Bought a Sludge lemon. Is it fixable? BG flush?

[someonesomewhere]

Would it be OK to put some seafood and also rev it to 3k rpm. The bottom end of the eengine didn't have that much sludge.
I'm wondering if there is some sort of blockage causing oil starvation to the top end which caused the sludge

If you're going to do this 'add engine flush and bring the revs up' technique, I would do so driving. Figure out what gear gives you the speed limit at that RPM, and run it down the road. Free revving for that time frame while sitting still just sounds like a great way to discover an overheating issue (lack of air flow), and it may be an old wives tale based on the old school V8s I grew up with, but we were taught not to free rev that much, lest bearings start spinning around and out through the block, followed closely by the con rods. Lol. Especially if you suspect oil pressure issues. I would want that extra airflow provided via movement down the highway!

Just my opinion, and what I would do, personally.

 

[iverson03tj]

If you're going to do this 'add engine flush and bring the revs up' technique, I would do so driving. Figure out what gear gives you the speed limit at that RPM, and run it down the road. Free revving for that time frame while sitting still just sounds like a great way to discover an overheating issue (lack of air flow), and it may be an old wives tale based on the old school V8s I grew up with, but we were taught not to free rev that much, lest bearings start spinning around and out through the block, followed closely by the con rods. Lol. Especially if you suspect oil pressure issues. I would want that extra airflow provided via movement down the highway!

Just my opinion, and what I would do, personally.

That's a great suggestion. The bottom end has a lot of darkened varnish. But not a lot of sludge. I did blow air through all the oil passages from the bottom to check for blockages. But the one big issue are those tiny oil squirter on the back end off the piston. It's like a pin hole at the tip.

I got 4 more oil filters. I'm still trying to weight the pros and cons of each method.

1) flood the engine with diesel. But without the engine rotating. I don't see how it can clea. Those tiny oil squirter

2) put 300-500 ml of ATF fluid as a flush. (Old diesel mechanic trick)

3) 2x the recommended amount of seafoam and take it for a good highway cruise.

4) BG (if I can get my hands on it) it's about 400 to 500 buck. But that's like the equivalent cost of 3 oil changes anyways.

5) HPL EC30. But I can't find it anywhere in canada.

I know going with a faster engine flush instead of the the slow way isn't recommended and it can clog the filter and cause the oil to bypass.
But I will keep an eye on the filter and replace it when it starts to clog up.

Thankfully Bmw filters are easy to remove and inspect.

Thank you all for the great suggestions. I'm no mechanic. Just learning as I go and this car has been. Quite a series of lessons.

 

[Donald]

I didn't measure the crank bearing clearance but I did check for radial play. Really dont want to drop the subframe again xD. I did that entire job on my driveway.. not fun.
As for the oil pump I opened it up and checked for signs of wear, A bit of scoring but no deep scratches. Spun it a few times to make sure it worked..

As for the oil pressure. Alldata says the resting oil pressure at idle and operating temp should be 1.5 bar. Which is around 21 psi. But many people with n55 engines state that they have 40 psi at idle...

I did some research into BG and alot of reviews from users state that their oil pressure increased.
But I think what's working for their product is that they rev the engine to 3k rpm for 45 mins.
Would it be OK to put some seafood and also rev it to 3k rpm. The bottom end of the eengine didn't have that much sludge.
I'm wondering if there is some sort of blockage causing oil starvation to the top end which caused the sludge

So if some oil treatment was going to "clean things up" it would be in areas where there is not great oil flow. Like the area on top of the heads where some engines develop sludge. It's not going to be in the oil galley because they have pressurized oil flowing all the time and should not have any sludge. Isn't there part of the oil pump that regulates oil pressure by dumping oil back into the oil pan when pressure is too high.

 

[eljefino]

Don't put seafoam in your oil. It's a solvent, it wrecks oil, that's it's job.

 

[meep]

Definitely not 2x dose of seafoam. I’ve run it at half can in the sump but not more than that.

Frankly, the bottom end pics look good. I wouldn’t overdo this. IF the oil pressure is low, cleaning isnt going to affect that. The engine seems in good shape, so “less is more,” applies here.

You need to drive the car and see what the oil consumption looks like over a few thousand miles. I had one particular Volvo, over 100k on it when i got it. It used a quart every thousand miles. I did what I said about, slightly sooner oil changes, half can of seafoam, penzoil platinum oil. Around 20k miles, I realized it wasnt consuming oil. The filter media always showed a collection of grit, even 60k miles later. The vehicle eventually rode a flatbed to a junkyard on the other side of the country, the engine still ran like new.

