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What do you think was the primary cause?

  • Belt failed and took out water pump

    Votes: 1 10.0%
  • Water pump failed and took out belt

    Votes: 4 40.0%
  • Silicates in green coolant took out pump bearings and in turn belt

    Votes: 2 20.0%
  • Classic "Chicken or the Egg" who-dun-it

    Votes: 0 0.0%
  • Teamwork: Belt, pump, green coolant, with a pinch of service neglect

    Votes: 4 40.0%

  • Total voters
1 - 9 of 9 Posts

4 Posts
Discussion Starter #1 (Edited)
This thread should be one-stop shopping for any working on the timing belt or coolant on a Toyota/Lexus 1MZ-FE motor. It contains links to info already written in better or greater detail rather than repeating it here.

1MZ-FE Carnage: Timing Belt & Coolant, A Cautionary Tale

The patient, a 2000 Toyota Avalon with VVT-i came to me with a broken timing belt. Actually, due to that, I came to it. This is what I removed in stages, including unspooling belt yarn off half the width of the crank sprocket. This is most of it.

I can only speculate as to the age and mileage of the former belt.

Here is one of the vertical bolts connecting the engine mount plate for the rubber dogbone to the lower part that bolts to the motor. Steel and aluminum shook hands. Steel kept some skin. I was able knock the aluminum out curl by curl and clean the threads. The bolt held specified torque so I did not helicoil.

Here is the water pump. Note its shaft is off axis with reference to studs and shafts.

Here it is from a different angle. I was not able to turn it by hand at first as if seized. Later, I could turn it almost 360 degrees with a wiggling shaft indicative of bad bearings before it would jam again.

Keep reading...


4 Posts
Discussion Starter #2 (Edited)
Here is another view. I removed the coolant reservoir (jiggle it up with lid on) and power steering reservoir (three bolts, 10mm socket). I disconnected the power steering hose at the pump which was kind of tricky to catch the outflow, but not as tricky as removing the two band clamps. You can see one on the hose at the bottom. Imagine trying to remove two of those hose clamps, one with all three release tabs that you would squeeze together with pliers broken off, the other somehow interlinked like magician rings, and trying to remove them to get the hose off between the fender well, fire wall, motor, drive shaft, and so on.

There was oil on the very tip of the dipstick. That didn't indicate the level as it was only what it was scraping off the sides of the dip stick tube. I added a 1/4 gallon the owner had. No change. Added a 1/2 quart I brought. Maybe a change but hard to tell. Owner provide a bottle of vintage 20W50 as it was all he had handy saying he would do an oil change the following day. That quart got it up to the low mark (hole) on the dipstick with the front right axle on a jack stand.

Haven't seen one of these in a while.

While we're taking photos, this is what I drained out of the engine block (front and back) and radiator. Looks low and brown which I first thought might be rust, but after sitting I didn't notice much sediment.

I was expecting around two gallons or so to drain out ("coolant capacity ... 9.8 quarts US") but only got about 3-1/2 quarts. My first thought was to wonder if was run while low on coolant, but I didn't check the level prior to draining, and drained before pulling the water pump. Upon asking, owner said he didn't see any leaks or steam when it died. I doubt the old pump would hold it's shaft seal, much less under 10-15 PSI, but no way of knowing the coolant level, before, running up to, during, and while towed after the timing belt went. Didn't spot any leaks in the system with the new pump.

I noticed it had a green hue when draining, but when held up to the sun (or in this case with a shop light behind it) it had a red hue at the top.

I asked the owner who said he just added "the green stuff" thinking keeping the coolant filled was good maintenance. No way of know which "green stuff," but the common stuff can contain silicates. I think of silica, and sand, and liquid sand paper designed to scour the insides of iron engine blocks clean.

TRICK: Flush Focus
When draining successive rounds of distilled water after running the engine a few minutes, that from the radiator was noticeably clearer on the second round compared to that from the engine block, especially the front. To save some time and water, one could focus on the engine block and heater core (was blowing hot) until it's as clear as the last radiator drain.

Keep reading ...


4 Posts
Discussion Starter #3 (Edited)
Here is the backside of the old water pump. It is gouged along one side. Owner ordered all factory Toyota parts including belts (timing, power steering, alternator), Koyo bearings for idler and tensioner, and Aisin water pump. The new hydraulic tensioner was a Lexus part with mount holes perpendicular (sideways) to the body instead of inline (vertical), so I put the old one back in per the owner, though I advised ordering the correct one and replacing it too which is simple compared to the rest of the job.

Note the gouge and wear.

Here's the engine block rear drain plug. I didn't locate a nipple to attach a hose like on the front side and at the radiator, though apparently there is one (see links). It is quite the awkward specialty bolt and aluminum too.

