Dwayne

You may recall earlier this year I posted a massive picture thread on an intake refresh procedure I performed on this car November-December last year. At the same time, I also performed a TB/WP change and new motor mounts, OPG and oil pan stud kit. Even though the car only had 35K miles on it, I figured the original water pump was 20 years old and it was best to replace it and be set for another 60K miles. I replaced the original with a rebuilt unit with metal impeller.

Everything went fine with the replacement and my wife has been driving the car for about 3000 miles over the last 6 months or so when I recently noticed coolant was low in the reservior. Upon further inspection, I also noticed coolant on the bottom of the engine. The only source I could pinpoint was at the bottom of the front of the engine - on top of the oil pan. The rest of the engine was bone dry.


I figured the leak must be coming from behind the cam/engine covers and was probably from a leaking gasket on the water pump. So I set about taking the front of the engine apart. But first I drained the coolant and noticed it was not exactly bright green. When one of the hoses leaked coolant on my cardboard covering on the floor, I discovered massive amounts of pretty sparkly metal glitter. Funny, I didn't remember adding sparkly metal glitter to the coolant! Here's a picture of a small amount of spillage on the cardboard after it dried.


At this point, I'm thinking something is seriously wrong. After removing the cam covers, I checked the timing belt tension and it was right where I left it after retensioning the new belt earlier this year - right at the upper end of the tension range on the Kempf tool. Could this be too tight I wondered??


The source of the leak appears to be near the back side of the WP pulley. You can see the trail of black residue from what appears to be metal filings in the picture. After I got the timing belt off, I noticed the WP pully did not move freely and felt like it was scraping - but on what??


When I got the WP off, I found a deep countersunk hole in the block where the impeller mated up.


Being a Noob, I wasn't sure what to think of the grooves.....


....but the impeller moved freely when the WP was off the block. Therefore, it had to be rubbing against the block. However, there were no audible clues or unusual running conditions when the engine was running last week.


I had to compare a picture from when I had the WP off last Nov/Dec to confirm for sure that the impeller had indeed dug into the block. Here's the previous picture of the block when I had it apart Nov/Dec. You can see the WP opening is smooth with no groove cut into it.


Here's the impeller on the failed WP.


It appears to have moved outward toward the block and began drilling away and neither my wife or I were the wiser.


So now I'm going to replace the WP but this time I think I'll go with a plastic impeller. However, with the damage to the block, I'm assuming that the new WP will not be as efficient as originally designed (i.e., with the new gap between the impeller and block, the pump will not be able to move the same volume of water or have the same pressure as originally designed). Correct??

So, I just happened to read a thread about a possible repair to a block that has been damaged by WP impellers using a newly developed tool. I will look into this next.

Just thought I'd share the latest adventure.

IcemanG17

DAMMM DAMMM DAMMM....so the only symptom was a leaking waterpump? No noise or overheating? I would think getting ground like that would cause quite a bit of noise...but I guess the water hid it? Damm...

ROG100

We need to know - rebuild, Laso old, Laso new, Porsche rebuild or Porsche new.
Metal impeller means not the latter two.
Maybe a HT.

worf928

Unfortunately, slow machining of the block is a silent death.

From the looks of your picture, yes. Have you measured the depth of the damage? It looks like several millimeter and IMO will result in some loss of efficiency.

My condolences. It surely sucks.

IcemanG17

Dwayne
I have a spare 87 motor...PM sent

BBX

Honestly, I think that water pump is defective. It still looks new, it should never have moved like that. I guess it might have been a rebuilt unit and pressing the bearings off and on again might have messed with the tolerances that keep the impeller put. I would call the company and ask them why they are selling water pumps that destroy engines!

Dwayne

Hello Brian,
Now that you mention it, about 4 weeks ago, my wife drove to Lancaster (90 mile trip one way) when it was about 105 degrees, with the A/C running and driving through Red Rock Canyon. She noticed the temperature reached to barely above the 2nd white line. One week later, she made the exact same trip, same temp about 105 degrees, with A/C, through Red Rock Canyon and she said the temp never rose above the mid-way mark between 1st and 2nd white lines (normal). This car has never gotten close to the 2nd white line that I can remember in the last 6 months (since the new WP). I was out of town at the time she made the trips so didn't think anything of it since it didn't repeat. I guess it's possible the impeller was extra hungry that day.....

Hi Roger,
The failed WP was a Rebuilt unit. I purchased it last November. We should add one more "FAILED" count to the Rebuilt metric.

Bill Ball

Argh!!! I hate it when that happens.

To paraphrase Betty Davis from Mommie Dearest: NO MORE METAL IMPELLERS!

Not that I like the plastic ones that much better. They appear to come loose more often but the damage they do is limted to overheating, which still destroyed one of our former Big 3's own stroker blocks.

Anyway, I'm sorry to see this, Dwayne. The fact that it failed so quickly argues that this was a badly rebuilt water pump and should never have been sold.

ROG100

Rebuild - another bad tick.
So sorry that happened. At least Greg & Steve have a fix.

Lizard928

looks to me that the bearing assembly moved inside the aluminum housing.

This is sad to see happen, depending on how deep it was will depend on how much efficency will be lost.

ROG100

In theory the company that builds the Porsche rebuild also builds the rebuild.
Lots of companies sell the rebuild which is available at very attractive prices.
Rebuild of rebuild is not good in my book.
The major wholesalers sell the rebuild. So even if the BIG 3 stop selling the rebuild along with 928sRus (big 3 and a half maybe) there are many other companies selling it.
Zims, Vertex, Pelican on and on.

namasgt

Im so sorry Dwayn. I think Im going to trow my rebiult Laso away and get a new design one, I only used it for about 3 to 4 minutes on the engine.

namasgt

okay Im confused, what Rebuild rebuilt are you guys talking about, are you talking about the Rebuilt Lasos ??

ROG100

Ali,
All Laso WP's are new. They are rebuilds if someones takes a used Laso, Porsche or HT pump and rebuilds it.
Roger

the flyin' scotsman

Dwayne............thats just not right. After all your hard work and excellent write up this happens.

You'll now hear a bunch of comments as to what pump you should now use; I went with a 'new' Laso WP from Roger. As well as many other projects, water bridge gaskets etc, the engine is running well and at the before guage readings; between marks 1 and 2.