This doesn't add up - Mazda MPV coolant replacement procedure

[rwl408]

I finally replaced my 2000 MPV coolant last weekend. Yes, it was over-due according to the maintenance schedule (36 months or 45000 miles). However that did not bother me that much but the coolant replacement procedure (from the OEM shop manual):
1. remove the radiator cap
2. un-screw the radiator drain plug to drain the coolant
3. flush the radiator with water until the water runs clean
4. screw the radiator drain plug
5. fill-in new coolant with the appropriate concentration
6. tighten the radiator cap
(a few more steps to purge the air trapped)

The problem was step 2 only drained 4.5 quarts of old coolant, out of a total capacity of 10.8 quarts! What that means is there still is about 60% of old coolant in the system. I seriously doubt that kind of mix will provide proper corrosion but what do I know. Interesting thing is that is exactly the same procedure I have seen in one dealer's ads for $59 the other day.

Since I wanted to replace the old Mazda coolant with Toyota red and no where in the manual I could find any indication of an engine block coolant drain plug, my only solution was to fill with distilled water and did the drain procedure repeatedly to dilute the old coolant further. I did a total of 5 times, which I calculated should have cut it down to 8%. To make thing complicated, I had to add some new coolan even after the 4th drain because I needed 5.4 quarts of new coolant in the system and that exceeded what it could take (4.5 quarts) per fill-up. Some math was needed to find out the exactly amount of coolant at the 4th drain since 40% of it would be drained out immediately in the 5th. Talking about fun for the Sunday afternoon.

 

[Papa Bear]

I took the upper rad hose off at the radiator and moved it over so it drained into a pan. Ran the engine and let the old stuff drain out as I refilled into the rad cap hole with distilled water. Shut her off when the fluid ran clear out of the rad hose and reinstalled the hose. Then I drained the rad (step2)and added fresh coolant.
I couldn't get quite enough fresh coolant in either so I ran it for a couple of days and drained out another liter (step2) and added a liter of concentrate coolant ( I kept the liter that I drained out as a "mix" that I can add later as a top-up in the reservoir). Bingo..new coolant at the right ratio.
Hope this helps.
P.B.

 

[rwl408]

Thanks, it certainly helps. I will do it this way next time around in another 5 years.

 

[Winston]

I do not understand how this would work. Since you are putting in cold water, the thermostat will ba closed and the coolant will not flow out the upper radiator hose. What am I missing here? Did you remove the thermostat?

 

[jmacmaster]

I don't like those instructions at all. As far as I know, there's two basic ways to do your own coolant system flush and antifreeze change.

A backflush kit from an auto parts store is one way. You put a T-shaped tube in a heater hose. You cut the hose and insert two ends of the tube. Then you hook a garden hose to the third end in the tube, take off the radiator cap, and turn the hose on. The hose water flushes out the system, out through the top of the radiator. When you're done you put a cap on the end of the tube that you hooked the hose to and leave the tube in place for later flushes.

As I see it, there's a problem with the backflush kit method. You use water from your garden hose. After flushing is completed, water from the hose is left in the engine part of the cooling system. Its best to use distilled water in your cooling system, because unlike water from the hose, it has no minerals in it that can cause problems. Yes, the problems are usually slight, and you CAN use hose water, but distilled water is better. When you fill the radiator so that half of what's in the whole system (engine and radiator combined) is antifreeze, you can use distilled water if you still need to add water, but you still have the water from the hose in the engine part of the system. For this reason, I don't backflush.

I use the second popular method. I drain the radiator, fill it with distilled water, run the engine until the temp gauge has gone up enough to open the thermostat and mix the distilled water that I added with what's in the system, turn the engine off, and wait 10-20 minutes. Then I do that again. Drain the radiator, top off with distilled water, run the engine till its hot and everything's mixed up, turn it off, and wait 10-20 minutes. Since in a typical vehicle, about half of the liquid in the whole system is in the radiator, each time you do this you drain about half of what's in the system. If you do this 5 times, after the 5th drain only about 3.125% of what was in the system (water plus antifreeze) when you started is left. This is negligible, and the system is flushed. You will see that after five cycles the liquid draining out of the radiator is clear, indicating that the flush is complete and there's little or none of the water or antifreeze that was in the system when you started left in the system. Then you can put in 50% antifreeze and, if necessary, top off with distilled water. Be sure to turn your heater on hot each time you do a cycle, so that the coolant goes through the heater hoses.

To determine how much antifreeze you need to reach a 50-50 mixture, simply consult the Owner's Manual for the engine coolant system capacity and put half of that amount of antifreeze in the radiator.

By the way, not all antifreeze is the same. Most antifreeze is either green (what most, if not all, vehicles USED to use), yellow, or gold in color. Most if not all late model Ford Motor Co. vehicles use yellow. Most if not all late model GM vehicles use gold (its called DexCool), and most if not all late model Chrysler products also use yellow. Most late model Japanese vehicles use green. There are certain other colors for certain other manufacturers. I found all this out after doing a lot of internet research a few weeks ago and I also found out that: (1) You need to use the color your vehicle came stock with; (2) You should not mix 2 colors together, because damage can occur and/or you may not get enough protection from heat and cold; (3) It is not recommended that you use the "universal", "mixes with and replaces any color", and "can be used in any vehicle" antifreezes now sold and being pushed by Prestone and many other antifreeze makers, and damage can occur if you do. Use only the color your vehicle came stock with.

The yellow was hard for me to find, as most auto parts stores don't sell it. I finally found some at Carquest. I can't remember who makes it. I think its Zerex. It says on the container what vehicles its for, including late model Fords. It is NOT cheap. I paid $18.08 for a gallon. I thought I was being smart and paying less than if I'd bought Mororcraft yellow-colored antifreeze from the local Ford dealer. I was wrong. I called the Ford dealer and they told me it was about $12.50 or $13.50 a gallon.

