Knocking Noise from Oil Pan

[Pasta_Ricer]

Hi guys,

The other day, I tried to race someone and the car wouldn't go past 170 km/h in 4th gear. Happens sometimes because of bad fuel and some electrical issues (I think) and didn't think about it much. (Mind that my ECU doesn't have a knock sensor)
The next morning, I turn the car on and I feel a relatively loud knocking sound. I looked around in the engine bay and it sounded like it was coming from the cylinder #1 side. Checked the oil pressure, 5.5 bars at cold and revved it up, oil pressure was perfect like always. The car warmed up and the sound settled down but it wasn't completely gone. It would only make the knocking noise when revving up and not when revving down. Past about 2.5k, the engine noise gets loud enough that you can't hear that noise anymore. I was kind of worried and also kind of did not care so I beat it a few times later that day and it was hauling! It has never spun in 2nd gear before but it did that day for a few seconds on 215s.
We took it to a service shop and my friend went under the car and said the sound seemed like it was coming from the oil pan.

Now, this engine was completely rebuilt 14,000 km before and it blew a head gasket in multiple places at around 13,500 km. It was caused by loose head bolts. Anyway, about 800km after the head work, this is happening. It had never blown coolant into oil.
Everything was new on the engine. From the whole head to oil pump and basically everything except the crankshaft, the block, and the rods which were all resurfaced by a pro.

I will be taking it to the first mechanic who overhauled it. I will try my best to make him rebuild it properly from his own pocket, but I'm scared of not being able to do and having to pay the rebuild costs myself (which can be a lot in here).

Any thoughts on what it could be?

Thank you all <3

 

[97egl]

Probably a rod bearing on its way out. Hopefully it hasn't spun yet but since you beat on it while it was knocking your chances are pretty good that it's spun now.

In my opinion since you beat on it while it was hurt it's not the responsibility of the engine builder to fix the excess damage.

 

[dwb]

(Mind that my ECU doesn't have a knock sensor)

So you have no idea if you are detonating, you drove it really hard, and now you have a knocking sound?
I see teardown in your future, but I don't think this is the mechanic's fault as much as it is not having proper safegaurds in place.

 

[Pasta_Ricer]

You are correct about the excess damage, but it shouldn't have done this in the first place. As they had f'ed up the head bolts and set me back quite a bit. I just told them that this had happened and I didn't take any legal action, just gave it to a different mechanic for the head. God knows what else they had messed up.
i just really really hope it's nothing serious and the noise is from something else

Could anything else like the starter motor (which I have repaired twice in 2 weeks) or the flywheel or something make this sort of noise? Anything on the lower side of the engine.

So you have no idea if you are detonating, you drove it really hard, and now you have a knocking sound?
I see teardown in your future, but I don't think this is the mechanic's fault as much as it is not having proper safegaurds in place.

It's completely stock. These NA versions didn't come with knock or oxygen sensors. The engine was great that night before the 4th gear pull when it fell flat on its face. The engine was also timed and AFR tuned by the same mechanic when I asked them if they had timed the CAS. It didn't fuel knock unless you made a mistake and tried to accelerate at low RPM and like 2nd gear or something. It was great honestly until this thing...

 

[dwb]

Could anything else like the starter motor (which I have repaired twice in 2 weeks) or the flywheel or something make this sort of noise?

Hard to say, I suppose the flywheel bolts could have come loose or your clutch has something rattling around. However, these are oposite #1 cylinder where you said the noise was comming from.

It's completely stock.

My bad, I should have looked at your profile first. I assumed you turbo'd an NA block.

Have you drained the oil and inspected for metal flakes?

 

[Pasta_Ricer]

Hard to say, I suppose the flywheel bolts could have come loose or your clutch has something rattling around. However, these are oposite #1 cylinder where you said the noise was comming from.

My bad, I should have looked at your profile first. I assumed you turbo'd an NA block.

Have you drained the oil and inspected for metal flakes?

You're right, my bad as well xd

Not yet. Can I see the flakes by taking out the oil level gauge and dipping it on some dark cloth? Maybe crank or run it for a few seconds to stir up the oil?

Also, could any pulleys or tensioners and stuff make this kind of noise? They were all replaced at the original overhaul but still wondering.

 

[dwb]

At this point, prepare for the worst but hope for the best. Which means not cranking the engine until you have drained all the oil and confimred it's clean (or not). If it is clean, then you can start looking at accessories, clutch, flywheel, stuck HLA, etc. If it's not clean, time for teardown.

 

[BLACK'98DSM]

You probably wouldn't see many flakes on the dipstick, as they usually settle to the bottom of the pan. Unless there were just a ton of it, though some aluminum flakes are lighter per volume than heavy oils. I've seen it float on gear oil but idk what kind of engine oil you're using. Regardless, just pull the drain plug and see what comes out. Might want to cut the oil filter open and look if it's really bad. Sounds like it may be roughed up though.

If you really want to get down with the diagnosing, get yourself a stethoscope and listen to various parts of the engine (oil pan, block, valve cover etc.) But it sounds like you're taking it to someone else anyway so maybe just save yourself the trouble.

 

[DSMPT]

Upload a video with good sound, otherwise nobody can tell you the cause. Also a pic of valve and balance shaft timing.

The car warmed up and the sound settled down but it wasn't completely gone. It would only make the knocking noise when revving up and not when revving down. Past about 2.5k, the engine noise gets loud enough that you can't hear that noise anymore.

This, what you described doesn't sound like rod knock. Could be bad balance shaft bearing or bad tensioner. Do you still have the balance shafts? And did you replace the timing belt tensioner recently?

 

[Pasta_Ricer]

At this point, prepare for the worst but hope for the best. Which means not cranking the engine until you have drained all the oil and confimred it's clean (or not). If it is clean, then you can start looking at accessories, clutch, flywheel, stuck HLA, etc. If it's

Upload a video with good sound, otherwise nobody can tell you the cause. Also a pic of valve and balance shaft timing.

This, what you described doesn't sound like rod knock. Could be bad balance shaft bearing or bad tensioner. Do you still have the balance shafts? And did you replace the timing belt tensioner recently?

The first mechanic did the balance shaft delete. And yes, all the tensioners and pulleys were replaced by new parts.

I will take a video from the engine, rotating the camera to get the sound better.

 

[1990TSIAWDTALON]

As Hiroshi points out, if the tensioner isn't the right tension or has failed for some reason, it will bang around inside the front cover, trying to keep the belt on the cogs of the gears. It would be good to inspect it at least.