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Cooling System Rebuild.  PICS!
Cooling System Rebuild. PICS!
Published by CirrusSR22
Default Cooling System Rebuild. PICS!

Cooling System Overhaul
1996 318ti Auto / M44.

Parts List

• Radiator, 17111728905 - $128 (ebay - AC Imports)
• OE Water Pump, 11510393338? - $79.82 (Tischer BMW)
• 1 Gallon Coolant, 82141467704 - $18.48 (Local Dealer)

Autohausaz.com Parts

• Thermostat w/housing, 11531743017 - $34.30
• Radiator Cap, 17111742231 - $9.78
• Upper Radiator Hose, 11531743535 - $13.70
• Lower Radiator Hose, 11531247261 - $8.63
• Combo Vacuum/Coolant Hose, 11151247903 - $15.35
• Small Reservoir Hose, 11531743295 - $13.61
• Misc. Hose #1, 11531247398 - $8.17
• Misc. Hose #2, 64211387010 - $5.94
• Heater Hose #1, 64218391252 (or 64211394295 on 4/96+ cars*) - $5.50
• Heater Hose #2, 64211394291 - $6.23
• Plastic Coolant Connector #1 (Block), 11531714738 - $11.54
• O-Ring for Block Coolant Connector, 11531709157 - $1.15
• Plastic Coolant Connector #2 (Head), 11531743679 - $8.18
• Lower Intake Manifold Gasket, 11611734684 - $3.50
• Upper to Lower Manifold Gasket (2x), 11611247478 - $2.92 total
• Block Coolant Drain Seal Ring, 07119963200 - $0.12

*My car was a 3/1996 build, but it used the newer 4/1996+ hoses.

Parts Total, with shipping and tax: $374.92 .

Quick Links to RealOEM.com Diagrams

Plastic Coolant Connector #1 (Block)

Plastic Coolant Connector #2 (Head)

Water Pump / Thermostat

Main Radiator Hoses

Intake Manifold Gaskets


Heater Hoses

And some new part pictures. Hoses, connectors, and gaskets.

eBay (Behr?) Radiator.

Close ups of block coolant connector.

Close ups of head coolant connector.

Tutorial Tools

By CirrusSR22 on 09-09-2007, 02:58 AM

The entire project is very involved, so a step-by-step guide is about impossible. I’ll try my best though!

Many parts need to be removed to have clear access to the radiator, water pump, and coolant connectors. Start by safely supporting your vehicle on jack stands of ramps. Disconnect the negative battery terminal.

In this picture I have removed the entire intake box, rubber intake boot, electric cooling fan and main intake tubing.

Other angles of the exposed radiator.

Next I removed the AC belt, and main serpentine belt to gain access to the water pump and pulley. The four main pully bolts were simple to remove, as long as the belt was still attached.

Here’s a pic of the old pump, after the pulley was removed.

Unfortunately I tapped the pully with a rubber mallet and it broke the pulley. I was not expecting the pulley to be plastic. Be careful! I eventually just pulled the pulley off by hand.
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By CirrusSR22 on 09-09-2007, 03:05 AM

Time to start into the intake manifold. Both the upper and lower sections need to be removed to access the coolant connectors as well as some of the coolant hoses.

Numerous electrical connections and vacuum hoses need to be removed for the upper manifold to come off. The throttle cable also need to be disconnected. There are 2 nuts and 1 long bolt holding the upper intake manifold on. Along with these are two other supports that need to be loosened, but not removed. Here's a picture of the upper mainfold pulled.
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By tastade on 09-09-2007, 03:39 AM

Thanks, that is a nice write up. I wish I photographed mine. I just did much of the same thing on my 1995 M42 while changing the starter. The sensors are a royal pain in the butt to unhook/and re-hook. Be sure to label some of them well, although it is somewhat clear where each one goes (use tape because permanent marker rubs off if you have grease on your fingers). I think it took me 15 hours to remove/reinstall the air intakes, all new hoses and misc, and the starter.