The green lasts the least amount of time. The DexCool gold colored lasts the longest, and yellow is in-between.

 

[rwl408]

Winston, I did just what jmacmaster said - the second method - and that was why it took me the whole afternoon. Sorry for not making it clear. I went for the method for two reasons. First the tap water will not sit well with the phosphates in the Toyata coolant. Secondly I tried to minimize the amount of old coolant mix that I had to collect and recycle. But with some modification to Bear's tap water method, it may work out. I was thinking about getting the bottles of distilled water lined up and using it, instead of the tap water, at the end of the flush. With someone to help, I think I can do it.

jmacmaster, the old coolant in my MPV was green. I used Toyota red because it has the same ingredients and cheaper - relative to what Mazda or Nission was asking. I paid $13.88/gallon (concentrated) when one dealer had it on sale.

 

[Test_Drive]

rwl408,
A slightly off topic question. What exactly are the specs for the MPVs coolant? I too own an MPV, although it is a 2003 model. The owner's manual only specifies "ethylene glycol" coolant, with no alcohol... which is not very useful.

What lead you to conclude that Toyota coolant is equivalent to Mazda/Nissan?

Thanks,
Test_Drive

 

[Papa Bear]

Winston said:
"I do not understand how this would work. Since you are putting in cold water, the thermostat will ba closed and the coolant will not flow out the upper radiator hose. What am I missing here? Did you remove the thermostat?"


This proceedure worked very well for me, the engine came up to temp and old coolant came out the top hose and drained into the pan that I had under the car. It only took a few minutes for the coolant to start running clear out of the hose. Be sure your heater control is set to max heat so the clear water is purging out the heater core as the engine is running. It is not necessary to have the heater blower on, just the control set to max heat.
When I removed the top hose from the rad, I put some masking tape over the hole on the rad fitting which allowed me to keep the rad topped up with distilled water as the old coolant came out of the top hose into the pan.
I did this proceedure as a drain & fill. The rad core was clean as a whistle when I looked down the rad cap hole and I didn't think a flush was necessary.
Using this proceedure I had no air lock problem and the levels were right on (reservoir and rad)after driving for 100's of miles.
P.B.

 

[rwl408]

test_drive,

Yeah, the manual doesn't tell much. My statement was based on the consensus knowledge that OEM coolants in Japanese cars contain phosphates but no silicates. Problem is no after market coolant (at least in US) has similar stuff and you either pay more to the dealers (for a peace of mind) or pick whichever after market coolant you think/reason the best substitute - OAT without both, HOAT with silicate, or conventional with both - and second guess your decision later. Some common recommendation is to use Zerex G-05 (HOAT with silicate) but personally I would rather go with OAT because of the presence of silicate.

How I ended up using Toyota red in MPV was simply the desire to use one single type of long-life coolant for the different makes of Japanese cars in the family that I maintain. I could have chosen Mazda or Nissan OEM coolant if the price was right. I used to use Prestone coolant and could have kept using it if I did not find Toyota red at $13.88. As a matter of fact, I put Prestone all makes all models coolant in my daughter's Toyota Corolla last May. That was after the guy at the dealer's parts counter told me that the over-priced $18 Toyota red coolant (with the big words "Long Life" on the label!) is only good for two years. Prestone was more attractive because of the 5 year life claim, not to mention the lower cost ($8.27 at Walmart). (Used coolant re-cycling is a hassle here. The only place I know about that doesn't charge a fee is the county harzard waste disposal program but only on a few certain days of the month and I have to make an appointment first.) Later I learned that Toyota red is actually HOAT type of coolant and should last longer than the convension ones. When I found a good price, I jumped on it and picked up 4 gallons - enough to cover my need for the next 5 years.

 

[rwl408]

quote:

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Bear said,
When I removed the top hose from the rad, I put some masking tape over the hole on the rad fitting

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Bear,

Thanks for this extra tip. It is important because of the way MPV cooling system was designed - radiator cap is not on the radiator but the "normally" coolant reservoir bottle. I used this method once but on a 14-year old car. With a newer car, I was so afraid of things might go wrong and chose the safer approach. I think it would if the radiator fitting is not plugged.

 

[BigOil]

I have a 2000 MPV as well. I saw the same pocedure in the service manual and decided it was "lame" (a technical term), and then took it to jiffy lube for an exchange (which I watched and sort of "supervised" carefully...these JL techs were competent actually...). The manual cycle flush add warm thing takes too long for me. The exchange uses the upper radiator hose and an adapter to swap old coolant into a tank and new coolant into the engine from another make-up tank as it idles ... simple with the equipment they have.

The MPV is not really very Japanese engine-wise it is a Cleveland-built USA Ford Duratec engine that uses conventional green coolant per spec. Mazda are Ford's better cars (!) but their Dealer network is rather poor...

 

[beanoil]

quote:

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Originally posted by Winston:
I do not understand how this would work. Since you are putting in cold water, the thermostat will ba closed and the coolant will not flow out the upper radiator hose. What am I missing here? Did you remove the thermostat?

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I have'nt seen a thermostat without a bleed hole to pass some water all the time. I'm fairly certain thermostats are not water tight when closed, but restrict the water flow more when closed, and less when open. BTW, I don't worry much about backflushing. Water seeks it's own level, so a backflush, and then removing the lower rad hose (lowest point) should get the system basically empty, short of some in the heater core. Then I refill with a 50/50 of whatever and distilled from the grocery, and replace the tee fitting with a brass "hose mender". I haven't had good luck with the caps on the tee's holding long term.