Whenever you purchase a used vehicle, whether you’re using it for a project or daily driver, the motor will definitely have some miles on it. The trick is, figuring out how many. Usually, the previous owner will tell you it’s been driven easy and has low mileage but that’s not always the case. And since the mileage plays a big part in engine health and therefore can determine how much you should pay for the vehicle, here are a few tests you can run to get a health report on an older engine.
If the engine is still in the vehicle or can be started up on a stand, start it up and let it run for a bit while seeing what comes out of the tailpipes. Hopefully, you don’t see anything but if you do see some light blue smoke that’s an indication the engine could be burning oil.
If you want a more scientific method, a compression tester is the tool for the job. As the crankshaft rotates and the piston moves up and down, it’ll trap air from the atmosphere and compress it. In order to compress the air enough, several parts need to be working up to par. It needs a good finish on the cylinder wall, good piston rings, good valve seals, and of course a good head gasket. Depending on what style of engine you have and what mods have been done, the reading could vary. But for a stock small-block Chevy like the C10, the reading should be somewhere between 140 and 180 psi if everything is working perfectly.
To conduct a compression test, first pull the spark plugs out. Then disconnect the power going to the ignition coil and the throttle plate needs to be held open for the duration of the test. With the adapter threaded into the head and the gauge connected crank over the engine until the gauge stabilizes. Then record the value and repeat for all 8 cylinders.
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Check the oil pressure too
Could have used a vehicle from this century.
its funny because i truly do have an old car that was owned by an old lady that just drove it to church. lived in a small town and only ever got it maintained by mechanics. only has 60,000km on it!!!!!!! (37,000miles) haha going to be awkward telling buyers that when i decide to sell it but i do have the paperwork for proof
So my stock 318 mopar is a 1988 model has not a lot but noticeable some when reviving I also noticed a lot of other mopars do that I seen a rebuilt mopar small block with blueish smoking coming out of the tail pipe mine has 142 thousand on the odometer and is running on 3 year old gas and hasn’t been driven more then around the yard should it stop smoking after it gets driven more or should I look for a new engine like a 360 or another 318??
I live In Florida and lots of condensation builds in the exhaust fast. I see water spurt out on start up almost all the time in the summer.
Don’t forget to put a battery charger one cranking it that much drains the battery and won’t give accurate results if it starts to crank slower
what about a 1994 dodge v8
Excuse me while I just take your car apart
Well done!
Compression tests only tell some of the story. Leakdown test. 150 psi = worn out? not where i come from.
is the magnum 318 motor a tuff motor
It would be great to have a follow up vid on doing a leak down test.
While a compression test is quick and identifies a weak cylinder, a leak down will tell you where the problem is. A leak down is also the only reliable way to identify a combustion chamber to coolant leak. Actual leak down numbers are less important than where the air is leaking out. Removing the check valve ( looks like a tire valve ) from the end of the compression tester hose gives you a way to pump air into the cylinder.
I love showing up to look at a vehicle with a tool box in hand lol. Makes the owner real nervous.
4.2 Trailblazer inline 6 with a turbo would be a sleeper in that truck!