The flange in between the manifold (which also houses the crankcase vent valve) oddly has coolant running through it.
You don't have to take this off until you remove the lower manifold. The entire flange with coolant hoses attached (remove the breather hose from the PCV valve) will slide between the intake runners by the sensor "squid". The reason I call it a squid will become apparent when you have it taken off. I think the M44 has a better design for the squid that will let you disconnect it from the main wiring harness. For the flange, on mine, one hose from the flange attaches to the tubular plastic piece on the side of the block, and the other hose attaches to the head somewhere below the intake, if memory serves.

I think there was 9 or 10 sensors and the starter and alternator wires attached to the squid, including the reverse light switch, which had me fooled. I couldn't find what was holding the squid in place. I think all the connectors are: 2 ping sensors low in the block, 2 sensors just under the intake, 2 running from a harness around the front of the engine, 1 going by the alternator, 1 going to a vacuum valve by the charcoal canister, 1 to the reverse light switch, and 1 to the ICV. Then the alternator has a positive cables and a control signal wire, and the starter has two large positive cables, and two small control signal cables connected to it (grounds comes from the engine block). I think those are all the wires on the squid that I recall.

Also the two fuel lines going to the fuel rails make it a pain to remove the lower intake manifold as it hangs up when you try to pull it over them. You might remove the rubber hoses from them to make it easier. Also, remove the fuel injectors carefully so you don't chip them. You don't need to remove the clips from them if you don't want, they all pop in as a unit attached to the fuel rail (unbolt the fuel rail and pull all 4 off at once).

Finally, it makes it easier to connect/disconnect wires from the squid if you remove all the bolts holding the lower intake in place so you can lift it a few inches to gain more clearance. There are 5 or so bolts on the head side, mostly easily accessible, and two large bolts holding it to a bracket above the alternator. If you can't disconnect the squid from the main harness, you will likely have to remove the vent piece for the cabin air filters (see the knowledge base articles) to release the main engine wiring harness, and disconnect all the connectors by the fuse box and pull the harness out across the engine to the battery side of the car so it is out of the way. Those circular connectors have neat little clips that hold them to the body by the fuse box. Very easy to remove. If you do need to remove the harness (i.e. your squid doesn't detach from the main harness), I attached a drawing.

I should point out again, that I have the M42, and it appears your vehicle is slightly different under the intake, the squid might be much easier to remove in yours. I see your Idle Control valve (attaches to the air lines going to the fuel injectors) is in a different location towards the front of the engine. Mine was attached directly to the top of the squid, and I just see the air hose for yours going off to the side where you have it disconnected.
Attached Images
File Type: jpg work5.jpg (137.1 KB, 1086 views)
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By CirrusSR22 on 09-10-2007, 03:52 AM

The injector rail needs to come off before you remove the lower intake manifold. The electrical connections need to be disconnected, as well as the fuel lines. Depressurize your fuel system with a cold engine. Depress the thing(?) on the schraeder valve that's welded to the fuel rail. Have a rag ready to soak up fuel. Gently wiggle loose the entire fuel rail/injector/air hose assembly.

With the fuel rail out of the way, the tangled mess of a electrical harness needs to be disconnected and removed. Unfortunately the wires run through the center of the lower intake manifold. The most of the connections are simple plugs, but you'll also need to remove three nuts & wires leading to the starter. There are also two nuts and wires leading to the alternator. They need to be removed as well. The starter wires are an absolute pain!

My-oh-my!! Look at my fuel injectors. I cleaned them up as gently as possible after this shot. Hopefully I didn't plug anything up....

Here's a shot after I have disconnected the wiring harness and folded it away (towards the USA driver's side)

I removed the intake manifold flange (with holds the PVC valve) by disconnecting the two coolant lines and the one vacuum line. The lower intake manifold was free to remove at this point. Only minimal wiggling is required to make it past the two fuel lines. The lower intake manifold and intake ports were absolutely CAKED with crud/carbon/whatever. I spent quite a while degunking the manifold, and spent a little time carefully cleaning the intake ports.

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By CirrusSR22 on 09-10-2007, 04:01 AM

All that prep, and finally we can start working on the cooling system itself. That's what I tore this thing apart for, right?? Here's the coolant connector that's attached to the side of the engine block.

