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First a little background, my car recently hit 100K and I started leaking coolant.  The coolant was apparent on my garage floor towards the back of the engine, close to the firewall.  Well I first change out the 4 hoses at the back of the engine, the ones attached to the rear water manifold / aux water pump and that didn’t solve my problem.  This coolant leak wasn’t so bad where I was having to top it up daily weekly or even monthly, so some people may wait it out but I just don’t like leaks under my car!  I started investigating a little more and actually found coolant pooling under but around the Intake Area, well the Valley Pan sits right under there so that was a dead giveaway!  With this information I knew I had a big job ahead of my, but what a great way to lump in 100K maintenance.  So here we go…..

Parts:  Always verify parts against your particular vehicle year and model!:


Tools:  I’m not naming them all, but you’ll need a fair amount of tools in your toolbox!:

  • Assortment size socket wrenches

  • Assortment of sockets [mainly 10mm and 13mm]

  • A Torque Wrench [I’m a stickler on this, and get a good one!]

  • Some angled box wrenches [mainly 10mm and 13mm]

  • Gasket Tack

  • A Mirror Wand.

  • Flashlight that has a head strap [you’ll look like a dork, but very useful]

  • Rubber Mallet

  • A 2 in 1 O-Ring remover [I also used this for the clips on the fuel injectors]

  • Loc-Tite Blue

  • Various drain pans for coolant

  • Small Boxes, tins or the like to put all the bolts, nuts and caps in

  • Couple empty soup cans [these work great for cleaning nuts, bolts and caps]

  • Finally, sorry if I missed something but you need a fair amount of tools and accessories so plan ahead if your tool cabinet is low on supplies.

Please Click On Any Picture Below To Enlarge That Picture.
First things first, remove the acoustic cover:
So we’ll be removing the fuel line that connects to the fuel rail on top of the intake.  This line will be under pressure, so we need to de-pressurize the system.  To do this I started the car, got out with it running and removed fuse 17 from the fuse compartment located in the engine bay.  Pull fuse 17, leave it out and let the car slowly die, then I put the fuse back in so I wouldn’t forget about it later:

Now Disconnect the Negative Battery cable in the trunk!

Now that the cars fuel system has been depressurized, and the battery has been disconnected we can remove the fuel line.  This is located behind the passenger side of the engine and attached to the firewall.  Have a metal can ready because some fuel will drain out of it, I like to use a soup can.  To disconnect this, simply push 1 towards 2 and 2 towards 1, once this is done hold the line over your disposal can and drain out the fuel:
I took a "before" pic so I could route all the wires, cable and hoses just as they were.  I guess it's my OCD, but it worked superb!

NOW STOP:  You have 2 options to thinks about here, you can drain the coolant out via the drain hose on the bottom of the radiator OR do what I did and leave it - your call.  I left it and used and old blow up pool I had had to catch all the coolant that dumps once you remove the rear accumulator.  Then once I got the valley pan cap off I scooped all the coolant out with a cup and then took shop towels to soak up what was left.

