--Starting problems unrelated to weather or outdoor temperature
--Poor fuel economy or increased oil consumption
--Unexplainable loss of power
--Excessive crank case pressure
On March 16, Fleet Owner published an excellent article by Chad Christiansen about compression tests, when to get them and what they can tell you. In the same way that a battery of tests at the clinic can help you avoid more serious health issues later, so can a compression test identify engine issues before they become more serious.
Christiansen opens with this:
"Compression in a diesel engine is essential for effective and efficient performance. And when compression is lacking, damage can result. That is why it’s imperative to know whether your engine’s compression is correct."
Compression tests aren't a necessary part of routine maintenance, he writes. They can be valuable if you're having issues like the ones cited at the beginning of this article.
As most diesel owners know, diesel engines operate on a different principle from gas-powered engines. There is no spark plug in a diesel. Diesel engines work by compressing only the air. This increases the air temperature inside the cylinder to such a high degree that atomized diesel fuel injected into the combustion chamber ignites spontaneously.
When you bring your truck to a mechanic to run compression tests, he or she will place a gauge in each of the cylinders to read how much compression is being produced when the engine turns over. If the pressure is too low, or too high, or if there is too much deviation between the readouts from all the cylinders, there is probably internal damage of some kind.
You can read the full story here.
* * *
Last summer CarPart.com published a good article on the signs and causes of low engine compression. Though written for car owners, the article by Sam O. is relevant for diesel owners as well, identifying the various kinds of damage that may be lurking inside your engine. They include:
Holes blown in the piston head
Leaky valves
Worn timing belt
Head gasket failure
Bad piston rings
Camshaft issues
Follow this link to read the CarPart.com article in its entirety.
* * *
Related Link
Here's a video on How to Use a Diesel Compression Tester.
On a healthy diesel engine, good compression usually falls between 275 to 400 psi, with a variation of no more than 10 percent between any two cylinders.
ReplyDelete