If oil pressure is truly a concern, test it with a manual, mechanical gauge before going much deeper.

 

[Owen Lucas]

Liqui Moly Sludge Remover. 1 can, 120 miles, no hard acceleration, and drain.

 

[someonesomewhere]

If oil pressure is truly a concern, test it with a manual, mechanical gauge before going much deeper.

Excellent suggestion; I just had that thought before I got to your reply. OP, you definitely need to verify your 'actual' oil pressure with an external mechanical gauge. There may be a partial sludging/blockage internal to your oil pressure sensor, or an issue with the in-dash gauge itself, so it's always best to verify with an external gauge before getting too deep into trying to resolve an issue that may be a mechanical/electrical apparition.

Usually isn't too difficult to plumb in a gauge, often you can just use a tee fitting in the port the stock oil pressure gauge screws into to add an temp extra port. An aftermarket gauge usually isn't too expensive either. You don't have to install it inside the car, you can just hook it up and use it in the engine bay for no longer than you'll need to have it hooked up to verify your pressure.

Here's a Bosch-branded sensor as an example via Amazon, $25. https://a.co/d/85xzY3A

 

[iverson03tj]

Definitely not 2x dose of seafoam. I’ve run it at half can in the sump but not more than that.

Frankly, the bottom end pics look good. I wouldn’t overdo this. IF the oil pressure is low, cleaning isnt going to affect that. The engine seems in good shape, so “less is more,” applies here.

You need to drive the car and see what the oil consumption looks like over a few thousand miles. I had one particular Volvo, over 100k on it when i got it. It used a quart every thousand miles. I did what I said about, slightly sooner oil changes, half can of seafoam, penzoil platinum oil. Around 20k miles, I realized it wasnt consuming oil. The filter media always showed a collection of grit, even 60k miles later. The vehicle eventually rode a flatbed to a junkyard on the other side of the country, the engine still ran like new.

If oil pressure is truly a concern, test it with a manual, mechanical gauge before going much deeper.

I think your right, im over thinking this. Bought the oil pressure tester but I just found a bmw service manual on the n55 engine. Looks like the oil pressure is actually normal! As for oil consumption, before I pulled the bottom end off I did drive it for about 6000km and it was about 1 quart.
Also the rod bearings didn't have much wear for a car with 180kms.

 

[Donald]

Yes as others have said. Replace oil pressure sensor. Try a mechanical gauge of known quality.

Replace oil filter in case yours is defective and it's cheap.

I would not go crazy with flush and solvents. Whats in the oil pan needs to be mostly a lubricant, not a solvent. Forget MMO.

 

[sw99]

Not a popular option on here due to the fact that everyone knows it all but regardless...I have had great results with a 20-25% MMO / HDEO 15w40 cleaning cycle. I do this on every new, used vehicle I purchase. I also do it every couple years on the older Corolla's I own just for good measure. The HDEO's have higher detergents across the board for the most part and the MMO does a good job at cleaning without being too harsh. I run a full OCI on the blend. I would try it since it's fairly inexpensive and readily available at WM.

 

[Sandstorm]

Not a popular option on here due to the fact that everyone knows it all but regardless...I have had great results with a 20-25% MMO / HDEO 15w40 cleaning cycle. I do this on every new, used vehicle I purchase. I also do it every couple years on the older Corolla's I own just for good measure. The HDEO's have higher detergents across the board for the most part and the MMO does a good job at cleaning without being too harsh. I run a full OCI on the blend. I would try it since it's fairly inexpensive and readily available at WM.

If you run that combo in a car with a turbo, the outcome might not be a ideal as planned. Even MMO doesn't recommend running their traditional oil with a turbo...

 

[BMWTurboDzl]

View attachment 251916

I did clean up the top end as much as I could with diesel. Vacuumed and then blew out anything loose. And flushed out everything before putting the new oil pickup tube and bearings

Just run M1 0w40 and not worry about it. You could also pull the vanos solenoids and inspect/clean the screens.

 

[demarpaint]

Another vote here for skipping the Seafoam.

 

[Cujet]

I am not a fan of Non-Oil solvents. Why not simply use a slightly higher viscosity oil that is known to clean? Solves the pressure problem and slowly cleans. 100,000Km later, the engine will be just fine.

Without the risk of dissolving gaskets with a strong solvent, or diluting your oil with a non-oil.

M1, HM 10W-40 will clean, as an example.

