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thump/knock coming from engine?
Alrighty. Did the search, but no luck.
I have a very, very light "knock, knock, knock" coming from the front of the engine. It does not increase in volume when the engine revs, but it does increase speed. It almost sounds like the fan is slightly touching something, or the belt is, but everything looks clear. I don't THINK its coming from inside the front of the engine. It's so soft, you have to almost try and hear it.
Any ideas? Its not spark knock or detonation, as Ive heard those before, and unless BMW has a more luxurious version, it doesnt sound like that.
Could it be the water pump? Someone told me once that they go bad on these engines.
It's a 1997 Z3 with the 2.8.
Thanks for the time in reading it, and I appreciate any ideas you might have.
-B
| | Reply » thump/knock coming from engine? |
[quote=bob lindquist]There are a few things it could be so a forum diagnosis is difficult. We will try to help narrow it down.
The fan clutch fails and throws the fan into the radiator.
The pump fails and similar result. there are lots of idler pullys also which can fail.
If the car is 100k miles and you haven't had the pump,clutch,idler pullys changed in 50k DO IT!
Change the thermostat and replace the plastic housing (if you car is plastic) with the alumnium one at this time also.
Double check oil level.
I agree with Bob. At 78.5k on same motor I had similar symtoms. Try this :Open hood (bonnet) grab the fan and see if you have any up and down movement or side to side. If so change, water pump!!! At first I thought it was Fan clutch but no. Nice to hear about daily drivers with over 100k.
 me
With apologies to Bob
"lifes a bear when drinking cheap shots"
| | Reply » thump/knock coming from engine? |
bmw called back, my knock,knock sound turned out to be 13 bad lifters, so after the camshaft sensor they finally found the problem. there's my christmas present
| | Reply » thump/knock coming from engine? |
Well, it turns out the belt itself was bad, threw a section of the grooves. I know, I know, I should have seen that, but every time I checked the belt (without removing it) before it seemed fine. In fact, it was fine in every other way. Weird.
Replaced the belt and she purrs like a kitten again. Just in time to play in the 16" of snow due to roll in tomorrow.............
Thanks so much for everyone's suggestions. I love these boards...
| | Reply » thump/knock coming from engine? |
Well, 13 lifters and assembly, a camshaft sensor and complete VANOS unit later my car came home. Sounds great, engine is very smooth, will run it for a while to determine if the car is ok. Thank GOD for CPO. If it weren't for the warranty work the bill would have been close to $3000. I guess my Christmas present is a $50 co-pay.
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thump/knock coming from engine?