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Old 05-19-2017, 05:51 PM   #1
pgib8
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the unnoticed blown head gasket

Hi, just came back from a 4 hour trip that took about 8 hours because every 20 to 30 minutes the low-coolant light came on, I had to stop, let the car cool a bit and fill it up with distilled water plus bleed the system (never overheated though, temperature needle always centered). A few times the hot air stopped blowing hot too. It was really tough and nerve wrecking to drive home like this but fortunately I made it!
This all started on the trip away but got worse on the way home. I brought all my tools on this trip and while there, I actually replaced the expansion tank and upper coolant hose. I was super nervous to break something but fortunately I didn't, because it was just one night at an rbnb with street parking.

i replaced those parts because i had during a previous stop seen a bit of steam exit from the expansion tank cap as well as the bleed screw. thought i had fixed the problem but on the way home it got a lot worse.
now i'm thinking it's a blown head gasket and that perhaps this has been the case for a long time but just now it got bad.
the thing is, the car otherwise runs just fine, there is no white smoke, there is no water in the oil, only thing is that the pressure from the cylinder must be leaking into the cooling system.
this is way over-pressurizing it so on the way home i was also worried something is just gonna burst, but fortunately that didn't happen.

I guess the radiator cap was always venting the excess pressure along with coolant (water) until the expansion tank was out of fluids and then i always pulled over.

I just took this video with the cap off, car is cold, i filled up the water to the top (just for this demonstration). As soon as I hit the throttle, water starts spraying out and i guess that's not supposed to be that way.



if i have to do a head gasket i'll also be bummed out because i just replaced my coolant hard pipes and i did a really good job on them and used RTV too.
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Old 05-19-2017, 06:07 PM   #2
jfoj
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Before you concede that there is a head gasket problem, might want to do some more research.

Cannot tell if the video was an issue because coolant was flowing back into the ET and spraying out??

Might want to read my comments in this thread as an option as well - http://forum.e46fanatics.com/showthread.php?t=1127986
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Old 05-19-2017, 06:30 PM   #3
pgib8
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because it was spraying out, somewhere i read it's not supposed to do that.
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Old 05-19-2017, 07:28 PM   #4
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I believe there is a coolant return passage in the ET near the top.

If you filled the ET to the top, this return passage may have been spraying water.

If you fill the tank about 1.5 inches below the top this might be a better indicator if there are bubbles, but be careful not to get fooled by the return coolant flow vs air bubbles.
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Old 05-20-2017, 10:54 AM   #5
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These engines are notoriously difficult to bleed. As many times as I have done it I have found that the only reliable way I have after going thru the 'bleed procedure' shut the engine off and let it cool. Fill the ET again, start the engine and run it until the temp is in the normal range, shut it off and let it cool, repeat. Do this until the water level in the tank is not dropping anymore and the temp is normal.

If the engine never overheated the head should not be warped.

Losing an entire tank in 20 minutes, repeatedly, is a lot of coolant. I suspect you have a coolant leak and never completely filled the system again (the no heat indicates that). Get a pressure tester and verify the system holds pressure/does not leak before you dive into expensive stuff.
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Old 05-20-2017, 11:02 AM   #6
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Agree that proper bleeding is difficult. I suggest unplug the heater control/hot water control valve.

Check and use this trick and/or make sure the thermostat opens. People stop short quit often when bleeding the cooling system not allowing the thermostat to open.

This is an option as well - http://forum.e46fanatics.com/showthread.php?t=1124821
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Lower hose temp switch O-ring - BMW #13621743299
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Old 05-20-2017, 01:13 PM   #7
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here is the thing, when the low coolant light came on and when i pulled over, i heard it sizzling out of the cap of the expansion tank, indicating over-pressure. The same thing was happening with the previous expansion tank (hence I replaced it). The other thing that I noticed on my way home was that when I kept the car just under 2k rpm, I was making it for about 40 minutes instead of 20 minutes before the light came on.

here is another video, take a look and let me know what you make of that.
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Old 05-20-2017, 01:20 PM   #8
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Nowhere near as convincing at this video below!! The small air bubbles and drop in level appears to be more of a problem with air in the system that is working its way out of the cooling system. Also keep in mind that water boils at a lower temperature than an antifreeze mixture, not sure if 100% water in one of these engine is unstable.

Keep in mind if there are hot pockets in the engine due to air, steam expands quite a bit. Also keep in mind if the the water pump is original it could have broken a vane or the pump section could have cracked and be slipping on the shaft causing a circulation problem.

If you still think there is a head gasket problem, it appears to be a small problem and could be addressed with an additive for far cheaper and faster than removing the cylinder head.

Tell me your thoughts compared to this video!

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Fuel pump failures - http://forum.e46fanatics.com/showthread.php?t=929501

Temp Info - http://forum.e46fanatics.com/showthread.php?t=964491

Hidden OBC Menu - Check Voltage, Temp, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

E46/E39 GM5 Door Lock Info - www.bmwgm5.com

Lower hose temp switch O-ring - BMW #13621743299

Last edited by jfoj; 05-20-2017 at 01:24 PM.
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Old 05-20-2017, 04:21 PM   #9
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Old 05-21-2017, 06:21 AM   #10
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Our E46 was "using" coolant recently. I rented a coolant pressure tester from Advance Auto Parts. Pressurized the system and found it was the plastic tubes under the intake. If you look straight down just behind the VANOS, OFH and where the first intake runner is you can see the head, block and plastic tubes. That is where mine was leaking. I could see it pooling there. I did my hard tubes and still I was loosing coolant. I looked and it was the same place. I removed the intake yesterday and found I damaged the rings when installing the hard pipes. Were you loosing coolant before you changed your hard lines? Maybe you did the same thing as me?
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Old 05-21-2017, 08:48 AM   #11
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Quote:
Originally Posted by z3pilot99 View Post
Were you loosing coolant before you changed your hard lines?
The coolant hard pipes are no concern because I went above and beyond when I recently replaced them. They popped in pretty easy and felt like an excellent install plus I used rtv for good measure.
http://forum.e46fanatics.com/showpos...5&postcount=13

i saw no coolant dripping anywhere and checked many times, it's just slowly steaming out from the cap on the expansion tank. also the upper hose felt extremely tight from the pressure (like unusually tight even for a hot car).
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Old 05-21-2017, 10:53 AM   #12
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There's no reason to put silicone sealer on the double o-ring fitting other than making a mess and increasing the chance that that stuff can actually get inside your engine.

