Ford Probe, Mazda 626 & MX6 FAQ v3

1. Site Objective

This website aims to provide a knowledge base for 2nd generation Mazda MX6 & 626, Ford Probe and all other cars using various displacements of the Mazda V6 engine in both Otto & Miller Cycle versions. Some areas are also applicable to the 1.8 & 2.0 I4 engines also utilised in these and other vehicles.

Coverage includes general maintenance, problem & workaround areas, plus developments of both engine and cars for objectives of comfort, handling & safety, as well as acting as a general resource for technical information.

2. General Owners Notes


HLA noise & diagnosis
Some HLA noise during cold startup is quite normal. During shutdown, 24 HLAs are in varying degrees of compression depending on where the 4 cams stopped at shutdown. Those HLAs experiencing the greatest compression from the cam-lobe (175lb/in spring) will take a correspondingly longer to pump-up at a cold-start compared to their less compressed counterparts. This HLA pump-up time is further compounded by the time elapsed between starts, and to a lesser extent dependent on where the HLAs is on the oil path - HLAs at the top left of the rear bank (cylinder #1) taking slightly longer. The use of centre-oiled cams (as favoured by Porsche in race engines over spray-bar systems) helps to ensure fast targeted oiling in both cold start & high-rpm conditions until ~430bhp is exceeded. After ~430bhp spray-bar lubing is required despite superior centre-lubed cams to avoid harmonic related fractures.

Oil changes must be regular, with oil level regularly checked to avoid a low oil condition resulting in aeration of oil. Factory oil filters are around 4$US (www.trussvillemazda.com) and £5.70 (UK Mazda Main Dealers).

Actual mechanism of HLA noise is a function of the degree of lash between the cam lobe and HLA surface. When HLAs are pumped up with clean oil & operating correctly they maintain lash at zero for all rpm (so achieving the self-adjusting maintenance-free operation of HLAs). Some HLA noise is often not from the HLAs but from a friction-gear used to reduced backlash noise from the two cam-drive helical-cut gears on the camshafts - for aesthetic noise reasons. Oil cleanliness has a direct bearing on HLA & Friction-Gear noise - as well as the acoustics of reflection of noise from the oil's surface in the oil pan. Hence after an oil change engines may be quieter.

Automatic (ATX) Gearbox Critical Maintenance
o The primary cause of automatic gearbox failure is due to insufficiently frequent oil changes & overheating.
o ATX oil (ATF) breaks down faster with each rise in oil temperature, and rapidly above 125oC. ATX gearbox oil is continually contaminated by the circulation of clutch-pack abrasive particles throughout the gearbox.

o Factory change intervals at 600hrs (24,000 miles at 40mph average) are twice as long as the 300hr high temperature service life of ATX oil.

See the FAQ below for Automatic (ATX) Gearbox Critical Maintenance

Mazda Factory-Remanufactured Automatic (ATX) Gearbox
A factory remanufactured unit is available from discount Mazda Dealers such as www.trussvillemazda.com. Trussville are ~2500$US with old unit as "core". Their benefit is that factory parts such as new cases are used if the original is out of spec, and the considerable design improvements from 1993-2000 are implemented. If sourcing a gearbox from elsewhere, ensure all updates are performed so you gain the (greater) reliability of the 2000 gearbox and enquire whether updated parts are available (stronger torque-convertor & Raybestos Blue clutches for example). Annual oil changes should be effected on any Probe/Mazda automatic gearbox as their cost vs repair is minimal. Sandwich Plate Design

o Upgraded Automatic Gearbox Parts
Upgraded parts for reliability & performance such as torque-convertors, clutch-packs, oil-pumps are available from Level-Ten.

Notchy Manual (MTX) Gearboxes
The correct all-temperature gearbox oil weight is 75w90. A GL-5 oil can only be used if it does not contain sulphur. Only one GL-5 oil in the UK at the time of writing does not contain sulphur, thus it is best to telephone the manufacturer of the oil using the number of the reverse of the bottle. The use of a gearbox oil which does contain sulphur will halve the life of the synchros & bearings as they are of a bronze/brass construction. The reason is that sulphur (eg, manganese sulphonate) becomes acidic. Hence, Mobil1 75w90 GL-5 is NOT suitable for Mazda gearboxes as Mobil confirm.

Notchy shifting is common place during cold mornings and can be corrected by changing the oil to Full Synthetic Redline MT90 75w90 GL-4.
Notchiness is due to synchros requiring an opposing viscosity of oil to differentials, yet both must share the same oil. Thus manual gearbox oil must not only cover both synchro & differential requirements, but do so over all encountered operating temperatures. Non-synthetic oil cold weather viscosity prevents synchros operating properly. Some manuals list ATF as an appropriate oil - this is incorrect. Engineering tolerances for ATF v 75w90 gearbox design differ.
A synthetic gear oil provides better gear-teeth protection & lubrication, reduces transmission losses during warmup so aiding the environment regarding emissions & fuel usage.

