Water Pump Failures - Fact or Misdiagnosis

[jp213a]

The water pump failures reported on this board are typically discovered when the timing belt is replaced. During the tear-down to replace the timing belt, small amounts of dry anti-freeze residue are found on the outside of the water pump housing. This is sighted as “evidence” of a leaky water pump shaft seal so the pump is replaced. But is this evidence of a leaking seal or completely normal? The water pump is constructed with a weep hole. The designers wanted minute amounts of coolant to travel along the impeller shaft where it passes through the seal to keep the seal lubricated. The shaft is machined (ground) to a specific degree of roughness to carry the correct amount of coolant through the seal for proper lubrication. A small amount of coolant reside on the outside of the housing is normal after 90,000 miles or more of operation.

Due to the huge amount of labor required to change a water pump on the 2UZ-FE engine, it is understandable why some owners elect to change the water pump with the timing belt as a precautionary measure because the additional cost is only $250. The purpose of this post is to help owners make an informed decision on replacing a water pump with the timing belt instead of succumbing to scare tactics used by dealers and mechanics that point to coolant reside as evidence of an imminent water pump failure.

I didn’t change the water pump with the timing belt and the original pump now has 153,000 miles. I do change the anti-freeze every 35,000 to 50,000 miles. The anti-freeze contains a water pump lubricant additive so this keeps the additive “fresh” so it can do its job.

 

[FirstToy]

jp,
this is common on alot of different vehicles, not just the 100. When changing the timing belt, change everything within gunshot that has to come out anyway- water pump, acc belts, etc.

the cost to replace is in labor, as you say, so to replace this stuff while doing the TB is minimal added expense and peace of mind PM.
The last thing you want is to change the TB and have your water pump go out 10K miles later... JMHO.

 

[donco]

I changed my t-belt & water pump & idlers at 100k miles. It had been leaving a slight puddle from a "mystery" leak before that for many 10's of k-miles. Now with a new pump, the leak is gone. The water pump impeller shaft pulley also doubles as yet another idler for the t-belt and being that far into it, I was not willing to trust it for another 100k miles. Between 2 new idlers and a new water pump, the slight knock it used to have at start-up is gone, can't say it was from the old water pump or old idlers. I will automatically put new idlers and water pump in at 200k the next time it's due, regardless of what the old water pump will look like at that time. The extra $130 amoritized over 100k miles is down in the noise.

 

[Tinkerer]

Good questions about the significance of the water pump weep hole residue.

I left my original pump in when I changed the timing belt at 89k.

Pump had slight trace of dried residue at weep hole. (I didn't change it because it was Saturday PM and I didn't want to wait to get a new pump during the week and finish the job the following weekend.)

Now at 103k with no significant leakage, yet.

It would be instructive to know whether fairly new & low-mileage OEM pumps also have coolant residue at weep hole. Has anyone looked?

It could be that a trace (very slight) amount of coolant leakage past the seal is considered normal, for reasons mentioned by j213a. Has anyone cut open a pump to see how the seal is made?

Meanwhile, if my pump fails (with significant leakage), I'll post here, for reference.

BTW, one thing that should be done to prolong the pump life is to always use only distilled water with the coolant mix, and change the coolant at prescribed intervals. (Some folks don't do this...)

 

[mtycruiser]

Without going too deep in the analisis, I have not actually checked on the design of the seal, I tend to agree with JP123a. I does not make any sense that with all the overengineering we see everywhere else on the truck, a water pump will fail or malfunction in 90K or less.
Having said this, I did change mine when doing the TB at the dealer, because of the "fear factor" and what might have been a "misdiagnosis" or mis-interpretation of the slight leak around the weep hole. I did not changed the idler pulleys and was not planning on doing the WP, but got a call from the dealer telling me the WP was leaking and strongly recomended the change.
Now the thing is how do we gather the facts about the real expected lifetime of the WP? Is the leak around the weep hole a failure, or "normal" ?
What's the life expectancy on the idlers?

 

[Landpimp]

on every cruiser I have had, when stuff is coming out of the weep hole.....it will keep coming and its not suppose to, yeah I drove our 62 with a weeping waterpump for 5K......never really got worse....but didnt get better.