 

[sw99]

At least iverson has some options to try. Hopefully he gets some positive results.

 

[sw99]

If you run that combo in a car with a turbo, the outcome might not be a ideal as planned. Even MMO doesn't recommend running their traditional oil with a turbo...

For the record, there is nothing on the MMO site that mentions it not being safe for turbos. Where are you getting this information?

 

[Sandstorm]

For the record, there is nothing on the MMO site that mentions it not being safe for turbos. Where are you getting this information?

Give them a call they'll advise against using it also they'll tell you that they came up with the synthetic version for the turbos. I wouldn't use either

 

[OVERKILL]

Just run M1 0w40 and not worry about it. You could also pull the vanos solenoids and inspect/clean the screens.

This. If you want to add HPL Engine Cleaner to the mix, buy the SAE 40 version from here:
https://www.advlubrication.com/coll...roducts/engine-cleaner?variant=41599501566145

 

[Craig in Canada]

That's a great suggestion. The bottom end has a lot of darkened varnish. But not a lot of sludge. I did blow air through all the oil passages from the bottom to check for blockages. But the one big issue are those tiny oil squirter on the back end off the piston. It's like a pin hole at the tip.

IMO you should also check/replace the oil squirter for the valvetronic gear and actuator area (top end). If flow was impeded here, the gearing on the actuator or the eccentric shaft may already be toast.

 

[iverson03tj]

UPDATE: I want to start by thanking this community and everyone who shared their ideas and knowledge with me.


Many suggested I scrap, sell, or change the car's engine. However, I was keen on gaining firsthand experience in dealing with sludge issues, fully aware that I might eventually need to replace the engine. As the saying goes, "The more you F around, the more you find out," right?


I tried to use BG Dynamic Engine Cleaner & Rinse Oil due to its proven results. Unfortunately, residing in Toronto, I found only one distributor, and despite multiple attempts, I couldn't even reach them. Purchasing online wasn't viable either, as shipping chemicals to Canada is restricted, and Amazon listed it at around $450. Considering I found a shop willing to replace the engine for $800 in labor, spending $450 wasn't economically sensible.


I was actually really excited to remove the valve cover and share the results, measure cam journals clearances and pictures when i removed the valve cover after running a quarter bottle of Sea Foam with Mobil 0W40 for 5,000 km. The plan was to, changed the oil filter every 2,500 km, anticipating that a clogged filter would trigger the bypass, rendering it ineffective. I did this once and the filter accumulated sludge, prompting me to adjust my plan to change the filter every 1,000 km.


Tragically, a drunk driver hit my parked car, resulting in a total loss. After all that effort, it feels like a part of me left with the car. Consequently, I can't inspect the cam journals or share further findings. I know that my aggressive approach might have caused more harm than good, but you gotta f around to find out!


For others facing similar issues, here are some insights from my experience:

1. Oil Pressure Increase: I observed a 2 PSI rise in oil pressure.
2. Engine Performance: Despite frequent redlining and reaching speeds over 180 km/h, daily driven and a heavy foot, the engine performed flawlessly. no oil pressure issues
3. Oil Pump Inspection: I went down the rabbit hole researching the code indicating low oil pressure before startup. Research suggested possible wear-induced gaps in the oil pump. Although I inspected the pump, I neglected to use a feeler gauge to check impeller clearances—a significant oversight.
4. Sea Foam Usage: While some caution that Sea Foam might alter oil properties or dislodge large sludge chunks into oil passages, I didn't experience definitive negative results. Given that oil pressure can exceed 40 PSI (over 58 PSI at 6,000 RPM in my engine), it's plausible that sludge could traverse oil passages and eventually settle in the oil pan or filter.
5. Oil Squirters Concern: I feared buildup in the tiny oil squirters. However, considering the pressure in those passages, it's likely sufficient to dislodge or break up sludge. In my case, some sludge resembled hardened layerslike something you would experience when scarping layers of paint off a wall, but crumbled under pressure.
6. High RPM Driving: If you're dealing with sludge and don't have issues like failing piston rings or valve stem seals Etc., driving at high RPMs to achieve higher oil pressure might help. Additionally, adding Sea Foam seemed to improve oil pressure, which surprised me, as I anticipated it might thin the oil. Perhaps Sea Foam genuinely delivers on its promises.
7. Final Thoughts: I wish I could further inspect the valve cover, but circumstances prevent that. Please consider my experience as anecdotal; your mileage may vary.

Thank you! PS: Yes,Chatgpt did refine this message. It was way longer lol