m50 rattling when coming to a stop

[02stu]

I just finished installing my m50 and there is a horrable rattle in the front when I slow down. Its not the valves or anything internal it sounds like something rattling on the exhaust, but its not. It stops before I can get to the hood to see where its coming from, any ideas? I know this is vague as hell but I thought someone might have experienced the same thing.
Thanks
Stu

[marleyofarley]

I just finished installing my m50 and there is a horrable rattle in the front when I slow down. Its not the valves or anything internal it sounds like something rattling on the exhaust, but its not. It stops before I can get to the hood to see where its coming from, any ideas? I know this is vague as hell but I thought someone might have experienced the same thing.
Thanks
Stu

do you notice a change in idle?

is the shifter rattling?

sounds like your driveline maybe? check driveshaft and the diff mount?

[BimmerToad]

vanos rattle?

[02stu]

its an non vanos, and the sound is coming from the front of the engine, none of the pulleys are loose though. There is some play in the waterpump but I doubt it could make this noise.

[BigD]

Just a thought but did you keep the fanclutch? How does your rad look? Maybe the fan is rubbing the radiator under braking.

[Bimmerboy91]

If there is some play, its most likely your fan clutch. try this, grab the fan with your fingers, standing from the side of the car, and gently move the fan back and forth if you can. Dont force it too much!. if there is alot, if not, some play, its your fan clutch.

[cahomey]

I have a similar sound. At around 3k when decelerating I get a wierd exhaust backpressure noise. Almost like a loose exhaust rattle.

I'm thinking it's the dimensions of the custom exhaust or when the pipes were being welded together it made an irregular texture on the inside which at the right flow and pressure the exhaust resonates in a wierd way.

[tjhartge]

it could be your clutch setup

if you are using the m20 clutch setup, there could be a rattle before coming to a stop and when on idle itself, either use a heavier viscosity oil in your gearbox or increase the idle (on the throttle body ,there is a small screw to adjust the idle a little)

if it's your fan clutch hitting something infront, better check your engine mounts and see if they are tight

[02stu]

Thanks for you help so far on this problem. I know a little more about it now, its louder on the right side of the engine and only rattles when the car is pointed down hill or like I said before slowing down. Sounds like it might be the timing chain or maybe oil pump chain. I just changed the head gasket 500 miles ago. Has anyone heard of a timing chain rattling when the car is pointed downhill?

[bdi_fc]

I have a similar sound. At around 3k when decelerating I get a wierd exhaust backpressure noise. Almost like a loose exhaust rattle.

I'm thinking it's the dimensions of the custom exhaust or when the pipes were being welded together it made an irregular texture on the inside which at the right flow and pressure the exhaust resonates in a wierd way.

I have this same noise.

[BimmerToad]

I have this same noise.

Same here. Moving to a smoother flowing Y-pipe reduced the noise in my 2-1 custom system, but it's still there.

[02stu]

Its not the exhuast its a mechanical rattle. I pulled the valve cover off and the timing chains are tight and the upper tensioner is tight. I don't want to pull the oil pan but I might have to to check the oil pump chain. Does anyone know if they rattle when they come loose? Thanks

[bmdubya84]

is it the fan hitting the rad? my friends did that post swap lol

whenever he hit the brakes the engine shifted forward just a tad and the fan would tap the top of the rad, ended up modding it like this



as you can see you just cut the little bit of lip off there if thats your problem :D

[bimmerboy570]

I just finished installing my m50 and there is a horrable rattle in the front when I slow down. Its not the valves or anything internal it sounds like something rattling on the exhaust, but its not. It stops before I can get to the hood to see where its coming from, any ideas? I know this is vague as hell but I thought someone might have experienced the same thing.
Thanks
Stu

put it on a lift get a friend run it till it makes the noise have a buddie spot it that way you can play around with it if possable

[cahomey]

Same here. Moving to a smoother flowing Y-pipe reduced the noise in my 2-1 custom system, but it's still there.

I heard of e36's making this noise as well. I wonder what is going on when it happends.