Now we’re ready to remove all the connections.  I labeled everything by naming it on masking tape, wrapping the name tag on the connector, and then labeling where it plugged in on that particular part.  Anal, yes, but it will save a ton of time later when you can’t remember what plugged where, a lot of these plugs look alike.  Oh, I also tapped over each plugs end because some of the plugs have little gaskets in then that can fall out.  Also remove the MAF and tube leading to front of Intake:
Now, onto the clips….These are somewhat of a PITA.  I had great luck working from the inside of the electrical boxes.  You need to unhook the back sides of the clip and there are 4 on each side and they connect to the fuel injectors:
OK, now that we have all 8 of those off we need to sing them over and get them out of the way.  I thought I’d cheat and just pull the wires over and around the dipstick, but that isn’t happening!  So in order for this to work crawl under the car and unhook 2 plugs, 1 goes to the oil level sensor attached to the lower oil pan and the other I’m not sure what to but you can’t miss the 2 of them when you are laying under the car.  Both cables run from under the car, up to the front and are taut.  Sorry no pic, but well, I am a 2 hand shade tree mechanic….re NO HELPERS:
Here’s what the driver side looks like with the electrical box unplugged:
Now sling these electrical boxes out of the way:
……And keep them there……..
Now that everything is disconnected from the Intake, let’s remove the Intake.  There are 5 nuts on each side, 13mm if I remember correctly and the tube that runs from the front OSV to the rear manifold cover.  To get this tube disconnected I chose to slowly and carefully lift the Intake up and shift it towards the rear to disconnect this tube.  I found that when I shifted the Intake towards the rear of the car, this tube basically fell right out.  This pic shows NOT everything disconnected yet, but that’s because I took it after the fact.  Remove the nuts, CAREFULLY lift the Intake up, back and out:
Now that the Intake is out, WE HAVE THE MONEY SHOT, proof that my valley pan was leaking!  Look at this shit, what a mess and yes that’s coolant pooled all along the side!:
More shots of all the coolant!!!!!:
Ok, sorry not to get off track, but I was pretty happy to see all that coolant because I knew that was the origination point of my coolant leak!  Now, you need to get the Intake ports COVERED, DO NOT leave them open for stuff to fall in.  I immediately stuffed shop towels in them, but shortly before I moved forward I taped them off.  You’ll see later:
As you can see in the last pic those damn tubes run right over the top of the valley pan!  Well I have already replaced My Water Pump so I’m going in from the rear coolant manifold this time.  There are 6 bolts holding this on, 3 on the left and 3 on the right.  4 of them are easy to get at and 2 of them are rather difficult, totally doable though!  I loosened these 6 bolts and slowly pushed it back and let the coolant drain [ok gush] into a blow up pool I placed under the car.  That’s right I did not drain the coolant system from the drain plug on the radiator or the engine block.  I just let it flow out of the back when I broke the seal on the rear coolant manifold, worked perfectly!  Here you can see one of the gaskets stuck on the engine L.  I also removed the Aux Water Pump to assist in getting more space to take off the rear coolant manifold:
Here’s a pic of the rear coolant manifold [accumulator] gasket that came off engine.  I was able to peel it off pretty clean with a little persuasion:
Here’s a pic of the rear coolant manifold [accumulator].  As you can see the passenger side came off with the part and the driver side stuck to the engine.  Not a big deal though, these are pretty thick gaskets and cleaning the residue for a clean seal when the new ones go in wasn’t too bad:
Here are the pipes, I’ll need to clean these up before the reinstall.  Especially the ends that go into the water pump and the rear coolant manifold [accumulator]:
Finally the Valley Pan area!  The black thing is the Valley Pan Cap & Seal Cover.  The blue lines outline it.  You can also see I switch to tape on the intake ports:
Look at the coolant, do ya’ think it was leaking, LOL:
Now let’s take a minute to understand how this drains down the back of the engine.  My leak appeared to be coming from the transmission area and upon inspection from under the car the leak residue was visible from the bottom of the transmission housing.  Sorry I didn’t photograph everything, but with the Valley Pan leaking it travels out of these weep holes and down:
Close up the passenger side weep hole:
Close up of driver side.  No worries, if you ever need penicillin just give me a call, NASTY!:
Alright let’s get that shit out of there.  Blue arrows are Valley Pan Cap Bolts and Yellow arrows are Knock Sensors.  Unbolt the knock sensors first 13mm if I remember correctly and set them aside, next the valley pan these are 10mm if I remember correctly:
This is the valley pan cap & seal with the black cover removed:
I took a screw driver and lightly popped up on these tabs to break what seal there was on the valley pan.  No harm, just don’t rank on it:
Passenger side the same:
Here’s the valley pan with the valley pan cap & seal removed.  When you first remove the valley pan cap & seal this will be full of coolant, I took all the coolant out so I wouldn’t have the nasty stuff circulating through.  Then I clean around all the edges with my shop vac:
Look at this, sorry but it is pretty gross in my book:
Tape a straw to the shop vac and suck all that stuff out and clean it up the best you can:
Here’s the bottom of the new valley pan cap & seal:
You can see the gasket [seal] is already on, hopefully this is a better design than the old ribbon style gasket:
New Valley Pan Cap & Seal in, waiting for the new cover to go on and get bolted down:
Black cover on and bolted down.  I used a small amount of loc-tite blue and torque’d it to proper specs:
Clean these ends up really well so they seal well when putting them back in:
Clean both ends, I actually just cleaned the whole damn thing:
Pull both these O-Rings out of the rear coolant manifold [accumulator] and put new ones in, coat the new O-Rings with a good lubricant:
Pulling out, be careful not to damage any surface on the rear coolant manifold [accumulator]:
Next, same thing:
Now remove the water pump O-Rings.  Mine are fairly new, but for a few bucks I’m not risking it:
Now comes the somewhat tricky part. If you don’t have gasket tack I don’t know what to tell you!  I applied a very light coat of gasket tack where the arrows dictate, let it set for a minute and then aligned them on the ends of the rear manifold gasket.  This worked perfectly and they held in place perfectly for reinstalling this.  I am also happy to report that since I have done this they are not leaking at all.  Just apply a light coat on the ends, ‘cause a little goes a long way and is strong.

