VaporiZe

So a few weeks back, with absolutely no warning, my timing belt light came on my dash while I was sitting at a light... long story short, my 91 GT was towed home and everything was torn apart in my garage. No damage to my valves and the belt did not slip off or skip any teeth.

But my OEM tensioner and my LASO water pump, which were replaced 18,000 miles ago in May of 2006, were shot. I could push the tensioner in by hand, and the bearings in my water pump were practically nonexistent. The pulley could just about be shaken to the moon and back there was so much slop, and the impeller could be spun while holding the pulley still. (See the video of water pump if you'd like) https://drive.google.com/drive/folde...DA?usp=sharing

From my understanding, the LASO water pumps with the metal impeller from that era are a POS. The newer ones with a plastic impeller are built much better with stronger bearings, and that is what I am putting in my GT now. If you have a LASO water pump with a metal impeller, you have been warned...

James Bailey

Fortunate that you still had a functioning belt tension light......

Adamant1971

10 years is beyond the factory interval. Glad you did not have any damage.

6 years or 60k which ever comes first.

GregBBRD

Something is radically wrong.

The factory tensioner design makes it impossible to push it "back in" by hand, from where it was adjusted at.

My guess is that the belt got really hot on the water pump and stretched...and the movement you are seeing is from that, not from the tensioner failing.

Try to keep in mind that the Laso pump is a low cost alternative to the factory pump.

There's a reason it's cheaper....

jcorenman

Actually the factory never said anything about the interval, only 60K miles. Common sense certainly tells us that time is a factor, as is heat, ozone, etc.-- just like any rubber. In the immortal words of Casey Stengel, "It depends...".

This failure was clearly the water pump, that's a different story.

mike77

"From my understanding, the LASO water pumps with the metal impeller from that era are a POS. The newer ones with a plastic impeller are built much better with stronger bearings, and that is what I am putting in my GT now. "

Haven't LASO stopped making these? What is the latest on which brand/pump to go for?

hacker-pschorr

The stronger bearing part is pure speculation, to my knowledge nobody has dissected one to confirm the brand or style of bearing.

However, just having the plastic impeller means if it does fail, you won't suffer block damage from a metal impeller. Just pull over before the engine overheats.

VaporiZe

When I compared the old belt to the new one they were the same length so the belt has not stretched. I could physically push the pulley in by tugging on the belt more when it was still on the car.

FredR

Your original post is being read as though you can push the tensioner piston back into the tensioner body. Whether you meant to convey this meaning perhaps you can clarify. The only way I can see such happening would be if the threads in the tensioner body failed but I cannot see anyway that would cause the impeller to break away from the pump shaft unless the sudden slack in the belt jarred the bearing causing the job lot to trash itself.

Have you looked at the casing volute to see if there has been any damage due to the impeller touching the casing? It was not clear from your little vid whehter there was much play of the impeller on the shaft but it sure sounded unhealthy.

As Greg says it seems there is something radically wrong here and the big question at the moment is "what was the cause and what was the effect". Was the pump the cause of the incident or the victim of it?

At least you got the belt tension alarm and responded to it. When the pump impeller comes off my experience is that it is only a matter of seconds before the temperature indicator needle shoots up and the red alarm light screaming "high temp" illuminates- did you see any of this happen at all?

Rgds

Fred

85euro928

My last two Laso water pumps with plastic impellers each lasted me about 10k miles before the bearings starting making noise. Needless to say they are now on my consumables list.

Bill Ball

There's really nothing to break and cause tension loss other than the bolt backing out and that only could happen if the lock nut was left loose. Of course, if the water pump pulley shaft was canted up due to bearing failure, the tension would be loose even if the bolt had not backed out. I think that is how you lost tension. You do understand that the tensioner is "fixed" and cannot compensate for a shift in the water pump pulley. The movement you are seeing in the tensioner is the end spring that is part of the low tension warning system. Normally it is compressed and the pin it supports is firmly in contact with the tensioner components forming a continuous shaft back to the adjusting bolt. Nothing in there to break. Oh, sometimes a few of the Bellville washers may fracture. They would all have to break. I service the tensioner at each belt, which involves cleaning, an o-ring and end boot. Take it apart and tell us what you find. It's probably fine.

jcorenman

Ouch! How many years?

I don't think the bearings in the newer plastic-impeller Laso pumps are any different. As noted, the advantage is that the plastic impeller won't chew up the block.

I've gone back to Porsche pumps, yes they are expensive but so are engines.

85euro928

I'd have to go back and look at my records but I think the first lasted about 3 years and the second about two years. The good thing is that w/o AC, an air pump, stock fan or shroud it's relatively simple to change out the WP and tbelt.

Schocki

I always used LASO pumps on my water cooled Porsches, with zero issues. The LASO in my GTS is an "old" model with metal impeller. Installed in 2009 and today after 20 kmiles no issues...

Adk46

Will an over-tight belt lead to early water pump bearing failure?