I've always drained / changed out my coolant by draining both the radiator and the block drain.

However, I realized that the block coolant drain is the LOWEST part of the system.

As such, I drained it from the block, with the fill-cap open, and blew it out with compressed air (about 30psi), and also attached my shop-vac to it.

I measured about 1.65 gallons was drained.

I assume the rest is in the coolant recovery tank.

Thinking I must drain the radiator as well, I checked the FSM (factory service manual) and it also just recommended draining at the block drain.

What's your take ? Any reason why I should drain the radiator as well when the block drain is the lowest part of the system ?

FWIW- I replace the coolant every year (Zerex G-06 with distilled water @ 70%).

:-) neil

 

Even though the block drain is the lowest part of the system, the lower radiator hose travels up hill to go to the engine block so you will not be able to drain all the fluid. Using compressed air to blow out the system i am sure helped but; Is it really that hard to remove your undertray and drain the entire system?

But, IMHO if you are changing your antifreeze every year there is no point in removing all the fluid out of the system because it is replaced so often. Think about it.. When you change your oil do you drain your oil coolers as well in order to get most of the old oil out of the system? I do not.


John

 

How many miles per year do you drive? Are you road racing the car? Changing the coolant that often seems like overkill.

 

Good point about the oil coolers.

Less than 2,000 miles per year. However, I take her to driving events and time-trials 4-5 times a year, and she is driven HARD with water-temps over 230-F in 100+F humid weather even with water-injection. 50/50 meth brings it down to 220F.

I'm prepping for a 3-day DE at VIR FULL-COURSE with time-trials both days!

:-) neil

 

^ I really think you are worrying too much about something that is not as important. You drain the antifreeze every year; the little bit that is left in the radiator or in the heater core IMHO will not matter. According to a quick google search the coolant capicity is 2.3 gal. you have just about a half gallon left in the system even less if you do not have an ast. or a little more depending what radiator you have.

Now, figure out how to get your coolant temps lower that is more important. What type of radiator and IC do you have?


John

 

Fluidyne radiator and ASP Medium intercooler. I think I need to work on ducting . . .

Also, I'm running the stock twin-turbos @ 14.5-psi. big heat sinks!

:-) neil

 

You may want to look into the remedy water pump as well as ducting Neil. I know ptrhahn said it dropped his coolant temp with twins 5 degrees Celsius. I know several others that have ran the pump that track and has improved cooling with twins. I also ran it on my single turbo track car, but my car always stayed at 84-85C on track before so I couldn't tell any difference, and my turbo was only oil cooled as I didn't want my water/coolant going through the extremely hot turbo.

 

I'm already running the RE-MEDY water pump!

Ducting baby . . .

:-) neil

 

IMHO, draining and refilling the coolant system once a year is a GREAT idea for ANY FD. Old coolant can corrode water passages and eat away the walls supporting the coolant seals, resulting in coolant seal failure.

Neil, doing the radiator drain and block drain is as good as it will get. You may still have a small amount of the old coolant in there but it's diluted by all the new stuff so it's not a problem. Also, keeping up on the coolant drain and fill will insure that even if you have coolant left in the system it's healthy coolant.

BTW, it's also a good idea to run distilled water. You can get a gallon of it from Wal-Mart for 70 cents or something. I get a jug of that and a jug of Prestone and it's good to go. Tap water has deposits and minerals in it that can build up in dead spots inside the motor. I've torn enough motors down and seen all the garbage that collects in those dead spots, it's worth keeping clean coolant in there.

Dale

 

I always use distilled water. I like the chemistry of G-05, and it's been keeping my Mercedes' iron and aluminum engines super clean compared to what I've seen "the green stuff" do.

Many makes have moved to a similar chemistry (nitrated HOAT) if not G-05 itself. The nitrite is intended to protect against cavitation, which is why it suggested for both gas and diesel passenger car use.

BTW: I also use a vaccuum coolant device. That is, it draws a 25-30in-Hg vaccuum, and then it slowly sucks in my 30%-coolant/70% distilled water mixture. You should see all the hoses "sucked" down".
This tool, along with the Lisle funnel, and I have not air-pockets after one warm-up to thermostat opening temp (heater on).

:-) neil

 

Neil, I always drain both the block and the rad.

What are you running for oil cooling? I've been monitoring oil temps at the filter pedestal and recently moved from the R1s up to the SakeBomb dual 25 row coolers. Even with the R-Magic ducts on my '99 spec front bumper, my oil temps got entirely too hot on a recent June track weekend...... 210ish constant with a peak of maybe 225 or so.

 

Why do you feel that's too high Rich? Just curious.