750iL 1995 Has Blown Head Gasket, liquid sealant?

[vvst]

7/3/22 - Editing this post again to update likely causes. I'm also brand spanking new to this car stuff, first time I took out spark plugs on a car was this 750iL and that was definitely an experience, but I genuinely love this stuff and am willing to take all advice and try everything possible. The original story was that I bought a 750iL 1995 with a couple of individual misfire codes along with a code for non functioning speed sensor, and it started to start rougher and rougher and after an oil change and a top off of coolant (significant auxiliary pump leak), it stopped wanting to turn on completely after a couple of days. Before it stopped turning on, I made this post thinking I had a blown head gasket due to the increasing lag of the car and heavy white smoke coming out the exhaust and asked what the proper way to do it was. Thanks to the gentlemen below, I now know that not only is this bad, but it may not be the case. When I got this car I purchased 5w40 oil and a new filter, and just paid a mechanic to replace them both since I needed them to run my codes for me anyway (autozones code reader apparently works for cars after 1996) Before the oil change and coolant addition, the exhaust did not smoke. I am guessing this is because the previous owner intentionally did not fill either all the way, maybe to avoid "excess" pressure, but I'm so new to this and am most likely wrong. All it would do is crank, engine would rev (and sound quite healthy at that) but it just wouldn't fully start and die after 2-3 seconds, before the engine can seemingly gather enough power. Battery was replaced so its definitely not the battery.

I didn't pull the spark plugs in the very beginning because I was mind boggled how the car can start and rev seemingly healthy and then out of no where just kapoot. Then again, this car was seemingly someone elses project car haha so who knows. I recently pulled all the spark plugs and they were literally all black. Not melted or anything, a couple of them had what looked like rust on the end that you screw in (all pictured below) and strangely, the entire passenger side of the engine was Bosch spark plugs, and the entire left side was NGK plugs. And, the wires on the right side that go over the plugs were barely even ON the spark plugs them selves. Almost like they were just sitting there, I pulled them out with absolutely no resistance. On the left side though, I had to put in effort. There was a healthy seal where the insulator wire goes over the spark plug. A couple of plugs on the right side, literally had black puddles of oil surrounding the plug. It was a mess. I cleaned everything until there was no black left using some brake cleaner, a towel, and a long extension that was slightly smaller then the diameter of the end of the spark plug. There was dry leaves, stiff oil, and just all around a shit show. But those insulator wires that go onto the spark plug, most were healthy. One had a TON of this yellow dust all over it, but the very inside ending of it was still a clean copper yellow. The dust was just on the outside, and this is the spark plug closest to the auxiliary pump. One of the plugs on the right side was so brittle and looked slightly melted, that when I pulled it out it just cracked up and you can see burnt oil all along the sides.

Also, I modded the OEM spark plug tool a little bit to attach it to a breaker bar, using a size 15 socket and by carefully removing the round outside extension around the OEM tool. The amount of torque I had to apply to these spark plugs to get them out was insane. Hope this little mod helps someone else with stuck plugs at these horrible angles xD

My theory is this: What if I just have a horribly failing valve cover gasket and to avoid changing it, the previous owner just changed spark plugs? Which would be wild, because these plugs look like theyve been changed once in its entire life time, with the 85k miles it has on the dash lol. I will change the entire valve cover gasket, I just need to turn this thing on and move it in the mean time lol. Any other preventative maintenance while Im there and advice would be extremely appreciated <3
I am buying all new spark plugs and the aux pump is going to be here in a week, I will change everything immediately and update the post when they come. For now, any observations of this would be highly appreciated:
2 (2).jpg Attachment 706022 This plug came out of this wire, its the number 2 from the top of the left drivers side. The inside of the wire was extremely clean, can I still use it? It just had that dust around it

2 (1).jpg For attachment limiting purposes, all the plugs basically looked like this. No real variation to the end of the spark plugs
3.jpgThe little tool I made to get better torque, using the OEM spark plug remover
4 (2).jpg This plug (number 3 from the top, right passenger side) was one of the 2 plugs that had a slight puddle of oil. The 2 plugs were right next to each other as well, 3 2&3 on the right side from the top. #2 was no where near as brittle and #4 was relatively fine as well, they were all just crudy. It's also worth mentioning that none of the plugs or oil puddles smelled like coolant, huge sigh of potential relief lol
And please! Don't cringe too hard at my replies below for extremely primitive and uneducated diagnosis! You may lose brain cells lol

[a777fan]

Meh. There isn’t a ‘proper’ way to use liquid head gasket sealant. Its a temp fix that won’t ever work 100pct. Its also likely to clog other paths within the cooling system.

I’d do a little more digging and investigating before attempting any fix. Test the coolant for combustion gasses, and send the oil out for a analysis to blackstone to confirm the contamination.