I removed the two bolts and three coolant hoses that are connected to it, then gently pulled it away from the block. SNAP! I think it was in a weakend state, because it gave way with very little effort. Here's a little carnage. It left the O-ring and some plastic in the block.

Time for the back of the head connector. Hard to take any pictures of it becuase it's so tight back there. This is a shot after the new one was in. Wow is this thing a b!tch. You need an open ended wrench for the top bolt, and a socket/rachet for the lower bolt. Sorry, I forgot the size. Getting the hose clamps off is really hard as well. That required a tiny 6 mm open ended wrench. Removing the cabin filter cover is pretty much required for this. It gave me a little more working room. My connector was still very study. I smacked it against the concrete a few times and jumped on it once. It didn't break.

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By CirrusSR22 on 09-10-2007, 04:15 AM

Radiator and water pump time. Removing the radiator is pretty simple. Shove a small flathead screwdriver into the main clips (look for the arrow), then pull straight up on the clip. If you have an automatic like me, the trans cooler needs to be unscrewed from the main radiator. The are 4 sheet metal screws connecting them, and thankfully the trans line DO NOT need to be opened. Here's a shot of my tans cooler!! This one is sandwiched between the AC and main radiator, so I don't understand how it got so caked with junk. The AC condenser (?) in front wasn't very dirty at all.? Nice to know I've been running without a trans cooler for quite a long time.

With the radiator out of the way, you now have pretty good access to work on the water pump. This is another tough one. I ended up breaking the old pump using the threaded holes to pull/press it out. It came out by gently prying it out with a hammer claw. I was pleased that the water pump bore was very clean and pretty much corrosion free.

Old vs. New. I believe the old one was a Thyssen. The new one was straight from a dealer with BMW logo and all. They definitely were not the same part. Both had a plastic impeller.

I lighly greased the water pump o-ring before installation. The pump requires quite a bit of effort to press in. The o-ring is quite meaty and gets compressed a fair amount.

Now's a good time to replace your thermostat. I didn't because mine was replaced just a year ago after it failed (stuck open). Here's the trans cooler attached to the new radiator. I cleaning as good as I could without backflushing it with a hose. That would have been ideal, but the work was done in a garage. Some carb cleaner and a brush did a fair job.

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By CirrusSR22 on 09-10-2007, 04:30 AM

And she sleeps. Kiboshed for the evening due to an incorrect hose. From the realoem.com and bmwfans.info diagrams, there was a coolant hose switch in 4/1996. My car is a 3/1996, so I ordered the older version. Turns out I have the newer version. I went this far, and dug this deep, I figured I ought to get the correct hose and do the job correctly the first time. Hopefully a dealer will have it in stock tomorrow morning.....

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By CirrusSR22 on 09-11-2007, 03:57 AM

Day 3. Thankfully a local dealer had the heater hose in stock so I as able to finish the project today. I didn't take any pictures as everything is just in reverse. Just make triple-sure you have tightened all the hose clamps, and made all the electrical connections. I filled the system with 50/50 BMW Coolant/Distilled water and bled the system following these instructions: http://www.understeer.com/waterpump.shtml I've tried the procedure in the Bentley manual, but it doesn't seem to work too well.

If nothing else, this project was good for just cleaning out that lower intake manifold. I wish I had taken a picture. There was a good 2mm - 3mm thick coating of gunk. After the cleaning, the car seems to rev smoother in the upper RPM range, and it seems to rev more eagerly.

One more recommendation. If you don't buy all-new hose clamps, make sure you oil or grease the threads on the old clamps. I've found the light corrosion the old ones get makes the clamps hard to tighted accurately. The new clamps from the dealer have a coating of oil on them.
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By CirrusSR22 on 09-11-2007, 07:11 AM

tastade, Thank you for your input. The M44 squid is still a tough bugger, but it seem a little easier than the M42.

From memory, here's what needed disconnecting.

• The starter was the hardest, with three nuts holding on four wires. The fourth was a red battery(?) cable that got paired up with the larger wire in the squid. It helped to remove the fuel rail first and install the rail last to gain access to the starter wire. I needed to work from above and below the car to access them all.

