Finally...the weather is going to break a bit this weekend so I can get out in the garage and do some maint. on the vette!!!! I am going to be taking a few long distance trips this year and its been a few years since I changed the coolant so I figured I would start there, I changed 95% of the hoses a few years ago when i changed the opti.

I have done some searchs on the forum and it seems that most people remove the thermostat to do this. My question is: 1. if you remove the thermostat what do you put in place of the rubber gasket that normally seals the water neck to the water pump, will a regular gasket do the trick to seal this area for flushing?? 2. what i am planning on doing is draining the radiator, refilling with water, run engine, and repeat untill the water is clean. Removing the surge tank and overflow
tank to clean, drain the block by removing the knock sensors, re-installing everything finish my 6 pack and fill it all back up, am i missing anything??

Thanks In advance

 

I just got done with this and did a ton of research on this topic. I have less than 45k miles on my car, but have no idea of if or when the coolant was changed last. The overflow tank was NASTY!

1. I took the thermostat out. It allows the coolant to freely flow without having to wait for the temperature to get up to 185. You will probably get some coolant on you when you drain it and 185 degrees will hurt!! Just don't forget to drain about 1 gallon (according to the FSM) before removing the thermostat so that you do not get the Opti wet. As for the rubber seal, just tighten the bolt back down. I had no issue at all. Do not over torque them. I think it is 8 in-lb for the LT1 and 18 in-lb for the LT4 or just use common sense when you are putting them in. My Haynes manual went told me 18...but it is for the LT4...I have an LT1...SNAP!!!

2. I read about removing the surge tank and cleaning it and I think that would be a good idea. Especially if it is nasty in there. But (1) I forgot and (2) once I remembered, I tried to remove the hoses and it was such a PITA that I passed on it. But I flushed the system enough that it came clean.

First things first, go to the auto part store and grab some Peek (or Peak?) flushing agent. If you are doing a light flush, you drain a tiny bit of the coolant and then pour the bottle in. Then get the car to operating temp (185) and let it run like that for 20 minutes. If you are doing a deep clean, you let it run for 6 hours...about 1 week of operating for me.

Anyways
1. drain some coolant and put flushing agent in, run car for X amount of time.
2. drain the coolant and THEN remove the thermostat. Put the drain plug back in and thermostat housing back on.
3. Fill the cooling system with water. I used de-ionized water, some say using hose water is okay, but my water is really bad so I passed on that idea. Bleed the air out of the system from both sides of the intake, add water, bleed, add, and continue until you bleed a light stream of water. Make sure you cover the opti with towels or something while you are bleeding.
4. Here, I ran the car for 5 minutes or so. Usually waiting until the temp got to 110-115 tops.
5. Open the drain and slowly crack open the radiator cap. Heads up btw, the pressure/gravity shoots that stuff WAY out! Be ready to catch it.
6. Put the drain plug back in, fill the water according to step 3 and repeat. Repeat this until the water drains nearly clear. Each time I did this, I was able to drain and replace about 6 quarts at a time. There is about 17 quarts in the system I think (correct this if I am wrong). I ended up flushing about 12+ gallons on DI water before it came out clean.
7 Once you drain it and it comes out nearly clear, start putting the coolant back in, not 50/50. Do the math though. I think I ended up doing a 45/65 mix. Consider that 1.5 gallons drains at a time and that leaves X amount of water left in the system and when you put Y amount of coolant back in...it won't be 50/50. You may have to drain a tad bit more water and add a tad more coolant if this is a big deal to you. Or if you pull the knock sensors, you will probably drain more water than I did. Just do the math for the ratio when you are finishing things up.
8 DON'T FORGET THE THERMOSTAT!!! I did the first time and damn I was running cool!!!!

NOTE: I did not remove the knock sensors. If I recall what I read, people suggested this if your system was really bad, such as if your coolant had contaminants in it. If you do remove them, please take pics that are clearly identifiable, they are hard to find!

