PontiacBonnevilleClub.com

hey guys, i bought my 04 GXP 3 yrs ago with 38K mileage, car just tripped 94k, run as great today as when i bought it save when the temps are down and when engine is cold. i change oil and filter religously every 3-4k, in the winter, (now its spring in virginia and as soon as temps went up i no longer heard the tapping)anyway in the winter, or temp below 35 when i start car sounds like bad lifter tapping until engine warms up 3-5 minutes and then its gone and car runs great, i had my neighborhood mechanic friend (he is senior auto tech at local gm dealership) listen and he couldnt hear anything that he thought might be a lifter or valve issue, he also said if it was a bad lifter i should get a "miss" in the engine as well. at this point i dont expect the noise to return until the leaves start changing colors, anyone else out there have a similar issue? thanks, robb in virginia

First off, the Northstar doesn't have lifters. It has dual overhead cams, so the cam pushes directly down on the valves (4/cyl). So you can rule lifters out immediately, lol.

Do Northstars get piston slap like a lot of small blocks do?

Northstars are known for that knocking sound. If it goes away after a bit of time, It could be as simple as piston slap/carbon buildup. Go WOT with it once in a while. I do it once a week. Northstars are built tough and made to be run hard.
Check out http://www.cadillacforums.com/forums/ and search tech info for the year 2000+ Northstar engine

edit:: ooops, not sure if I could post another sites forum link...

i love this site, only joined yesterday and already i feel like i know some things about my car that my local shop owners do not, thanks, robb in virginia

Skippy...you beat me to it. I was just readin about this yesterday on cadillacforums.com

The carbon builds up on heads and when the piston gets up to the top they slap the carbon.

These northstars are meant to be used and abused and they actually last longer when they are ran hard as that is what they are made for.

You gottin start Wotting that car.

Normally you would want to buy a grandma driven car but not one of these. Lol

The Rule is if you floor it and black smoke comes out tail pipe you need to WOT mote and when you WOT and no black smoke that means the carbons cleaned out.

Our list of forums you can't post links to is very short...

I remember my dad telling me that same thing about Cadillac engines well before the Northstar ever came out. I guess that's just the way Cadillac likes to build them?

Ok, I gotta ask...what is 'WOT'?

Wide Open Throttle.

Yikes! Where are you supposed to do that? There's LEO's in these here parts!

Choose wisely.

You don't have to be going fast just do it from a stop until you get up to the speed limit
the little rivers won't believe what your "grandpa car" (not IMO) can do. Lol

OK, I gotta ask.. what's LEO's?

I do it on on-ramps. Gets up to 6000 rpm in a hurry. Let it slow naturally, and punch it again. No need to speed. Once a week. Not good on mpg average though.

I wondered that too. Does it stand for Law Enforcement Officer?

Yes.

As far as the ticking noise. That's just the nature of the beast on an all aluminum engine. Aluminum doesn't insulate like cast iron does. So all those moving parts that make noise as they move aren't being insulated as well.

Seriously, unless it's obnoxious, doesn't go away/quiet down some, loss of power, or excessive oil consumption, I wouldn't lose sleep over it.

GXPete wrote:Yikes! Where are you supposed to do that? There's LEO's in these here parts!

There are LEO's, redlight camera's at every corner, aerial speed enforcement zones, etc, every 20 feet here, and I manage to go WOT many times a day.

This may be off topic, but are on and off ramp's speed limits enforceable? I read the yellow signs with black numbers are recommended speeds, not enforceable. Any police officers out there?

Well I'm a bit gunshy at this point, because after 22 years of not-so-much as a parking ticket, a young, overzealous LEO got me for doing 37 in a 25 last year. I had been driving on a US Route that went from 55 to 45 to 35 to 25 and I was in the final end of the 35 in the town that I live in at 9 p.m., middle of the week, not another car on the road. LEO was sitting 100 ft. behind the 25 speed limit sign that was halfway down a small hill, nailing people as they transitioned speed zones. I think this is the worst form of tax collecting there is. I was slowing down (was probably doing 38-40 in the 35). I drive right, I live right, but nothing mattered to this guy, he was younger than my driving record and he was out collecting taxes. He was a nice enough guy, I just felt he could have let me off with a warning. Chief of Police in my home town (across the river) agreed with me, but I couldn't get him involved. Family friend, my family knows everyone, we have a long and decorated history of [good] community service in the area; we're good citizens. Blah, blah.

I went to court and got the same treatment, in fact, if you bother to fight a speeding ticket, they try to throw the book at you for wasting their time. I made a good case defending myself, but the deck was stacked against me from the onset and the asst DA tried to introduce my priors back in the '80's. Whatever, they weren't listening either. So I paid the stupid $137 and got on with my life. I never cared about the fine, I didn't want the hit on my driving record.

So WOT makes me a little leary, but screw 'em, I can find a spot to do it.

Anyway, sorry for getting off topic. Lifters was it?

Well guess i feel alittle better about mine doing the same thing... It does do it all the time, but still!! Thanks for the info guys!! Also would fuel injection cleaner help with the carbon any?

Where is the carbon?

If it's a major issue talking about combustion chambers, piston heads, intake/exhaust tracks, etc, a top end cleaner, or Sea-Foam, would probably be better choices. If you're just talking about maybe some carbon build-up on the back of the valve from the EGR system working, right in the direct fire of the injector, then you might get a little help from a good fuel injection cleaner.