Are you loosing coolant? How fast does it ‘disappear’?

If you do confirm head gasket failure, i’d think long and hard about doing it the right way (actually replacing the head gasket) before dumping any goop into the crank case.

[vvst]

Thanks for the reply, I really don't want to use the liquid sealer. I may end up just selling this car to someone who has the space and time to take this beauty apart and restore it. Thank you for the help!

[a777fan]

Yeah, if it is the head gasket, its certainly not an easy driveway job.

I still find it weird that it didn’t smoke before you took it to the mechanic, and now it seems like its smoking like a chimney? You should post some video of what its doing, and perform those tests I mention in my last post before throwing in the towel.

Additionally, someone else might be able to chime in, but I think m73 head gasket failures are very rare. I certainly haven’t read about many (if any) of them…


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[vvst]

I really don't want to throw in the towel, this cars such a beauty. I've been doing non stop research and honestly don't know where to start. Everything points to a problem with the head gasket, or maybe a cracked block. But like you said, I can't seem to find anyone else that had this problem either. I want to run more tests but the battery in the car died, so I have to wait until I can buy a new one.

Would you happen to know what else can cause white exhaust smoke in a v12?

[R Shaffner]

Well, I once had a Saab that the previous owner used mostly water in (too little or no antifreeze). The result was a corroded aluminum head that developed a pinhole leak between the water jacket and an exhaust port. The car drove normally, but once the exhaust system warmed up it produced a lot of steam. The leak happened to me suddenly on a trip. After a while I realized that it helped to leave the coolant cap loose, so it wouldn't build up pressure and push coolant out so fast. That kept it from smoking as much and losing coolant so quickly. After I returned I learned I had to replace the head to fix the leak.

That experience makes me wonder about your car and exactly what's going on. A blown head or head gasket can cause all kinds of leaks, or any combination. (Thinking generically; I don't know that engine.) In my unusual case, there was just a breach between the cooling system and the exhaust system. No coolant was making it into the oil/crankcase or into any cylinder.

What you've talked about so far would be the trifecta, a common breach between the water and oil passages and a combustion chamber. Of course a blown head gasket could cause that combination of leaks.

Getting the oil and coolant checked makes sense. There are other tests that come to mind to see what combination of leaks you might have.

For example, if you have a breach between the water jacket and a combustion chamber, then it would make sense that coolant could be pushed into the chamber from pressure in the cooling system. If that cylinder isn't firing, then coolant could be sucked in during the combustion stroke (without combustion) and then pushed out into the exhaust system, and when it got hot enough coolant would turn into steam. So coolant would build up in the system when cold. It wouldn't produce steam right away, but it would make a lot once it got hot. (You said you have misfire in a couple of cylinders -- that could be it.)

If there were a coolant breach into a firing cylinder, then it seems that you'd be getting a much bigger leak in the other direction, from the combustion into the cooling system. In that case you'd be getting hot gasses blown into the cooling system, which would make it hotter, put air pockets where you don't want them, and force air/coolant out the pressure release valve in the cap.

Is any of that happening? Is your cooling system building pressure? Or is it getting too much pressure? What happens if you start the car with the cap off? And then leave it off while the car warms up?

If you have coolant leaking into any cylinder (firing or not), that's obviously not good. (You don't want coolant to collect there and cause hydrolock.) A leak into the cylinder might not be too bad if the coolant system is never building pressure. That is, maybe it wouldn't leak that much when the engine is stopped.

I'd pull the plugs on the suspected bank to see what's going on, to look for signs of coolant and/or oil. And I'd probably try starting the engine with the plugs out on any cylinder that looks suspect. (If you do that on the right cylinder, then it won't suck coolant in, and it would tend to get coolant in it only when the cooling system developed pressure. If you did that on the right cylinder with the coolant cap loose, you might not get any steam at all out the exhaust.)

You see where I'm going with all this. There are other ways to test things. (You could remove the oil dipstick to see what's happening to pressure in the crankcase, for example.) Similar tests told me that I had a head problem, instead of a head gasket problem.

However, I'm not sure how much all that helps in a way. Fixing any of those issues means the head has to come off. But you might narrow things down. Or you might learn more about what's wrong. (You might find that you need the head to be repaired or replaced, like I did, and not just a new gasket.)

Good luck.

[vvst]

Yessss! That's a great way to tell, I recently seen a video about that method of pulling out the plugs and starting the engine to see the reaction it had on the coolant! I'll provide a link, check it out:https://youtu.be/MCo0SLeMEfk
All in all, I'll take both of your advices and try the combustion gas & the plug tests. Will update the thread as soon as I'm done, waiting for everything to come in the mail!

