3.4 Broken camshafts

[crm617]

I'm looking to find out what anyone knows here about the 3.4 breaking cams. I understand its happening on higher milage motors, usually 90k plus miles. Of course this is not something anyone whats to have happen. I know there are cam kits out there and you can/could do this work before it might break. From what I know now this is not happening to all motors. What I'm trying to find out here does anyone know years, engine build runs, etc. so I might pin this down. I'm approaching 75K miles and the most prudent thing might just be to sell the car rather than have to repair the motor should the cam break(every expense) or step up and replace it before it does(cams kits about $300.00 my labor). I have a 99 GT1, thanks for any help or information.

[gran_dam98]

camshafts breaking??? never heard of such an issue.. only issue that is for certain with this motor, is the LIM leak.. lower intake manifold leak.. costs about $800 for a shop to fix it.. It is pretty much un-avoidable.. every 3100/3400 engine has it..

[sunrunner_pei]

I've never heard of camshafts breaking on these engines either. :shrug:

[rabidpanda69]

Maybe he's thinking of the DOHC 3400? There was one of those just not in Grand Am's right?

[sunrunner_pei]

Right. The 3.4L DOHC was used in the Grand Prix for a few years and is a completely different engine.

[slowbird]

No...the 3400 does have a hollow camshaft and I've heard concerns about the Cam possibly Snapping.

Unless you have alot of mileage and drive you car hard I don't think you'll have any issues with breaking the Cam.

There are guys running the 3400 in 2nd Gen Cavaliers, running them hard under boost and spraying them, and taking them to 6500rpm on the stock Camshaft and they haven't snapped the Cam yet.

Unless you are going racing, you'll be fine. Just keep up on the Oil changes ;)

[sunrunner_pei]

Originally posted by slowbird
No...the 3400 does have a hollow camshaft and I've heard concerns about the Cam possibly Snapping.

But have you heard of one actually snapping?

[slowbird]

Originally posted by sunrunner_pei
But have you heard of one actually snapping?

Who me!?! Sorry no. I don't think anyone keeps their 3400's that long :D

Yea, I have no idea whether one has actually snapped in a motor...I doubt any of us have anything to worry about.

I wonder what kind of racket it would make...

[sunrunner_pei]

:nervous:

[Bjornboy81]

Originally posted by slowbird
I wonder what kind of racket it would make... somewhere between obnoxious and rediculous :D

[slowbird]

Originally posted by Bjornboy81
somewhere between obnoxious and rediculous :D

LOL...nice.


Sunrunner...that a sarcastic scared face?

[sunrunner_pei]

Not sarcastic. I just meant that I can't even imagine how terrible that would sound. :toast:

[slowbird]

Yea...you'd just be driving along then Crunch! Bang! Pop!

All done.

[crm617]

So here's what I know. As I understand it 1999 and 2000, possibily to 2001 used the hollow cams. I know cams in these motors break. Although at higher milage as I indicated and more so with motors that have the LIM problem(which are most of the motors out there) and not replacing the gaskets. When and if it breaks it will be catastrophic. First off these are not free spin motors. So when the cam breaks and the timing is off your going to kiss valves on the pistons, bend valves, and push rods. Thats just the start, what also happens is that oil pressure is lost to the cam bearing and they heat up and the cam bearings and subsequentilty the cam journals are ruined. Now the top of the motor can be repaired, but the journals are usually beyond even being re-lined bored. So simply said you get to replace the short block. There are two factors for this problem. First one you have some control over, change the oil frequently. The coolant from any LIM leaks play havoc with the bearings, crank, rod, and cam. So frequent oils changes help that. The second problem is and you have no control over this is fatigue on the cam its self. Because its hollow and not as strong as a solid cam (read, weight saving and cost for GM). So with bearings that can be marginal because of coolant in the oil and the physical properties of a hollow cam they can or in some cases break(and yes..snap in half as some of you said). The bottom line is fix any LIM problems, change the oil and hope it doesn't break.

[slowbird]

So from 2002 and up the 3400 motors came with a Solid Cam. A Solid Roller Cam?

[Bart001]

yeah the 3400 i bought for 150 bucks.. That was one of the problems is the camshaft snapped in half.. they are hollow, but that isnt the cause alone....
If you get a coolant leak it will ruin the oil and the cam bearings will get destroyed... and the cam might seize on the oilpump side, under the throttlebody, looking at the engine from atop..

Its a good design , lighter....F1 racing uses hollow cams, with almost 1inch lobe lift and its DOHC...
Wanna get tips on engines.. look at what F1 does....
Natually aspirated at around 900hp in a 3.0L engine...
Now they're going to 2.8l cause they make too much hp....lol