Me....if its weepin.......I'd replace it......AFAIK they are not suppose to weep

 

[Jim_Chow]

I replaced the water pump on my 4runner at 125K miles and 16 yrs. It wasn't leaking or anything, but a reman OEM one was only $50 with $0 in extra labor (it's on the outside of the timing cover), so it was a no-brainer. I inspected the parts afterwards. The bearing on the old one wasn't very smooth compared to the new one. That's the only thing I noticed.

 

[LEXUSBEN]

Here is my .02. I tell customers the decision to replace the w/p while doing the t/b is entirely up to them. It doesn't matter to me if it is replaced or not. But if you do not you're betting that it won't fail before 180,000 miles. That is alot of miles on a w/p. And if the pump fails odds are against you that you are going to bend valves. About the only place this won't happen is if you're sitting at a stop light and the pump comes apart ruining the t/belt in the process.

Personally on my own truck. It gets replaced when the belt gets done & my labor is free. There are some things that are worth doing pm.

As far as i've ever been told the weep hole is a direct passage to the w/p front seal. If you have coolant coming out of the weep hole the seal is leaking. The
extent of the leak or coolant trail is always arguable. 2UZ's don't always leak out the weep hole, I've seen many leak on the other side of the pump where it mates to the block. Got to take if off to fix, might as well put a new one on.

 

[Tinkerer]

<snip> And if the pump fails odds are against you that you are going to bend valves. About the only place this won't happen is if you're sitting at a stop light and the pump comes apart ruining the t/belt in the process.

<snip>

I've never heard of a catastrophic water pump failure where the unit actually falls apart, such as might lead to timing belt being dropped & resulting valve impact.

Has anyone else seen credible information that this has happened?

The only thing I've ever witnessed or heard of failing, in a water pump, is the seal: It will eventually start leaking enough that the pump will require replacement. Then, it is replaced to stop the coolant leakage problem, but not because the bearing/shaft are near failure.

Dunno for sure about the pump on the 100 series, but knowing Toyota, and knowing the application, I would bet that it will not fail catastrophically before the seal fails with significant leakage. (A catastrophic failure might be expected of a design produced by "The Three" (formerly "The Big Three"), but not Toyota.)

Anyway, gimme several more years to drive it up to 180k miles...I'll post if it fails before then. hehe

 

[FirstToy]

just a quick Q- assuming the 100 water pump impeller is all metal- they didn't change this to plastic did they? I highly doubt it but if it is, just another reason to swap it out whenever convienent.

 

[donco]

The original pump from my '00 LC 100 has a plastic impeller. The new replacement pump from Toyota is also plastic. You can see that the plastic impeller is molded to an intermediate brass hex sleeve which I assume is press fit to the steel shaft. As long as no stray chunks get ground thru the vanes and as long as the engine doesn't get severely overheated for other reasons, I don't think the plastic impeller will ever become a problem. Numerous manufacturers are going this route.

The weep hole goes from the front seal to the back of the pump. Mine would drip approx. 1-2 teaspoons of coolant overnight when temps got into the 20's or lower in the winter, not enough to be a big concern yet enough to have to check the level every week or so. It hasn't dripped at all since I put the new pump on. A few pic's:

 

[FirstToy]

donco,
thanks for the pics! well I am a bit surprised that the impeller is plastic. you are right, it is more and more common.
I hear of oem plastic impellers blowing and f-ing everything up..at which time they buy metal impeller pumps (never heard of this happening in LC's tho).

I certainly don't think it's something to worry about but it is just slightly disappointing to see it's a "regular pump" instead of some super-duper LC "rebuild it and last forever" pump
Just curious (if anyone here knows), is the 80/60/40 impeller plastic too?

I just feel like, as long as you are in there..might as well change it.

 

[Tinkerer]

donco - thanks for the pix!

How many miles on that pump? What was your coolant change schedule? Did you use distilled water to mix at every coolant change leading up to pump replacement?

 

[donco]

donco - thanks for the pix!

How many miles on that pump? What was your coolant change schedule? Did you use distilled water to mix at every coolant change leading up to pump replacement?

Pic's of the water pump have 100k original miles on it. It had a fresh change with Toyota Long-Life red stuff at 31k miles in May, '03; doubt they used distilled water. I collected most of what drained out at 100k in Jan '06 when I did the timing belt. I topped it off with 50/50 new Toyota Long-Life and distilled water. It's due for new hoses in the spring and I'll discard the old coolant & flush it & use a 50/50 mix of Toyota Long-Life & distilled water at that time. That should tide me over until 200k when the t-belt is due again. Just for grins I'll take the right cover off at 190k & do a visual on the belt to make sure it looks like it will make it to 200k.

