Are these spark plugs toast?

**shadze36** · 05-12-2019, 03:35 PM

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The main reason I’m examining the spark plugs is to see if there is any signs of a blown head gasket. If what I’ve learned is correct there would be a whiteish color? I don’t see any signs of that but there’s a bit of oil on them which i heard is normal.

I also looked down into the holes and didn’t see any signs of coolant anywhere. Am I missing something here? Car overheated in the red 2x in the past month.

**Eric93se** · 05-12-2019, 04:20 PM

You have to do a compression test, that's the easiest way to confirm. leave all the plugs out and disable the fuel pump, put a brick on the fuel peddle and a charger on the battery. No need to crank like crazy, just do it a few time till the pressure no longer increases on the gauge.

On a dead cylinder you can put one squirt of oil in the cylinder and try again (again don't go crazy cranking) if pressure returns then that's an indication of bad rings.

Understand that rarely does the HG go bad, more typically on the these staright six engines, the head warps and can also crack. There are MANY threads on this topic.

**jclausen** · 05-12-2019, 04:52 PM

I would test the coolant for combustion gases.

**marvinstockman** · 05-12-2019, 07:48 PM

Did car overheat on the highway or at a stoplight?

Could be something as simple as a flaky fan or a flaky thermostat.

Is there coolant in your oil, or oil in your coolant?

Does temp bounce around, like get hot then get back to normal?

**zellamay** · 05-13-2019, 01:39 AM

I say relax. Overheating does not mean a bad head gasket. Those plugs don't look like they've had water on them, but looking at them is not a good test. The first test is the test for combustion gases in the radiator is cheap, used to be around $30 at local shop. A compression test may reveal any number of reasons for poor compression, so do the gases in radiator first. Also, you could just put some Blue Devil in it now. For $50, you will probably fix any small head gasket leak. My wife's 325i had water coming out the exhaust (yes, way more than is normal), and the BD fixed it. But then ... onto why it was overheating. There are many possible reasons. Marvin is right. Figure out when it does it; highway vs stopped?, hot then not?, does turning the heater on max help?, test the fan clutch, replace the Tstat, check out/replace the radiator, does the aux fan work properly? Are you losing radiator water? Sometimes leaks are small and hard to find.

**shadze36** · 05-13-2019, 01:59 AM

I replaced the entire cooling system little over a year ago, mishimoto rad, metal water pump, new tstat and all. The car overheated once a few weeks ago on the track when a coolant hose came loose, and then a few days ago driving home in the streets coolant was beginning to spurt out of the expansion tank cap before I was able to pull over and stop it. Seemed like it built up too much pressure, and yes the cap was on tightly. There are no external coolant leaks as far as I can tell. Haven’t driven it since it overheated the 2nd time.

No oil in coolant, no coolant in oil. I did notice very tiny bubbles rising up through the expansion tank, which led me to believe my head gasket is toast. I will be doing a compression test sometime this week when I have free time.

Im guessing the spark plugs are fine then?

**zellamay** · 05-13-2019, 10:48 AM

Originally Posted by shadze36

I replaced the entire cooling system little over a year ago, mishimoto rad, metal water pump, new tstat and all. The car overheated once a few weeks ago on the track when a coolant hose came loose, and then a few days ago driving home in the streets coolant was beginning to spurt out of the expansion tank cap before I was able to pull over and stop it. Seemed like it built up too much pressure, and yes the cap was on tightly. There are no external coolant leaks as far as I can tell. Haven’t driven it since it overheated the 2nd time.

No oil in coolant, no coolant in oil. I did notice very tiny bubbles rising up through the expansion tank, which led me to believe my head gasket is toast. I will be doing a compression test sometime this week when I have free time.

Im guessing the spark plugs are fine then?

Again I suggest doing the combustion gasses in the radiator first. It's faster, cheaper and more accurate than a compression test, for determining a bad head gasket. I'd replace the spark plugs.

