is my water pump on its way out?

[300TE4Matic]

I have noticed a regular thrumming noise (similiar to a wheel bearing on its way out) coming from the water pump area of my '92 300TE 4 matic, this has only recently started and the noise is in time with the pumping action as felt through the top rad hose, getting faster as the engine revs rise, should I replace the water pump or is there another possible cause?

 

[television]

I have noticed a regular thrumming noise (similiar to a wheel bearing on its way out) coming from the water pump area of my '92 300TE 4 matic, this has only recently started and the noise is in time with the pumping action as felt through the top rad hose, getting faster as the engine revs rise, should I replace the water pump or is there another possible cause?

It is the idler that gives the most problems, slip the belt off, and turn it by hand, if it feels lumpy, change it, the same goes for the water pump, though these normally leak, if you can feel the balls as you turn it or them they are shot.

malcolm

 

[Stevie A]

I agree with all that Malcolm has said. To add, there is a little hole under the pump that drips when the pump is ready to fail. It's a fail safe mechanism.

 

[300TE4Matic]

thanks for that quick reply but not really sure what you mean by the idler and can't find this mentioned in the service manual or workshop manual CD's could you give me any direction on where to find it?

 

[television]

the idler is the smallest wheel/pulley it is joined to nothing, its often spring loaded, it is normally adjustable to take up the slack in the belt. I have lost my link for a picture. You have one pulley for alternator, one for water pump and the other is for power steering, the large one at the bottom is the crankshaft, this means its the one that's left.

malcolm

 

[300TE4Matic]

Once again the folks on this forum are superb, I have been out for the last 3 hrs climbing all over the engine bay with a long screwdriver attached to my ear like a doctors stethoscope and have pinpointed the noise to exactly that component so will be off to the dealer to get the replacement part this coming week. once again thanks for the help.

 

[television]

Once again the folks on this forum are superb, I have been out for the last 3 hrs climbing all over the engine bay with a long screwdriver attached to my ear like a doctors stethoscope and have pinpointed the noise to exactly that component so will be off to the dealer to get the replacement part this coming week. once again thanks for the help.

Your bit about the screwdriver as a stethoscope is the one tool that I have had since the 50's, cant beat it. Pleased that you are sorted.

Malcolm

 

[MW]

Well done finding it.
As an aside, some of these water pumps have a little black tube that runs underneath from the hole in the water pump body onto the plastic undertray. If the pump seals are going, water drips out from hear to avoid the bearings. A sure sign a new pump is needed.

 

[anyweb]

Once again the folks on this forum are superb, I have been out for the last 3 hrs climbing all over the engine bay with a long screwdriver attached to my ear like a doctors stethoscope and have pinpointed the noise to exactly that component so will be off to the dealer to get the replacement part this coming week. once again thanks for the help.

what component was it then ?

cheers
anyweb

 

[300TE4Matic]

I took the car into MB Chateauroux today for a fan belt & Idler Pulley change which cured the noise problem the big old bus is purring along nicely and quietly guzzling it's way through the federal oil reserves once again, one pleasant suprise out here in central France is how reasonable the labour charges are so it didn't hurt the pocket much more than the monthly tankful .... thanks for the pointers as to what to look for it certainly impressed the workshop manager that one of his customers knew which part had gone wrong.