engine is so unstressed and the ancillaries were rather more reliable than the 5.0 incarnation in the original E32. Most V12s will be long-wheelbase models and won’t be much quicker than the 4.4 740i. What’s more, they’ll return 5mpg less.

As with the E32, gearbox problems are more likely on the V12 for some reason. Check for sump oil leaks as well – a real cow to rectify!

The 5.4-litre M73 V12 was a bit of a technological dinosaur, even when it was new in 1994.

Rate this blog entry:
Market Watch BMW M5 F10
Engine in focus BMW M60/M62 V8

Related Posts

Comments (0)

There are no comments posted here yet