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I am working on a very neglected 2004 325xi. It runs great but...I pulled the valve cover to replace the gasket and it was completely coated with dried up oil sludge to where there was almost no bronze color of the cams showing. I don't know how oil was even getting around in this thing. I carefully loosened and sucked out most of the bigger sludge and also cleaned the inside valve cover but the head is still pretty black and tarry looking. Is there a way to clean it without disassembling it? Can I drain the oil, leave the pan plug open and then flush the head with something till it’s clean and then refill it with fresh oil? Is that a bad idea?
 

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I have not tried it and am not recommending it, but people have used ATF to reduce sludge....Please search on it. Most people seem to add a quart of ATF a day or two before an oil change (making sure it doesn't over fill oil pan - remove a quart of oil if you have to) then change the oil as usual.

you could try pouring a little ATF into the crank case with valve cover off, then draining oil, but I don't think it magically dissolves sludge on contact, I think it needs to work around the engine a little bit.
 

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E30M3 Race F10 535 R1150Rt M Coupe
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Cleaning out a "sludge bomb" is challenging. First and foremost we don't want a large piece of sludge to find it way to the oil pump pickup screen. It could cavitate the pump---BAD.

With the valve cover off, one could start to lift/scrape larger bits of goo out, however we don't want one of those to find it's way to the oil pump pickup. Kapish?

If it's like some of the ones I've seen I would likely scrape out most, but one needs to be careful about globules finding their way downstairs via an oil return hole and/or down the front cover. Those blue shop paper towels blocking off such are your friend! Also a good supply of disposable (hard to get now) gloves.

So how do we go about rectifying years of neglect? I would be using plane jane dexron III. Add in a quart with fresh oil (so that's 6 oil, 1 ATF) and filter (copiously clean all of the inside of the oil filter housing) and let the car run. You can even drive it and should, however drive it like your grandmother would. The idea is to keep the revs down in the normal range and not tempt fate by pounding on it. All the while the goal is to A: Get the oil HOT. B: Let the ATF which is very high detergent get thoroughly circulated in/around everything. C: Be prepared ahead of time and after say some 2 hours of gentle driving, perform an oil change on the engine HOT.

The later being pernicious. The hot oil thinned with ATF will come out fast and hard, so be ready! (Changing oil hot is always best, but it can often be @ 80°-85°C!)
If you can perform the above yet again.

The idea is not to let the detergent fortified oil cool. Let the ATF go to work, and while the oil is hot AND the sludge suspended drain the nasty goop out. Let drain for 1/2 hour. Naturally slowly loosening the oil filter cap 1st. and when done clean the OFH yet again.

From that point forward I would suggest a regimen of two aggressive oil changes of about 1,500 miles with Liqui-Moly Leichtlauf 5-40. It's a high detergent additive package oil that's meant to combat coking of the piston rings, amongst other things. I'd suggest for the later two oil changes adding in a 1/2 qt. of ATF again and driving for 1/2 hour. Again always change hot.

After those two I would suggest two oil changes being ~3K and then 5K with the LM 5-40.

Given it's a sludge bomb, there's every likelihood that it will be an oil consumer. You'll want to change the CCV system if old, and will likely need some sort of BG or L-M product to clean the rings at some point. Unless the consumption is egregious I would wait until the 4th. oil change before doing so.
Lets clean the engine internals slowly and safely VS that of an aggressive chemical that does it in one shot. You'll be a much happier camper doing so. It can be brought back.
 

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Discussion Starter #4
Thanks for the great replies and the step by step. I did a ton of reading on it last night and was considering draining the oil/replacing the filter and filling with cheap synthetic 5w30 and Liqui Moly Flush/running the engine for 10 minutes/draining/filling again with 5w30 to flush the LM/running for 10 minutes/draining again then changing the filter and filling with mobile 1. How does ATF compare to LM flush? Is it a slower more gentle (safer) cleanse? Also, do you recommend always running LM 5-40 over mobile 1? This car doesn't drive much, just short trips here and there (especially in these corona times) so I may need to change on months vs miles.

I did the complete CCV system replace, disa rebuild and valve cover gasket last weekend (to address lean codes and vacuum leaks).
 

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E30M3 Race F10 535 R1150Rt M Coupe
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All of the above works, albeit the ATF is slower/more gentle.

M1 & L-M 5-40 are both VG oils, however since you'll need to be cleaning, the L-M has a much higher detergent package.
 

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Thanks MrMCar, great advice. I'll be beginning the clean cycle this weekend
 

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I am working on a very neglected 2004 325xi. It runs great but...I pulled the valve cover to replace the gasket and it was completely coated with dried up oil sludge to where there was almost no bronze color of the cams showing. I don't know how oil was even getting around in this thing. I carefully loosened and sucked out most of the bigger sludge and also cleaned the inside valve cover but the head is still pretty black and tarry looking. Is there a way to clean it without disassembling it? Can I drain the oil, leave the pan plug open and then flush the head with something till it’s clean and then refill it with fresh oil? Is that a bad idea?
Lather, rinse, repeat.

At least that is what I was taught about washing my head ;)
 

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Funny sidebar.
1st. Yr of college, business 101.
Hella Corp changes the directions on the shampoo bottles. They add one word, repeat.

Sales of shampoo jump 39%

Good on starting the cleaning. Just watch out for the hot nasty fast flowing oil.
You may need to get to the chemical route at some point....?
We're trying to avoid the globules in the oil pump pickup.
 

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Funny sidebar.
1st. Yr of college, business 101.
Hella Corp changes the directions on the shampoo bottles. They add one word, repeat.

Sales of shampoo jump 39%
Isn't it "Wella"

Tho Hella is a WAY better brand name!
 

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Discussion Starter #11
Are there any indications (symptoms) of a clog in the pickup or would it go undetected until Boom?
 

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Any restriction with regards to intake of oil is not a good thing.

To answer your question, it could clog it, then the oil press light would come on. However since the oil pressure light only comes on at a very low threshold, lets say you're passing somebody and the engine is ~ 4,500 RPM & climbing and the restricted pickup is only providing 8 PSI. Oil light is not on, but wholly an insufficient amount of oil for the engine at that speed/load.
Eventually bad things are likely to result in time.
 

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Discussion Starter #13
ok thanks. BTW I'm having trouble finding DexIII. Only seeing Dex/Merc or DexVI. Will they work the same?
 

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All trans fluid is high detergent so that will be fine. They're also backward compatible broadly if you look at the labels.
 
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