This is a pre-emptive question. At idle all is quiet under the hood. If I increase the throttle to about 1500rpm or higher, I hear a tinny rattle from the front/top of the engine. Right about where the water pump could be. Or, it could be a loose thermostat rattling around. It does make a lot of noise.

Do I need to take off the large metal plate on the front of the engine to make a better diagnosis? I had thought the pump is at the fan base.

Should I get my long stick and do a better job of pinpointing the rattle?


I need to get a green manual! Asking all of these dumb questions is getting on my nerves :)

Klaus
--
Common sense trumps a PhD

If it has a fan clutch, they can get noisy. At idle, the fan speed closely matches the pulley speed, so little or no noise.

At higher RPM's, the pulley speed increases more than the fan speed, so they can start to rattle.

Another possibility is the timing gear - the nylon outer part starts getting loose on the center hub. A very common occurance on the old push rod engines.

What a relief! The sound seems to be emanating from the alternator.
When I pushed the support bracket rearwards, the noise decreased considerably.

The fan appears to be of the fixed design, it will not turn freely with the engine off. The blades are on tight, no vibration when tapping with my fingers.

The timing gear I don't want to get into, but it does need inspecting at some future date.

Klaus
--
Common sense trumps a PhD

Good job, Klaus. Go for the easy stuff first, and then dig deeper if you have to. I would have been quite surprised to find a factory issued period correct clutch fan on your vehicle. One thing that I've got on my 130 is a redrilled, 5-bladed plastic fan off of I think a 140, minus the clutch fan. Quite a bit lighter and easier on the bearings in the water pump, and it moves a little more air at idle, when you need it the most.

It could be that my fan belt is a tad too tight and pulling the alternator forward. I do not have a tool to measure the "correct" tension, so everyting is by feel.
When I push on the belt on the driver's side, it gives almost 1/2 inch, which feels pretty good. But when I push down on the alternator side, the bracket actually moves a bit(less than 1/16), which bothers me a little. The noise could be from the alternator bearings and that is not a good thing.

Klaus
--
Common sense trumps a PhD

Check that all the alternator mounting bolts are properly secured. If that is OK then slack the alternator off, remove the fan belt and spin the alternator and water pump by hand. If the alternator bearings or pump bearings are shot you will most certainly hear them. While the belt is off you should also be able to determine if there is a lot of axial float on the water pump shaft.

Alternator bearings are not all that difficult to change and it will give you a chance to check the condition of the brushes and slip rings at the same time.

I had a 1974 164E whose alternator bearings were very noisy and after I changed them everything was so unbelievably quiet that I could hear the fuel injectors opening and closing.

Klaus-
The fan will amplify the sound of a water pump bearing going south.
Usually it starts getting loose before it starts to leak so there are a couple things you can do.
First see if the bearing seems to be good and tight by trying to move the fan blade.. (acute)
Second, keep looking for signs of coolant exit from the front of the water pump.
It will manifest as a ring across the hood and around the engine compartment. (chronic)
If you keep plenty of coolant in it you probably won't get into an emergency situation unless you
drive it on a long trip.
--
George Downs, Bartlesville, Heart of the USA!

Klaus-
The fan will amplify the sound of a water pump bearing going south.
Usually it starts getting loose before it starts to leak so there are a couple things you can do.
First see if the bearing seems to be good and tight by trying to move the fan blade.. (acute)
Second, keep looking for signs of coolant exit from the front of the water pump.
It will manifest as a ring across the hood and around the engine compartment. (chronic)
If you keep plenty of coolant in it you probably won't get into an emergency situation unless you
drive it on a long trip.
--
George Downs, Bartlesville, Heart of the USA!

Green books available at http://volvoamazonpictures.se/

Navigate to the Documents/service manuals.

Old engines make noise. If it runs cool enough, don't worry about it until it becomes something to worry about. You will drive yourself nuts trying to make the engine silent.
--
Mr. Shannon DeWolfe -- I've taken to using mister because my name misleads folks on the WWW. I am a 53 year old fat man. ;-)

Thanks for the manual, Shannon. It is not the water pump :)

I guess I will have to do a little sluthing tomorrow. This car does need a new overflow bottle, it is cracked on top where the bottom of the neck is. But the temp gauge is showing excellent cooling properties.

Compared to the 850/70 POS I had, this is so simple. It is fun!

Klaus
--
Common sense trumps a PhD

I, too just sold an 850. It was turning in to a real maintenance hound. These old Amazons may not be the quietest or smoothest cars around, but they are a lot of fun, and for the most part, I even understand some of how they work!