Timing in Mazda 3.
This is a very vital element of every diesel engine. Due to the high compression ratio – the valves are never safely located in relation to the piston and very drastic conscientiousness is required in terms of replacement and selection of parts. Connecting rod (moved by pistons), injection pump drive (or high pressure) and camshaft (moving the valves via levers) are fastened with a timing belt. At the same time, the water pump is driven (the same stripe) and on the other side of the engine (drive transmitted by the camshaft) empty parade (vacuum pump – brake booster) and via chain/sprocket power steering.
A broken belt in diesel engines results in a very expensive repair, often exceeding the price of a new motor. Mazda designers have developed a system of vertically positioned valves and the appropriate shape of the combustion chamber in the piston to ensure that any breakage of the timing belt causes the least possible losses.. And you have to admit, that they succeeded (VW designers creating the engine 2.0 TDI 16V created an almost identical head, based on the same principles, but a few years later than the Japanese ).
The valve train is under greater load at higher engine speeds. Therefore, people, who love to rev the engine to the limit may later complain about the reduced life of the timing belt and tensioner.
The most “unreliable” an element in timing is human stupidity or cunning.
Two extremely important elements – the belt and hydro-tensioner are the most responsible elements. The original Mazda belt is Unitta and the hydro-tensioner – NTN, the water pump mounted on the timing belt may be original or manufactured by e.g. GMB (in DiTD replacement every 180k km).
To sum up:
At DITD, we replace timing kits every time 90 thousand km. Water pump every 180k km.
UNITTA belt tensioner and NTN rollers
There is no reliable and reliable method for assessing the timing mileage.
Amateur tinkering with the timing ends in disaster.
Possible tensioning of the tensioner is possible (link below) but you MUST NOT squeeze it in any other position than VERTICAL ONLY (at all, if there was one “stretched” it can't be flat)
Maximum pressure force on the hydro-tensioner (destructive) is 25kg vertically
http://i72.photobucket.com/albums/i190/magicadm/napinacz_sciskanie_DITD.jpg
For the inquisitive – the hydro-tensioner becomes air-filled when compressed in a different position than vertically… you can try to bleed it, which, however, takes a lot of time – slow vertical compression + expansion (it's going really fast). Air lock usually ends with the timing belt failing.
Additionally, you should pay attention to the danger “stupefaction” hydro tensioner when leaving the car “in gear”. This is dangerous in one case – when the car is tilted, e.g. forward and left it in reverse or vice versa. In this case “opposite” side of the belt (relative to the tensioner) will be loose and when starting, the belt may jump over a tooth (one, two, Three, lots of, lots of… lots of $$).
Co 30.000 (DiTD) belongs officially (unofficially as well) adjust the valve clearances. Suction valves (inlet, these longer levers) they should have 0.15 mm of clearance (on a cold engine) and exhaust (shorter) 0,35mm. When making this adjustment, new overflow washers must be used (5 pieces – ory PLN 130, fakes from MAN are much cheaper) and the gasket under the valve cover (I guess, that no “she sat down”).
The original Mazda overflow pads are electroplated with silver metal (silver, nickel??) due to the material – the head is aluminum and copper has the opposite “voltage sign” and electrochemical corrosion occurs. Hence the difference (Man have a cast iron head) and it's hard to say authoritatively, whether and to what extent this is excessive concern…
The condition of the camshaft should also be checked periodically, which in the case of DiTD (and, as practice shows, probably also in the newer CR) is exfoliated. She's the culprit here “factory” and poor quality of the material (Weird, that mazda doesn't do anything about it). However, it is an indisputable fact, that the peeling roller does not damage the head or bridges (what happens in TDI designs, where the rollers usually wear out on the bridges and not “noses”).