3.9L V8 Cooling System Question (Plastic Elbow Under the Intake Manifold)

[cewhite3]

Im working on a 2004 3.9L V8 cooling system. The car had a high pressure cooling leak at the front of the engine. I suspect something in the plastic thermostat housing / cross over pipe system is leaking under pressure. Since the car is 10 years old, I figured this would be a good time to replace all the plastic parts and the related hoses. The thermostat housing and the crossover pipe are easy. However, there is a plastic elbow attached to the block under the air intake that connects to the crossover pipe. This elbow is difficult to access. The shop manual is mum on this part. It looks like I need to remove part or all of the intake manifold to get to the bolts that attach the elbow to the block. Any advise on how to proceed would be appreciated.

It appears I have two options - 1) remove the complete intake manifold including the throttle body and throttle body spacer or 2) remove the throttle body and throttle body spacer. The shop manual covers removing the complete intake manifold. The shop manual does not cover removing the throttle body spacer from the front of the intake manifold (it stops at removing the throttle body from the spacer). I hesitate to remove the throttle body spacer from the intake manifold for a couple of reasons. The manual does not address how to remove the spacer and therefore I have no idea of the torque requiremets for the screws that attach the spacer to the intake manifold. Since I am screwing into a plastic part, I am worried that the torque setting are critical for when I reinstall the spacer to the manifold. Secondly, the spacer to intake manifold gasket is no longer available from Ford. Aftermarket versions are available, but it worries me that Ford doesn't offer this gasket (O-Ring?). This implies to me that Ford does not approve removing the spacer from the manifold. I hate working on plastic parts and fear that removing the metal spacer from the plastic manifold might lead to disaster.

Should I assume that plastic elbow between the block and crossover pipe is OK and not likely to fail or should I replace it (the part is cheap). If I should replace it, what is the best method to access it?

Thanks for any advice

Ed White

 

[joegr]

There are many threads on here that hit on this. Here is the most recent.
http://www.lincolnvscadillac.com/forum/showthread.php?90449-Replacing-cooling-components-(genII-V8)

In my opinion, removing the whole intake manifold (with throttle body attached) is no more difficult than removing just the throttle body. Removing the whole manifold is the correct way to do the repair.
If you remove just the throttle body, You will still have to cut off the two bolts at the back of the pipe. Then you have to hope that shorted bolts will have enough thread engagement.

No, don't assume that pipe is okay. The one on my 04 failed. Like the rest of the plastic, it deteriorates with use. By the way, look really close at the throttle body heater hose that comes from under the manifold. The one on my 06 cracked (it didn't split all the way through such that it leaked, but it looked like it would soon). Anyway, the only way to replace that hose is to remove the intake manifold. You might want to do it as PM while you have everything apart.

PS: The torque on the throttle body bolts is 10 Nm. You are screwing into metal inserts, not directly into plastic.

 

[cewhite3]

Thanks for the reply. Looks like the intake manifold needs to come off. Is it best to remove the throttle body first, or can I just remove the entire assembly? Any tricks? Looks like i have to disconnect all the injectors. Is that going to be a big deal?

Thanks for the pointers.

Ed

 

[joegr]

Thanks for the reply. Looks like the intake manifold needs to come off. Is it best to remove the throttle body first, or can I just remove the entire assembly? Any tricks? Looks like i have to disconnect all the injectors. Is that going to be a big deal?

Thanks for the pointers.

Ed

The procedure in the manual is pretty good.
http://deneau.info/ls/s6x~us~en~file=s6x31006.htm~gen~ref.htm

I just left the throttle body on. The injectors and fuel rail come off with the manifold, no need to disconnect them. You only have to disconnect the fuel line connection to the rail. You need the disconnect tool for that. Clean off as much dirt as you can before you do this. Vacuum out any that falls into the intake ports once you get the manifold off. Stuff rags into the ports to keep anything from falling or pouring in while the manifold is off. You can probably reuse the manifold gaskets, but they are cheap enough to replace. The hardest part (believe it or not) is to get the wiring harness clip loose at the back of the manifold.

