YD25 D40 R51 Heater Oil Cooler Hoses

D40 R51 heater hose plastic fitting failure     D40 R51 heater hose plastic fitting failure closeup YD25 D40 R51 upgrade heater oil cooler hose kit
D40 R51 heater hose plastic fitting   Composite fitting that fails YD25 D40 R51 upgraded heater oil cooler hose kit

Cooling system issues

All modern cars are fitted with plastic fibreglass radiator tanks and fittings. Older cooling systems used copper, brass and tin lead solder. Concerns over lead exposure to humans and environment has seen lead free cooling systems being used in modern vehicles. With the introduction of lead free cooling systems composite materials consisting of resins and fibreglass have replaced the reliable copper, brass and lead metal components. Over time, resins break down with heat and this limits the service life of resin based components.

Radiator top tanks
We have seen the header tank hose barb on the side of the radiator cap mount fail as low as 110k kms. These failures result in total coolant loss within a few minutes. To check the radiator top tank, remove the cap (when cold) and look and feel for brown blemishes in the cap mount. If in doubt, talk with a radiator specialist about replacing the top tank.

Heater hose T and elbow fittings
OE components are made from the same composite materials as the radiator top tank and are exposed to similar coolant temperatures. The heater system circulates engine coolant even when the heater is turned off.  Any failure in these components can result in total coolant loss within a few minutes.

Oil cooler lines
Oil cooler lines are made of a coolant resistant grade of rubber and generally have twice the service life of the resin fibreglass composite cooling system components. The oil cooler lines are located under the oil filter and can be subjected to oil spills when the oil filter is changed.  Over time, oil spilt on the lines will rot the rubber. We have heard of oil cooler lines failing at 120k kms. It is important when changing the oil filter that any oil spills on cooler lines are degreased off.

YD25 D40 R51 Heater/ Oil Cooler Hose Kit
Our heater hose kit includes a long life aluminum T to replace the OE composite T piece. The kit also includes a molded heat resistant hose that replaces the OE composite/ metal line fitted to the firewall. Our replacement hose mounts behind the existing heater hose but unlike the OE part, allows much better access to the oil filter. Our oil cooler hoses are heavier duty than OE hoses to suit vehicles with an aluminum oil cooler. We have OEM stainless steel oil cooler hoses. Before ordering please check your oil cooler and advise if it is stainless steel or aluminum

Last updated September 2017