The really annoying thermostat and 9n499 change

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thenewguy

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Hey guys just bought this lovely car last week and first day it overheated on me. Ive been reading this forum non stop for the last week and see this is a common problem with the thermostat housing and the elbow part 9N499. I was hoping someone can please help me out since most these posts on the forum are missing pictures because of broken links so im a bit confused. This is my first time working on a car ever but I love to learn. So on my 2006 LS v8 with 146k miles on it Im replacing everything touching the thermostat.

Im stuck on how to go about getting the bolts for 9N499 out. Ive read either pry or cut.

My question is if i pry do i just loosen the bolts on the intake manifold only and just lift it up a bit with a pry bar? Are the only bolts I loosen number 15 in this diagram ? Do I need to replace the gasket too since im not opening all the way(#16 in the diagram)? Is there anything else I should worry about like fuel lines or anything dangerous? Really don't want to make a mistake.

If I go the cutting route do I just unscrew as much as I can cut half of the screw and unthread the rest by hand? Do I need to also disconnect anything like fuel line? Is it safe making sparks under the hood? Again this is my first time working on a car but got to learn somewhere. Sorry if my questions come across to you as obvious or dumb but this is a brand new language to me. Thanks for your time and any help is greatly appreciated!
 
You really don't need three posts on this. You other posts have been answered. If you don't like those answers or they didn't go far enough, then respond to them with more questions.

I feel like it's easier and safer to remove the intake manifold, but to each their own.
If you don't remove the intake, you don't have to disconnect the fuel line. (It takes 10 seconds to disconnect the fuel line with the tool. I don't even depressurize it. I just throw a rag over it before pulling it apart to keep it from spraying in my eyes.)
I would replace the manifold gaskets even if you just loosen it, but you'll have to remove the manifold to do that.
Sparks are safe under the hood, but don't let any of them (tiny bits of metal) get into the intake or the cylinders.
Here's the shop manual: http://deneau.info/ls/
Be sure to use the correct tightening sequences and torques.
Be sure to clean the metal surfaces of the engine where the coolant gaskets touch.
Be sure to follow the bleed procedure exactly. (don't put the degas cap on until the engine warms up and the level drops.)
http://deneau.info/ls/s6x~us~en~file=s6x33004.htm~gen~ref.htm#extract_142
 
Hey Joegr you are right and I apologize for writing up 3 posts. I wasnt sure if these members where still active and was getting a little desperate hoping to get the right persons attention to help. Again thank you for taking the time to help me out. Im leaning mostly towards cutting.Your help is greatly appreciated thank you
 
dont worry, if you post in a thread, it will pop it back up to the top and most people will pop in it to see whats new and give you what help you need.

you can also seen when the last time a member was on by clicking on their name to the left of the post, then when the pop down menu pops up, choose "view profile", it shows when they joined and the last time they logged on.

also even if you find an old thread from someone that hasn't been on in years, still ask your questions as more than likely there are still plenty of people here that have had your problem.
 
Also...

I would NOT recommend trying to cut the bolts while still in the block. If you gouge the surface where the TS housing mounts,,, you may never get it to seal again. Some pull the intake... while others pull the throttle body and notch the face of the intake where the throttle body mounts. The bolts for the TS housing are usually cut after being pulled,,, just for easier installation. Just remember... the more you pull apart,,, the more you have to worry about getting back together right.

Not to discourage you,,, but if you have never worked on a car before... this may not be the best "first job" to try and tackle by yourself. If you have a knowledgeable mechanic friend,,, it may be best to ask for his or her help... and then assist and watch then do the job.
 
04_Sport_LS said:
Also...

I would NOT recommend trying to cut the bolts while still in the block. If you gouge the surface where the TS housing mounts,,, you may never get it to seal again.
Click to expand...

The bolts hold the thermostat down. You would only risk gouging the back of your old thermostat, which is garbage anyway. Well, assuming you're using a Dremel with a cutoff wheel and not a 4" grinder
 
Last edited:
Also not being blind and having a steady hand helps.
 
There is no need to cut the bolts on the thermostathousing itself. The way Joegr and I understand it... the OP is talking about the gooseneck (above and behind) the block and actual thermostat/crossover housing. If you decide to pull the intake,,, then there is no need to cut any bolts. If you decide to pull the TB and shortcut by pulling just the gooseneck, (instead of the whole intake),,, then the bolts will have to be cut... and/or the TB side of the intake will have to be notched for a "relief" to pull the bolts. Cutting the gooseneck bolts by 3/16 to 1/4 inch only helps if the intake wasn't pulled in the first place,,, and only helps with the re-install of the goosneck, (part behind the TS housing).

