1995 850 noise under hood with and without running engine

rred · Post by **rred** » 03 Feb 2018, 07:18

This is a 1995 850 with more than 170k miles. I've been driven it for about 10 years.

What I notice is some noises under the hood.

Without starting the engine, I can hear the following sound.

I feel it comes from someplace at the passenger side. But not sure where exactly it is.

After starting the engine, besides the above noise, I can hear a louder noise with less frequency and I can see the engine is shaking a little bit.

I have no idea about the first noise. About the second noise, I found some posts and it looks like it may be caused by the serpentine belt idler pulley. Any suggestion about the causes of the noises and how to repair them? Thanks a lot!

Post by **RickHaleParker** » 03 Feb 2018, 09:37

Sounds like your Secondard air pump. Not hard to find, it is a electric motor powered air pump. Unplug it see if the sound goes away.

Post by **cn90** » 03 Feb 2018, 10:29

- Without starting and the Aux Fan is running in the first video...probably bad Aux Fan Relay shorting out.

- You have many many issues: bad idler pulleys, maybe bad alternator bearing etc. etc.

- Best is to overhaul the timing belt, pulleys x2, hydraulic tensioner, serp belt, serp belt idler pulley. While there, check the alternator bearing.

Post by **rspi** » 03 Feb 2018, 17:44

Could be a wiper motor for the head lights.

You can pull the serpentine belt and start the car to see if any belt noise continues in the timing belt path.

Post by **wizechatmgr** » 03 Feb 2018, 18:28

What song was that in the background? Kind of catchy =)

First clip sounds to me like the secondary air pump - I've had them whine and not growl. If it were it would only do so for maybe 30-60 seconds after startup. Since it is also happening without the engine running - I'd look at the cooling stack.

Second clip sounds like a slightly bad bearing on a pulley or idler.

rred · Post by **rred** » 06 Feb 2018, 19:37

Thanks a lot for all your advice.

The first noise turns out to be the motor for headlight wiper. Somehow it gets stuck. I'm not sure whether I'm going to fix it or just disconnect it. I don't fell the headlight wipers very useful. Actually, the driver side one has missed the wiper for years.

Post by **abscate** » 06 Feb 2018, 20:18

They work a lot better with the wiper

Post by **scot850** » 07 Feb 2018, 11:41

Just disconnect it at the plug above the rear of the headlight on that side. The motors need to be stripped and re-built once in a while (maybe 10 years?) as they get sticky and don't always return to base when used, or can break a drive tooth preventing returning to base position.

Neil.

rred · Post by **rred** » 29 Apr 2018, 13:26

Thanks, I think I'll just disconnect the flug.