If it begins to round, get a new one. I used a specialty socket to extract and a box lined with a trash bag as a catch basin. Owner said go with it so I only snugged it lightly as if the head rounds more you'll have a devil of a time getting anything up there. It takes about a 10" extension and a 14mm six-point socket (do NOT use a 12-point).

If you have trouble locating one, try searching for the following:
"90910-09104" or "9091009104" plug
"96761-19004" or "9676119004" o-ring
"96761-19006" or "9676119006" ???

Keep reading...


4 Posts
Discussion Starter #4 (Edited)
There's coolant specs, ratio math, and more at the end.

This parts diagram shows that back plug and nipple as part of the EGR system, hence draining may be different with blocks with different emission packages.
(If you don't see any images, just do an image search for "Toyota 90910-09104" or "Toyota 9091009104" and you'll get an idea.)

Here's another diagram to help locate the plug.

And here's one relating it to photos from Rob4226. Please go to his thread for the full photos in full size.

Tips, Tricks, and Links

at a minimum I suggest getting a new timing belt, water pump with seal, idler pulley, tensioner pulley, tensioner, seals for camshaft sprockets and crankshaft, 1-2 gallons of coolant*, and then be prepared to spring for that back plug.

SUPPLIES & TOOLS: In addition to what others suggest, I found a two-foot (60cm) section of 9/32" (~7mm) rubber vacuum hose works well if you want to relocate it, or buy double that and cut to length for tap-to-jug for each of the three points if you want to leave them in place (away from exhaust pipes) while flushing. Six-point sockets in 8, 10, 12, 14, 17, and 22mm. I was able to brace the flywheel and cam sprockets/damper without any special tools via creative use of strong points, levers, and tools on hand of "just the right" length, strength, and shape. Applied physics is cleverly simple when successful, and Rube-Goldberg-stupid when it fails, so I'll not tempt liability with further description.

TRICKS: The water pump studs were not a problem on the Avalon. You remove the long top bolt for the lower engine mount over the water pump, free the other, then slide it back, tip the top toward the motor, and if it is far enough back on the studs you get the radiator side (right) one off, then swing it up and slide it off the other. Same for water pump. I never had to jack the motor and the stands were on the frame.
The rear cam seal is the hardest, so hone your technique on the front one. If you can bend enough of the face of the seal out, then hit it radially to cave in one side (careful not to nick shaft or bore), it frees up nicely.
The crank has two timing marks: the one outside the belt on the flat sprocket against the motor goes up (12:00) to the motor mark, and the one inside on the face of the belt sprocket goes right (3:00) to the dashed line on the belt.
Clamp the belt to the crank, then water pump, front cam (radiator), clamp it, back cam, clamp it, then rest. Turn the cams CW a bit to match up the line, then let go back CCW to take out slack.


COOLANT CHANGE/FLUSH LINK: drain plug location photos)

* The amount and type of coolant fluids depends on the job.
to 2005: Toyota Long Life Antifreeze Coolant p/n 00272-1LLAC(-01) in RED sold as concentrate** for 2 years -or- 30,000 miles (whichever first) and must be mixed with distilled water
2005 on: Toyota Super Long Life Coolant p/n 00272-SLLC2 in PINK sold as pre-mixed 50/50 for 5 years -or- 150,000 miles (whichever first)
Some say you can mix the two a little (to top off) or a lot, that there is one-way or two-way (pink -> red, & red -> pink) compatibility, and plenty of threads like this discussing it:
This vehicle was put back to RED (Pentafrost A1 by Pentosin, concentrate, at $10/gal) as it is a 2000 Toyota Avalon with VVTi and it coolant tank labeled for future reference to avoid complicating matters.
(Had I not found that A1, the other local options were Toyota LLAC concentrate from the dealer or this Valvoline/Xerex pre-mix for $13/gal at wallyworld rated as LLAC and SLLC compliant for about the same net cost.)

My recommendations for what to have on hand are as follows
Water Pump Replacement: just draining just both sides (~3 front, ~1 rear) of the block to replace the water pump = 4 quarts - (1 gallon USl)
Draining/Replacing Coolant: for draining the block and radiator = 2 gallons
ing the whole system (block and radiator)
Flushing: 3-8 gallons of distilled water and 2 to 2-1/2 gallons (10qt) of coolant. The system is rated at 9.8 quarts (US) but unless engine block, radiator, heater core (passenger compartment), thermostat, reservoir, and all related hoses and passages are bone dry, you'll have a hard time actually putting in 2 gallons. My experience was about 3+ qts at the motor's front plug, ~1qt at the rear, and ~2qts from the radiator at each drain. If using RED you can calculate the presumed remaining distilled water and add accordingly, but for PINK this means amount of water in your system will always be less than 50%, which may be bad, or good.

