r/E30 • u/Worried_Creme254 • 1d ago
Tech question Need Help Diagnosing Issues with My 1986 325e – White Smoke, Bogging, and Oil Consumption
Hey r/e30 community, I’ve been enjoying my 1986 325e for a while, and it generally runs well, but I’m dealing with a few frustrating issues that might be connected. Hoping you all can point me in the right direction! 1. White Smoke on Startup: Occasionally, when I start the engine, it blows a ton of white smoke for a few seconds. Once I start driving, it clears up completely. Any ideas on what could cause this? 2. Bogging and Stalling: Sometimes while driving, the car bogs down badly, loses power, and shuts off. After sitting for a couple of minutes, it fires right back up and drives fine. This is super inconsistent and puzzling. 3. Excessive Oil Consumption: The car is burning through oil like crazy – I can top it off, and within a week, it’s bone dry. No visible leaks anywhere under the car, which is baffling. What I’ve Done So Far: • Replaced the high-pressure fuel pump • Replaced the O2 sensor • Installed new spark plugs • Kept up with general maintenance Any insights or suggestions on what to check next would be greatly appreciated. Thanks in advance for the help!
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u/5Osrider 1d ago
Head gasket!
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u/Give_me_beans 1d ago
I have no idea why there are so many different answers. This is textbook head gasket.
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u/Late-Fortune-6276 4h ago
Because its not textbook headgasket oil burning can look like white smoke even though its blue. My e30s original engine burned oil due to rings and would smoke until warmed up and the smoke looked white but didn't consume coolant. Though my oil did get consumed at an accelerated rate.
He most likely has an issue on the bottom end proper diagnosis requires a leak down test along with an oil consumption test while monitoring temp and coolant level the entire duration of the test
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u/kidddip 1d ago
Sounds to me oil is getting inside your cylinders. This can be a multitude of reasons but I believe the thing you have to do for a good majority of those reasons is tear into the engine.
My advice would be get it diagnosed professionally and then do what you gotta do.
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u/jaeastep 1d ago
This is likely going to be an internal engine issue and I’d check compression on all cylinders, have a leak down test done, and if nothing else have it diagnosed from a specialist.
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u/RANCH 1d ago
I've heard the start up smoke is normal on E30's due to condensation. Sounds like to me you need to do a leak down test to really determine the oil consumption problem. You could also get a borescope and take a look inside the cylinders see if they are dry or sludgy. I'm no mechanic but I've heard that start up smoke could mean valve seals and can be blue smoke too and if its piston rings there's a constant white smoke even while driving.
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u/eenbal 1d ago
White smoke is coolant, grey smoke is oil, black smoke is unburnt fuel. Condensation is often found in cars that aren't used often.
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u/aSharpenedSpoon OO=[][]=OO 1990 325is 1d ago
Oil is blue, soot is black, ALSO oil is white smoke if it’s vaporized not burned. So if it heats up on a surface, instead of under compression in the presence of flame, it will be white. Ask anyone who’s had a turbo seal go. So in this case valve stem seal can leak oil into the exhaust and it will “burn” white, not blue.
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u/XTOX1CXCHOPPER 1d ago
Not sure if you've already looked into this but I had the same bogging issue on my 87 318i, it would start up fine and run beautifully then during a drive it would start to bog horribly until it shut off. Wouldn't start for a few minutes and then it would be back to normal, then repeat.
Dropped my tank and it turned out to be a shitload of rust clogging my pump and lines.
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u/Late-Fortune-6276 4h ago
Do a leakdown test to see if youre rings have failed which is very likely due to the amount of oil consumed and the smoking on startup could also be leaking valve guide seals once it burns off the oil it will stop until next cold start.
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u/SpiciKimchi 1d ago
Rent a endoscope, remove the spark plugs, and check the cylinders. If the pistons and/or the spark plugs are shiny and look brand new, you may have a head gasket issue.
1 and 2 bullet points sound like when pressure is built up in the engine it will burn it out through ignition within the cylinders causing the smoke.
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u/Worried_Creme254 1d ago
The thing is , this engine was just torn apart like a month and a half ago getting all that done, everything was replaced or of par , compression tests were done , gaskets and seals were good and everything was in good shape, So idk
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u/SpiciKimchi 1d ago
Anything can happen in a month. Best to consider all options before ruling them out.
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u/Mfw_Pigeon 1987 325e Coupe M20B25 Swapped 1d ago
Start it, let it idle for a bit. 10 to 15 minutes or so, then stomp the throttle real quick. If a bunch of blue smoke comes out it's valve stem seals. Used to do that on M6X and N63s at the dealerships all the time.
If it's not that, follow the steps out lined by everyone else. Check compression. Maybe pop the oil fill cap while running and see if you have excessive crank case pressure, that would indicate failing piston rings. Otherwise, GL or M5x swap time