Some would discuss (at great length) the transition from Classic to New MINI and whether it signalled the start or the end of MINI’s fortunes. Here at Lohen, we’re always respectful of the heritage behind MINIs but see how the brand has grown in leaps and bounds by embracing new design and technology to keep the MINI alive.
The development of the first generation MINI was not without its pitfalls; notchy gearboxes and oil leaks were some of the most obvious issues to afflict the Tritec engine, however, it still remains a solid unit for well-maintained examples of the early cars, also proving worthy of tuning to significant proportions with the right level of TLC.
Over the years Lohen has been lucky enough to work on all variants of the Gen 1 engine and has found it a solid platform when looked after properly. Regular servicing is advised to keep it in tip-top condition, however, engine health checks including leak down and compression checks are particularly useful when preparing to modify your MINI.
In our experience, the Tritec unit is a strong engine, often capable of withstanding big power upgrades without too much fuss. Sure, it often leaks like a sieve, however, you could do far worse as a base component for modification. Taking all of our experience into account, we’ve put together a list of some of the very common failures to look out for with the Gen 1 units.
Oil Leaks
Probably one of the most common issues on 1st Generation MINIs in the Lohen workshop, oil leaks can account for significant engine failure if left unchecked. We’ve seen them all: rocker cover, timing cover, sump gasket and rear main seal are all common. Some make sense to repair if you’re considering upgrading work for example timing cover when performing a crank pulley upgrade, rear main when installing a new clutch. It goes without saying how important it is to check your oil regularly to prevent significant engine failure, particularly if leaks are evident and can’t be rectified in the short term.
Midland 5-Speed Gearboxes
Early Ones and Coopers were fitted with the 5-speed Midland gearboxes until the facelift Getrag version took over in July 2004. It proved to be one of their weaker points, particularly when tuned or driven hard. Some people look to perform repairs where possible but it’s also an option to swap out the Midland box for a Getrag 6-speed box as seen on the R53. Historically people have liked this as it not only serves to replace the faulty Midland part but also can be considered an upgrade but be warned, there’s a lot of other components that need swapping at the same time so it’s not for the faint of heart.
Dipstick
Notoriously brittle after multiple heat cycles, the end of the dipstick is prone to discolouration or breaking which can be catastrophic for your MINI’s engine. At best the broken tip will fall wholly into your sump: at worst it could disintegrate making retrieving it a much more complicated task. Lohen recommends the CravenSpeed dipstick: manufactured from aircraft aluminium, it’s not only functional but also beautiful with a powder coated handle that looks superb in your engine bay.
Supercharged Tensioner Assembly
The Supercharger Tensioner Assembly performs an essential part in the effective running of the S and JCW variants’ engine. It guides the drive belt between the crank and supercharger pulleys and performs a dampening role when the engine comes on and offload.
It’s common to experience failure of the damper within the tensioner assembly over repeated or hard use. Unfortunately, the OEM option only allows for replacement of the complete unit, assembly and damper, however, Lohen has recently released a singular damper to replace the faulty part saving S and JCW owners over £130 on the OEM complete unit.
Finally, you could look to upgrade this damper yet further by installing Powerflex bushes. Developed with Lohen, Powerflex created this robust polyurethane set which is particularly effective with highly-tuned cars experiencing large ranges of load when accelerating and decelerating. It’s also worth noting Lohen offers an Alta Tensioner Stop, a neat bar installed over the damper to limit damage should the supercharger belt fail and the assembly falls towards the crank pulley.
Supercharger Belt
As a service part, we’d recommend you swap the belt during your regular servicing intervals. It’s particularly important, however, when having a reduced supercharger pulley installed. Just make sure your pulley is properly aligned or your belt will shred leaving you stranded very quickly.
Bypass Valve
The Bypass Valve on S and JCW variants is an integral part of the engine’s performance, where a sticky valve that won’t close all the way due to a weak or broken spring will jeopardise precious boost. There’s little available beyond the OEM part and Lohen would suggest getting the valve checked at intervals as it’s easy to become accustomed to how the car drives and miss that extra sparkle over time when you put your foot down.
Engine Mounts
The constant rocking of the engine under load wreaks havoc on the various mounts around the engine bay. Lohen regularly replaces the oil-filled drivers’ side mount as well as offering Powerflex bush inserts and replacements to other mounts. For the performance enthusiast, you might want to consider something from the Vibra-Technics range which offers mounts for fast road and race, all around the engine and gearbox. Of course, there’s some compromise needed; uprated chassis mounts can alter the feeling of the car and transmit more vibration, however it’s a small price to pay for the chassis improvement you’ll see.
Coil Pack
Over time the terminals of the OEM coil pack corrode meaning a lesser or non-existent spark; this can detract from your MINI’s overall running and lead to a lumpy idle or misfire. The MSD Ignition High Voltage Coil Pack is a direct replacement for the standard part and looks great in the engine bay and Lohen recommends this, particularly as the MSD is now less expensive than an OEM replacement. Function and form for less? Can’t say fairer than that!
Intercooler Couplers
Perishing over time, the OEM rubber intercooler couplers can deteriorate to suffer air leaks on S variants. It may seem purely cosmetic however you’ll be losing precious boost and performance so it’s worth considering replacing these rubber parts with something like the Alta silicone intercooler couplers. Available in a range of colours, they perform and also look great in your engine bay.
Fluid Bottles
We’ve all seen it: the header tank split with crusted on coolant trailing away to the depths of the engine bay. Alongside this, the Power Assisted Steering (PAS) tank suffers, too, and both are prone to suffering poorly sealing caps. Lohen can help, whether with an OEM replacement or something a little bolder with the Forge Motorsport Header and PAS Tanks. They not only look fantastic in your engine bay but should help eliminate some of the splitting issues all too common with these Gen 1 MINI’s.
It’s worth noting how important these tanks are as they can be a direct indicator of the health of your engine. The header tank, in particular, forms part of the pressurised system responsible for keeping coolant under control so should be in great form. Finally, it can prove a warning for any head gasket issues, where mayonnaise type fluid would become apparent around the cap as oil and coolant mix. Don’t underestimate it!
