Landman
Viper Owner
I'm getting ready to put a new thermostat in my 02 GTS. Is this a pretty simple job? Any advice before I get into this job?
Thermostat install?
- Thread starter Landman
- Start date
VIPER BAZ UK
Enthusiast
Need to remove the intake so you will need the gaskets.....
dave6666
Enthusiast
You have to pull the intake manifold. Includes depressurizing the fuel system. Would highly recommend a factory manual and some good tools. You'll need a pair of intake gaskets too. About $30.00 a pair.
I did it on my '01 without removing the intake manifold completely and didn't have to mess with the fuel system. Unfortunately, I didn't take pics. I'm going to replace the 172 degree tstat with a 180 degree tstat over Thanksgiving and will do a detailed writeup. Definitely invest in a Viper Service Manual for your year/model. The most difficult part of the install for me was removing the old t-stat gasket material from the t-stat housing. DO NOT USE A METAL SCRAPER as it will scratch/scrape the t-state housing horribly. Use a plastic scraper and a little elbow grease and you'll be fine. You should be able to find service manuals on ebay.
Purdue_Boiler_Viper
Enthusiast
Do it as part of your Roe SC install. If you're going to pull the intake manifold, might as well stick something better back on! 
Purdue_Boiler_Viper
Enthusiast
I'm not sure how Tony did it without removing the intake manifold. But, I had the same problem with the old gasket. Thermonuclear bonding held that SOB on. I used some gasket remover (about 5 times) and a plastic scraper. Good advice on the manual as well. Much good info there, and you can get one for about $50 on ebay.
Purdue_Boiler_Viper
Enthusiast
Ah, I get it. You just unbolted the manifold and propped it up while changing the Tstat at the front. I assume you relieved the pressure through the Schrader valve first.
BTW, Landman, remove your gas cap when doing this so that you don't build up pressure if your gas tank heats up.
Tony, why the 8 degree change?
I did loosen the manifold by removing the bolts that hold it down but instead of disconnecting the fuel line, map sensor, other connections and removing the intake from the engine I raised the front of the manifold about 2". This was enough room for me to work around the thermostat housing. I placed a scrap piece of 2x4 underneath the front of the manifold to hold it up.
No, I didn't relieve the pressure first and looking back I think I took a risk by not doing so. At the time, I didn't see the issue with not disconnecting the fuel line since I wasn't going to be touching the injectors or removing the manifold. It may have been a dumb move. Next time, I will follow the procedure in the service manual.
In another post, Tator says that the lower degree thermostat may cause the PCM to throw codes if the operating temperature is too low. This *may* be an issue in cooler climates but I'll find out as soon as the temps start to dip here. I'll ask Tator about this at his tech session this weekend.
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Racer Robbie
Enthusiast
Guys,
There is no need to remove the intake manifold. We have done a ton of these as described below.
This is a very easy install and the only thing you need to remove is the air box assembly as a complete unit. You remove the 2 fasteners on the front lip of the lower air box, remove the clamp on the throttle body hose, and unplug the air temp sensor on the air box by sliding the red clip out and undoing the connector. Remove the upper radiator hose at the thermostat housing. Next drain down the cooling system from the bottom of the radiator where you will find a drain plug. You do not need to drain the system completely. The remove the 4 bolts on the engine cross brace so that you can move the brace around. This will give you access to the 4 bolts on the thermostat housing so you can remove them and slip the housing aside enough to remove and reinstall the new thermostat. Put everything back together in reverse and then open the small vent on top of the thermostat housing and connect a long clear piece of tubing to it and put the other end into a clear clean soda bottle. Fill the soda bottle with antifreeze so that the hose is covered and then slowly fill the coolant overflow tank. You will see air burping out of the clear tubing into the bottle. I like to fill the tank all the way and let it sit overnight so that all the air comes out. You can then remove any excess coolant with a turkey baster the next day. Tighten the vent but do not remove the hose. Start the engine and allow to warm up until the thermostat is fully open and then crack the vent until you see no air in the tubing. Clean everything up and you are all set.
There is no need to remove the intake manifold. We have done a ton of these as described below.
This is a very easy install and the only thing you need to remove is the air box assembly as a complete unit. You remove the 2 fasteners on the front lip of the lower air box, remove the clamp on the throttle body hose, and unplug the air temp sensor on the air box by sliding the red clip out and undoing the connector. Remove the upper radiator hose at the thermostat housing. Next drain down the cooling system from the bottom of the radiator where you will find a drain plug. You do not need to drain the system completely. The remove the 4 bolts on the engine cross brace so that you can move the brace around. This will give you access to the 4 bolts on the thermostat housing so you can remove them and slip the housing aside enough to remove and reinstall the new thermostat. Put everything back together in reverse and then open the small vent on top of the thermostat housing and connect a long clear piece of tubing to it and put the other end into a clear clean soda bottle. Fill the soda bottle with antifreeze so that the hose is covered and then slowly fill the coolant overflow tank. You will see air burping out of the clear tubing into the bottle. I like to fill the tank all the way and let it sit overnight so that all the air comes out. You can then remove any excess coolant with a turkey baster the next day. Tighten the vent but do not remove the hose. Start the engine and allow to warm up until the thermostat is fully open and then crack the vent until you see no air in the tubing. Clean everything up and you are all set.
dave6666
Enthusiast
Sounds easy enough. But you say to tighten the vent back up but leave the clear tube on. Then what is the tube connected to on the t-stat housing at that point? There's a pipe plug in the housing and if that is reinstalled, then the hose ain't connected anymore. Or am I missing something here?
JiPi
Enthusiast
Robbie, you're talking about a Gen3, but the question was about a Gen2.
dave6666
Enthusiast
The mystery is solved... I will briefly feel smart again.
