Hey guys;
This weekend I replaced ALL the coolant lines (along with a bunch of other stuff), including new radiator main hoses, thermostat housing, and thermostat. I drained the coolant fully from the radiator drain plug and am 100% positive I couldn't find an engine-block plug...never the less; I got about 6 quarts out of it....I knew it was running WAY low as I lost about a quart when the hose blew...and lost probably another quart to quart and a half in the hoses and heater core upon removal.
Here's the big question(s):
A) Why can't I find a block drain plug? It's absolutely mystifying me...to the point I took damn near every plug out of the bottom (was due for an oil change anyway) less the transmission fluid.
B) Upon closing up the system...I was only able to put 3/4 a gallon (a little over 3 quarts) back in before overflow tank was full. I am parked uphill, heater full open and 80 degrees...heat is coming out and I don't have a leak anywhere visibly after running for about 5 minutes, 20 minutes of cool down, 5 more minutes. Heat is coming out HOT...but I'm REALLY worried about only having 3 quarts in there and it all being up front (radiator/expansion tank). I did this with cap off the first round, cap on and bleeder open the second time. Not getting an ounce of overflow from the bleeder after 20 minutes the second time. I am not overheating...at least not by the gauge. I am about to take it around the block a few times to see if there's an air bubble gumming up the works, but I REALLY don't want to run this girl with 3 quarts when it should take upwards of 10. Any suggestions on what might be happening here? Am I missing something???
Jesse
1995 BMW M3/2/5 - Alpine White - Vaders - Stage II Maxsil Pistons, Chipped, 24# Injectors, MagnaFlow Exhaust, and heated door locks!
And as supplemental information; I am not a professional mechanic… But I have completely rebuilt entire engines on multiple occasions throughout my life, I granted they were Chevys. So you can rule out any plugging something into something else where it doesn't belong… Or flooding the interior with coolant... I have flushed entire systems on two or three of our cars at least once a year for probably 20 years now… It is just that this is the first time I've done it on an m3, and the first time I haven't been able to get Coolant back into the damn thing.
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1995 BMW M3/2/5 - Alpine White - Vaders - Stage II Maxsil Pistons, Chipped, 24# Injectors, MagnaFlow Exhaust, and heated door locks!
I believe the S52 holds right at 3 gallons, so sounds like a lot is still in the block. The drain plug is on the exhaust side of the block.
04M3 TiAg 69k slick-top 3 pedal
99M3 Cosmos 61k S50B32 euro 6Spd
88M3 AW 43k miles Project FS
WTB: 3.5" Eurosport/Conforti CAI
The block drain is right behind an O2 sensor. You pretty much have to remove the O2 sensor to get it out.
As for bleeding, you don't even have to run the engine. I've been doing a new "cold bleed" procedure that works perfectly.
Raise front of car a bit. Ignition on, heater to max, engine off.
Remove bleed screw, remove tank cap
Start filling with water/coolant until the bleed screw hole fills and spills out. then install bleed screw and tighten. Never touch it again, especially with hot coolant.
Keep filling coolant until its at the very top of the coolant tank. top top, slightly overflowing top
Massage coolant hoses, you'll see air come out of the little hole in the tank neck where the overflow tube connects.
Keep massaging and adding coolant as necessary to keep the fluid up.
You'll get 90% of the fluid in the car this way.
Start engine and let it run for about 10 seconds. You do NOT want to the coolant to heat up and expand. This is only to get trapped air out
With engine off, repeat massaging and adding coolant.
When no more air comes out of the little overflow hose hole in the tank neck, you're done. Siphon the coolant down to the cold level, put the cap on and you're done.
Thank you; I will look for that when I get home… I know exactly where that O2 sensor is, but didn't see the plug there. I will pull it and take a look. Near an O2 sensor, passenger side behind exhaust manifold?
'95- s50 here...manual calls for 10 quarts (2.5g), but that's good to know.
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1995 BMW M3/2/5 - Alpine White - Vaders - Stage II Maxsil Pistons, Chipped, 24# Injectors, MagnaFlow Exhaust, and heated door locks!
There's no O2 sensor in that location on 95s. 95s have only one sensor located in the midpipe.
JayhawkM3: If you didn't pull the block drain plug you missed half the coolant. That's why you're unable to get more than a few quarts back in. The block drain plug is halfway up the block between cylinders 4 and 5 on the exhaust side. It's behind the exhaust manifolds and may be difficult to see. Should be a 19mm hex wrench to loosen it.