** 50/50 or 60/40 or 30/70???
Here's the scenarios, stats & math:

The best ratio of coolant (
ethylene glycol, etc.) to water is like picking your poison. Water has the capacity to carry a lot of heat energy (1.00 †), but will freeze and crack your engine block below 32°F while boiling off at engine temps above 212°F. Coolants stay liquid over a wider range of temperatures, but can't carry as much heat energy (0.56-0.60 †).

Lastly, coolant doesn't raise the boiling point like it lowers the freezing one. Boiling points rise as pressure increases (water boils at higher altitudes faster than lower) which a capped system allows. Avoiding leaks and faulty radiator caps raise coolant's high end, with radiator caps rated 15 PSI common.

So, going heavy on the coolant(/water) with 65% can get the freezing point -60°F and boiling point to 240°F but you'll likely see motor that runs hotter (and a radiator that...). There's recommendations for Camaros and Nissan GTRs (which generally don't plow snow) to go the other way with 70% water for better cooling. If you add one gallon of concentrate (or two gallons of 50/50) to a system flushed with distilled water that has a 9.8qt US, you're ~40/60 (coolant/water) mix has a freezing point is -12°F (versus -34°F with 50/50), which is fine for Florida but not North Dakota. So a little bit of fudging can be ok, even desired for some climates.

For PINK (50/50) coolant, if my math is right, for a 10qt system with 2qt distilled water trapped, adding 2gal of 50/50 will eventually mix to
40/60 (coolant/water) good to about -12°F. Here are three different PINK examples, and one RED, of ratios achieved under ideal mixing conditions (engine block, radiator, heater core, fully open thermostat, etc.). If driven long enough to fully mix and circulate and then...
1. drained 2 gallons and refilled with another 2 gallons of 50/50, it will eventually mix to a ratio of
48/52 (coolant/water) good to about -30°F. Repeating mix/drain/refill with 2 gallons again will mix to a ratio of 49.6/50.4 (coolant/water). If your could be parked near -12°F, it's worth bumping closer to the -34°F of 50/50 the first round, but a measly 1.6% more the second.
2. drained 1 gallon and refilled with another 1 gallon of 50/50, it will eventually mix to a ratio of
44/56 (coolant/water) good to about -20°F. Repeating mix/drain/refill with 1 gallon again will mix to a ratio of 46.4/53.6 (coolant/water). So if you only have one extra gallon of 50/50, that extra 4% can help, but if you have two gallons, it's best to do them both at once rather than sequentially.
and lastly
3. let's try this for a 9.8-quart system that only drains 7 quarts (1-3/4 gallons) so traps 2.8 quarts and PINK 50/50. Starting with 9.8 quarts of distilled water, draining 7, then filling with 7 of 50/50 pink would mix to
35.7/64.3 good to only about 0°F and is also pushing it even by Camaro standards (remember there is other protective additives in coolant you don't want too watered down). Draining 7 quarts off that and refilling with another 7 quarts of 50/50 will mix to 46/54 which will be good to -20°F, enough for most drivers, and if you've bought 4 gallons (16qts) you'll still have 2 quarts left for topping off and the reservoir tank after two 7-quart fillings.
4. let's try this for a 9.8-quart system that only drains 7 quarts (1-3/4 gallons) so traps 2.8 quarts and RED concentrate. Drain 7 quarts (or just 4qt if really stingy), then fill with just 1 gallon (4qts) of red concentrate, and topping off with distilled and you get 40.8/59.2good to about -12°F. If you added just another 0.8qt of concentrate, you'd be at 50/50 and good to -34°F.

Four gallons of PINK at $23.97/gal and 8% sales tax:

One gallon of RED* at $10.00/gal, -10% store discount (I didn't even ask for it), and 8% sales tax:
* Pentosin's Permafrost A1 on closeout by Autozone.

Want more math?

S = system capacity
D = amount that drains
R = un-drained fluild that remains, S - D

For RED (concentrate) coolant, you can subtract the last drain amount (D) from the capacity (S, e.g. 9.8qt) then add that of amount (R) of pure concentrate, then fill the rest from there with RED 50/50 mix. If you do not see why many people prefer to deal with concentrate, aside from saving money mixing it with water themselves (usually 1:1), continue reading.

For PINK 50/50, some more math is required to figure out your coolant
S = system capacity
D = amount that drains, amount that is added
R = un-drained fluild that remains, S - D
PC% = prior coolant percentage

[(D/2)+(R*PC%)]/S = coolant percentage
Use (D/2) for 50/50 mixes, (D) for concentrate, and (D * X%) for any other ratio of X coolant / 100-X water ratio.

