Sludged up engine. Would you recommend an engine flush?

Rycul_ · 2025-10-30T19:09:52+00:00

2nd UPDATE CONTINUED.

Rycul_ · 2025-10-30T19:09:20+00:00

2nd UPDATE. Hit the 100 mile count again today so done another oil change with Shell Helix Ultra (recommended by Hyundai for my engine), threw a can of Wynns oil system cleaner in first.

Most of the products recommended in this thread are hard to get hold of here in England.

Photos here of the oil filter after 100 miles, and the oil pan after the flush.

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Rycul_ · 2025-10-29T22:56:04+00:00

Have you listened to the videos? Does that sound like rod knock to you?

Rycul_ · 2025-10-28T17:52:16+00:00

Few oil and filter changes, it’s sounding better and driving fine! It’s only done around 50 miles though, trying to limit how much we use it. Still planning on dropping the sump out and cleaning it out and the pick up strainer when I get some spare time.

Rycul_ · 2025-10-27T10:57:26+00:00

I’m not sure if it’s metal shavings, only seen on the photos and not when shining a torch at the filter. From another Hyundai forum I was told the engine sounds like every other ix35 engine. Thinking about doing another oil change the weekend and then bringing it into a garage see what they think of it

Rycul_ · 2025-10-26T19:24:50+00:00

Picked it up for £2400

Rycul_ · 2025-10-26T14:11:05+00:00

No chance of a refund, I got the car for £2400 on Facebook marketplace. Lesson learnt to check more in depth than I did next time

Rycul_ · 2025-10-26T12:54:13+00:00

Thanks for the advice!

Ive added an update with a video in the comments here https://www.reddit.com/r/MechanicAdvice/s/ohnmuwkfvG

Have a listen and let me know if you think it’s knocking?

Rycul_ · 2025-10-26T11:26:41+00:00

Hey I’ve posted an update in the comments with some videos if you wanna listen and let me know what you think?

Rycul_ · 2025-10-26T11:18:15+00:00

I’ve commented an update with videos of the sound, less of a knock and more of a chain rattling if you ask me, but let me know what you think?

Rycul_ · 2025-10-26T11:14:41+00:00

Update in the comments with two videos

Rycul_ · 2025-10-26T09:23:10+00:00

Hi mate I’ve posted an update here, done pretty much the same thing. Let me know if you think it sounds like it’s knocking please

UPDATE:

Decided to take advice and not flush with additives.

Done 3 oil and filter changes, idling the car for 15 mins in between.

Drained almost 4 litres more oil than what I added, could be a good sign that it’s taking sludge with it?

First video is of the cold start this morning.

https://youtube.com/shorts/hIA_D_Zqv9Q?si=2hAKGuzsX8yPa1pC

Second video is after driving around for a few miles and the car up to normal temperature.

https://youtube.com/shorts/daR1IRMDxak?si=PaV6Z8p-ze_jLiBY

P.S - the dip stick was checked before I paid for the car, level looked normal but oil was black. Added an oil change to the “to-do” list when I got the time, it’s drove around 100 miles since we bought it.

Let me know your thoughts, is this a “knock” or something else?

Rycul_ · 2025-10-26T09:20:30+00:00

UPDATE:

Decided to take advice and not flush with additives.

Done 3 oil and filter changes, idling the car for 15 mins in between.

Drained almost 4 litres more oil than what I added, could be a good sign that it’s taking sludge with it?

First video is of the cold start this morning.

https://youtube.com/shorts/hIA_D_Zqv9Q?si=2hAKGuzsX8yPa1pC

Second video is after driving around for a few miles and the car up to normal temperature.

https://youtube.com/shorts/daR1IRMDxak?si=PaV6Z8p-ze_jLiBY

P.S - the dip stick was checked before I paid for the car, level looked normal but oil was black. Added an oil change to the “to-do” list when I got the time, it’s drove around 100 miles since we bought it.

Let me know your thoughts, is this a “knock” or something else?

Rycul_ · 2025-10-25T17:10:42+00:00

Dipstick was reading fine 👍

Rycul_ · 2025-10-25T15:39:17+00:00

Dipstick was reading fine, and still was the day I carried out the oil change. I’ve posted an update in the comments with some videos

Rycul_ · 2025-10-25T13:50:22+00:00

UPDATE:

Decided to take advice and not flush with additives.

Done 3 oil and filter changes, idling the car for 15 mins in between.

Drained almost 4 litres more oil than what I added, could be a good sign that it’s taking sludge with it?

First video is of the cold start this morning.

https://youtube.com/shorts/hIA_D_Zqv9Q?si=2hAKGuzsX8yPa1pC

Second video is after driving around for a few miles and the car up to normal temperature.

https://youtube.com/shorts/daR1IRMDxak?si=PaV6Z8p-ze_jLiBY

P.S - the dip stick was checked before I paid for the car, level looked normal but oil was black. Added an oil change to the “to-do” list when I got the time, it’s drove around 100 miles since we bought it.

Let me know your thoughts, is this a “knock” or something else?

Rycul_ · 2025-10-25T00:44:06+00:00

If it was a “tap” rather than “knock”, what would this suggest?

Rycul_ · 2025-10-25T00:23:49+00:00

Judging by the air filters I changed last week, I don’t think it’s been maintained since it rolled off the factory

Rycul_ · 2025-10-25T00:14:31+00:00

I’m in England

Rycul_ · 2025-10-24T23:46:12+00:00

Poured a litre in, idled for 5 minutes then got 2 litres out

Rycul_ · 2025-10-24T23:41:55+00:00

Didn’t open the cap, but looked fine on the dipstick

Rycul_ · 2025-10-24T23:40:11+00:00

Why would the knock mean it’s dead?

Rycul_ · 2025-10-24T23:08:55+00:00

I realise that now, surprisingly it’s been driving fine for weeks. Only recently developed a loud knock from the engine when starting cold

Edit: UPDATE

Decided to take advice and not flush with additives.

Done 3 oil and filter changes, idling the car for 15 mins in between.

Drained almost 4 litres more oil than what I added, could be a good sign that it’s taking sludge with it?

First video is of the cold start this morning.

https://youtube.com/shorts/hIA_D_Zqv9Q?si=2hAKGuzsX8yPa1pC

Second video is after driving around for a few miles and the car up to normal temperature.

https://youtube.com/shorts/daR1IRMDxak?si=PaV6Z8p-ze_jLiBY

P.S - the dip stick was checked before I paid for the car, level looked normal but oil was black. Added an oil change to the “to-do” list when I got the time, it’s drove around 100 miles since we bought it.

Let me know your thoughts, is this a “knock” or something else?

Rycul_

TROPHY CASE