Hot-starting Problems

“Hot-starting” refers to the ability of an engine to fire up and start whilst still at operating temperature (after a breif period of being off).

Unfortunately this is an issue most RX-8 owners will have to face at some stage in their cars life and is particularly common in ageing vehicles – that said, this is not how your RX-8 should behave or perform.

It is important that owners understand, this is a common fault and not a characteristic. Your rotary engine should start and stop just like any other conventional engine.

Early signs of hot-starting problems will be prevailant in a delayed starting when hot. Someone who knows their car well will notice almost immediately if their car suddenly needs to crank over a little longer before starting. A new owner however may not be quite as perceptive. The issue will continue to worsen until the point where once the vehicle is switched off it will simply not start up again until the engine has cooled. This can take as long as 15-20 minutes and is often found when stopping for any breif period of time, such as to refuel at a petrol station or nip into a shop for instance.

[ ! ] Hot-starting is not to be confused with or mistaken for ‘Engine Flooding‘, which occurs when the engine is cold and will not start, nor be rectified by leaving the car stood for any period of time.

There are 2 main reasons why your car may develop ‘hot-starting’ issues:

  1. Your engine may be suffering from low compression
  2. Your engine may have a slow starter motor

There is a 3rd lesser reason, and this relates to the condition of your ignition coils (although this will manifest itself slightly differently to the classic hot start problem).

The only way to accurately determine the exact cause of hot-starting problems, is to have your engine hot compression tested by a rotary specialist (such as ourselves) or a Mazda dealer. It is very important that the test be carried out using a rotary engine-specific compression tester, as using a conventional analogue piston engine compression tester will produce inaccurate results and measurements that without a reliable cranking speed, are all but useless.

Rotary Revs uses only, genuine Mazda Compression Testing equipment to guarantee the most accurate of results when testing your car for compression issues (hot or cold).


It should be noted that hot-start problems are potentially very serious and although fixable, the repair of a hot start problem can be expensive, often involving the full tear-down of the engine and then rebuilding with new components. Anyone considering purchasing a Mazda rotary engine vehicle that is displaying signs of this common fault must accept that they could potentially be faced with a large repair bill to put the car right again. For this reason the compression test is vital to be certain of the engines current health prior to repair works or proceeding.

If, post compression test, you find that your starter motor is slow but your engine is healthy, we can simply replace the start motor component with a faster one and away you go. Unfortunately, in most cases however, it is low compression at the heart of these problems (albeit, not helped by a particularly slow starter motor on older cars) and in this instance you have two further options….

We can either a) fit a new starter motor (masking the main issue but simply deferring it an uncalculable quantity of time) or b) opt to have your engine stripped down and rebuilt, with all new parts, giving your car a new lease of life.

Good RX-8 and rotary specialists are few and far between – so don’t be afraid to travel! Choose a specialist based on reputation rather than convenience.

We provide a range of engine rebuild options designed to suit varying performance requirements and budgets. Feel free to contact us and speak with one of our specialists who will be happy to answer any questions you may have and discuss your options with you.