Purdue_Boiler_Viper
Enthusiast
Ahh, PCM throwing codes. Might be a problem in CT, but only if you have snow tires.
Let us know what Tator says. You'd also think someone might sell a PCM memory change that would use different temperatures to throw the codes. That would be easier than changing your Tstat.
Ahh, PCM throwing codes. Might be a problem in CT, but only if you have snow tires.
Let us know what Tator says. You'd also think someone might sell a PCM memory change that would use different temperatures to throw the codes. That would be easier than changing your Tstat.
...yeah $600 for a PCM reflash to change the temperature settings vs. $39 T-stat...I'll swap out the T-stat thanks.
PhoenixGTS
Enthusiast
One of the bolts holding the housing on broke off from corrosion when I did mine. Would have been impossible to drill the dang thing out without the intake manifold off.
viperdude118
Viper Owner
Did you have to take off the windsheild cowl for clearance?
I had the windshield cowl off at the time because I was installing AB's wires and needed to work behind the manifold and reach the coilpacks. If I were to remove the intake manifold completely from the engine I would leave the cowl on. If I were to prop up the manifold as I did during my t-stat install, it would hit the cowl and I would need to either loosen the cowl or remove it because it would be in the way. I have less than 1" clearance between the top of the manifold and the cowl.
topsnake
Viper Owner
Hello Tony,
I am a little confused to the bleeding of the fuel line. Isn't this done after turning the key a few times around without starting? That's new to me. I thought, this happens by it's own.
dave6666
Enthusiast
From memory...
You pull the fuel pump fuse.
Run engine until it starts to quit.
Something like that.
Parisianviper
Viper Owner
An answer to the same question by the Wizard:
The way I take the intake off is I only bleed the pressure off at the shrader valve on top of the manifold. Take the cap off, put a rag around it, then with a small screw driver push in on the valve. There will 50psi on the fuel system, so it will squirt pretty good!! Now when you disconnect the fuel line down on the left frame rail, all the fuel that is in the manifold will drain out [no open flames! EEK]. Un-plug all your injectors and then you can leave the wiring harness on top of the motor.
Coming off you can do it by your self but going back on you'll need someone to help you because you'll need to route the fuel line back down under the coil packs
Hope this helps?
Cheers
Chuck
Taking out the fuse will throw some codes,you'll have to erase.
The way I take the intake off is I only bleed the pressure off at the shrader valve on top of the manifold. Take the cap off, put a rag around it, then with a small screw driver push in on the valve. There will 50psi on the fuel system, so it will squirt pretty good!! Now when you disconnect the fuel line down on the left frame rail, all the fuel that is in the manifold will drain out [no open flames! EEK]. Un-plug all your injectors and then you can leave the wiring harness on top of the motor.
Coming off you can do it by your self but going back on you'll need someone to help you because you'll need to route the fuel line back down under the coil packs
Hope this helps?
Cheers
Chuck
Taking out the fuse will throw some codes,you'll have to erase.
viperdude118
Viper Owner
Did you have to disconnect the injectors to raise up the intake manifold, or was there enough slack in the injector wires to leave them connected?
No, I didn't have to disconnect the injectors or mess with any of the throttle linkage, etc. I only had to lift the front of the manifold up about 2-4". I'm going to be working on changing out the thermostat over thanksgiving. I'll take pics this time and post them when I'm done. For reference, if you can get yours hands on a service manual there's a detailed procedure for replacing the t-stat and removing the intake manifold. It's good to have handy when you're doing this swap so you'll know the bolt sequence for the manifold and as well bolt torque specs.
viperdude118
Viper Owner
Yep, already have the service manual and was looking through it last night. Seems like it tells you to take apart everything all the fuel lines, throttle linkages, etc......I think just to tip the intake manifold up like you say enough to get the T housing out, won't require quite as much dissassembly.
I would do the fuel pressure bleed procedure to be safe. Find something tall enough to prop up your manifold (like a 2x4) and wrap it with rags so nothing gets scratched. I wrapped a 2x4 with rags and rested it across the valve covers. The manifold sat on top of the 2x4. It worked well althought I don't remember if it was a 2x4 or 2x6. If for some reason this doesn't work for you, can move on and remove the manifold anyway. Good luck. Keep us posted.
01ACR/VIPER
Enthusiast
if you let the car sit overnight,there is very little fuel pressure left in the system.you can just break the line loose and it will bleed off quikly.
dave6666
Enthusiast
Changing your thermostat alone will not lower the running temps once the engine has warmed up.
viperdude118
Viper Owner
I know that it won't change the operating temps, but wanted to leave the option open later for a better radiator if I decide to do that. I was changing the coolant anyway and decided might as well switch the thermostat while I'm at it.
So I was also thinking of sending my pcm to you guys later on for a re-flash, but read where you need a 170 degree t-stat. I opted for a 180 after talking with C. Tator, he mentioned that a few of the people with 170's were getting too cold too long trouble codes stored. I didn't want that so I just went with the 180.
Is it mandatory to have the 170 for a re-flash?
viperdude118
Viper Owner
Finished this job today, overall pretty easy. I ended up pulling the intake completely off and replacing all the gaskets.
Used a dremel and dremel bit scouring pad to remove old gasket, worked really well and only took a couple of minutes to clean everything up.
Pulled out bleeder screw on the T stat housing and filled the system. Replaced the plug with a 1/8" pipe thread plug from NAPA.
Then used Tator's process for refilling the system. It was effortless, and got 99% of the air out before I even started the engine.
All this stuff about burping and this and that isn't really needed on a Gen II if you take your time and do this method.