**tjm3** · 05-13-2019, 02:23 PM

Combustion gas test is hit or miss. Works, but not reliable.
Oil in coolant or coolant in oil works but not in all cases. But if either shows up you definitely have an issue.
Compression test won't show any more than just running the engine would show except for the actual numbers. Low compression or compression leak between cylinders doesn't necessarily mean a coolant issue.
Leak down test usually turns out to be the best. Check for leaking coolant or pressure at the bleed screw AFTER releasing system pressure. Listen at the other normal places.
If there is coolant leakage into the cylinder and the engine runs a bit rough for a few seconds at first start of the day then try this after sitting overnight.
Pull the plugs, lay some newspaper, paper towel, cardboard or similar over all six holes and crank a few times. Look for wet spots. Works.
Works faster if you can keep the cooling system pressurized for a couple hours.

**Eric93se** · 05-13-2019, 03:22 PM

OMG just do a compression test. Don't put any blue-devil shit in you car and new spark plugs won't fix anything right now.

You lost a lot of coolant, warped the head, now combustion gasses are getting into the coolant.

**spyderg0d** · 05-13-2019, 03:59 PM

If you hit the red 1 time, you have a 50% chance of warping the head and cracking it. (Depending exactly how hot it got for how long) Headgaskets dont go when they get hot, the heat warpes the head so the gasket cant seal to it anymore is the real issue. Headgaskets only really go from age, being so many heat cycles the gasket loses seal and usually starts allowing cross compression on pair of cylinders. And a really old gasket might mix coolant and oil at the few select front oil amd coolant passages that are close.
If you hit red 2x, its most certainly atleast warped and probably cracked, and is for certain without a doubt if your loseing coolant.
The cracks are always small, even if the gasket didnt lose complete seal, usually only leaks while the engine is warm, the cracks expanded and the cooling system up to pressure.
A compression test is void as heat plays a critical part in the cracks leak amount. Coolant leakdown test is void for the same reason.
As above said, dont use any head gasket sealer as it wont straiten your head or hold the pressure, and it wont keep the crack from expanding everytime the car goes through a heat cycle.
Tjm seems to be on the right path as far as confirming. But I can without a doubt promise after going into the red 2 times, youl need atleast the head planed (if its not cracked) and a new gasket set.
Coolant loss is what it is if theres no leaks, the engines eating it.
Spark plugs wont really give you a clue, as coolant can sometimes clean the cylinders and plugs, sometimes its only enough coolant to do nothing or a rich condition look. It varies by circumstance.

**zellamay** · 05-13-2019, 05:01 PM

Well it looks like different people have had different experiences. All I can do is relate mine. My wife drove her 94 325i into the red twice, a few months apart. Then it started overheating and losing water. I discovered water coming out the exhaust. Didn't need to test further. We were looking at rebuild/junkyard engine/abandon car? The car is in nice shape, so we'd hate to lose it. I tried Blue Devil. It worked. The car has shown no signs of losing water or overheating in various driving conditions in 95+ heat. Of course there are no guarantees that it will last forever, but no question it is working now.

**XnWarden** · 05-13-2019, 10:26 PM

Sounds like its time for an engine swap. Put an S52 in there!

Sent from my VS987 using Tapatalk

**spyderg0d** · 05-14-2019, 07:12 AM

Zella may does have a piont. Sometimes these products will hold you over until possibly an owner has to use the car until the repair can be afforded. I had a customer who once wrecked his 328is in a parking garage at 20 mph. Swapped the recently rebuilt engine into a 318. Found the engine had cracked in the crash(without ever being overheated). Used some coolant based headgasket sealer and got 6 months out of it until the crack had expanded enough to suddenly eat coolant at about a gallon a minute. Lol. The only thing that was negative, getting the concreted sealer off the block where it had filled inbetween the gasket. Not fun. And if he wasnt also a good friend, icertainly would have charged more to get that crud off the block. Wasnt easy to do without nearly having to remove the block and get it surfaced.

**shadze36** · 05-25-2019, 12:45 AM

Thanks all for the info.
I finally got around to doing a compression test:
Cylinder 1: 205
Cylinder 2: 205
Cylinder 3: 185
Cylinder 4: 190
Cylinder 5: 185
Cylinder 6: 200

At this point I’m not sure what to do. The coolant looks fine, oil looks fine.
I let the car sit for about 2 weeks, and the coolant sat at the Kold mark until I began to unscrew it, then a hissing sound as it released pressure and rose about 2 inches. Does this pretty much confirm that gases are getting trapped in my cooling system? I’l order some coolant test strips tonight to confirm.

