Maintenance Tip of the Week: Battery Cables 11/09/2015

Maintenance Tip of the Week – Battery Cables 11/09/2015

Battery cables are flexible. Periodically check your cables by flexing them. If your cables are defective, you should hear a crackling sound when flexed, in which case, replace them.

Cylinder head gasket damage: Is it the cause or a symptom?

The failure of the cylinder head gasket is often blamed for causing severe engine damage in marine engines. However, if gasket failure a cause of damage or is it merely an indication of other, more serious problems?

Gaskets are designed to seal. They either keep various matter inside of something or keep it out, whether gas, solid, or liquid. In the case of cylinder heads, gaskets deal with three different components, all related to combustion:

  • Oil
  • Water
  • Gas

If a gasket is properly installed, it should function as designed for a very long time. What are the indicators of gasket failure?

Namely, that the gasket is no longer sealing. The cylinder head gasket not only seals the cylinder from external factors, such as preventing water from getting inside the cylinder, but from between different cylinders on an engine (such as gas from one cylinder leaking into an adjacent cylinder. Obviously, such leakage interferes with the combustion process, and engine damage is the inevitable result.

So, what tells the operator that a gasket may be damaged?

  • Poor cold starting
  • Loss of power
  • All cylinders not firing
  • Different colored smoke
  • High water temperatures

All of these indicators mean that the cylinder head gasket may be damaged. So, you disassemble the engine and replace the gasket. The problem with this is that the gasket may not have been the cause of the failure, but rather a symptom of a different problem. Gasket failure can be caused by a number of different factors, including:

  • Improper torque on the cylinder head bolts
  • Rapid acceleration of the engine after cold start
  • Roughness on the cylinder wall
  • Uneven cylinder top
  • Loose cylinder liner
  • Compression incorrectly set in the ECU
  • Defective thermostat
  • Cooling system blockage or leak
  • Pump failure
  • Exhaust system back pressure caused by either leaks or blockages

How do you know that the gasket itself caused the failure?

  • Discoloration of the gasket (The area of discoloration usually shows the location of the leak, due to heat, whether caused by the gasket or something else.)
  • Excessive flexibility
  • Corrosion along the edges or eyeholes of the gasket
  • Rough surfaces on either the gasket or engine block

This last point is critical. Modern gaskets for marine use are designed of materials that are engineered to be resistant to corrosion and degradation. In most cases, if it is the gasket itself that has failed, rather than another part of the engine, it is usually the result of improper installation of the gasket. In particular, improper tightening of bolts and installation on dirty surfaces causes these issues. Why?

Simple. The gasket must seat properly and seal. Tightening bolts too tightly warps the gasket, preventing the seal. Dirt or liquid under the gasket prevents a proper seal. Since combustion produces heat, the problems are magnified as the heat becomes excessive, further speeding up failure of the gasket.

So, what can be done?

  1. Refer to your manual. Marinediesel always lists the torque for bolt tightening in the manual.
  2. Use only OEM Genuine Spare Parts. The gaskets we use are designed for the engine and made of materials intended to withstand their designed use.
  3. Realize that gasket failure may be a symptom, rather than a cause. If something is causing gasket failure and that cause is not corrected, the failures will continue.





Maintenance Tip of the Week: Fuel Filters 11/02/2015

Maintenance Tip of the Week – Fuel Filters 11/02/2015

Always use the correct size of fuel filter, as specified in your manual (most Marinediesel engines require 10 micron size). Incorrect, or cheap, fuel filters can seriously damage your engine, especially in locations where fuel quality is a problem. Inexpensive fuel filters are often of poor quality and are usually not much cheaper than quality brands.

Need to contact Marinediesel for technical assistance? We need your engine serial number.

Though we recently posted this question in our   Engine Maintenance FAQ, this subject is really important, so we will occasionally post reminders about it on the blog.

Why are we making a big deal out of the engine serial number?

Quite simply, because the engines are continually evolving and changing from one year to the next. As an example, there have been about ten versions of the Marinediesel VGT Series. As engines progress from idea, to development, to testing, to market introduction, to production, different components are either tweaked or changed based on field experience and feedback from our customers.

In a way, it is very similar to the updates that computer software publishers make as bugs are discovered. Indeed, given the electronic nature of the VGT Series and the use of the NIRA ECU, software updates are often one of the changes we make.

When an engine is manufactured, detailed production notes are kept about that specific engine during the production process. We know, for example, which turbocharger was equipped on the engine, what software version was installed, and custom configuration, etc.

Additionally, the engine serial number allows us to see any changes made to an engine, by Marinediesel, since that engine was sold. Indeed, we recently has a mechanical issue with a customer where there were changes made to the engine, and nobody (including our customer!) could remember what was specifically done to the engine. Our technical team having the serial number eliminates problems and issues like that.

So, before contacting Marinediesel with technical questions, you should look up the engine’s serial number first, so we can give you an accurate solution for your engine problem.


Location of engine serial number, VGT Series


Maintenance Tip of the Week: Zincs 10/26/2015

Maintenance Tip of the Week – Zincs 10/26/2015

The pencil zincs your engine came with are absolutely critical to preventing galvanic corrosion, which can ruin your engine very quickly. Always change your zinc anodes after 100 hours of operation, more frequently if the vessel is in water with high salinity or if the vessel is inoperative in the water for an extended period of time. Zincs are cheap protection.

Genuine Spare Parts – A difference worth choosing

You will often hear us telling our customer to only use Marinediesel genuine spare parts when performing maintenance on their engines. Though this may seem like merely a way to earn additional profit, there are some very good reasons to only use spares provided by either Marinediesel or our official distributors:

  1. Marinediesel engines are designed, tested, and certified with parts that are tested by us specifically for your engine model. We have no control over the production standards, quality, or compatability of aftermarket parts. Though the part may work to immediately fix a problem, it may not be 100% be compatible with your engine.
  2. On marine engines, all genuine spare parts are marine grade spares. Aftermarket parts may not be suitable to the marine environment.
  3. Only Marinediesel Genuine Spare Parts carry a one year warranty from Marinediesel.
  4. The use of improper spare parts or replacement parts will impact your warranty. Marinediesel’s warranty is issued with the expectation that parts either manufactured by us or provided by us will be covered under the warranty. In other words, using an improper part may void your warranty.

This article is not intended in any way as a comment on the quality of aftermarket spare parts. Indeed, in most cases aftermarket parts will be adequate. However, in order to ensure a long, proper service life of your engine, and compliance with your performance standards, only Marinediesel Genuine Spare Parts should be used for your maintenance and repairs.

Maintenance Tip of the Week: Raw water pump 10/19/2015

Maintenance Tip of the Week – Raw Water Pump 10/19/2015

The raw water pump on your engine is critical for the cooling system. Under heavy load, your engine’s raw water pump can fail, making inspection a critical maintenance task. Always check for corrosion, leaks, and seal before operating your engines and as part of Marinediesel’s recommended maintenance schedule.

Maintenance Tip of the Week – Exhaust Risers 10/12/2015

Maintenance Tip of the Week – Exhaust Risers 10/12/2015

Always inspect your exhaust risers and gaskets for corrosion as stated in your manual’s maintenance schedule. Exhaust riser failure is a leading indicator of critical, and very expensive, engine damage.

Maintenance Tip of the Week: Oil 10/05/2015

Maintenance Tip of the Week – oil 10/05/2015

Always use the proper SAE oil when changing the oil in your engine. Marinediesel has tested its engines for many hours to determine the correct oil type, and using the proper oil, as specified in your manual, can easily extend your engine life by as much as 50%.