Author Topic: strange rattle.... (Read 3817 times)

hesgone2fast · « **on:** October 30, 2006, 06:59:50 AM »

I'm experiencing a rattle on my engine, here's the situation:
I got my m42 engine from a yunkyard september last year, with 115k kms, and mounted it in place of my old M40, did all the wiring change and everything. I never saw this engine running until last month. During the last year I have been rebuilding the engine, replacing all seals, gastkets, piston rings, bearings and all, ported the intake, exhaust, replaced a couple of valves, machined the head just yo make sure was flat. put the M40 flywheel(lighter). and a new exhaust header.
Well, now that I have completed the project, since I started the engine, I hear a loud noise coming from the top, but strangely, when I step slightly on the gas at iddle it goes awayfor a second, when I accelerate "hard" seems to go away, until I let go the gas and retains. the noise doesn't sound when cold, just after 30seconds of start.
What do you guys think? lifters? chain(not changed, as well as tensioner)
Any help would be really helpful.

maxwellredrum · « **Reply #1 on:** October 30, 2006, 07:09:56 AM »

Intake gasket leaks, exhaust manifold leaks, timing chain tensioner shat the bed etc, did you change the tenisioner??

FL318is · « **Reply #2 on:** October 30, 2006, 07:41:11 AM »

First thought is the timing case and it's inner workings. And just for giggles, is your oil cannister gasket on properly?

Alpine003 · « **Reply #3 on:** October 30, 2006, 10:19:39 AM »

Just curious as to why you didn't replace all the wear item basics while you were rebuilding your engine. Seems like you did a half job...

hesgone2fast · « **Reply #4 on:** October 30, 2006, 05:50:23 PM »

first of all, the tensioner has not been changed, the gaskets don't seem to be an option sincethe noise is definetly mechanical.
Oil canister, is this the oil filter housing? if so, yes the gasket has been placed properly.
Wear item basics? what do you mean by that? I have replaced the entire gaskets, seals, rings. measured the whole engine (which is whithin tolerance), machined the head for perfect seal with the bolck, and as far as the chain deal, like I said before, I had not heard this engine moving before, but once everything was dissasembled, everything seemed fine sprockets had no wear, chained seemed new, so first wanted to run the engine.
I forgot to mention that the engine seems to have not enough power.
any more ideas?

Alpine003 · « **Reply #5 on:** October 30, 2006, 06:15:59 PM »

Quote from: hesgone2fast;12938

first of all, the tensioner has not been changed, the gaskets don't seem to be an option sincethe noise is definetly mechanical.
Oil canister, is this the oil filter housing? if so, yes the gasket has been placed properly.
Wear item basics? what do you mean by that? I have replaced the entire gaskets, seals, rings. measured the whole engine (which is whithin tolerance), machined the head for perfect seal with the bolck, and as far as the chain deal, like I said before, I had not heard this engine moving before, but once everything was dissasembled, everything seemed fine sprockets had no wear, chained seemed new, so first wanted to run the engine.
I forgot to mention that the engine seems to have not enough power.
any more ideas?

OK. fair enough. Have you checked the cam timing? Cam sprockets aligned correctly? Did you use a tool to realign the cams?

BMW_sauberf106 · « **Reply #6 on:** October 30, 2006, 10:33:45 PM »

Have you checked the idler pully for the ac pump?
I had a rattle that came from a bad pully before.

hesgone2fast · « **Reply #7 on:** October 31, 2006, 04:31:35 AM »

First of all, thank you guys for all these quick responses.
Since I assembled the engine I have not checked the timing assuming it was ok. I have not tools to align the cams, and at a local bmw dealer, they would not give me the degrees or anything, not even sell me the tool they use for alignment. I blocked the flywheel(M42flywheel) through the hole in the rear of block, put the cams with the rear squares horizontal. and with the marks pointing upwards.
I�m positive that the cams are on their right position, but now I�m wondering if I could have inverted them(intake on exhaust) I also notice that above 300rpm the car feels better, a little more power, but far from 140hp. which makes me think that the timing is not set properly...

hesgone2fast · « **Reply #8 on:** October 31, 2006, 04:33:21 AM »

a/c pulley can�t be, because right now i�m running without the a/c belt, and whern I first started the engine was without power steering pulley. so just with the water pulley.

maxwellredrum · « **Reply #9 on:** October 31, 2006, 11:56:49 AM »

Quote from: hesgone2fast;12987

I�m positive that the cams are on their right position, but now I�m wondering if I could have inverted them(intake on exhaust) I also notice that above 300rpm the car feels better, a little more power, but far from 140hp. which makes me think that the timing is not set properly...

We are talking about the adjustable cam gear on the front end of the motor, you can tweak them, you may need to advance it a little if there isnt low end power, thats just IMO..and i do believe your prob is with the chain tensioner, just change it and mess with the cam gears and i gaurauntee it will solve your porblems.
-Max

hesgone2fast · « **Reply #10 on:** October 31, 2006, 12:34:47 PM »

I already know about the adjustable cams, +- 6 degrees. from the factory come set to 0 degrees, and advancing the admision makes change the power curve higher. which makes the idle worse.Right know my cams are set to 0 degrees(factory). and if I advance the admision, will have even less power on low rpms. Before I ment to say I feel more power above 3000rpm.

Author Topic: strange rattle.... (Read 3817 times)

maxwellredrum

BMW_sauberf106

maxwellredrum