[vvst]

Think ive made some progress. After my last shin dig (driving home from oil change) I parked the car and it never turned all the way on again. The engine revs and the key cranks, but the as soon as the engine revs for a Few seconds it shuts off with white smoke following out of the exhaust. My new theory based on some research is that the fuel injectors are bad, and they've been bad for a while. I read those cause misfires when they're dirty and there was 2 misfire codes before the oil change. I bought and tested a new battery inside the car and it didn't help the situation, so it definitely isn't the battery.

I don't think the gasket is blown. I think the previous owner would change spark plugs after they would go bad to avoid changing fuel injectors. The coolant level only drops because of the heavily leaking auxiliary pump. Will still do the combustion tests to see what's up.
Going to add new fuel injectors, ignition coils, and spark plugs to the list of things to buy. Within the next few hours I'll also get a video of how the car starts and dies for anyone to maybe get a better idea

[R Shaffner]

So you think you're just seeing smoke/fumes from a mixture that's too rich? Well, yes, that would be a very different series of tests and diagnosis.

Some other thoughts:
A rich mixture can foul plugs, but I don't think it would hurt the coil packs. You might be able to wait on those.
A systemic rich mixture (across multiple cylinders) might be a fuel pressure problem, instead of or in addition to injector problems.
I'd think you'd get codes for such a rich mixture. And yes, fouled plugs on the affected cylinders.

[vvst]

At the moment its my best bet. I also did have 2 individual misfire codes on cylinder 2 & 12 before this whole ordeal but that's the only codes it had aside from non functioning speed sensor
And really? I'll definitely hold off on the ignition coils then, the fix is getting pricey lol �� but I will still check their condition when I pull them out.

Also would you happen to know what would be a test for the fuel pressure?

[a777fan]

I’d start simple and cheap. Pull all the plugs and check their color. Make sure you keep track of which plug is from which cylinder. Dark and sooty means a cylinder is rich. White can indicate lean. Most importantly all should be consistent. If you have an odd one or two out, that could help narrow down your issues.

There is a ton out there on how to read plugs, but here is a link to info from ngk.

https://ngksparkplugs.com/en/resources/read-spark-plug


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[R Shaffner]

Yes. If you have so much gas flowing that you can see it in the exhaust, I think you'd be able see it real easily in the cylinders through the plug holes, probably after just after a few cranks with the plugs out. Or maybe some injectors are letting the fuel/pressure leak out after the engine is shut off.

[vvst]

Incredible guys, thank you so much. I will pull the plugs for sure within the next week or two, I need to get a particular type of ratchet for this engine since it's apparently quite uncomfortable getting to the spark plugs as opposed to the V8 model. Some people on other posts recommended a swivel socket, thread pictured below:

Screenshot_20220628-025107_Chrome.jpg

Also, here's a link to the video of me cranking the car:
Damn the low quality, let me know if I should re-upload somewhere else:
https://youtube.com/shorts/OOlUrllXaSM?feature=share

[vvst]

I will reorganize the title of this post and the description to revolve around our newly diagnosed problems, it looks to be one of a kind with this model. I owe you guys a beer lol

Also, it's worth noting this weird thing the previous owner did. He obviously welded some pipe together to make this cold intake work, lol. I can try and go part an OEM intake from someone else's car if this is a no no, but what I'm worried about is this plug that's just floating there. I've researched all the parts I know exist to try and match the plug, but I'm seriously new to this and barely even know what to search, but here's a picture, all it says on the plug is made in italy, no product codes or anything :

[TheAngryBear]

Your vehicle toolset in the trunk/boot has a spark plug wrench that works well. I just did mine and used that. Also deleted the vacuum lines as I went with “normal” injectors. Got them from Max Lumens, have to do a few things but works well.


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[vvst]

I read somewhere on this forum about the vacuum line delete, but I believe that is only for post 98 or something 750iL M73n engines but I could be mistaken. About the spark plug wrench, thankfully this car did come with those and I will attempt that for sure!

[TheAngryBear]

Ha! Missed you had a 95. I mean only in the title etc …
So even easier for you as the Max Lumens are for the E31 which uses the non-vacuum system that you have.


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[vvst]

Hey man call me a pinecone but is Max Lumens a unit of measurement? No companies on google popping up with that company name lol

[TheAngryBear]

[mention]Max Lumens [/mention]is a member here, mainly on the E31 side. He developed/makes a gasket kit for the intake manifold gaskets that aren’t $12-1600 for the set. He also has some fuel injectors and other stuff. http://bmw8.us/Brand%20New%20Fuel%20Injectors.htm
You can contact him at maxlumens@finemotoring.com for his prices etc.


