thermostat replacement procedure?

[valentine_viper]

I have the DC reflash and I need to change my thermostat to the 170. Looks like a fairly easy job, but wanted to see if there are any special tips I should know about that might make the job easier. Mostly, I'm concerned about radiator fluid leaking out in the engine compartment when I disconnect the upper radiator hose from the thermostat housing.

Any way to avoid a mess here?

Thanks for your help!!

 

[Shandon]

It was just messy when I did it. Not a big deal though. You will have to move the cross brace (********* bar) back to pull the housing back & get the thermostat out.

 

[Hamrhead]

I just did this 2 weekends ago. Not a bad job, but a little messy as usual when draining anti-freeze.

I jacked up the car and put a small hose on the radiator petcock, then drained it right into an empty gallon milk bottle (washed out of course). Petcock is on the drivers side of the radiator, and you only need to drain enough coolant so that's it's below the level of the T-Stat. 1 - 1.5 gallons should be more than enough. Some coolant 'missed' the bottle, but I put some newspaper down just in case.

I also removed the cross brace - 4 bolts. I suppose you could just loosen it and possibly squeeze the t-stat housing out, but IMO it's just easier to get the brace out of the way completely.

Otherwise, remove the upper rad hose at the t-stat housing, bend out of the way, and 4 bolts for the housing itself.

I reused my rubber o-ring gasket - just swapped out t-stats and started putting it back together that quick!

When reinstalling the housing, I found it easiest to install the hardest bolt (lower inside bolt) with the housing all at once. Just put a socket and a short extension on the bolt and spin it in while aligning the housing with your other hand. After that, the other 3 are gravy.

Once you get everything buttoned back up, you'll have to purge the cooling system to get the air out using the bleeder on top of the t-stat housing.

I managed to get all but a quart of coolant back in when I did mine. Took it for a drive and let it sit overnight. I was able to get the last quart in the next day.



What do you think of the DC Flash? I had it on my SRT Ram and really liked it. It's one of my next mods for the Viper.

 

[B767DRIVER]

Thanks for the info Hamrhead! I'm also installing the DC flash and thermostat tomorrow. I will dyno next week to see what the benefit looks like on paper.

 

[valentine_viper]

I just did this 2 weekends ago. Not a bad job, but a little messy as usual when draining anti-freeze.

I jacked up the car and put a small hose on the radiator petcock, then drained it right into an empty gallon milk bottle (washed out of course). Petcock is on the drivers side of the radiator, and you only need to drain enough coolant so that's it's below the level of the T-Stat. 1 - 1.5 gallons should be more than enough. Some coolant 'missed' the bottle, but I put some newspaper down just in case.

I also removed the cross brace - 4 bolts. I suppose you could just loosen it and possibly squeeze the t-stat housing out, but IMO it's just easier to get the brace out of the way completely.

Otherwise, remove the upper rad hose at the t-stat housing, bend out of the way, and 4 bolts for the housing itself.

I reused my rubber o-ring gasket - just swapped out t-stats and started putting it back together that quick!

When reinstalling the housing, I found it easiest to install the hardest bolt (lower inside bolt) with the housing all at once. Just put a socket and a short extension on the bolt and spin it in while aligning the housing with your other hand. After that, the other 3 are gravy.

Once you get everything buttoned back up, you'll have to purge the cooling system to get the air out using the bleeder on top of the t-stat housing.

I managed to get all but a quart of coolant back in when I did mine. Took it for a drive and let it sit overnight. I was able to get the last quart in the next day.



What do you think of the DC Flash? I had it on my SRT Ram and really liked it. It's one of my next mods for the Viper.

I just finished. I didn't drain the radiator first, but managed to catch most of the coolant in a plastic container. A little messy, but not too bad. How do you use the bleederon top of the t-stat housing? I just let it run a while with the pressure cap off the tank and added coolant back in as it ran. Took it for a test ride and seemed fine. How do you know if you have air in the system?

Also, the coolant temperature didn't seem any different. Still reads right at 180. I ran the DC flash for a while with the stock thermostat and got the exact same temp. Only difference now is the fan doesn't run all the time. Dan said I would wear the fan out if I didn't go to the 170 thermostat.

As far as the DC flash goes, much better than the factory tune. Car is much crisper on the throttle and generally runs better.

 

[B767DRIVER]

. How do you use the bleederon top of the t-stat housing?

My tech told me to open the bleeder with car level and fill tank until anti-freeze begins to run out.

 

[Hamrhead]

I just finished. I didn't drain the radiator first, but managed to catch most of the coolant in a plastic container. A little messy, but not too bad. How do you use the bleederon top of the t-stat housing? I just let it run a while with the pressure cap off the tank and added coolant back in as it ran. Took it for a test ride and seemed fine. How do you know if you have air in the system?

Also, the coolant temperature didn't seem any different. Still reads right at 180. I ran the DC flash for a while with the stock thermostat and got the exact same temp. Only difference now is the fan doesn't run all the time. Dan said I would wear the fan out if I didn't go to the 170 thermostat.

As far as the DC flash goes, much better than the factory tune. Car is much crisper on the throttle and generally runs better.

Basically what B767 said for bleeding. Open up the bleeder and see if any air bubbles come out. If not, you're good.

The DC Flash sounds similar to how it felt in my SRT Ram. Good thing, because I just ordered one for my Viper last night! (and a set of 3.55's from Unitrax today!! )

 

[Racer Robbie]

The most important thing here is that you drain the antifreeze from the bottom of the radiator and not at the upper hose or thermostat as you will induce air into the system. The cross brace does not have to be removed nor does the air box. You can un-clamp the air box hose at the throttle body, remove the 2 fasteners at the front of the air box, loosen the wing nut under the air box and then move it out of the way. You only have to remove the bolts from the cross brace, you do not have to remove it to gain access to the thermostat. To bleed the system attach a long piece of clear tubing to the bleeder screw on the thermostat housing and stick the other end into a clear container filled half way with clean antifreeze. Now you fill the overflow tank until there are no bubbles in the container. I let the car sit overnight so the air purges to the top and then I fill the system again.Once you start up the engine and warm it up to full operating temperature then crack the bleeder to remove the rest of the air. Remember to keep the clear tube in the container of antifreeze at all times. By the way it is a good idea to pick up an extra gallon of the proper antifreeze before changing the thermostat.

The antifreeze to use is:

Mopar Antifreeze/Coolant 5 Year/100,000 Mile Formula or an equivalent Extended Life Coolant with the Hybrid Organic Additive Technology (HOAT) inhibitor system.


Robbie

 

[Schulmann]

I just changed my thermostat. It took me an hour. It was a very easy job ( ... as soon as I removed the cross member ). The cross member is easy to remove.

My procedure was:
- Jack Viper (5 min)
- Drain radiator at bottom (5 min)
- Remove air box (5 min)
- Remove cross member (5 min)
- Remove the 4 bolts holding the thermostat housing (5min)
- Replace thermostat (1min)
- Reinstall everything and fill up water tank (25 min)

 

[Racer Robbie]

No need to remove the cross brace, just remove the bolts and move it aside a little bit. The most important thing is to burp the system as I explained above.

Robbie