Also, there are pipes the car can leak from that are not at the front of the engine. I suggest checking everything under the intake, behind the cylinder head, at the firewall, at the heater control valve, and back to the expansion tank. Best to remove the intake if you decide to go that route.
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Old 05-22-2017, 07:57 PM   #13
pgib8
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Quote:
Originally Posted by shoman24v View Post
There's no reason to put silicone sealer on the double o-ring fitting other than making a mess and increasing the chance that that stuff can actually get inside your engine.
Actually there is a reason, at least for me. Despite all my efforts the holes into the block still had pitting as well as protruding deposits. All it takes is one little path through the o-ring (and the second one) for a leak to develop. For good measure I added the red RTV and if you saw the pictures from my thread you would see that I didn't use very much and I highly doubt it got into the engine.

In any case, there is no need to worry about an external coolant leak, here are the reasons why:
1. absolutely no dripping under the engine even after hours of driving on the highway.
2. coolant hose very firm, indicating high pressure.
3. slight venting at ET cap due to excess pressure, same symptom after replacing hose and ET.
4. small bubbles exiting et with cap off, especially noticeable at higher rpm (see video). system was properly bled.

basically if there was an external leak and the cooling system was under high pressure, i imagine it would push more coolant out through the leak as opposed to sucking in air.

i guess as my next test i will buy some of that block tester stuff that changes color.
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Old 06-03-2017, 05:09 PM   #14
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today i received the correct spark plug socket, which is 5/8 (basically 16mm) and i was able to do the compression test.
here are the numbers:
cylinder: cold psi / hot psi [note: per instructions i waited 10 minutes after shutting car off before removing spark plugs from aluminium head]

1: 175 / 170

2: 160 / 165

3: 170 / 175

4: 175 / 170

5: 175 / 170

6: 170 / 175

That tells me cylinder 2 has the blown head gasket. I'm still thinking about doing the block tester liquid for peace of mind.
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Old 06-04-2017, 01:29 PM   #15
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If a head gasket was blown why would it make any compression at all? You'd get 0 psi on a blown chamber, no?
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Old 06-04-2017, 02:06 PM   #16
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Those compression numbers don't look too bad. I think you need more definitive evidence such as "sniffing" the coolant for hydrocarbons.

On another high mileage BMW I was once sure I had a bad head gasket because of fluctuating temps and mystery coolant loss. Turned out to be a bad reservoir cap. Can't assume new ones are good, either.

Before doing a big job like a head gasket I'd want a compression test, leakdown test, cooling system pressure test, cap test or replace, coolant hydrocarbon test. For good measure probably also preventive water pump and thermostat replacements if not done recently, just because of their track record.

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Old 06-04-2017, 03:14 PM   #17
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Quote:
Originally Posted by shadetreemech View Post
These engines are notoriously difficult to bleed. As many times as I have done it I have found that the only reliable way I have after going thru the 'bleed procedure' shut the engine off and let it cool. Fill the ET again, start the engine and run it until the temp is in the normal range, shut it off and let it cool, repeat. Do this until the water level in the tank is not dropping anymore and the temp is normal.

If the engine never overheated the head should not be warped.

Losing an entire tank in 20 minutes, repeatedly, is a lot of coolant. I suspect you have a coolant leak and never completely filled the system again (the no heat indicates that). Get a pressure tester and verify the system holds pressure/does not leak before you dive into expensive stuff.
You bleed the car with the ENGINE OFF.
It's a common mistake to bleed with the engine running,

I repeat, You bleed the car with the ENGINE OFF.
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Old 06-05-2017, 08:31 AM   #18
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I'm assuming that you have verified that these two basic needs are occurring:

1. Coolant is circulating (Thermostat and waterpump)
2. Rad is being cooled (Electric fan)

Without ensuring the above 2 items are 100% operation no amount of bleeding is ever going to resolve your pressure buildup and overheating.
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Old 06-05-2017, 11:09 AM   #19
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Quote:
Originally Posted by pgib8 View Post
today i received the correct spark plug socket, which is 5/8 (basically 16mm) and i was able to do the compression test.
here are the numbers:
cylinder: cold psi / hot psi [note: per instructions i waited 10 minutes after shutting car off before removing spark plugs from aluminium head]

1: 175 / 170

2: 160 / 165

3: 170 / 175

4: 175 / 170

5: 175 / 170

6: 170 / 175

That tells me cylinder 2 has the blown head gasket. I'm still thinking about doing the block tester liquid for peace of mind.
I was going to forward 50's kid compression test video but it looks like you viewed it already and mentioned you're cylinder #2 results (Gizmo? yesterday?) I'm with you and unfortunately leaning towards a head gasket issue. Good luck, subbed.
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Old 06-05-2017, 05:43 PM   #20
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those compression numbers look acceptable to me, for a higher- mileage engine.
Yes, #2's rings might be leaking a bit more, but nowheres near terminal.
Now, if you try a leakdown test and the radiator pressurizes, THEN you gots
a bad head gasket.

Might try a leakdown, next, for grins.

hth
t
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