Here's a photo of my S50 block showing plug location. You'll know when you got it because coolant will spray out everywhere like from a garden hose. I use a small funnel with a rubber hose attached to direct flow into a bucket as much as I can, but you'll find it's impossible to catch it all. It goes in all directions when the plug is removed.
IMG_1901.jpg
and you CAN get it off without removing any of the exhaust or the o2 sensor, I've done it twice. Word to the wise, though, you have NO control over the flow as it comes out. I dilluted mine with as much reverse osmosis water as I could before opening that plug up, so that most of what spilled all over my garage (and the o2 sensor) was just water. A standard box/combo wrench will get the plug off even with the exhaust in the way
On my car I couldn't get anything on the drain plug without removing the O2 sensor first. I took out the O2 sensor, wrapped it in a plastic bag and got it as far out of the way as I could, and then undid the plug. Good to hear you won't have that issue on the 95. Just look from the passenger side of the engine block from underneath and you should see it in there by the pipes.
Word of warning, coolant sort of goes everywhere from the block drain. It will be messy. Wear eye protection.
Definitely messy but if you slip a rag in there, it might not spurt around. I use flex head ratcheting wrench. I forget the size.
Yeah I've tasted just about every automotive fluid at some point. When I was doing my brakes I was sticking my head in the small space between the hub and rear fender to get a look at the brake lines from above and my mouth was partly open. Got a lip full of brake dust/grime from the dust shield, and of course the reflex was to lick my lip.
I bought a big storage bin from Walmart to use as a collection pan. Still lost a little, but I'd say 98% found the pan. I had 4 track cars to do, so I bought the vacuum fill rig from ECS. Worked great. I didn't want to get to the track and have to deal with air pockets.
'95 M3 S54 Track Toy
'19 X5 40i M-Sport
'16 Cayman GT4
‘23 GR Corolla
I can get my block drain out without removing anything else but I do have long tube headers.
I use a large plastic bin/tray, catches most of it.
'03 911 Turbo 6MT fun car
'18 Toyota Land Cruiser Daily driver/Ski Machine/Off Roader
'15 Cayenne Diesel Wife's DD
'17 KTM 690 "Adv" 2 wheeled Adventurer
The sensor had to come completely out of the bung, so the inside portion was exposed. I figured it was silly to take any chances and it took 30 seconds for me to wrap it up.
1995 BMW M3/2/5 - Alpine White - Vaders - Stage II Maxsil Pistons, Chipped, 24# Injectors, MagnaFlow Exhaust, and heated door locks!
I just did mine on my M50 the other day. It's definitely nasty, but its towards the back of the block and hidden a bit under the exhaust manifold logs. If its all rusty and dirty under there, it might be hard to spot, but it is there.
For some reason, I'm thinking mine actually required an Allen Hex to remove the plug, but who knows what has happened to that car since 1993 lol.
I tried the bin method and got a majority of it, but be aware when you restart the car, it is going to smoke A LOT as it burns off all of that coolant that will get all over everything.
Good luck!
If you will pull the aux fan switch from the passenger side of the radiator and fire up the car. Add your coolant. Once the thermostat opens it will push out most all of the air out of the system with the sensor out. Once you see coolant starting to flow out the sensor bung just screw the sensor back in. Been doing this for years. Works great. Big air bubble gets trapped in the radiator. After that hit your bleeder screw a few times and the next morning and your good to go. This will solve this issue. Just FYI
Last edited by jskicet; 03-13-2017 at 08:21 PM.
Didn't pull or wrap anything...little spillage…
But it was diluted down to water so much that it really didn't matter. It would be my biggest suggestion; drain the radiator, fill up with distilled water, run it a while, drain the radiator again, drain the block.
When I pulled the plug, I made sure to leave it in for its last thread… Kept a nice steady stream for about four minutes. At the four minute mark I got impatient, pulled the plug, had about 1 quart left, which is what you see in the picture. Had I been three more minutes worth of patient… Wouldn't have spilled a drop.
For anyone having as hard a time as I did, seeing the picture of the upside down block above helped me a great deal. I was able to slip a little hanging flashlight right underneath The M on my cover and that's where it was. Got to it from the bottom pretty easily with a 9 inch 19mM box wrench.
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1995 BMW M3/2/5 - Alpine White - Vaders - Stage II Maxsil Pistons, Chipped, 24# Injectors, MagnaFlow Exhaust, and heated door locks!
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