I put the tubes in the water pump side first, and then slide the rear coolant manifold [accumulator] into the pipes.  The pipes need to be attached before you can slide the rear coolant manifold [accumulator] in place to bolt it down.  Once everything is in place, take your time getting it bolted down.  I started finger tight and then went around tightening the bolts to get a good seal:

Hook all your hoses back up and put the Aux Water Pump back in.  Make sure you hook all the hoses back up now, it’s much easier:
Here’s a shot of the rear coolant manifold [accumulator] gasket in place and bolted down:
Other side, gasket in place:
Here are all the hoses and Aux Water Pump hooked back up:
Moving on to the intake, it’s on the garage floor.  Remove the throttle body [4 bolts, 10mm I remember] and then remove the 6 T-30 Torx bolts off the front intake cover and replace the gasket and the arrow points to:
Just a nice shot inside the intake for you:
Another, you can change this tube out if you want, I didn’t, but if you want you need to also remove the rear intake cover and replace that gasket too.  The front and rear cover gaskets are the same part number:
New gasket going in:
Time for a break, so here a picture of the POS old valley pan cap with the seal [gasket] that is trashed:
I pulled each one of the guides out, cleaned them, inspected the rubber washer and then lubed them prior to re-installation.  They were all in good shape:
This is what I lubed, cleaned and conditioned:
Ok, as you can see that’s back in.  Now it’s time to take the tape off the intake ports and clean them.  Mine had some grit, so I took a micro-fiber towel with a small amount of gas on it and wiped them clean:
Clean around each, 8 total, I took a soft micro-fiber towel, dipped it in a little gasoline and then lightly worked my way around cleaning the ports.  Be very careful and DO NOT use any type of abrasive style pad.  You do not want to scratch, nor do you want to scrap, ding, mar or nick.  I hope you get my point!:
Prior to putting the Intake back in I did a once over and found that this pipe had a crack in the rubber hose attachment.  I count myself luck that I found it because had this part failed I would have had to take the Intake back off.  The crack was small, but the flashlight caught it and when I flexed the tube sure enough it had a small slit / crack in it:
Here it is, I’m flexing the tube to enhance the crack:
Here’s the new part:
Close up of part number:
This tube just pulls out, with some force and pops back in.  There are no bolts or anything, just an O-Ring that snaps in place.  Make sure you lube the O-Ring prior to snapping it in place.  Now finally put the Intake back on and tighten down the nuts to the proper torque specs:
Now assemble everything in reverse.  Make sure you put the new Intake Gaskets on, once you put the intake gaskets on the intake they stay pretty good, so you should have no problem flipping the intake over,  seating it properly and then when tightening the intake, tighten from the middle out alternating sides as you go.  Hook up all the wires you removed and finally put the acoustic cover back on.  Looks good doesn’t it!:
Just to summarize:  I had a coolant leak that was indeed the valley pan leaking, because after replacing it I no longer have any leaks, duh.  Basically the cooling system is a real sore spot on these cars.  I’ve replaced the Radiator, Expansion Tank, Water Pump, Thermostat, all the cooling hoses from the front to the back, Aux Water Pump and now the Valley Pan with Gasket.  I can only hope this will keep me going leak free until I have to replace the radiator again, lol!

I chose to DIY this for reasons I’m not sure of now, it’s a big job, a big job because it is very time consuming!  I don’t think anything was all that difficult, it was just very time consuming and tedious.  I’m also sure I saved a TON of money by DIY’ing it!  For parts, and this included spark plugs, intake gaskets, coolant, valve cover gasket and so on, I was around $500 and that is at an internet dealer price.  A quote from my local dealer for this repair was between $1500-$2000 dollar range for parts and labor depending on what “exactly” needed to be replaced once they got in there, and I know they would not have taken the care to clean each item as they moved along.

As far as torque specs on the parts you’re reinstalling, I am an absolute stickler in making sure all the nuts and bolts are torque’d properly!  In my opinion this is a MUST!  Review your TIS disc for these specs.

Thanks for reading, I hope you enjoyed and most importantly I hope you learned something new or got a perspective into a 740 that maybe you didn’t have before!

Disclaimer:  I am NOT a professional mechanic.  I am just very handy and take the documentation available to me, study it, plan ahead and get’er done!  I under NO circumstances warrant anything you CHOOSE to do to your car, nor do I assume any liability!  I am just an enthusiast trying to give you an inside glimpse into what I encountered during the repair of my own car.

UPDATE:  I’ve put 14K miles on the car since this repair and I have not seen any leaks or otherwise!  I'm a happy camper!!!


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