Diagnosing & repairing Engines in Car Mechanic Simulator 2015 can be difficult, but this guide will help take the sting out of it.
Visual inspection can show you a few things. As can various tests. You can use the Compression Tester and the Electronic Meter to do some of the tests, and if the car is equipped an OBD Reader it can also be of use. In the case where the engine still runs then you'll also be able to do a Test Drive.
Keep in mind that the Air Filter and Fuel Filter can also be problems, along with the Fuel Pump. Less obvious would be things like the wires, where the steering pump and alternator are easy to spot.
On V8 OHV engines you'lll find that removing the engine head covers will reveal the rocker arms and push rods. These can cause all manner of engine problems and are easy to inspect. Just take a close look. Rocker arms that are badly rusted are probably finished, and if the push rods are a dark or black color they need replacing. The Compression Tester may reveal problems with the Pistons, Rocker Arms, and Push Rods.
Ignition Coils can only be evaluated with the OBD Scanner. Of course, you can just pop the coils cover and take out the coils to determine their condition.
Timing is one of those things you'll have to dig a bit for, but once you have the timing cover off it's a simple matter. Camshaft bearing covers are easy to inspect. They can be exposed by removing the head covers. Keep in mind the V8 OHV does not have these parts.
If you are not fully equipped with tools for testing, then the pistons can be difficult to diagnose. There is an easy solution for this: drain the oil and pull off the oil pan. This will allow you to see the crankshaft bearings. If you look up you'll be able to see the amount of rust on the piston rods.
You'll also quickly discover that a problem may be listed under more than one category and that when you fix it in one place, it will be marked as fixed in all of the categories. An example would be Change Oil & Oil Filter and the problem Engine Is Choppy. If the oil filter is listed under both categories you only need to replace it and the problem is marked resolved in both categories.
There is one last point that is very important. Sometimes engine compartment noises and knocks are actually caused by a faulty exhaust, and not always the manifolds under the hood. If you still can't find the issue, there is one other place that sometimes creates an engine compartment noise: check in the gearbox. Faulty flywheels, clutch plates, clutch pressure plates, and clutch release bearings can also cause this problem.
These screenshots show repair orders for the various engine problems, along with the parts responsible for the troubles. In the early game these are filled out for you, but later on you must figure out the parts yourself.
With these lists, you'll be able to take some of the mystery out of it until you get familiar with Car Mechanic Simulator 2015.
To help you learn the diagnostics side of Car Mechanic Simulator 2015 as quickly and easily as possible, I have created a few short but comprehensive guides covering each problem category. For a complete listing of these guides, check here:
Diagnostics & Repairs - Car Mechanic Simulator 2015
If you are looking to learn about the early and mid-stages of the game, you may find these pages of interest:
Your Garage, Tools, Tests, & Upgrades, Jobs & Job Management
And if you are wonding what awaits beyond and where the real cash is hiding, check out this link:
Rebuilding Guide - Car Mechanic Simulator 2015