**Eric93se** · 05-25-2019, 01:01 AM

Ok those results are good. How old is the expansion tank and cap.

- - - Updated - - -

Run the car in your drive way. Let it fully warm up then raise the rpm to ~1500 and observe, make sure the fans cycle as they should, make sure it doesn't overheat. You can use a IR thermal gun to watch rad temps and engine temps.

**shadze36** · 05-25-2019, 01:08 AM

Expansion tank and cap were replaced with everything else about a year ago. Im going to try to bleed the system some more, but if the air keeps coming out and it really is exhaust gases, it will just bleed indefinitely right?

Also; with the car idleing in my driveway with the heater on full blast, it only blows cold air.

**R Shaffner** · 05-25-2019, 07:05 AM

Originally Posted by shadze36

Thanks all for the info.
I finally got around to doing a compression test:
Cylinder 1: 205
Cylinder 2: 205
Cylinder 3: 185
Cylinder 4: 190
Cylinder 5: 185
Cylinder 6: 200

At this point I’m not sure what to do. The coolant looks fine, oil looks fine.
I let the car sit for about 2 weeks, and the coolant sat at the Kold mark until I began to unscrew it, then a hissing sound as it released pressure and rose about 2 inches. Does this pretty much confirm that gases are getting trapped in my cooling system? I’l order some coolant test strips tonight to confirm.

What did you unscrew when you heard the hissing sound and saw the coolant level rise? The tank cap or the bleed screw?

Normally, if you loosen both the cap and the bleed screw on a cold engine that has the right amount of coolant in it, you'll let a little air back into the top of the radiator. That will let water flow backward into the expansion tank. These systems are SOMEWHAT self-bleeding. If you did that on a normal engine and then put cap and screw back and drove it, the hot and cold cycling would push the air from the top of the radiator back to the expansion tank. The next morning the coolant level would be back down to where you started and the radiator would be full of coolant.

I've often heard a little air pressure hiss when I've loosened the tank cap on a cold engine. That seems normal. If it's a lot every time, then I see your point and your concern. But I've never heard of the coolant level changing just from opening the tank cap.

**spyderg0d** · 05-25-2019, 07:13 AM

The system should be under pressure EVERY time it gets hot. You fill it and cap it when its cold. Then it gets hot and creates pressure system. Water steams.. It doeant matter if it hisses when you pull the cap off. It only matters if its boiling over with coolant or you have to keep adding an endless supply of coolant. If you have ever had to put in more than 3 jugs, besides from a completely empty system, its leaking or eating coolant. If its not leaking, its eating. A half a gallon of coolant doesnt leak and not leave a drip mark or wet spot.

**R Shaffner** · 05-25-2019, 07:18 AM

Originally Posted by shadze36

Expansion tank and cap were replaced with everything else about a year ago. Im going to try to bleed the system some more, but if the air keeps coming out and it really is exhaust gases, it will just bleed indefinitely right?

Also; with the car idleing in my driveway with the heater on full blast, it only blows cold air.

Wait! That's a big warning sign that your coolant system isn't right and probably isn't full of coolant. Whatever bleeding you're doing might not be right, or enough.

Personally, I don't like to rely on the aux pump. With a cool engine, I'll start with the cap and bleed screw off, the cabin heat on high but the fan on low. Then I'll start the car, add coolant whenever it drops below full, and watch it as it warms up. I'll look for leaks as I keep adding coolant. If the thermostat is working properly, it will take a while (maybe 5 minutes or more) before the top radiator hose starts to get warm. At that point warmer air should be coming from the cabin heater and you can turn it back down or off. Keep adding coolant whenever needed. At first just air will come out of the bleed screw, then coolant with bubbles (sputtering), then just coolant. When the top hose is hot and just coolant comes out of the bleed screw opening, you'll know both the pump and thermostat are working. Then put on the screw and cap (again making sure it is at least at the full mark). Then I let it continue to idle to make sure the system builds and holds pressure, and that no leaks emerge as the pressure builds. I'll also let it idle long enough to see if the electric fan comes on as it should. If all looks good, then I'll take it for a drive and check again for leaks when I return. You'll prob need to add a little more coolant after the engine cools and the coolant contracts.