PS Get two 6-packs

 

You know with today's wonderful machine's that are out there, they have at car dealerships flush machines that will suck out all the fluid from system, and then fills it with new antifreeze. When they do to that way, there isn't any bleeding the system. There is no mess, that will make your engine compartment nasty looking.

While you are there, you might ask, if they have machine that changes transmission fluid if you own automatic. That machines sucks all the fluid out, and refills with fresh fluid.

 

Bobby Joe, THANKS for the reply, to clarify you took the seal off the thermostat and installed the seal without the thermostat (correct)

Yes I know, that is what i do with my daily drivers...But with the Vette I trust no one, If there is something i cant or wont do then I will take it in...But you see if I am not out in the garage working on the Vette smoking cigars and drinking beer. I would have to help the wife clean the house on saturday morning...So I will be in the garage hahahaha

 

I feel for you, I know how you feel, my man cave is mine, and the wife and her do list, stays in the house. Have fun.

If you decide to pull the thermostat out, for the flush, here is tip old timer gave me when I ran service dept. told me what to do to bleed the system. People are going to say different, but this best way I found to bleed mine, and had no troubles, in the years I owned the car, it was done just like that with no problems, and makes sense.
Before you reinstall the thermostat, take match book, and cut a very small piece and wedge it in the thermostat to keep it open just little bit. Cut it small. Then install, service the system and while the engine running that little opening you made in the thermostat is bleeding the system out, and when it get warm enough to open it just floats away, and since they are made biodegradable there isn't anything in your system.

 

SEIJack: I removed the entire thermostat, seal and all. No issues. I replaced my thermostat with one that has a larger opening and I had to swap the seal to the new one.

1bdvet: That way may work, but I wouldn't. When your system is running with a gap in the thermostat housing and no thermostat in there, I would expect the coolant to leak/spray out. Don't forget the Opti is under it!

All I did to drain it each time...actually, looking back I would do it like this. Open the radiator cap. Slowing crack open the drain plug on the radiator. The drain plug is located on the back side of the radiator, passenger side of the car. And make sure you didn't heat the coolant too much as to spray you when you open the cap. There is a 1/2 point that you can stop at. I had no mess this way.

 

Thanks Guys,

When I got home yesterday I looked in my stock take out/off box and found that I still had the original thermostat soooo. I took a dremel tool to it and did a few modifications so now I have a good tool to replace the thermostat with and do the flush without worrying about leaks from the housing...I will post pics tomorrow

I can not wait to get out in the garage and do some work...I have got spring fever BAD, we also have 6+ inchs of snow!!!!

 

snow...what's that?

 

This is how I did it with the truck and I would do it the same with the Vette...

You Tube

Works really well to flush the whole system and you can keep the thermostat in!

 

Now you are killing me...it will be gone this weekend supposed to be the the low 60's this weekend. SNOW: it's the stuff that I will not miss when I move to Florida in 15 years

 

dogfish246, bobbyjo and 1bdvet..Thanks for all the input. I got the job done on saturday!!!It was not a bad job at all, and since I did it myself I know it was done to my satisfaction. I ended up finding my old thermostat and altering it a bit so i know i would not have a leak when doing the flush. See the pics...This worked very well.

I ended up doing the procedure by 1.draining the radiator filling it and then opening the drain on the radiator and filling the system at the same time as in dogfish246 video. Since I did not have access to a hose i filled the system with a bucket this worked very well. 2. Once the water all ran clear. I drained the whole system Radiator, overflow bottle, and pulled the knock sensors. 3. I removed the can at the base of the windshield that the heater hoses connect to and flushed it out in the utility sink. I would consider this a very important step!! It took me almost 30 minutes of running water thru the can shaking it and draining and repeating before it ran clear. You really have to shake all the particals loose before it is really clean. 4. I installed all cans and knock sensors and re-filled the system...What a fun day, and the weather was in the low 60's

p.s. each time you add and drain the system let the engine run 5-10 minutes to circulate the new water thru the system.

On to the next project...replacing all the door and roof seals

 

Nice work! and great idea!