Blue smoke from the exhaust on a cold start. Causes and solutions

Blue smoke from the exhaust is a clear indicator of oil in the system. The engine oil’s typical function is lubricating the vehicle’s different moving parts.

If your car is functioning correctly, then there should be no oil entering your car’s system. Any oil in your car’s system indicates malfunctioning somewhere in your vehicle.

Several potential causes are resulting in oil getting into your car’s system, which might mean excessive oil is in your vehicle’s system. Below are some reasons why your car has blue smoke from the exhaust on a cold start. 

What Causes Blue Smoke from Exhaust on Startup?

1. Fuel Is Mixed With Oil

The first cause is oil mixing with fuel. Suppose your car has run approximately 10,000 miles in between oil changes; there is a possibility that the oil will be inefficient in friction reduction function.

With this, high heat generation heats and cools the gaskets, and as a result, these gaskets become dry and eventually crack.

With dry and cracked gaskets, separating fluids is challenging, and this can lead to the vehicle’s oil getting mixed up with oil, and the final product undergoes combustion, resulting in the blue smoke from the exhaust.

2. Oil On Engine Parts

Another cause is oil dripping to the engine’s hot parts. Suppose the head gasket is spoilt and the engine leaks some oil; it is likely to drop to hot parts of the engine and eventually evaporate as blue smoke escapes through the exhaust.

When your car is idle, the smoke will come out from under your car’s hood. Also, if the inside of your vehicle smells like something is burning, it is vital to have your car’s parts checked.

When your glow plugs go bad, there is a high possibility that this also contributes to blue smoke coming out of your car’s exhaust system for diesel engines.

3. Bad Spark Plugs

With faulty glow plugs, your vehicle will not start usually, and the cranking time may be longer. To be sure that your glow plugs present a challenge, use a 12-volt test light on your battery’s positive terminal, then check the reading of each glow plug.

If you realize that the glow plugs have an issue, you can consider replacing them, though this might be costly. 

How to Fix Blue Smoke on a Cold Start?

Consider changing your valve seals if the problem is from leakage. The valve seal costs approximately $40. This fixture is relatively cheap, provided you have the necessary tools to fix the valve.

Suppose you have a wrench and are handy with the tool; instead of incurring the labor costs, you can change the valve and not engage a mechanic because it can be costlier.

Suppose the issue is lousy piston rings which lead to leakages; replacing the entire engine is necessary to fix the problem and eliminate the blue smoke from your exhaust system.

This replacement is expensive as it could cost approximately $7000 and above, which might dig deep into your finances. However, if your car is new, it must be under a warranty which might cover these extra costs.

You should consider replacing your car’s glow plugs if worn out. Replacing these glow plugs can be costly depending on whether you choose to do it or have another party, such as the mechanic, handle the issue.

The glow plugs can cost between $100 – $500; it is crucial to make sure they are bad before trying to change them because it is a costly activity. 

While it is possible to drive while your vehicle emits blue smoke, it is crucial to have the issue checked out to avoid replacing the entire engine, which is quite costly.

Your engine should not run with fuel mixing with the oil. Before it gets to the point of replacing the engine, ensure you have your vehicle constantly checked and maintained to prevent such issues.

Routine visits with the mechanic are not costly, and it is better to have these regular visits than one expensive visit.

Take away

Your vehicle requires constant maintenance to prevent specific issues, such as oil mixing up with fuel resulting in blue smoke from your car’s exhaust system.

It is possible to still drive under such a condition, but you must handle any issues before they become major. While the replacements involved in providing a solution to the problem are costly, it is better to ensure you drive a car without any issues.

Ensure your car’s gaskets, valves, seals, and glow plugs get checked whenever you notice blue smoke from your exhaust.

Scroll to Top