Knocking...edit: Need Datamaster help.

[K5Cruz]

I've searched and read a few posts, but none seem to be my specific case. I'm getting a faint knocking sound at idle and low RPM. You can hear it from outside of the truck, but its faint, like an exhaust leak. Sometimes when the truck is warm the sound is totally gone, sometimes its actually pretty loud, but when I give it some gas the sound speeds up but doesnt really change in volume. I cant hear it in the cab even with the doors open. It isnt injector tick, its a seperate sound. It sounds like its coming from the back and down low, I cant tell if its the left or right side, but the right sounds a little bit louder. Truck idles kinda rough sometimes, but runs very strong, stays cool and has good oil pressure. It does seem to be about half of a quart overfilled, I'm going to change it this weekend. Its a lower mileage truck (63k) and bone stock. I pulled the filler and didnt feel any blowby and I'm not getting a check engine light. I dont have an ALDL yet so I cant run the Datamaster. Sorry for the long post, but I'm trying to provide all the info I can. Am I a paraniod new owner or does it sound like I have a serious problem? I'm used to these kinds of problems after all these years of 2 stroke performance work.. Thanks in advance.

 

[Luke]

Re: Knocking Sound

Re: Knocking Sound

see if the tab on the downpipe is bolted to the trans like it is suppose to be, sound like it might be hittin the trans?

 

[TYTILIDIE]

Re: Knocking Sound

Re: Knocking Sound

I have two things in mind. One would be the worst, sounds to me like your mains may be toast. Or rod knock. First time my motor went out, I it was fairly suddle for a about a few days then just got progressivley worse. How long has this been going on for? Second thought I have is that maybe one of your TC bolts fell out. Its possible, its happened to me on my Vette but can say that the noise it made was pretty ridiculous. Is it a knock or a ping? A dink or a clink?

 

[EcSy#2671]

Re: Knocking Sound

Re: Knocking Sound

I had something similar in my motor went I first got my truck. First start of the day sounds like a tick from the engine or a lifter problem. After it warmed up it went away. Oil pressure was great. Turns out it was the rod bearing, not saying that is what it is, but just giving you the heads up. If can when you change your oil, cut open the oil filter and look for metal in it. That should give up a hint if something is going wrong down there. just my :2cents:

 

[K5Cruz]

Re: Knocking Sound

Re: Knocking Sound

As much as I'm trying to convince myself it's something else, I'm fairly sure its an internal noise coming from directly under the intake. Its almost like a tapping sound really. I only bought the truck a week ago, and this started around saturday night. I'm going to call the old owner up and see what the deal is, as he was very upfront about everything else wrong on the truck. When it revs a little it almost sounds like vavle clatter for a second, then goes back to a faint knock. What are a few ways to determine which cylinder is making the noise?

 

[bezerk]

Re: Knocking Sound

Re: Knocking Sound

take off each plug wire one by one, when the engineis running, and notice when the noise goes away

 

[Luke]

Re: Knocking Sound

Re: Knocking Sound

take off each plug wire one by one, when the engineis running, and notice when the noise goes away

do that, after reading the description a little closer, kinda sounds like a rod

 

[UR50SLO]

Re: Knocking Sound

Re: Knocking Sound

I would prefer that he take each injector clip off VS trying to take the plug wire off while running.

Is this a Typhoon or Syclone?

Depending on your build you'll have anywhere from 2000-5000+ in parts and machiene work.

I just got done with my build. It was in the 5000 mark real quick.

Stock rebuild would be at the bottom end of that number range with out labor. I did all my work except for the actual machiene work.

There's alot to these with removal and installation.

Parts just aren't sitting on the shelf so plan on a wait for some stuff.

Stinks you just got it and now you've got a heart attack right off the bat.
Anything we can do to help let us know
~Scott

 

[Big Mike]

Re: Knocking Sound

Re: Knocking Sound

After you bought this truck did you get on it?? Did you hear it ping at all? It could also be a stuck lifter, cracked crank, broken flex plate, main or rod bearings. piston slap. Welcome to the world of the GMC Syclone/Typhoon, you will be able to put part time mechanic on your resume. Did you do any of the tune up stuff yet? Take a long screwdriver and put it against the engine and your ear or get an engine stethascope you will be suprised at what you can hear going on. Good Luck.

 

[K5Cruz]

Re: Knocking Sound

Re: Knocking Sound

After you bought this truck did you get on it?? Did you hear it ping at all? It could also be a stuck lifter, cracked crank, broken flex plate, main or rod bearings. piston slap. Welcome to the world of the GMC Syclone/Typhoon, you will be able to put part time mechanic on your resume. Did you do any of the tune up stuff yet? Take a long screwdriver and put it against the engine and your ear or get an engine stethascope you will be suprised at what you can hear going on. Good Luck.

I ran the truck hard on the testdrive then drove it 200 miles home a few days later, it was silent. I'm going to drain the oil and cut the filter tonight, and if nothing scares me there I'll unplug injectors and find out where the sound is coming from. I havent used the screwdriver trick in a long time, thanks for the reminder. I'm already a fulltime aircraft mechanic, part time sportbike, 2 stroke and 4x4 mechanic. Now I do Syclones too.

Drained the oil and cut the filter open. There was only 3 tiny metal pieces in the oil, but they look like they came from cutting the case not from the engine. I'm overnighting an ALDL so I can datalog, but I will probably try tonight to pull injector tops. Anything else to look for? Thanks again guys, I'll keep yall updated.

Edit 2: Played with paperclip, no engine codes.. but I did manage to get my ABS to work, seems after the previous owner had all the work done no one cleared the codes, I have a perfect working abs system now and no blinding lights.

Also; my buddies came over tonight with a stephascope and I'm not hearing much noise, tranny area, oil pan, manifold and exhaust manifold all all pretty quiet. I got a little sound from inbetween 3 and 5 on the intake side. My friends all say I'm over reacting and it sounds more like valvetrain noise than rod knock. Hopefully they are right. I'm going to datalog when my cable comes then pull valve covers and have a look around, probably saturday.

 

[SY2767]

Re: Knocking Sound

Re: Knocking Sound

My truck has a noise that sounds the same as what you are describing so i am interested in what this turns out to be.....but my truck has 135,xxx miles.

 

[K5Cruz]

Re: Knocking Sound

Re: Knocking Sound

Paranoid I am. I'm losing sleep over this deal. The only place I'm getting any sound is from intake beside the injectors and the round part below the EGR on the intake, its directly below that and attached with a vac line, it leaves and T's out behind the intake. I'm starting to think its an injector and me being paranoid.. ALDL should be in today, I guess we'll see if that will tell some secrets.

 

[K5Cruz]

Re: Knocking Sound

Re: Knocking Sound

I ran datamaster today, pulling a lot of timing down low and knock count is fairly high at lower speeds also, but the retard is low at high rpms. Where can I upload these files so you guys can check them out?

 

[K5Cruz]

Re: Knocking...edit: Need Datamaster help.

Hate to postwhore, but I would like to get some opinions so I can do some work tonight.

Thanks..

 

[midnightbluS10]

Re: Knocking Sound

Re: Knocking Sound

I ran datamaster today, pulling a lot of timing down low and knock count is fairly high at lower speeds also, but the retard is low at high rpms. Where can I upload these files so you guys can check them out?

You may want to post a new topic in the chipping/tuning section asking if someone will look at it.