Water pump AND tensioner?

'94 Taurus 3.0 V6 87K miles had thrown its serpentine belt. Water pump pulley/shaft were wiggly loose, and coolant was gone. There may have been some precursor noise (rattle?) some days before the failure. I guessed that the pump was bad (Duh!) and had the car towed in to highly recommended indy. Mechanic also replaced tensioner, saying it was completely shot – no spring action at all (and that it looked like the original tensioner, which is probably was). He also recommended a coolant flush rather than drain-and-fill (“we put in a chemical that cleans out the deposits”) every couple of years.

I have no gripe with the pump or the tensioner failing, but I can’t figure a scenario where they appear to go simultaneously. Does that seem like straight talk to you?

The tensioner didn’t necessarily fail simultaneously. It may have slowly failed until it was noticed when changing the water pump.

That word ASSUME so often shows up with regard to mechanics and their customers. There is such a broad range of opinion on the subject of a complete repair and preventative maintenance. I will admit that when working on “family” sedans, I try to do all that I would if it were my family driving the car and would probably insist that the customer allow the complete repair, as was done. But I wouldn’t assume that the owner agreed, so I would ask.

With a car this age…no surprises at all . Just as AlanY states, The failure wasn’t simultaneous, just noticed at the same time as the other work was being done. Now don’t be surprised as other problems start to crop up . Not a lot of miles but you must consider the AGE of the systems like poeple who are about 60 years old.

One part can hurt another. It sounds like the parts should be changed while the mechanic has the stuff apart. You don’t want to be taking it apart next month.

I need to write more clearly. Thanks for the responses; I agree with them all. In fact, those are the reasons for my question.

If the mechanic had replaced the tensioner because it was about to fail, or even just as a preventative measure, I would not have questioned. But he said the tensioner was completely shot – no spring action at all. So, if the tensioner failed like that, and if that failure is what let the belt loose, then the water pump was still running at the time. But the pump’s shaft bearing was completely gone, so it would have been losing coolant before the tensioner failed. I hope the driver would have noticed overheating ('94 Taurus has a guage rather than an idiot light).

(I’m kind of in denial about the possibility that the car was driven for a while overheated from a failing water pump shaft seal, and then the tensioner broke. Side point #1: Maybe “idiot lights” and “service engine” lights are not such a bad idea for most drivers. Side point #2: If engine temp is monitored by a coolant temp sensor then maybe you do not get a warning of overheating if the coolant is gone; not a fail-safe design.)

OTOH if the pump failure is what let the belt go loose, then the tensioner should have been holding tension up to then. So why did the tensioner show zero spring after the failure?


  1. The pump failure let the belt loose, and when the ancient tensioner sprang back something inside it failed.

  2. The mechanic was overstating the tensioner failure, either to simplify it for the customer or to justify replacing the tensioner without checking with the customer.

I am still curious, but won’t feel disappointed if there are no more responses.

Again, thanks.

It is a typical CYA situation when replacing a serp. belt to also replace the tensioner.

Sounds like a job for auto CSI.

Yes, the mechanic could be lying but I have seen failed tensioners that appeared to hold tension until you released the tension to change the belt and then would NOT spring back. So by all appearances it seemed okay until you discovered otherwise when changing the belt. It was just stuck or frozen in the tension position. As I said, the mechanic could be lying but not necessarily.

AlanY has a credible version of my possibility #1. I’ll accept that.

And I did not say the mechanic was lying, only that he was avoiding a complicated explanation that most of his customers would not understand.

And, yes, I probably should have expected that the tensioner would have to be replaced. I did not replace it myself when I changed the belt a year or two ago. Nor did I dig thru my Dad’s 10 years of maintenance receipts to see if it had ever been changed before he turned the car over to me. :>)

Thank you, all.

I would like to take just a minute to share a little information if I could. I work for a major belt company and just to let you know the tensioner is an item that should never be considered a ?Hard Part? such as a water pump or alternator. It is a usable product and depending on severity of service can see failure begin to creep in between 30k to 60k miles. There are three distinct issues associated with tensioner failure. All of these issues lead to one corrective action which is tensioner replacement.

o The first area of concern is undue belt noise or squeal. Belt squealing indicate the spring inside the tensioner has lost its tensioning ability allowing the belt to slip. In addition to being noisy and creating heat for the bearings, the system may also have lost its ability for the alternator to charge or cool efficiently. Hearing belt squeal and seeing glazing on the underside of the belt is a good indication that tension has been lost and the tensioner along with the belt must be replaced

o The second area of concern is pivot bushing wear in the tensioner which results in the tensioner arm moving away from its base creating misalignment. Look for belt ?Off Tracking? on the pulley or any indication of side wear on the belt. Belt side wear can go from a slight scrubbing on one side to huge chunks lost. In any case, both belt and tensioner must be replaced to correct the problem.

o The third area of concern is damper failure and should not be confused with loss of spring tension. An Original Equipment (OE) style tensioner will have a damper built inside the case which acts like a brake on the arm. Its sole job is to dampen the pulsation of the engine as it fires. Once it has lost its dampening ability the arm begins to oscillate (bounce) or hammer the accessory next to it creating premature failure of that part as well. Can this lead to water pump failure if not detected early? Absolutely.

To answer your question on loss of tension, there is no real test to determine if a tensioner has lost its spring tension other than, with the belt installed check with a tension gauge. With that in mind there are proprietary spring tensions for each tensioner and there is no way for you or I to know what they are. So my rule of thumb is, replace the tensioner each time the belt is replaced. I can say that sometimes when you break a tensioner over to remove the belt things happen inside especially if it is a flat spring tensioner. The reason is any dirt or any object that may have entered the casing fall to the bottom of the spring and lock it in the open position resulting in no spring tension…

I think your technician was a smart guy!

Hope this helps