 

[cewhite3]

Thanks. It looks doable. I sort of felt I had to go that way and I even already have the intake manifold gaskets. I just wanted to make sure there wasn't an easier way than removing the entire manifold. I wish therew as a metal replacement for that elbow. I never trust plastic in those sorts of applications.

Do I need to do anything special regarding draining the coolant? I've already drained coolant at least to the bottom of the water pump. I noticed a caution statement about being sure to drain the coolant (I assume the fear is that coolant could flow into the intake ports). I believe I have it far enough down for that, but would hate to be surprised when I pull the manifold.

Ed

 

[joegr]

I just drained it from the radiator. This left the vertical tube still full of coolant, so I used a shop vac to suck that out do that it wouldn't spill into the intake ports. Alternately, you could pull the water pump out.

 

[cewhite3]

The procedure in the manual is pretty good.
http://deneau.info/ls/s6x~us~en~file=s6x31006.htm~gen~ref.htm

The hardest part (believe it or not) is to get the wiring harness clip loose at the back of the manifold.

I do believe that the connector is the hardness part! How did you get it loose? My son suggests that I can remove all the manifold bolts and then reposition the manifold to get access to the connector. Any opinions on that idea?

How much trouble was loosening the EGR tube?

Ed

 

[joegr]

Disconnecting the EGR tube was easier than I thought it would be. I had to get the right size narrow service wrench because my adjustable wrenches were too think to get in there. I put a pipe over the handle to get leverage to break it loose.

It's actually not a connector, it's just a plastic harness holder that is bolted on in two or three (forget which) places back there. One or two studs point at the firewall. You only have to greatly loosen the nuts on those, the nuts don't have to come off. I'm pretty sure that there is one more nut than is shown at step 22 that has to come off or be loosened. You won't be able to move the manifold enough to help to get that harness off.

I was very tempted not to bolt it back on when I put it back together, but I did.

 

[cewhite3]

Disconnecting the EGR tube was easier than I thought it would be. I had to get the right size narrow service wrench because my adjustable wrenches were too think to get in there. I put a pipe over the handle to get leverage to break it loose.

It's actually not a connector, it's just a plastic harness holder that is bolted on in two or three (forget which) places back there. One or two studs point at the firewall. You only have to greatly loosen the nuts on those, the nuts don't have to come off. I'm pretty sure that there is one more nut than is shown at step 22 that has to come off or be loosened. You won't be able to move the manifold enough to help to get that harness off.

I was very tempted not to bolt it back on when I put it back together, but I did.

Are you sure? What I am asking about is the electrical connector at the rear of the passenger side fuel rail (Step 5 - Fuel rail temperature sensor electrical connector). My hands are too big to get around it to press the release button.

Is the wrench for the EGR tube a 27 mm?

My helpful son managed to break the nipple off the Fuel pressure sensor - another $100 down the drain (sigh).

Ed

 

[joegr]

Are you sure? What I am asking about is the electrical connector at the rear of the passenger side fuel rail (Step 5 - Fuel rail temperature sensor electrical connector). My hands are too big to get around it to press the release button.

Is the wrench for the EGR tube a 27 mm?

My helpful son managed to break the nipple off the Fuel pressure sensor - another $100 down the drain (sigh).

Ed

I think that 27mm is correct. I got a full set of service wrenches at Harbor Freight fairly cheaply. Funny, I got a narrow wrench because I was afraid I would break the fuel pressure sensor. I don't recall having any real trouble with the fuel temperature sensor. If there are two of you, one should be able to hold the manifold up and forward while the other releases the connector.

 

[cewhite3]

Disconnecting the EGR tube was easier than I thought it would be. I had to get the right size narrow service wrench because my adjustable wrenches were too think to get in there. I put a pipe over the handle to get leverage to break it loose.

It's actually not a connector, it's just a plastic harness holder that is bolted on in two or three (forget which) places back there. One or two studs point at the firewall. You only have to greatly loosen the nuts on those, the nuts don't have to come off. I'm pretty sure that there is one more nut than is shown at step 22 that has to come off or be loosened. You won't be able to move the manifold enough to help to get that harness off.

I was very tempted not to bolt it back on when I put it back together, but I did.

