Older Cars And Fluid Leaks

Seals and gaskets on older cars may be an even bigger problem on some models

The modern internal combustion engine (ICE) is a technological marvel and extremely complicated. The lifeblood of an ICE is the oil that lubricates the moving parts and prevents the various moving parts from touching each other and wearing out; these parts skate on a thin film of friction-reducing oil pumped through the engine at high pressure by the oil pump. Coolant keeps the whole ensemble at the correct temperature and prevents overheating. Both liquids circulate through the engine block and cylinder head and where these parts meet, gaskets and seals prevent them from mixing or leaking out.

What Happens When These Fluids Are No Longer Contained?

There are many places in the engine through which the oil can escape and when that happens:

• Friction increases because there is less oil to lubricate the engine’s moving parts
• Variable-valve-timing systems dependent on oil pressure stop working correctly
• Temperatures increase along with friction until the engine overheats
• Gaskets and seals may fail, and cylinder heads and engine blocks may crack
• Moving parts start to touch each other, wear, and become physically damaged
• If the engine is still running, it will eventually run out of oil and seize

The Job Of Gaskets And Seals In An ICE

Various types of seals and gaskets are used to keep these liquids at bay and these are the major ones:

• Cylinder-head gaskets. This is the most hard-working gasket in the engine. Modern gaskets are made from various materials such as elastomers, laminated steel, and copper, often in layers. To withstand high combustion pressures, cylinder heads are clamped very tightly to the engine block, with this gasket in between to seal off the coolant passages, oil galleries, and combustion gasses from each other. These gaskets are riddled with holes – big ones for the pistons and much smaller ones for the liquids to pass through as they circulate through the block and head, back down to the oil pan.

 

• Valve-cover gaskets. On top of the cylinder heads, you’ll find the valve gear that opens and closes the valves, and these are covered by a lightweight metal or plastic cover to keep contaminants out and oil in – with another seal between this and the cylinder head.

 

• Chain-cover gaskets. Engines with chain-driven camshafts usually have an additional cover that encloses the cam chain and through which the chain, pulleys, sprockets, and tensioner can be accessed. This cover has its own seal.

 

• Main crankshaft seals. The crankshaft rotates inside the engine and multiple round seals sit around it where it exits the engine to keep the oil in and contaminants out.

 

• Sump/oil pan gaskets. The oil pan is the reservoir at the bottom of the engine that contains the valuable liquid and where the oil pickup sits from where the pump sucks it up and pumps it through the engine. There is a seal between this pan and the engine block.

Older Cars And Failing Seals And Gaskets

When engines get old, repeated heat cycles and continual expansion and contraction take their toll on gaskets and seals, which break down, lose their elasticity, and start to leak. It doesn’t matter what you drive, rack up enough a high enough mileage and your engine will spring a leak.

To add insult to injury, engine manufacturers have not been able to cure these leaks, despite centuries of refining their art. Modern engines run higher compression ratios in the interest of improving horsepower ratings, fuel economy, and emissions, and almost universally employ turbocharging – pushing up under-hood temperatures to way beyond what they were in lowly naturally aspirated low-compression engines of 50 years ago. This puts additional strain and pressure on these gaskets and seals. Some manufacturers like Toyota and Subaru use an RTV-type sealant that is applied to some parts like the chain cover and no conventional gasket at all. Given enough time and heat cycles, this sealant deteriorates even sooner than most conventional gaskets.

Oil Leaks And The Jeep Wrangler

One of the common Jeep Wrangler JK problems is oil leaks on the 3.8-liter EGH V6 engine and it’s not just because this is an old engine design. Based on the 3.3-liter V6 from Chrysler circa the late-80s, the iron-block engine was a little behind the times from the get-go. Despite having a reputation for corrosion problems and excessive oil consumption, it’s been known to exceed 250k miles when looked after properly, while those that have been neglected and worked hard aren’t likely to get half that.

The third-gen Jeep Wrangler 3.8-liter engine is prone to oil leaks – and severe ones at that – often stemming from the timing-chain cover and failing o-rings. The valve cover gasket has also been known to leak as the engine ages. Following this, the engine also burns oil at a rapid rate; in severe cases, a quart every 1,000 miles. On the Jeep Wrangler of this generation, fouled spark plugs were often reported as a side-effect, identified by rough idling and misfires. Although reports on these issues vary wildly, with some owners reporting disastrous levels of oil consumption and leaking, others seem quite content to just keep an eye on the situation and top up as necessary. Still, the numbers suggest that the overwhelming majority of total engine failures in these power plants result from low oil levels.

BMW 3 Series Oil Leaks

Similarly, one of the most common BMW E90 problems when these cars start to age also revolves around leaking oil. And that’s despite the fact that engines such as the BMW N52 used in the E90 are new designs – having been launched in 2004. This holds true for all ICE sedan, coupe, crossover, or truck models you can buy in the USA.

On fifth-gen 3 series cars, oil leaks are often reported from the valve covers, which isn’t exclusive to the BMW. These leaks on the 3 series, however, are often from the actual plastic valve cover itself and not the gasket. Because the plastic becomes brittle with age, they tend to crack and need replacing. Oil leaks like this can be extensive and could also mask other serious leaks from the oil filter housing. If these are left unattended, the serpentine belt can be derailed with catastrophic consequences. A leak from the oil filter housing is less common in this generation of 3 Series cars, but it’s best to monitor for leaks regularly.

Last Words

Until EVs take over, we are going to have to deal with ICEs and all the maintenance that goes with them. And when our vehicles get old, this usually means leaks of all kinds. As always, preventative maintenance is key and if you make sure you fix small leaks when they appear, you should never have to deal with a big catastrophe. Small oil leaks aren’t serious, but big ones are, as are any type of coolant leak whatsoever, big or small. Considering the enormous list of possible failures that can occur due to low oil and coolant levels, a little preventative maintenance is the least you can do to save yourself many headaches and thousands of dollars. What’s more, a well-maintained engine will always deliver better performance and mpg in comparison to a neglected one, regardless of how much the odometer reads.