Weird knocking sound"I think?" need some help

[87gn-newbee]

I have about 70 miles on the car after heads,cam and intake swap. It seems the car is knocking/ratting "SOME" times above 3200RPM. Thing is nothing shows on SM or a KR detector. I had the wife get in the car engage the Tbrake and I couldn't hear anyhying. There was a little white smoke comming out of the breathers when she was on the Tbrake. I have not changed the oil yet was planning to do it after a 100 miles or so.
Besides the noise at times car runs great and halls a**.

Cam break in went great.

Anyone have any ideas?

I'm off to look for anything touching that might cause a rattle or something. Just seems louder than a rattle

Dan

 

[Razor]

Not a whole lot of info...

Is the knock coming from the bottom of the motor, top, front, back?

bet its the belt tensioner by the AC.. or a bad alt/ac compressor.

Drop the oil and give it an inspection.. and assure good oil pressure.

Probably something simple. these things are hard to do from a distance.

J.

 

[87gn-newbee]

seems like DS can't realy tell

I put in the AC delete bracket from Champion and it's all tight

I just dumped the oil and it looks good does smell like gas or anything and no water in it.

I hope it's something small just can't track it down.

If it was knocking would anything show up on SM or KR detctor?

Dan

 

[Razor]

Well a rod knock for example wont show on DS. You need to put a stethescope and pin point the knock. Can be a loose converter bolt, cracked flywheel, bad converter, piston slap, valvetrain, etc... if you have no debris in the oil.. your probably ok. Just let the oil settle for some time before draining the pan. That way you can capture whats going on.

Downpipe? Describe the knock a little better. And if its internal.. it will do it whether in gear or not. Only thing is like the thrust bearing.. but you would have copper in the pan if that bearing went out.

 

[Dan Thompson]

Is the down pipe hitting the frame?

I have a stock dp and when I change out my high performance cat for smog test sometimes mine will hit the frame

 

[87gn-newbee]

It's not the DP,x over I don't see anything rubbing.

only happens when driving so I'm going to check the converter bolts and fly wheel for cracks.

I'll wait for the oil to settle in the milk jugs and see if anything is in there. Maybe cut the filter also.

If it was internal wouldn't make the sound all the time and get louder as RPM increases?

The wife was on the Tbrake until 3600rpm and I couldn't hear it. heard a lot of whistling though


Dan

 

[87gn-newbee]

ok nothing in the oil put it through a fine stainer. Going to fill up with 6 quarts of oil tomorrow and see what it does.

no cracks on the fly wheel and all TC bolts tight.

Dan

 

[87gn-newbee]

ttt

 

[Razor]

Well ya say it happens when driving.. does it happen only with speed, gears, rpm's.. If you put the car in neutral.. does the sound still happen. Could it be driveshaft? Or front suspension?

Is the noise definetely centered under the motor?

Putting the wife to t-brake the car at 3600 RPM's.. Your my hero

 

[87gn-newbee]

Hey Julio I appreciate the help thought there would be more.

Anyway the SM and KR detector does show knock when I have the car in park and rev it up past 3500-4k. It sound more like valve train noise I guess. I took both covers off and looked over everything and it looked good re installed and torqued to specs.

The car still hauls but and doesn't show KR on SM. I've been up 20 psi no oil leaks oil PSI is at 26 hot 70 cold.



Dan

 

[Razor]

Do you have an adjustable valvetrain?

Make sure your rocker arms are in good order. They sometimes get play and could cuase your condition. Especially since the car is 20 years old.

If it all checks good.. then what can ya do?

 

[87gn-newbee]

valve train is not adjustable but replaced them with new ones from Mike from the other board. They were on the car for a feww hundred miles before the new heads.

I'm going to check the spec on the rockers when I get a chance and find out how to do it.

Is there adjustable rod available to use with stock rockers or do you have to go all out for adjustable rockers?

I'll keep posting results you keep posting ideas

Dan

 

[Razor]

My close friend has an 87 GN that on the passenger front valve cover you hear a tapping sound. He has the same rocker arms. he swapped the rockers from driver to passsenger and same thing. Lash is correct.. shafts have minimal play. And its definetely valvetrain related.

If your oil is clean... its probably not an issue.

You could unbolt the converter and push it torwards the transmission... start the motor and rev it.. see how it sounds. See if the knock goes away??

These motors rev quick without a TQ weighing it down.

 

[87gn-newbee]

After talking to vendor I got the heads from and telling him the problems he thinks I might be to lean above 1900 so tomorrow I'm going to play with the ME-R and fatten up the mid range and go down on the MAP.

I'm hoping that helps and maybe that might explain the car going lean on the SM when in idle reving up to 3800. O2's drop down in the 100's and thats when it gets KR and shouldn't.

The noise is between 3200-4000 and seems fine at WOT. Just put in a new DP'er I'm going to check tomorrow.

If it was vavle train I would think it would make some noise at idle but it doesn't and the car runs great.

I'll try unbolting the TC also.

Dan

 

[GrndNatnl]

Cut an oil filter open and check for excessive metal, or fine bronze.