Engine Seal Leaks: Diagnosis, Prevention & Treatment

Seal failures leading to leakage in auto engines are caused by a host of reasons. However, regardless of the type of failure, corrective active should be quick and crisp. While you may be able to ward off the effects of an irregularity for some time, in the end, the only practical differences between doing an immediate fix, versus doing it later, relate to time, money, and hair pulling.

To gain a better understanding of what might be happening under the hood when you spot a dark puddle under your car, here’s a short primer on engine seal diagnosis, prevention, and the application of useful mitigating treatments.

Seal Components For Typical Engines

Today’s automotive market harbors a constellation of engine types, ranging from vintage to late model ICE/Electro-hybrid configurations. In the former case, typical seal components are largely driven by ensuring that oil and lubricants are retained within the engine block. However, in the case of more modern engines – like turbo-boosted, hybrid, or multi-fuel powerplants for specialized vehicles – seal elements can be found in a number of other places within the overall engine complex.

Ultimately, there are three central categories of seal in the universal engine market:

• Engine shaft seals
• Magnetic encoders
• Valve-stem seals

This still encompasses a long list of elements that need close attention, so to further simplify things, we’ll narrow our focus a little more. Here, we will discuss core seals associated with typical ICE and/or Diesel engines. That leaves three central areas of interest:

• Crankshaft seals
• Main seals
• Piston seals, i.e. ‘cylinder rings’

Seal Leak Diagnosis

Engine oil leaks are one of the most common causes of vehicle damage. Unfortunately, pinpointing exactly how the leak started and where it’s coming from takes a little investigating. To set the scene, let’s take a look at a list of some of the major reasons for seal failure:

Full Contact Failure

Even if a seal ‘looks good’ it can still be failing, leading to leakage. In this event, the only way to be sure is to do a physical removal and investigation of both primary and secondary seals.

Major corrective steps:

• Check if secondary seal was scratched during installation
• Investigate for signs of porous damage on seal face
• Check for low emissions failure due to incorrect seal type
• Check for materials failure due to mis-fitting

Negative Coning

This is another common failure. In this case, the outside of a seal may ‘appear’ to mate properly with a secondary seal at the outside diameter, while the inside diameter doesn’t. As a result, the seal operates properly under high pressure, but leaks under low pressure. Again, physical investigation is called for.

Major corrective steps:

• Check for over-lap flatness
• Check for previous over-pressurization

Thermal Distortion

In this case, leakage may occur by over-temping of the seal complex. Symptomatically, this failure typically shows itself as leakage when a shaft is turning, while no leakage is apparent when a shaft is stationary.

Major corrective steps:

• Check for overall flatness

Mechanical Distortion

Leakage here can exhibit irregularities between outer and inner seal faces. Symptomatically, this seal failure typically leaks whether a shaft is turning or stationary.

Major corrective steps:

• Check for overall flatness
• Investigate for mechanical deformation

High Wear and/or Excessive Grooving

Like thermal and/or mechanical distortion, leakage in this case can involve irregularities between outer and inner seal faces. Typically, you’ll spot this leak whether a shaft is turning or stationary, and you may also hear unusual popping sounds during operation.

Major corrective steps:

• Check for poor lubrication
• Check for burring, chips and/or metal flakes in/around shafts or pump activities
• Investigate poor cooling
• Check for poor installation

This section represents only a partial list of the reasons for seal failure. However, in the event of leakage, it’s important to take immediate remedial action.

Prevention And Treatment

There are all kinds of ways that seals can fail inside a typical engine. Most root-causes, though, ultimately involve some kind of physical damage that allows oil and/or lubrication to escape the engine’s ‘envelope’. Sometimes, failures simply occur due to wear and tear over time, but in the case of more modern engines, a regular schedule of prevention can avoid most major failures.

Since heat and friction are big contributors to seal failure, reducing these factors is key to a good prevention program. While there are a number of products on the market that promise to help, it’s generally accepted that Lucas Oil Products represent the top rung of a very tall ladder.

Here are just a few Lucas Oil products designed to extend protection for the long haul.

Lucas Engine Break-In Oil

As the company likes to say, this product is for all who fear the initial break-in period of any new motor. Specifically designed to take care of engine piston rings during the first 5,000 miles of operation, Lucas Engine Break-In Oil is particularly efficient for engines running a flat tappet or roller camshaft.

The product’s goal is to maximize early ring sealing that otherwise might cause problems during engine break-in. Its formula further enhances viscosity to aid proper lubrication of main and crankshaft seals.

Lucas Deep Clean Fuel System Cleaner

While in-direct when it comes to the extension of engine seal life-cycles, Lucas Deep Clean Fuel System Cleaner offers a host of engine extended life values. In this case, the company’s formula primarily reduces carbon deposits throughout the entire fuel system – including the combustion chamber, along with engine piston tops.

This reduces friction, leading to over-temping and ensures proper emissions control, while also aiding piston ring life. Regardless the kind of vehicle, Lucas Deep Clean Fuel System Cleaner is an excellent addition to a solid extended-life program for rings, emissions components, and engine seals.

Lucas Engine Oil Stop Leak

If you unfortunately find yourself with seal leakage, Lucas has your back. The company’s Engine Oil Stop Leak product is designed to renew worn seals while quickly blocking leakage, regardless of the location or problem. Compatible with petroleum, semi, and full-synthetic oils, it contains no harmful solvents that could cause damage or corrosion down the line.

Along with its impressive properties as an engine sealant, the introduction of Engine Stop Leak also allows older engines to boost oil pressure, while reducing overall oil consumption. For best results you can apply a refill ratio of 1:4 based on each oil change.

It’s important to note that while these are great products with a long list of happy users, they don’t work in situations where a seal is totally worn down, scoring on a sealing surface exists, or when a component is severely warped. If your engine seal is in that bad of condition, you need a permanent solution – not a stop-gap. However, if you need to buy some time until you can hunt down the leaky culprit or you’re looking to repair some older, hardened seals, these products can help.