So for a 9.8qt system that only drains 7qt, the math looks like this adding 50/50 following a distilled water (0/100) flush:
After the first round ...
[(7/2)+(2.8*0.00)]/9.8 = [(3.5)+(0)]/9.8 = [3.5]/9.8 + (0) = 35.7 percent, cutting it close
And after the second round ...
[(7/2)+(2.8*0.357)]/9.8 = [(3.5)+(1)]/9.8 = [4.5]/9.8 + (0) = 45.9 percent, pretty good
And after the third round ...
[(7/2)+(2.8*0.459)]/9.8 = [(3.5)+(1.286)]/9.8 = [4.786]/9.8 + (0) = 48.8 percent, nearly even
And the fourth ...
[(7/2)+(2.8*0.488)]/9.8 = [(3.5)+(1.366)]/9.8 = [4.866]/9.8 + (0) = 49.7 percent, diminished returns
And the fifth ...
[(7/2)+(2.8*0.497)]/9.8 = [(3.5)+(1.392)]/9.8 = [4.892]/9.8 + (0) = 49.9 percent, arguably Pyrrhic

This page goes into more on measuring concentration ratios.

What's the math when flushing out bad stuff?
Might as well cover get a fluid out of the system such as if someone filled it with GREEN coolant, right? So let's look at how much distilled water it will ideally take, if fully circulated and mixed each time, and all contaminants are in suspension versus in the process of un-depositing. For this example we are trying to get the GREEN coolant mix (and any gunk) from 100% to 0%

S = system capacity
D = amount that drains, amount that is added
R = un-drained fluild that remains, S - D
PC% = prior coolant percentage

(R*PC%)/S = percentage of old stuff left

So for a 9.8qt system that only drains 7qt, the math looks like
[(9.8-7)*100%]/9.8 = [(2.8)*1]/9.8 = [2.8]/9.8 = 28.6% left after first round. (2.80 qt.)
[(9.8-7)*28.6%]/9.8 = 8.16% left after second round. (0.80 qt., or 25.6 fl. oz.)
[(2.8)*8.16%]/9.8 = 2.33% left after third round. (7.32 fl. oz.)
(2.8/9.8)*2.33% = 0.67% left after fourth round. (2.09 fl. oz.)
0.67% = 0.19% left after fifth round. (0.60 fl. oz.)
(2/7)*0.19% = 0.054% left after sixth round. (0.17 fl. oz.)

How Toyota Red LL and Pink SLL differ
And no, pink is NOT just diluted red

Ingredients listed from greatest percentage to least along with their CAS number. They have the same first three (PINK has more water as a 50/50 pre-mix)...
Water (7732-18-5)
Ethylene Glycol (107-21-1)
Diethylene Glycol (111-46-6)
Water (7732-18-5) ^

... but differ on Benzoic versus Sebacic acid, though there may be other unlisted "proprietary" ingredients.
Organic Acid Salt* (532-32-1)
Sebacic Acid* (111-20-6)
Hydrated Inorganic Salt (1310-58-3)
* Sodium benzoate added to water becomes Benzoic acid. A Sebecate is the product of a Sebacic acid interaction.

Rather than trying to figure out the compatibility with all the possible metals, plastics and seals, the safe bet is to stay with what your vehicle came with, not mix types, and repeatedly flush with distilled water per the above if switching.


Super Moderator
12,804 Posts
Nice work! I added this to the DIY sticky.

Man, the neglect these Toyotas will tolerate! I bet the spark plugs are still the originals too!

2001 Avln, 2009 Taco
176 Posts
WOW! Great writeup and pictures too!

FWIW, I switched from Toyota OEM Red + distilled water ($0.89/gallon @ Walmart) to Toyota OEM Pink when I did the timing belt and water pump on my '01 Avalon in 2016. When I bought the car in 2012 one of the first jobs that I had done was a coolant change. The coolant that came out was pink-ish, so I did not flush.

I noticed that Toyota OEM Pink has a YELLOW top, and Toyota OEM Red has a RED top. I bought 1 bottle of Toyota OEM red, and cut it with 50% distilled water and refilled the two yellow top bottles.

2001 Avln, 2009 Taco
176 Posts
Thanks for the PM warning that Toyota Red and Toyota Pink are NOT THE SAME!

User BigD1 at bobistheoilguy summed it up with this pic;

It looks like Zerex Asian Vehicle Long-Life Formula is equal to Toyota Pink. While Zerex G-05 HOAT comes close to Toyota Red, it contains silicates, so there is no equivalent to Toyota Red.

Look in sig
8,665 Posts
There is some very good information. Props! I've been busy lately, but I all got something special for y'all.

I'll edit this with the link to the new thread in a bit.
1 - 9 of 9 Posts