[jrfintex]

97 Merc GM with 160,000 miles.

About a week ago I noticed a short, 1 second brrrrp. noise when starting the engine after it's sat overnight. It dose it once and then it's usually, but not always, fine the rest of the day with no odd noises of any kind at any RPM.

I'm thinking timing chain. Maybe the starter is hanging up but that wouldn't explain the once a day occurrence.

I've never done a chain on a modular motor before but I am fairly handy with tools and replace my intake 30K ago. I'm not too concerned about replacing it if that's what is needed but about how long does the job take for a weekend DIY'r who has never done one?

Thanks!

 

[R.S.LOGAN]

Before you get too involved , you might want to consider changing the engine oil and filter first . Using a good filter with a decent drain back valve like OEM . It may be taking a wee bit longer for the oil getting round the engine / tensioner before pressurising and reaching the top .

 

[jrfintex]

Before you get too involved , you might want to consider changing the engine oil and filter first . Using a good filter with a decent drain back valve like OEM . It may be taking a wee bit longer for the oil getting round the engine / tensioner before pressurising and reaching the top .

That's great advice but I just changed the oil last week and no change. I've used Full Syn 5W30 with a Motorcraft filter every 4500 miles and I don't think the motor could not possibly run better if it were new.

I live alone so calling the wife or kids over to crank it up while I listen isn't a workable plan. I'll see about getting a remote starter button. That may get me closer to the source. It's a sharp, rapping noise that lasts for maybe a second, and I've heard starter drives get hung up trying to disengage the flex plate make a very similar noise.

Oh..... and cranking .No odd noises at all. I've tried the flood mode to let it crank for 7-8 seconds before starting and don't hear any unusual noises until I let it start.

 

[R.S.LOGAN]

Usually if timing chain is badly worn it tends to rattle , batter it's brains in most of the time , not just on initial start up . Dirt on starter pinion shaft , possibly , and just needing a clean up to allow better throw back if slightly sticking ..

 

[amclark]

97 Merc GM with 160,000 miles.

About a week ago I noticed a short, 1 second brrrrp. noise when starting the engine after it's sat overnight. It dose it once and then it's usually, but not always, fine the rest of the day with no odd noises of any kind at any RPM.

I'm thinking timing chain. Maybe the starter is hanging up but that wouldn't explain the once a day occurrence.

I've never done a chain on a modular motor before but I am fairly handy with tools and replace my intake 30K ago. I'm not too concerned about replacing it if that's what is needed but about how long does the job take for a weekend DIY'r who has never done one?

Thanks!

I think I would explore the starter hanging up theory. It would be possible for it to act fine after everything is warmed up and only hang up when everything is cold after sitting overnight.

 

[jrfintex]

I have never heard any rattle of any kind while running. It's only for a second usually at cold start up. I finally have a weekend off so I'll take a closer look and see if I can locate the source.

I appreciate the advice!

 

[jrfintex]

Problem solved. Time to update.

Sure sounded like a chain slapping the timing cover for a second but the noise started lasting longer until it reached a point where I could get my ear under the hood and ID the location, and it was definitely coming from the rear. I purchased a new Remy starter from RA and replaced it. Not fun by the way, hell would be a better description, but I suppose I should be glad it's not a Cadillac NorthStar with the starter buried under the intake.

For anyone who may face this noise in the future, it starts as a rattle when cold, as mentioned above, and gradually gets worse. Mine eventually developed a whooshing sound almost like a fan in the firewall lasting 4-5 seconds followed by the short rattle. It was very common with a cold engine but got worse as seasonal temps dropped. At 35 degrees the noise lasted long enough finally locate. I'm not suggesting 35 is a special number, just pointing out how cold weather made it easier to identify. As it continues to fail it may produce the sound when warm. Mine did.

My guess is the starter drive (do they still call it a Bendix?) was hanging up in the flex plate. The "whoosh" was the flex plate spinning the starter like a top and the rattle was the starter slowly retracting its teeth from the flex plate.

Apologies all around in advance if everyone already knows this. It was new to me and difficult to pin down with my limited hearing, and with so much talk on the web of engine noises being associated with cam chains I naturally thought I was in big trouble.

Thank you all for the tips and advice.

 

[Bajarider]

Thank you for the update. We can learn from this.