The OP seemed to question cutting the bolts on the gooseneck,,, after loosening them... hoping to get the gooseneck out that way. I don't recommend that,,, because again... if you gouge the gooseneck mount face on the block itself... (topside under the TB),,, good luck getting anything to seal against the block properly
 
I thought it was 2 of 4 vertical bolts holding down the thermostat. As you back out the back 2, they hit the intake. Maybe I'm just thinking of the Gen 1 that doesn't deal with the TB in the front?
 
Hey thanks for the the help I read the write up on the link you gave me thanks for that. In that post he talks about cutting the back 2 bolts on part 9n499 . My understanding of the shortcut is it to remove the throttle body unscrew the bolt as much as i can cut the top 1/4 off after unscrewing as much of it as I can. Is this correct?

The write up I have for removing the Throttle body is this one , seems to be missing the steps to go all the way to the manifold is that necessary to go all the way or just the steps shown? Does anyone know if this is the correct write up or have the correct one they can share
 
LSFrank said:
I thought it was 2 of 4 vertical bolts holding down the thermostat. As you back out the back 2, they hit the intake. Maybe I'm just thinking of the Gen 1 that doesn't deal with the TB in the front?
Click to expand...

this is specifically a 2nd gen problem. the thermostat housing bolts to the coolant outlet pipe, behind the coolant outlet pips is the 9n499 elbow. the two back bolts of the 9n499 are too long to just be taken out.
 
thenewguy said:
...seems to be missing the steps to go all the way to the manifold is that necessary to go all the way or just the steps shown? Does anyone know if this is the correct write up or have the correct one they can share
Click to expand...

I'm not sure what you are asking... Your page shows removing the four bolts that hold the throttle body to the manifold. BTW, the on-line manual for the 2006 is valid for your 2004 V8.
 
The steps seem to show only the removal of the first half of the throttle body. I might be mistaking but looks like there is a whole other section of the throttle body left aftwr you remove what's instructed
 
throt.jpg Looks like instructions up untill this part. Am I missing something? Seems like there is a second half of the TB left?

throt.jpg
 
Okay, fair enough. Don't remove the throttle body from the adapter. Instead remove the adapter with the throttle body still attached (four bolts to the intake). You'll have to disconnect the EGR tube as well as the vacuum lines to the assembly. By the way, there are high odds that those hard line vacuum tubes with crumble to dust when you start to remove them.
 
You are going to want to change that belt when you are finished. Belts and coolant don't go well together.
 
Hey thanks again Im going to give this a shot right now. And thanks for the heads up about the serpentine belt. Can I buy this part at any auto store or should I go direct to Stealer(dealer)?
 
OK so I messed up really bad.... I took off the throttle body and everything else was going smoothly. I got to the last two screws the ones to cut. The first one on, the right screw unscrewed no problem. The one on the left has been stubborn as hell. I tried and tried and noticed im starting to strip it so I stopped. I tried lubricant, I tried banging it a couple times, and stupidly kept trying and trying now the bolt is rounded and stripped. Anyone have any idea how to get this last screw out that's ruining my life? Problem is the angle is weird and i think I just don't get a proper grip on it. The spot is too small to get a normal wrench in there. Please any help is appreciated and please don't respond with your F*cked I know I am. Thinking of selling the car as is if I can. Any ideas or help please!!!?!?!
 
Remove the intake manifold, and cut the bolt head off. After you pull the pipe off, there will be room to lock a pair of vise grips on the remainder of the bolt and screw it out. Be sure to stuff rags in the intake ports to keep anything from flying into them. Also, be sure to remove them just before reinstalling the intake. If you didn't buy intake gaskets, you can put a little (very little) gasket maker on both sides of the old gaskets.

Alternately, you could use a bolt-out, but you'd still have to remove the intake to use it. At that point, I think just cutting the bolt is easier since you aren't going to reuse the pipe anyway.
 
Really should use swivel sockets whenever possible. A quick right (tighten), to break loose, then all left to undo technique works every time. When one realizes a nut/bolt is going to give some trouble, it's best to spray it with some penetrating fluid and leave it for a bit. Open ended wrenches are the worst for stripping nuts/bolts. Should never start with something like that. Always use 6 sided sockets to crack nuts/bolts loose.
 
BigRigLS said:
Really should use swivel sockets whenever possible. A quick right (tighten), to break loose, then all left to undo technique works every time. When one realizes a nut/bolt is going to give some trouble, it's best to spray it with some penetrating fluid and leave it for a bit. Open ended wrenches are the worst for stripping nuts/bolts. Should never start with something like that. Always use 6 sided sockets to crack nuts/bolts loose.
Click to expand...

I've also found that with a stubborn one, in addition to the above if you TIGHTEN it just a hair, it can help them to break loose. I'm not talking quarter turn stuff here, as soon as you feel it starting to move you stop then loosen. Don't know why it works, it just does.
 
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