Hello everyone,
I hope you're all doing good!
I have just recently bought a used 2017 Hyundai accent 1.6 Diesel automatic car for 17500$ (it is a very expensive price, but those are the average prices in my country 🙂 ) Its mileage is 110,000 kms which is approx 68,000 miles. I have gotten it tested before buying it and all was good. However when I went to change the oil right after buying it, I decided to open the oil Cap while the engine was running just for a good and a curious check, and I found out that there is air blowing from the oil cap hole after the oil cap was removed. Now, this is my first diesel car and so, I m not that experienced for when it comes to diesel cars, so I directly went on the internet and got the biggest panic of my life. I mean some opinions say that is normal but many others say that this is a dying engine sign. The air blowing from the engine cap in my case is not very strong, but rather it is a moderate breeze with some small sprinkles of oil. The car has literally 0 signs of any leaking whatsoever and is very clean in every aspect (even the under carriage).
Is anyone experienced enough with diesel engines to tell me whether that is normal or not?
I wish the Scotty Kilmer car community and Scotty Kilmer himself the best of luck!!
I have a little experience with 4 cylinder tractor engines. Diesels have a huge stroke compared to a gasoline engine and as such there is a lot of air turbulence inside the crankcase as the pistons displace air. What you perceive as blowing out is air rushing in and out as the pistons go up and down. Generally you don't want to operate diesels without the filler cap. There is a crankcase fume recovery system like a PCV and EVAP system on a gasoline engine that might be effected by leaving the cap off along with the splashing out which might occur. I would check with a diesel mechanic but in general if there is any thing wrong with a diesel it won't last long and it will make lots of noise just before it seizes. Plus there is no source of outside air in the crankcase. Blow-by from the rings would smell like exhaust but typically if you get that much blow-by the engine won't run as it can't develop enough pressure to ignite the fuel.
Just for the people who can't read I did say consult with a competent diesel mechanic and I am not an expert.
I mean it does make sense, since usually the oil Cap is right above the camshaft. Obviously I wasn't going to operate my car without the oil cap but I just removed it out of curiousty to have a better look at the engine as I said. So in summary, are you saying that this is probably normal, and that if something was bad, the engine wouldv'e seized already?
I drove the car about 100 miles since I bought it, and it drives great btw.
As always, thank you for your answer and opinion, I know you're not an expert, but a second opinion from the car community is always good. Sometimes experience speaks better than knowledge.
Every engine has a certain amount of gas that "blows by" the piston rings - that's why they put PCV systems on them (and pollution control). I would say the best measure of your engine's piston/cylinder/rings condition is how much oil the engine consumes between oil changes.If it consumes less than a liter between changes, you're good, more than a liter per 1000 km, you;re in trouble.
That is true, I will start watching it every now and then to check for any consumption. Eventhough it seems unlikely since I stated previously that the physical state of the engine was checked from the outside and there isn't any sign of a leaking. Other than that when I recieved the car the previous owner had driven 3,200 kms on the oil as he stated and when I drained it; it was full (approx 5 liters) which is the normal capacity of a diesel engine.
As you already know, there are two opinions about it. You better off finding an honest shop who works on Diesel engines and get a professional opinion.
Hello again and thank you for your answer!!
I did take it to a mechanic, well I m not so sure whether to trust him or not since its my first time visiting him, however he said it seems just fine, but I felt like he just wasn't so sure. I am just curious, does anyone in this form have a diesel engine in which they can remove the oil cap and compare with me whether this thing actually exists and normal?
Hello!
Generally diesels cost more than petrols when you buy and maintain them. Useful if you drive a lot on long distances.
Since you are new to diesels, there is something that might interest you:
https://carkiller.com/scottykilmer/postid/103284
https://carkiller.com/scottykilmer/postid/55996
https://www.autosmartmechanical.com.au/diesel-engine-maintenance/
Good luck!
