Techmail

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NEW HILUX TYRE ISSUES

After a burst tyre on the tar road between Beaufort West and Aberdeen, I consulted Supa Quick and Toyota in Graaff-reinet about the specific Hilux tyres. It seems that the new-model Hilux has different Bridgestone tyres to the previous models. The new Hilux is equipped with Bridgestone Dueler A/T tyres (D693), which apparently are “softer”. Probably good on tar, but worse on the unpaved roads in the Karoo. The previous tyre (D694) is “tougher” and I had my burst tyre replaced with this model of Bridgestone. According to my sources, this change in tyre is common practice for new Hilux owners.

Toyota’s customer relations department explained that tyres are regarded as wear-and-tear items and are therefore excluded from the vehicle warranty. The tyre manufacturer and not Toyota SA Motors carries the tyre warranty. I wonder if there are more Hilux owners experiencing this problem? BERT SCHADE Aberdeen We asked Bridgestone South Africa to comment on the difference in tyre model and the specific Hilux application:

“Bridgestone South Africa was awarded business to fit tyres to the current Hilux and Fortuner models (also referred to as IMV) in sizes 265/65 R17 and 265/60 R18. Our approved tyre designs are D693III A/T and D684II H/T, respectively.

The Toyota IMV is a global vehicle platform manufactured in various production plants worldwide (in the case of South Africa, they are also exported to other African countries and Europe).

The tough specifications required from Toyota cover a wide range of road and market conditions, including both on- and off-road operating conditions, which leads us to believe that our current designs will fulfill the requirements from these markets.

We cover any tyre manufacturing-related defects for five years from the date of production.

BATTERY TERMINAL MELTED

I witnessed an interesting phenomenon on a 1990s Land Cruiser diesel while trying to start the engine. The negative battery terminal became extremely hot and eventually started to melt while cranking. Could it be that electrical overload was caused by the windings of the starter motor? After testing the starter, everything appeared within specification. What could have caused the terminal to melt? JEREMIAH MNISI Hazyview The cause is heat generation that is in excess of the melting point of the material (usually lead). The starter motor is the component that draws the most current from the battery (during the cranking event) and this creates heat in the electrical circuit. The starter circuit is mostly un-fused (normal fuses are not able to handle the current draw) and utilises a thick-gauge wire to permit the high current draw. Excessive heat will be generated if:

• The battery terminal connector is not well secured.

• There is a dead short between the battery’s positive terminal and ground in the starter circuit. This can occur if the positive starter wire is touching an engine component or the vehicle body.

• The starter is worn (brushes) and draws too much current.

• Excessive cranking continues when the engine does not start immediately. It is quite possible that a combination of the above is the cause.

XC90 OIL CONSUMPTION

I was looking at the August 2017 issue and spotted that CAR has a Volvo XC90 in the long-term fleet. My wife drives our 2015 XC90 Inscription AWD with 65 000 km on the odo. Since we bought the car as a demo at 11 000 km, we have had to top up the engine oil before every service. The last service was at 60 000 km and now at an indicated 65 000 km, the engine oil level is already at 50%. I am no specialist mechanic, but blow-by symptoms are evident.

Is your test vehicle also using oil? Both Auto Baltic Volvo and Edenvale Volvo tell me this is normal. I am very concerned about engine-rebuild costs after the warranty expires. If this oil-consumption rate is indeed normal for the XC90, potential customers and owners need to be aware of the situation. KOBUS VD MERWE Via email We’ll presume you own the diesel (D5) version, like the one running in our fleet. We agree that any oil consumption is concerning and we will monitor our long-term XC90’S oil level, although it has covered only about 10 000 km.

Usually, the standard OEM warranty limit for oil consumption is 1,0 L/1 000 km, which we believe is excessive. As a test, the dealer should fill the engine with oil to the correct level, seal the oil plugs and dipstick, and allow you to drive the vehicle for a thousand kilometres before checking the oil level again. If the oil usage is above the warranty limit, the problem needs to be fixed under warranty.

Oil consumption in high-mileage vehicles can be attributed to cylinder and ring wear (causing excessive blow-by of combustion gases into the sump, as you mentioned) and worn valve-stem seals. As your vehicle is still fairly new, excessive wear is unlikely, so ask the dealer to inspect the turbo seals; this is another path for the oil to either end up in the exhaust or accumulate in the intercooler (which is easily checked).

WINTER DIESEL?

Apparently, the owners of diesel-engined vehicles in the cold regions of the Western Cape are experiencing diesel “freezing” that prevents their vehicles from starting early in the mornings. Is this possible and can an additive be added to diesel to lower its “freezing” point KOBUS SAAYMAN Via email Diesel fuel does not freeze like water, but enters a waxing phase under extremely cold conditions, where it will block the diesel filter and prevent starting. The technical term for the temperature this happens at is called cold filter plugging point (CFPP). In South Africa, the SABS (SANS 342) legislates two diesel-fuel specifications: summer diesel (1 October to 31 March) with a CFPP of 3 °C; and winter diesel (1 April to 30 September) with a CFPP of -4 °C in the cold regions. Therefore, a diesel vehicle that is subjected to temperatures of below -4 °C for long periods can theoretically experience the problems you mention. There are additives that can lower the freezing point (in Finland, diesel is still useable at -40 °C) but our advice would rather be to park vehicles in garages overnight in affected regions.