Originally Posted by tscompusa

Yep BTK is whats on mine also. can we find these direct below dealer prices or is it pretty much impossible?

did you write all that info in your own words or are you going off a 3rd party?

if in your own words then you know a crap load about how the pumps designed.. and based off what i just read, welding the weep hole shut will lead to a catastrophe if you will.. a seized up pump correct?

Originally Posted by barneyb

No, these are just my thoughts. At one point in life I was a chemist and chief operator at a brown trout farm (also known as a wastewater treatment plant). Not a career path I would necessarily recommend. But, we had a lot of pumps.

Anyway, the weep hole is there to keep coolant from going through the bearing. Now, a wet bearing might seize or maybe start to disintegrate and get loose. You don't want grease mixing with water. Sometimes when the seal leaks it is because the bearing went first and allowed the shaft to wobble. Another thing to consider is that the ceramic seal is just two flat rings rubbing against each other, a tiny bit of leakage can be normal.

Originally Posted by tscompusa

would you be interested in looking at a bad pump i have here and giving us more of your thoughts on whats happening? if so ill send you one.. you seem to be more knowledgeable then most on here about this stuff and considering your background job career i feel you could share a lot of information about the pump if you taken one apart.

Originally Posted by barneyb

The OEM pump, at least the one that came off of my car, was made by BTK, a Japanese company headquartered in Tokyo. However, their oil pumps and water pumps can be found on vehicles worldwide including American makes.

The pump has a ceramic seal. These first appeared for large industrial pumps, as I remember, back in the 70's and were an expensive upgrade. The seal consists of two ceramic flat rings that slide together, one stationary in the housing and the other on the shaft, their mating surfaces pressed together by a spring. Large industrial pumps, depending on what was being pumped, required what was called gland water, clean water pumped into the seal area at a pressure higher that what the pump was capable of producing. The reason for this was that any particle harder than ceramic that managed to work its way between the sealing surfaces would cut them to pieces. The ceramic material is so hard that the surfaces can rub together at the speed the pump operates at and not wear out for many thousands of miles on a car if not contaminated.

I remember the pump that was used on my DSM twenty years ago and all it had was a hole that went directly into the area between the seal and the bearing. The Evo pump has two weep holes (if they are both drilled into the interior) so evidently the pump is used in another application and mounted differently. But instead of a hole there are passageways along the pump housing that are apparently to bring any leaked antifreeze to the outside of the timing belt area.

So, what you have going from the inside to the outside of the pump is impeller, ceramic seal, weep hole and bearing. The bearing is also sealed but the seal is to keep out dirt from the outside and keep out coolant, not under pressure, from the inside.

So, having a sealed weep hole on a failing water pump means that first the seal would leak a little and then the space between the seal and the bearing would fill and eventually the coolant would work its way into the bearing. Then the bearing would fail. This would occur even if the seal was leaking so little as to not otherwise cause a problem.

Originally Posted by n2oiroc

so the shaft rides on sealed bearings. where is the mechanical seal?

Originally Posted by bigben

I'm sure glad I read this yesterday. I did a timing belt/water pump change about 2 years ago and it's always leaked some coolant, of course all the parts I used were aftermarket, not oem. Anywho, I went with a Mishimoto radiator about 3 years ago, and I noticed that it has a 19psi radiator cap. The oem one is 1.1bar, or 16psi. I thought it was weird that everytime I would top off the radiator and refill the overflow tank up to the specified mark, that it would be back down to where it normally leaks out to within a few days. I guess because the radiator cap had a stronger spring that it wasn't opening like it was supposed to, building up extra pressure, and then leaking out of the water pump.

So, I put the oem radiator cap back on, and we'll see how it acts. I sure hope this fixes the problem, even though I am going to do the timing belt/water pump again sometime next year.

Originally Posted by drb

I agree with all that you have said with one exception. For an automotive water pump one of the mechanical shaft seal faces is probably ceramic and the other is normally made out of carbon graphite. Both seal faces are lapped extremely flat which makes it difficult for water/antifreeze to pass between them. The seal faces are lubricated and cooled by a boundary layer of water/antifreeze between the faces that can be measured in micro inches. All seals of this type leak, although the normal leakage rate is very small, and it is normally classified as non visable. You definately don't want to plug the weep hole between the seal faces and the bearing/lipseal, because as you said the weep hole is there to funnel the normal seal face weepage away from the bearing.

Originally Posted by barneyb

I slept on your offer and still don't see what can be achieved by tearing down what is a throw-away part. It is unfortunate that the water pump on our cars requires considerable work to change out. However, with the under hood packaging now-a-days, this is true for some parts on any car.

All, I can suggest is that, at the time of purchase, you seek some assurance of warranty and keep the receipt.

Originally Posted by alexui90

ok..i bought oem pump, oem belt, oem thermostat, oem radiator cap and ''PEAK'' antifreeze..wish me good luck...=]

THANK YOU ALL GUYS...I APPRECIATED

Originally Posted by drb

I agree with all that you have said with one exception. For an automotive water pump one of the mechanical shaft seal faces is probably ceramic and the other is normally made out of carbon graphite.

Originally Posted by barneyb

Thanks for the help. That, and your explanation of how the seal works is much better than my attempt.

I don't see the pressure cap being all that important. Sure, more pressure is going to make a leak bigger but a leak is a leak. Below the sealing surfaces is a spring and bellows. A manufacturing defect there may also cause a leak.