Wow, you weren't kidding about that nut at the back of the manifold on that harness holder. I got two off easily. I am having trouble with that one that points towards the firewall. What sort of tool did you use to get at it? You implied I don't need to completely remove the nuts. What does tha mean? I thought I need to reposition the harness so I could get the manifold off.

BTW, the nut on the EGR valve was a 27mm nut. I soaked the joint with penatrating oil. Once I had the right right it unscrewed ver easily.

I am glad i am not in a hurry to get the work done, becasue it is a total PIA. I am 60 and my skin is like tissue paper and I brruise very easily. My hand and arms look like I lost a bar fight.

Any advise you can give me on that last harness locator nut is greatly appreciated.

Ed

 

[joegr]

Wow, you weren't kidding about that nut at the back of the manifold on that harness holder. I got two off easily. I am having trouble with that one that points towards the firewall. What sort of tool did you use to get at it? You implied I don't need to completely remove the nuts. What does tha mean? I thought I need to reposition the harness so I could get the manifold off...

I used a socket and a small socket wrench. It doesn't have to come all the way off because the hole in the plastic holder is U shaped with the bottom open. Once you get it loose enough, you can lift (with difficulty) the harness up and then move it back a little.

 

[SoulSoak]

Wow, you weren't kidding about that nut at the back of the manifold on that harness holder. I got two off easily. I am having trouble with that one that points towards the firewall. What sort of tool did you use to get at it? You implied I don't need to completely remove the nuts. What does tha mean? I thought I need to reposition the harness so I could get the manifold off.

BTW, the nut on the EGR valve was a 27mm nut. I soaked the joint with penatrating oil. Once I had the right right it unscrewed ver easily.

I am glad i am not in a hurry to get the work done, becasue it is a total PIA. I am 60 and my skin is like tissue paper and I brruise very easily. My hand and arms look like I lost a bar fight.

Any advise you can give me on that last harness locator nut is greatly appreciated.

Ed

I recently did this procedure of installing new plastic cooling components. The bolts on the plastic harness junction behind the intake manifold were 5/16's if I recall correctly. I used a 1/4" drive rachet with a socket. I positioned the socket on the bolt head you're referring to, then attached the rachet to the socket and wrenched the bolt out. Once it came out, I drop kicked it into the neighbors yard.

 

[SoulSoak]

Oh and the elbow you're referring to is part "9N499".

 

[cewhite3]

I used a socket and a small socket wrench. It doesn't have to come all the way off because the hole in the plastic holder is U shaped with the bottom open. Once you get it loose enough, you can lift (with difficulty) the harness up and then move it back a little.

Good to know. I only wish I had read this before I removed the nut completely Impatience has its penalty. At least I know I can start the nut back before I reinstall the manifold. I managed to break the cylinder head temperature sensor when the connecting wire got tangled in the intake. Oh well, at least I will have a new one. I wish I had waited to do the Degas bottle after I remove the intake manifold. It would have been so much easier.

I believe the nut needs a 10 mm wrench (5/16" ~8 mm) but I guess I'll have to go and check to be sure.

Ed

 

[cewhite3]

Good to know. I only wish I had read this before I removed the nut completely Impatience has its penalty. At least I know I can start the nut back before I reinstall the manifold. I managed to break the cylinder head temperature sensor when the connecting wire got tangled in the intake. Oh well, at least I will have a new one. I wish I had waited to do the Degas bottle after I remove the intake manifold. It would have been so much easier.

I believe the nut needs a 10 mm wrench (5/16" ~8 mm) but I guess I'll have to go and check to be sure.

Ed

You definitely need a 10 mm wrench for this nut. One of the fancy hinged ratcheting box end wrenches is what works best. My fixed head ratcheting box end wrench worked OK when reinstalling the nut, but one with the hinged head would have been even better.

After being out of town for a week, I finally got back in town and reinstalled the intake manifold. I had problems with the knock sensor wiring. I needlessly disconnected the connectors for these before I removed the intake manifold. The wiring for the knock sensors must be positioned properly at the front of the engine so they can stretch around the front of the intake on either side. It took me a few minutes to reposition these with the intake manifold in place (I was worried for a few minutes).