 

[Tinkerer]

Pic's of the water pump have 100k original miles on it. It had a fresh change with Toyota Long-Life red stuff at 31k miles in May, '03; doubt they used distilled water. I collected most of what drained out at 100k in Jan '06 when I did the timing belt. I topped it off with 50/50 new Toyota Long-Life and distilled water. It's due for new hoses in the spring and I'll discard the old coolant & flush it & use a 50/50 mix of Toyota Long-Life & distilled water at that time. That should tide me over until 200k when the t-belt is due again. Just for grins I'll take the right cover off at 190k & do a visual on the belt to make sure it looks like it will make it to 200k.

Good info - thanks!

If you had reported changing every 30k with 60/40 mix of coolant & distilled water, I would have started to worry about my pump.

(The pic of your pump weep hole discharge shows evidence of corrosion scale.)

 

[Campfire]

The weep hole goes from the front seal to the back of the pump. Mine would drip approx. 1-2 teaspoons of coolant overnight when temps got into the 20's or lower in the winter, not enough to be a big concern yet enough to have to check the level every week or so. It hasn't dripped at all since I put the new pump on. A few pic's:

Well here is a question that gets me going. As a ASE certified Master Technician with 18+ years in the shop and the experience of changing hundreds of timing belts let me give my .02 cents. The above picture is a GREAT example of what most will find. Would I have changed it? Borderline! I would have called the customer and given them the choice. BUT, with a full explanation of installing everything else, it would be an great time to do it.
If any more residue was present I would have strongly recomended replacement. I've been chewed out for wasting a customers money by doing this. I've also been threatned to be taken to court because the customer declined the repair, then 16,000 miles later there is a coolant leak coming from inside the timing cover and it's "all my fault" because I touched it last. The customer refused to sign a teardown estimate because they were sure that it was not the waterpump but crappy workmanship. We tore it down and found the pump had started leaking getting coolant on the belt and then required a complete timing belt job again less idlers and seals. Legal action threatend until the signed repair order was pulled out stating the customer declined the waterpump replacement after it was found to be leaking.
Have I seen catostrophic failure? Twice. Not a lot for all the pumps I've changed, but are your willing to bet on it? It comes down to insurance, do you want it or not. Don't blame the mechanic for covering his ass for something you don't have the tools or know how to do. If you're doing it yourself, more power to you and just ask yourself "how many times do I want to do this?"
Do I sound tainted? You betcha ya! Been cussed at by guys and gals that can't change a tire, but I'm ripping them off. I quit the automotive career after 23 years because the industry needs change, but our schools only want to teach computer skills.
Rant over.
Educate yourself, go down and talk to the tech, have them show you the parts and explain, but don't OK an estimate blind.
Sorry guys, I just regressed for a moment.

 

[Tinkerer]

<snip>
Have I seen catostrophic failure? Twice. Not a lot for all the pumps I've changed, but are your willing to bet on it? <snip>

My apologies for not being specific - I was speaking of catastrophic failure as in "pump comes apart and belt comes off pulley", NOT as in "belt gets wet with coolant and fails".

Personally, I will sense slight coolant leakage by smell and other signs under the hood long before it creates other problems such as wet belt, in all likelyhood. (I'm not ASE-certified, but I did 2 years full-time auto mechanics training at community college vocational school, plus a few years experience in the field, before I went back to school. )

But to be sure, the average owner should take the most conservative route with this and replace the pump while it is naked, since the typical owner will not detect problems until more severe or catastrophic.

I understand the rant: I too left the wrench-spinning career for reasons including those you mention. But don't forget that the BS is practiced on both sides of the (auto repair) transaction, by dishonest types among both mechanics and customers. Unfortunately.

 

[e9999]

sounds like replacing the entire pump is what most folks do. These can't be rehabbed as in new seals?

 

[Campfire]

sounds like replacing the entire pump is what most folks do. These can't be rehabbed as in new seals?

Correct, replace the pump assembly. First, you can't find replacement parts for the pumps, and you have to use a press to take it apart anyway. These pumps are driven by the timing belt, so they have a nice even tension on them at all times unlike those driven by the altenator belt that can be overtightened.
And of the different pumps I've seen, this is typical Toyota stuff. BUILT! Good solid bearings and a decent support casting holding everything. The weep hole does channel the coolant away from the belt in this model if it does start leaking.