How long do I have? - PeachParts Mercedes-Benz Forum

300holst · #1 11-23-2006, 06:12 PM

Thanksgiving greetings to all,

I have an '86 300E. The water pump (original, with 155,000 miles) is getting noisy. I could hear a 'rattley bearing noise' from the front of the engine. Using a mechanic's stethoscope, I checked all the bearings which run off of the serpentine belt. All were quiet except for the water pump. So far the pump hasn't started leaking but it seems to be getting louder slowly.

My question is how likely is the pump going to last until the Spring and warmer weather? I have studied the procedure for replacing the pump and I think I could do it. The problem is I'd have to work in the driveway and it is getting a bit cold and wet now that winter has arrived here in Oregon. I know it is still much milder than back East but still nor very nice to work in at my age.

The Alldata site lists 5.5 hour labor for this job which would be pretty expensive.

If the job can wait until Spring, I'd rather do that, keeping in mind I'd monitor the coolant level and the bearing noise regularly.

Your opinions and experience are appreciated.

Coming Attractions:
I just finished improving my dash lighting with LEDs and I can actually read every thing in the dash at night. I'll post with photos as soon as I figure how to do that.

Gilly · #2 11-23-2006, 06:19 PM

Try shaking the pulley on the front of the waterpump up and down (check for bearing looseness). Main thing to be concerned with is what you'll do if the pump "lets go" while driving? Are you a doctor? Wife pregnant? Mob chase you very often? Like outrunning cops? If you can answer "yes" to any of these, AND this is your everyday "ride", you might want to put this on the front burner. If "NO", and you're retired, plus have a couple other cars to drive, and have a AAA membership, sure let it go. Always have a cellphone handy. And a peashooter under the seat in case Alfonse and Tony are chasing you again.
Gilly

Jackd · #3 11-23-2006, 06:24 PM

Many moons ago, I had a Volvo with a noisy water pump. Being short of cash at the time, I postpone the repair to whenever it got worst or spring arrived.
Not a drop of coolant, the noise did not get any louder for months months.
This was until I got that noise coming from up front and the alternator light came on.
When I opened the hood, I discovered a big hole in the radiator, a cracked timing chain cover, a few dented pulleys, a missing fan belt and some other collateral damages a failed water pump bearing did. The water pump casing simply disintegrated, distributing broken part all over.

Your pump can probably last 'till spring, or probably not.
Good luck

Roncallo · #4 11-23-2006, 08:55 PM

You have exactly as many days as it is to the absolutly coldest day of winter.

John Roncallo

Motorhead · #5 11-23-2006, 11:13 PM

Quote:

Originally Posted by Gilly

Try shaking the pulley on the front of the waterpump up and down (check for bearing looseness). Main thing to be concerned with is what you'll do if the pump "lets go" while driving? Are you a doctor? Wife pregnant? Mob chase you very often? Like outrunning cops? If you can answer "yes" to any of these, AND this is your everyday "ride", you might want to put this on the front burner. If "NO", and you're retired, plus have a couple other cars to drive, and have a AAA membership, sure let it go. Always have a cellphone handy. And a peashooter under the seat in case Alfonse and Tony are chasing you again.
Gilly

I agree with Gilly.... You also have to ask yourself, "What is a complete engine going to cost me if I overheat it bad".

Strife · #6 11-24-2006, 01:20 AM

I've seen the "failure mode" of water pumps increase expotentially; that is, 100000 miles till noise; 1000 miles till a little seepage; 100 miles to a spectacular gaping leak.

300holst · #7 11-24-2006, 05:05 PM

Quote:

Originally Posted by Gilly

Try shaking the pulley on the front of the waterpump up and down (check for bearing looseness). Main thing to be concerned with is what you'll do if the pump "lets go" while driving? Are you a doctor? Wife pregnant? Mob chase you very often? Like outrunning cops? If you can answer "yes" to any of these, AND this is your everyday "ride", you might want to put this on the front burner. If "NO", and you're retired, plus have a couple other cars to drive, and have a AAA membership, sure let it go. Always have a cellphone handy. And a peashooter under the seat in case Alfonse and Tony are chasing you again.
Gilly

No car chases and my wife isn't pregnant ( long past those years!)

I tried moving the water pump pulley but can't feel any movement. There is a very, very small amount of lateral movement when the engine is running.

300holst · #8 11-24-2006, 05:13 PM

Quote:

Originally Posted by ellington

be sure to check the serpentine belt tensioner "shock." the bushings wear out and will rattle. if the noise is indeed the water pump, don't mess around. fix it ASAP.

Thanks for the idea. I took my stethoscope back out and did some more listening. Here is what I heard:

1. Water pump - bearing noise is a bit louder than on the PS pump or alternator. There is a metallic click in the sound.

2. Tensioner shock - At the top of the tensioner shock the noise I've been hearing is much louder than at the water pump bearing. At the bottom of the shock the noise gets louder yet and I can feel a strong vibration there. I can't see any runout of the tensioner idler pulle but it's hard to see much down there.

QUESTIONS

: Does this sound like a bad shock? a bad idler puller? or a bad tensioner? How would I check these out? So far I have tried applying pressure to the top of the shock but no change in the sound resulted.

300holst · #9 11-24-2006, 05:19 PM

Quote:

Originally Posted by Strife

I've seen the "failure mode" of water pumps increase expotentially; that is, 100000 miles till noise; 1000 miles till a little seepage; 100 miles to a spectacular gaping leak.

I agree with those of you who say 'better safe than sorry'. If I can determine what the problem is, I'll get it done. Maybe I'll just take it in Guenther and say 'fix it'.

Maybe at 155,000 miles and 20 years, it would be wise to just replace the WP, tensioner, and shock all together. Lots of the labor steps seem to be common with all the. It will really add up though.

Tomguy · #10 11-24-2006, 05:31 PM

Quote:

Originally Posted by Roncallo

You have exactly as many days as it is to the absolutly coldest day of winter.

I agree with John and Murphy's Law. It WILL fail in the worst possible place at the worst possible time.

Replace it. I've had a water pump fail on an old Nissan 240 pickup, and I was VERY lucky to have been able to simply replace it. The shaft snapped, the fan whacked the radiator. Had the fan had metal blades, the radiator probably would have gone the way of the average US student's math comprehension

. I learned from my mistakes - as SOON as my pump on my Cherokee started making noise (~120k), I replaced it.

sixto · #11 11-24-2006, 05:38 PM

You can run the engine with the belt shock disconnected to help diagnosis. Make sure the ACC is fully off so the compressor doesn't engage.

Sixto
93 300SD

Gilly · #12 11-24-2006, 05:49 PM

Since it does seem to be the tensioner shock, then I'd feel a bit better about advising you, in reference to your original question, in waiting until "shade tree" season opens up again.
Gilly