I have one final problem.....the vacuum lines that connected to the EGR Valve - does it matter which one goes where? There are two of them (plus another to the fuel pressure sensor), but it appears to me that both care connected to the same vacuum source. I am guessing one is for the MAP sensor and the other provides vacuum to operate the EGR valve. If this is true, it doesn't matter which goes where, but I'd like this confirmed.

Thanks again for all the help and advice. I hope all the pain will be worth it! The "English Influence" is written all over these crappy plastic cooling system parts. I would love to replace the entire system - plastic elbow, plastic crossover and the plastic thermostat housing - with a metal casting. I dislike the rectangular cross section O-rings used to seal the parts to the block and the thermostat is a kludge straight out of the English auto industry design guide of how to guarantee cooling system failure. It is like the English need to take bad German cooling system ideas and make them even worse. Designed to fail!

Ed

 

[joegr]

...The "English Influence" is written all over these crappy plastic cooling system parts. I would love to replace the entire system - plastic elbow, plastic crossover and the plastic thermostat housing - with a metal casting. I dislike the rectangular cross section O-rings used to seal the parts to the block and the thermostat is a kludge straight out of the English auto industry design guide of how to guarantee cooling system failure. It is like the English need to take bad German cooling system ideas and make them even worse. Designed to fail!

Ed

I do believe that you have picked the wrong group to blame. Jaguar didn't use the gen II plastic cooling parts that you are complaining about on their cars, those parts only went on the LS. In fact, the gen II Jaguar S-Type used a metal thermostat housing. (No, you can't use it on the gen II LS, it won't fit. However, it does fit on the gen I.) If you look at other Ford/Lincoln/Mercury cars, you will see that Ford, like everyone else, is big into the use of plastic under the hood.

 

[cewhite3]

I do believe that you have picked the wrong group to blame. Jaguar didn't use the gen II plastic cooling parts that you are complaining about on their cars, those parts only went on the LS. In fact, the gen II Jaguar S-Type used a metal thermostat housing. (No, you can't use it on the gen II LS, it won't fit. However, it does fit on the gen I.) If you look at other Ford/Lincoln/Mercury cars, you will see that Ford, like everyone else, is big into the use of plastic under the hood.

I know you are right about the parts not being used on the Jaguar engine, but my new plastic parts were marked made in UK. I have to believe the design of the crossover pipe was directly from the mind of an English engineer who spent too much time study BMWs. The design is overly complicated and bound to fail with age. You are using a rigid plastic part filled with very hot coolant to tie together two aluminum cylinder heads mounted on an aluminum block. Furthermore that plastic connecting pipe is constrained in the middle by a plastic elbow that is connected to the center of the block. All the thermal expansion and flexing is bound to destroy the part sooner or later.

The English have built some amazing vehicles, but speaking from sad experience designing for reliability is not one of their strengths. I was sad to see that the new crossover parts I am installing are exactly like the original parts they are replacing. I was hoping for some obvious revisions that might have given me a warm feeling that the new parts were improved over the old. Hopefully the new parts will make at least 5 or 6 years. If they last that long, I am sure a future replacement will be someone elses problem.

Since you brought up the Gen 2 Jaguar engines - what do they do for a crossover between cylinder heads? I keep thinking it wouldn't be all that hard to design a replacment arrangement that could replace the plastic parts with a metal distribution manifold and flexible hoses. I am worried worried that I do not understand what they were trying to do with all the complicated geometry molded inside the plastic crossover pipe.

Ed

 

[joegr]

I believe that on the S-type, it was a plastic tube with some hose connections.

I fully agree that there are places that plastic just doesn't work long term. BMW certainly found more such places than Lincoln or Jaguar. I was also lucky enough to have one of the Ford 4.6s with the plastic intake manifold that cracked due to stresses at the front of it. (They redesigned it to use metal in the high stress locations.)

 

[cewhite3]

I believe that on the S-type, it was a plastic tube with some hose connections.

I fully agree that there are places that plastic just doesn't work long term. BMW certainly found more such places than Lincoln or Jaguar. I was also lucky enough to have one of the Ford 4.6s with the plastic intake manifold that cracked due to stresses at the front of it. (They redesigned it to use metal in the high stress locations.)

