Rattling on engine

[e30m3ochoa]

So I'm buying a 1991 318i and the guy mentioned that the oil pump might have been not working. I heard the engine crank and at first it rattled a bit but then the engine started to idle fine. Any ideas. I know it's not a lot to go on but that's all I know as of now.

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[kwill22]

Rattle as in metallic tap or actual rattle?

[e30m3ochoa]

Like the engine shook a bit. Kinda sounded like a grinder then it settled down.

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[jaywood]

Like the engine shook a bit. Kinda sounded like a grinder then it settled down.

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Unless you're planning on an engine swap, walk away.

[e30m3ochoa]

Unless you're planning on an engine swap, walk away.

What do you think it is?

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[kwill22]

If the engine sounded like a grinder. That could be anything. Somthing loose or broken. Either way. Like jay said unless Ur doing a swap, or getting a some crazy deal. In which case you'd still probably be looking at an engine swap or rebuild. Walk away.

If you're feeling froggy you can ask the guy to get a pre-buy inspection and make him pay for it.

[Bmwdayz]

The timing chain tensioner goes bad on M42's and it makes the engine sound terrible at idle like a bag of bolts is being shook around. If you rev the motor up does the sound go away? If it does you just need a tensioner.

[Balleristic31]

That rattling could be something as simple as a loose spark plug wire heat shield on the valve cover. Don't run yet... Is the oil pressure light on? Where is the rattling coming from? Why does the owner think the pump is shot?

[e30m3ochoa]

The timing chain tensioner goes bad on M42's and it makes the engine sound terrible at idle like a bag of bolts is being shook around. If you rev the motor up does the sound go away? If it does you just need a tensioner.

Ah I see, well I didn't want to rev the engine because I didn't want to risk any damage to the engine. The weird thing was that the grinding sound only lasted like a couple seconds then it went away.

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[e30m3ochoa]

That rattling could be something as simple as a loose spark plug wire heat shield on the valve cover. Don't run yet... Is the oil pressure light on? Where is the rattling coming from? Why does the owner think the pump is shot?

Very true, no the oil pressure light wasn't on and I'm not really sure from where just that it was from somewhere in the engine bay. He took it to his mechanic and that's what he said it was.

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[kwill22]

If it's something simple I don't see it going away as the engine warms up.

[e30m3ochoa]

So you think its something more complicated then?

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[e30m3ochoa]

So what would be the symptoms of a failing oil pump?

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[oldmann]

My M-42 Starts with a rattle every day, Gone in a few seconds, unless its 20 deg. or colder, then it might last 10 sec.
Has been this way for 5 yrs. hasn't gotten worse. Noise did get worse with synthetic oil. switched back to 10-50 Delo.
Engine has 177k. Have changed to new style chain tensioner. That made no diiference to start up noise.
I suspect low oil pressure on startup keeps tensioner from operating correctly for a few seconds.
Once warmed up, will run to redline in all gears.

[e30m3ochoa]

My M-42 Starts with a rattle every day, Gone in a few seconds, unless its 20 deg. or colder, then it might last 10 sec.
Has been this way for 5 yrs. hasn't gotten worse. Noise did get worse with synthetic oil. switched back to 10-50 Delo.
Engine has 177k. Have changed to new style chain tensioner. That made no diiference to start up noise.
I suspect low oil pressure on startup keeps tensioner from operating correctly for a few seconds.
Once warmed up, will run to redline in all gears.

Oh I see, upon start up does it sounds like a diesel engine and then it goes away? If that's the case then sounds just like what this car has.

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