Some notchy shifting may be due to a non-disengaging clutch, either through wear or use of non-OEM parts (eg, ACT which require adjustment).

Power Steering Oil
Redline D4ATF Synthetic ATF reduces steering effort on cold mornings, reduces steering wear and increases temperature protection. As per the manual, holding a steering wheel at lock even for 5 seconds can overheat the fluid which destroys its lubricating properties and wear increases. Replacement is easiest by the fractional dilution method, using 2Q of (ideally) synthetic fluid: syphon old fluid out of the reservoir, replace with new, drive the car & repeat again until all 2Q have been used up. Thus the old fluid is diluted 1:1 1:2 1:4 1:8 1:16.

Coolant
Maintenance interval is 2yrs/24k miles, however coolant turns acidic within 9 months thus annual replacement is advised in light of a galvanised steel pipe running the width of an aluminium engine. Mixing aluminium & steel in a cooling system results in galvanic depletion of the coolant in under a year and scale deposits in engine heads can cause head cracking, hot-spots that modify ignition deflagration and elevate top-end wear. It should be noted that corrosion does not affect the stainless-steel head gaskets.

3. Mazda 626/MX6/Probe most common Problems & Solutions

1993-94 V6s Ignitor Module
- Failure mode: engine cut-out, restarting fails specifically due to no ignition spark being produced, restarting may be possible after a short period during whilst the power transistor in the power transistor undergoes thermal reset, no ECU code will be set, 1993-94 only affected.
-- Ford-UK parts -- Coil 3974598 at ~£33.15 & Ignitor 3974599, the TSB is known to all Ford & Mazda Main Dealers.
-- Mazda-US parts -- Complete refurbished distributor, 277$US from Trussville Mazda, USA, parts@trussvillemazda.com.
It is not necessary to replace an entire distributor, only the parts which are an easy DIY filt.

1993-1995 Rear-Brake-Caliper
-- Failure mode is refusal to release handbrake with retardation evident during driving & overheated rear brake discs. Manual manipulation of the handbrake lever-arm at the caliper end may release the brake, but the caliper will eventually seize. See detailed FAQ below.
-- Ford/Mazda-UK parts -- Ex-gratia or import from the USA
-- Ford/Mazda-US parts -- Remanufactured, 75-90$US, Trussville Mazda, Main Dealers, www.autopartsgiant.com, www.carparts.com.

All Years Ignition-Leads
As per MX5/Miata, the deep spark plug well design requires new ignition leads every 5-6 years.
-- Ford/Mazda UK parts -- Mazda Main Dealer, Magnecore fail the same way.
-- Ford/Mazda USA parts -- Mazda/Ford Dealers, NAPA, aftermarket NGK/Bosch, Magnecore fail the same way.

All Years Automatic Transmissions
See general notes below, each year has reliability improvements to that previous, however all years require annual ATX oil changes & upgraded ATX oil cooler.

4. Mailing List Support & Other Details

Old USENET Newsgroup Support is provided in alt.cars.Ford-Probe although traffic is very limited due to only virtual fuel being available.

Old Mailing List Support is available from lists.amber.org/mailman/listinfo/probe-perf.

NEW Mailing List Support is available from www.probetalk.com and has over 6,500 registered members, accessible via the "traditional" email digest format and also very usable online browser application. MX6 owners also have www.mx6.com.

Site Webmaster may be contacted at webmaster.server@ntlworld.com, however replies may be slow in forthcoming. Please check this site and www.probetalk.com before emailing.

5. Discount Main Dealer Mazda Parts

Discount Mazda Parts are available worldwide via Trussville Mazda, USA who are an Authorised Mazda Main Dealer with several million dollars of stock. Trussville (formerly Roebuck) are particularly popular with Miata/MX5 & RX7/RX7-TT rotary-engine owners, with prices generally 50% below those of the UK even after shipping/taxes. A limited number of items are cheaper from Ford such as PCV Valves & Distributor Rotors and so all prices should be compared from both suppliers - both in UK & USA.

6. FAQ Contents

A) Problem & Maintenance Areas

B) Sourcing Components & Regular Maintenance

C) Manuals

D) Wear & Performance/Safety

E) Upgrades regarding enhancing performance/safety


Ford Probe, Mazda 626 & MX6 FAQ

Disclaimer & Legal Statement

This web site, and contents herein have no connection to or endorsement by any Mazda/Ford Dealer, Company or Corporation. They are provided as-is without warranty as to purpose, or fitment for such purpose either by statement or implication and are derived from end-user discussion. All trademarks and copyrights mentioned in this site belong solely to their respective owners and are hereby acknowledged. Images contained within this site are provided solely for illustrative purposes, and remain the property of their respective copyright holders. Crash safety data & comparisons are reproduced from the US NHTSA. ABS braking data is reproduced from Robert Bosch AB Technical Data.

Last Upload: 28th January 2002; V1.50Beta
Copyright J.A.F.Bradbury 1994-2002. All rights reserved.

URL: http://homepage.ntlworld.com/dorothy.bradbury/probemx/index.htm