Remove T-Stat for Cooling System Flush?

[The Critic]

I will be performing a coolant flush on my Saturn this Thursday, and I was thinking about removing the thermostat to speed up the process. However, as part of the coolant flush, I will be adding Prestone Super Radiator Flush to the system. I am concerned that without a thermostat, the engine may not reach its normal operating temperature. As a result, could this affect the cleaner's ability to do its job?

I ask this because GM used to have a service procedure for cleaning severely neglected cooling systems. The procedure was outlined in a TSB and it involved using a two-part Prestone Heavy Duty Cleaner. In the TSB, it stated that proper engine temperature was extremely important as the flushing procedure was reliant on heat as a catalyst in order to be effective.

My cooling system only has minor buildup, so my situation is not as severe as the ones that are covered by the TSB. Besides, the product that I'm using is only sodium citrate (citric acid?), not the heavy duty stuff that was used in the TSB. Still, I don't want to waste my money. So, is normal engine coolant temperature necessary for the Super Flush chemical to do its job?

Thanks!

 

[Audi Junkie]

Definately pull the thermostat.

 

[Shannow]

Hard to answer conclusively.

Need to see how the cooling system works, whether it's got a cold end function etc.

If it's a simple system, then you can pull it, and block off the radiator to get the temperature that you need.

 

[mechtech2]

Pulling the T Stat is correct.
A total pain, but how else will the relatively cool coolant circulate to effect it's cleaning?

That said, only clean it chemically if you really have a need. Normal maintenance of changing to fresh coolant is not enough need.

 

[dishdude]

I vote for pulling and replacing it also. How old is the car? Why not just do a drain and refill if it isn't a neglected system?

 

[Audi Junkie]

Be shure to reverse flush with a garden hose inserted into the lower rad hose....etc.

 

[c3po]

I always do this on my small block chevy and I get the coolant flushed quicker.

I would rather take the chance of slightly warmer coolant coming out since when I change the bucket I do not have to worry about hot coolant irritating my hands.

 

[Bamaro]

If you are worried about it getting hot enough, temporarily block part of the radiator with some cardboard.

 

[The Critic]

I'll take out the thermostat. Thanks for the advice.

 

[moribundman]

Originally Posted By: The Critic
I am concerned that without a thermostat, the engine may not reach its normal operating temperature. As a result, could this affect the cleaner's ability to do its job?


I use citric acid to clean scale from my coffee machine and my water boiler. Works best with boiling hot water. I presume coolant system cleaners will also be most effective in hot water.

 

[The Critic]

Originally Posted By: moribundman
Originally Posted By: The Critic
I am concerned that without a thermostat, the engine may not reach its normal operating temperature. As a result, could this affect the cleaner's ability to do its job?


I use citric acid to clean scale from my coffee machine and my water boiler. Works best with boiling hot water. I presume coolant system cleaners will also be most effective in hot water.

Tried it with hot water. 22 ounces of Super Radiator Flush and 6.4 quarts of water yielded a very foamy mixture that was brown when I drained it. Yuck!

 

[Jonny Z]

This brings up a question: how do the coolant flushing machines the shops use, do a complete flush without having to remove the t-stat?

The coolant flushing machine connects to the upper rad hose. The fresh coolant is driven in by compressed air and the new coolant, in turn, purges the old. With new coolant going in and engine off, I can't see the t-stat remaining open during this process.

 

[StevieC]

I have never flushed and filled the coolant. I just drain out whats in the radiator every 2 years and refill with 50/50 mix and then repeat in another 2 years. I have never had a problem and have driven many miles on vehicles with original radiators/water-pumps... I don't think a flush is necessary if you keep your coolant always fresh and topped up. Just my $0.02.

 

[Ben99GT]

Originally Posted By: Jonny Z
This brings up a question: how do the coolant flushing machines the shops use, do a complete flush without having to remove the t-stat?


It's simple, they don't. Those are half-assed procedures, it is no comparison to a good flush w/o a t-stat. They leave a ton of old coolant in the engine.

 

[SHOZ]

I just leave the cleaner in and drive out on the highway for a hour or so. Never had taken out a t-stat for a flush.

 

[Crashbox]

Yeah, for a thorough flush I'd pull the 'stat. Thanx for the reminder

IIRC the two-part HD cleaner is oxalic acid (cleaner) and sodium carbonate (neutralizer)... Hmmm... I've got a few pounds of BOTH somewhere in my house from my B/W photography days... Time to do the '77 Chevy again.

 

[benjamming]

sodium carbonate is a degreaser as well, working better at higher temperatures per typical