That 4.6L Manifold was clearly a case of cost cutting gone wild since the Ford engineers designed a more robust manifold for "heavy duty" use. At least whoever did the 3.9 crossover pipe didn't try to hang the alternator off of it

Ed

 

[Gus_Mahn]

I was able to change the elbow on my '03 without pulling the intake. I loosened the front bolts on the intake and pried up on the intake a little. The bolts are way long for no reason. I ground the rear bolt a little shorter before reinstalling it.

 

[joegr]

I was able to change the elbow on my '03 without pulling the intake. I loosened the front bolts on the intake and pried up on the intake a little. The bolts are way long for no reason. I ground the rear bolt a little shorter before reinstalling it.

I've tried it both ways. To me, it was easier to just take the manifold off. (You don't have to remove the throttle body from the manifold to do this.)

 

[lincoln2004LS]

I am a new member and just went through the process of changing out all the plastic parts, themostat, hoses and belt and pulleys on my 2004 Lincoln ls with 85K on it.. Maybe I missed it but my original issue was that my cooling fan was running on High speed once the vehicle warmed up. I had read somewhere that the thermostat could be the issue so I gathered all the parts up for a couple of weeks. The thermostat housing plastic was disinigrated where the shaft is usually inserted in the copper insert molded piece. The coolant neck was also deteriorated the inner wall that retiains the oring was separated almost all the way around. I went the route of removing the throttle body and loostening the intake bolts and prieing up the intake to get the back coolant neck bolts out. I also cut them back a little and marked them with green paint so they are easily identified in the future. Pretty frustrating that they make things so difficult to work on. I have to report that once all this was completed the cooling fan is back to normal and everything should be good for another 85K. Truely the thermostat was not working properly but luckily the vehicle was not overheating or leaking. If you have a similar problem do your research get all the plastic parts and just replace everything because you are on borrowed time. THe throttle body to intake gasket is availabe through aftermarket although I did not have the luxury of time to order a new one. Mine still had squeeze left so I felt it would be ok. Anyway I wish that someone would have done a youtube video or even a list of all the part numbers and details of this job because it took a while to figure it all out. Even putting the thermostat into the housing is no trivial task and I had to improvise a simple spacer and use a socket to press it down far enough and evenly to get it into the housing properly. Thank god I have patience because this car requires a lot of it. Also replaced the heater control valve as well which is another weakness of this car that will have you thinking you have a bad AC system when in reality the faulty valve overcomes the ac with hot coolant.

 

[thenewguy]

I went the route of removing the throttle body and loostening the intake bolts and prieing up the intake to get the back coolant neck bolts out. I also cut them back a little and marked them with green paint so they are easily identified in the future. Pretty frustrating that they make things so difficult to work on.

I hear you man. I know this is a shot in the dark but im stuck and could really use some help. I saw your post about changing all the plastic parts because of the engine cooling problem you had. Did you only loosen number 15 in this diagram and thats it? Did you have to change the gasket (#17 in diagram) as well? Did you have to release the fuel system pressure or Disconnect the fuel supply tube from fuel rail? And what did you use to pry it up? IM REALLY SORRY FOR TAKING YOUR TIME. Im really stuck with my car and its in pieces please if you could shed some light i would greatly appreciate it. THANK YOU FOR YOUR TIME!!

 

[LS4me]

I hear you man. I know this is a shot in the dark but im stuck and could really use some help. I saw your post about changing all the plastic parts because of the engine cooling problem you had. Did you only loosen number 15 in this diagram and thats it? Did you have to change the gasket (#17 in diagram) as well? Did you have to release the fuel system pressure or Disconnect the fuel supply tube from fuel rail? And what did you use to pry it up? IM REALLY SORRY FOR TAKING YOUR TIME. Im really stuck with my car and its in pieces please if you could shed some light i would greatly appreciate it. THANK YOU FOR YOUR TIME!!

He hasn't been here in a year and a half......

I had to loosen the entire manifold, IIRC, to be able to raise the front of the manifold enough to get that piece out. Just take your time and you should be able to figure it out as you go...