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[a777fan]

Ugh. ‘Cold air’ intake. No clue what the thought was on replacing the air box on one side and leaving the other alone. I’d source an OE airbox on ebay and get that junk outta there.

You’ll have to trace that connector back to see what it is hooked up to. It looks a lot like a knock sensor from an M60 V8. I don’t know if the knock sensors on the M73 are similar.

[a777fan]

Incredible guys, thank you so much. I will pull the plugs for sure within the next week or two, I need to get a particular type of ratchet for this engine since it's apparently quite uncomfortable getting to the spark plugs as opposed to the V8 model. Some people on other posts recommended a swivel socket, thread pictured below:

Screenshot_20220628-025107_Chrome.jpg

Also, here's a link to the video of me cranking the car:
Damn the low quality, let me know if I should re-upload somewhere else:
https://youtube.com/shorts/OOlUrllXaSM?feature=share

So the engine was NOT running when you were standing at the rear if the car filming the smoke coming out of the tail pipe?

Does the engine stay running? Or does it always stall?

[TheAngryBear]

A few questions:
1) is the CAI wet? It looks like there are water spots at the joints and the bottom…
2) did the engine die or did you turn it off in the video?
3) does your brake booster area have a bunch of junk in the bottom of it?
4) how are the brakes when you use them?

Edit:
5) what is the alphanumeric on the display that “stayed on” that you commented about?


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[vvst]

The engine was not running when I took the key out and walked to the back of the car, it literally just continued to smoke that way for about a solid minute. The numbers on the display were actually just the odometer mileage, but since the speed sensor was broken, the odometer reading isn't actually accurate. But everything on the underside looks so new, it can't be much older then the 85k miles thats on there. All of the warning lights show up when I turn the key, Im guessing that just means the electronics and most sensors still work. Ill answer all the other questions as soon as Im out of work, a few hours

[TheAngryBear]

Main reason I ask:
It is possible that the brake booster was flooded due to drain blockage. If bad enough, the brake booster can fill with water that can be sucked into the manifold through the vacuum.
Iirc, the booster is only linked to the left manifold (drivers side) which feeds bank 1 (right or passenger side).
The V12 also “naturally condenses water” and spews very light smoke from this.
So, in theory, you could have significant water in bank 1 that is being vaporized and drifting out.

Just trying to get all the possibilities out there…

PS another possibility is that the leaking aux pump (iirc) is spewing onto the sucking jet pump and into the vacuum system and following the same above.

Hard to tell any of this from pictures etc but some things to look for as this is really happening on bank 1 vs simultaneously (per the video).


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[racer2086]

Just read through this quick and maybe missed where you diagnosed injectors, plugs, and coils as the problem? I think you're in "throw parts at it mode", which can get very expensive. You need to get yourself a code reader, so you can read codes yourself.

There are a million things that could cause your problems. Start with the easy stuff. To diagnose coils, take a coil from the misfiring cylinder and move it to another. The error code should move to the new cylinder. If it doesn't it's not your coil.

I would not have the injectors high on my list of suspects. Plugs either. You can pull the plugs and look at them. If they are intact and all look similar to each other, plugs are probably not the problem. When you pull them, you can examine the color to get an idea for how the cylinder is running, but your engine has to run in order for it to deposit on the plug. If a plug is very white, the cylinder is running lean. Black and sooty is running rich. Wet is burning oil.

Here's where you need to start to diagnose this properly without wasting money on parts you don't need:

Trace the wire of that connector in your picture. That should be plugged into something. It has 3 pins like the cam sensor or ICV in my M62. If it is one of those, that is important. If anything else is very obvious botched or hacked up by the previous owner, I'd fix that also before going deeper.

First thing you need to do is figure out why it won't start anymore. 3 things are needed to run: spark, fuel, and compression.

Test the fuel pressure to make sure you are getting gas at the rail. You are not going to have 12 bad injectors all at once. Make sure you are getting spark. You can use a spark plug tester for that. If both of those are good, then it is time for a compression test, which is also easy to do. That will give you a very good idea for the health of the engine.

Your symptoms kind of also make me think of possible clogged catalytic converters that are causing too much backpressure. That would also explain the smoking exhaust after the car is off (unless there is a bunch of coolant or oil burning off under there). You can test that by pulling the pre-cat O2 sensors to release pressure and seeing if the engine can start. Clogged cats often start with misfires, sluggish engine, and then if clogged enough can cause problems running/starting.

Edit: I just read through another post that you put up about the aux water pump leaking. Did you fix that? That aux water pump would leak coolant right down onto your hot exhaust causing all kinds of steam.

Don't the V12 engines have plug wires, caps, and rotors for each bank? I'd pull the caps and inspect the contacts and the rotors.

Report back with results. These are all free to do and should give you a good idea where to go next.