Then you know all key parts of the system are working and that it's full of coolant.

**shadze36** · 05-25-2019, 11:32 AM

When I unscrewed the tank cap is when I heard a lot of hissing and coolant level then rose about 2 inches.

I will follow your bleed procedure today and try to get the heater working again. When you say “full mark” do you mean the Kold line? Or do you mean completely full to the brim?

**shadze36** · 05-25-2019, 01:11 PM

Ok so I just attempted to bleed the cooling system again. I followed the steps above exactly. With the tank cap and bleeder screw off, I filled up coolant to the brim and turned the car on. For the first 2-3 minutes there were very few bubbles. Then became a steady stream of bubbles coming out of the bleeder screw. I monitored the coolant level and it didn’t seem to be dropping, it stayed around the full line. I watched air bubbles and coolant come out of the bleed hole for 20-25 minutes straight with literally no heat coming from the heater at all, even at full blast. The bubbles just kept coming and coming. Top radiator hose was warm/hot, but didn’t get stiff, just sort of squishy. This is the same result I got from bleeding it last time. It doesn’t make sense that there would still be air in the system after bleeding it for that long, more than once, with no heat coming from the heaters at all.

**shadze36** · 05-25-2019, 02:39 PM

Just attempted another bleed. This time I revved the car pretty high a couple times every minute, and hot air came out of the heaters after a couple high revs. After that the top radiator hose got hot and stiff like it’s supposed to be. Then with the expansion tank cap and bleeder screw closed, I revved high many times and idled a few minutes for a while to see if it would hold pressure and it seemed to do it fine. Now the heater blows slightly warmer air when idleing, but definitely not hot as it should be. Not even close.

I also performed a combustion leak tester, using the NAPA Universal Combustion Leak Tester, and there showed no signs of any combustion gases. WTF?

**zellamay** · 05-25-2019, 02:41 PM

Some thoughts: After 20 minutes, the car is hot and all that "bubbles and coolant" could be just boiling. When I run the engine with the bleed screw out, I do it until the Tstat is open, (temp guage reaches normal operating temp), but not much after that, to avoid boiling. ..... I would consider a complete drain and refill, measuring how much water/coolant I put in there ( According to Pelican it's 10.5 liters). When I fill, I park with the nose of the car uphill, unhook the upper hose at the radiator, then put a spare hose on the radiator. I tilt both of those hoses up so they are higher than everything else. I then fill into both hoses, taking about 10 minutes to give the air time to escape. When both hoses are full, I quickly pull the spare hose off the radiator and push the upper hose onto it. I lose a little water of course, which I bleed out by pulling the bleed screw and squeezing the upper hose. I then start the car, and just loosen the bleed screw a little. I can see air escaping in bubbles at the screw. When those bubbles become only water, I close the screw. .......................... Separate FYI: I changed plugs on my wife''s 325i that definitely had a bad head gasket, (so far cured by the Blue stuff). Those plugs showed no signs of water consumption, so using plugs as an indicator is probably not a very good idea. I know the combustion chamber and valves would show water consumption, by being really clean, because I once owned one of the infamous Toyota turbos that all lost head gaskets.

**shadze36** · 05-25-2019, 02:50 PM

Forgot to note that my car nose is also elevated. I am really confused that the combustion gas tester is not detecting any combustion gases. If there’s no gas leak in the coolant, is there just a huge air bubble that is impossible to get out by bleeding? I can try bleeding a few more times.

**zellamay** · 05-25-2019, 04:48 PM

You have good compression numbers. The combustion gas tester revealed no gases in coolant. I suggest you let go of the idea that you have a bad head gasket. It's possible that you have air trapped, but it is not "impossible to get out". Start from the beginning in filling as I described. Fill it slowly, giving the air time to escape. Do not let the car get hot while you are bleeding. Do it when the car is barely at operating temp. Do not open the bleed screw or coolant cap when the car is hot.