• The alternator wires were pretty easy. Just two nuts/wire with fairly easy access.

• The knock sensors were not part of the squid. They ran to the main harness under the intake manifold. I didn't need to touch them.

• The camshaft postion sensor just plugged into the side of the squid body, so it was easy to deal will.

• One more plug into the side of the squid body, but I forget what this was leading to.?

• One plug to the DISA

• One plug to the oil pressure switch

• Four plugs leading to the fuel injectors. These were all topside, so they were easy.

• One plug to the idle control valve. Another topside easy one.

• One plug to the throttle position. Topside and easy.

• One plug leading to something on the side of the head. I think it was a temp gauge/switch of some sorts.
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By elfhearse on 09-17-2007, 02:22 AM

I'm rebuilding my cooling system right now....a few observations:

* Check the vacuum hoses on the distribution "tree" for the fuel injectors. Several of my hoses were cracked at each end. I used Goodyear 7.8mm fuel/emission hose from Autozone to replace the four hoses.

*I have 96K miles on my car and the coolant block and head manifold were both in good condition. Water pump had a tiny bit of play in it, but looked to be in good shape too.
*Removing the throttle and cruise cable were the biggest PITA so far, followed closely by the wiring harness "squid". Not looking forward to reinstalling the lower manifold / wiring harness and installing all the connectors and mounting hardware.
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By tastade on 09-17-2007, 03:09 AM

Originally Posted by elfhearse View Post
*Removing the throttle and cruise cable were the biggest PITA so far, followed closely by the wiring harness "squid". Not looking forward to reinstalling the lower manifold / wiring harness and installing all the connectors and mounting hardware.
The throttle cable shouldn't be hard to remove. You pull the throttle slightly open (by hand) and unclip the end. Once you have the end unclipped, you snap the cylinder on the end out from the clip holding it. The clip that was holding the cylinder on the end of the cable to the throttle actuator will come off the cable through a slit on the side if you pry it open slightly. Once this is done the cable with the cylinder can be threaded through the throttle actuator hole.

This still leaves the bracket. You slide the throttle adjuster screw out of the rubber grommet, then you pop the rubber grommet out from the bracket. Once the grommet is released from the bracket you can pull everything through the bracket hole, and the throttle cable is free to do as you please.
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By CirrusSR22 on 09-17-2007, 03:57 AM

Here's a hose that fell apart on me. It runs from the Carbon Filter to the "Fuel tank breather valve". That then runs to the throttle body, right below the ICV. I'm not quite sure if this hose carries a vacuum or not, but it's not a standard rubber hose. Kind of a corrugated plastic flexi pipe.
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By elfhearse on 09-27-2007, 03:54 AM

everything back together....turn ignition and just get a whirring* sound from the starter solenoid- no ignition/engine won't turn over.

update: check TIS and troubleshoot: ~14Volts at battery and hot (red cable) starter solenoid. Ignition to start to measure volts and terminal 50 (small 14 ga. black wires at solenoid) and they read ~14 volts too.
Ohm meter check between battery negative & starter housing: ~0
replace solenoid.
UPDATE Part Deux: (I am a D*ckhead/or/don't wire ur starter after a 14 hour day & waiting two weeks to reinstall)
Got the remanufactured starter/PB Blaster soaking for about 5 hours and finally got the (2) E12 torx bolts off. In my late night wiring harness install, I had placed both "small" black wires on the post @ 11 o'clock (#30) = symptoms described above. Well, I have a nice "new" starter to go with the cooling system.

For future reference if anyone (like me) forgets where the starter wires go, here is a description.
Facing the starter solenoid from front of car:
(1) 14 ga. black wire mounts on pin at ~ 11 o'clock (#30)
(1) Red heavy ga. wire from battery mounts on large post at 2 o'clock
(1) 12 ga. black wire mounts on pin at ~ 5 o'clock (#50) below red cable.
a bit embarrassing to post...but it may help the next guy
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By CirrusSR22 on 09-28-2007, 04:03 AM

Hmm... That's too bad. I doubt you wired the starter wrong, because it's just about impossible since all three terminals are different sizes. The big one is the only one that had two wires to the terminal. Good Luck!!
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