GM 3.1L camshaft failure?

A coworker just asked me for some advice, his mechanic just told him the 3.1L in his '97 Olds has a broken camshaft. That seems odd to me, but I know nothing about those engines. Is that a reasonable possibility, or not?

I have never heard of that happening in those 60* V6's. I had a '96 Cutlass, same engine. never had any issues with the engine.. The transmission was a different story though. Sadly it was totaled at around 200k miles

I've seen them lose lobes, but haven't actually seen one break. I'd suggest its pretty easy to tell if its broken once a valve cover is off, and if so, it probably falls under one of two explanations- E36 M3 happens, or there were other parts swinging around in there that broke it.

Ok, probably lost a lobe & the diagnosis got lost in translation through a non-car person.

Thanks!

since the zink was removed from the engine oil it has doomed all flat tappet engines to death unless you add some.

I had a 95 Monte Carlo with the 3.1. At 181K miles, the camshaft broke in half, literally. Probably due to some cost saving tactic, the cam is an assembled piece made of a hollow tube with lobes pressed on. The cam is driven from the front and the back of the cam drives the oil pump. Mine broke leaving the back three cylinders and oil pump at a dead stop. The engine ran on the front three cylinders (obviously there was a slight misfire) with no oil pressure. Upon disassembly, I found the inlet runners of the close valves full of gas (since the injectors kept spraying and the valve never opened), open valves were bent, and the cam bearings on the front wallowed out. I think the flooding is what stopped to car from running well enough to drive (I wasn't driving when it broke). The wallowed bearings and journal suggest it was left running for a while with the broken cam and no oil pressure.

The mode of failure was the cam. No other evidence of the cam being a collateral victim of another part. I may still have the cam and paper-thin bearing around somewhere. I think I posted a picture of it here probably six years ago.

It's a death blow to the engine. I bought an eBay engine for $500 delivered and kept going.

petegossett wrote: A coworker just asked me for some advice, his mechanic just told him the 3.1L in his '97 Olds has a broken camshaft. That seems odd to me, but I know nothing about those engines. Is that a reasonable possibility, or not?

Happens occasionally. It's caused by someone putting off the intake gasket that leaks at about 30k (or having the dealership do it, so it leaks again after about 15k) and the coolant leaks down and damages one of the cam bearings, I think the rearmost one. When conditions are "right" it will sieze and the cam is the weakest point.

TL;DR: It does happen, but it's due to improper maintenance/repair.

Or, in my case, despite proper maintenance, high mileage can do it in. I can't imagine a seizing bearing breaking the camshaft rather than spinning the bearing. I also can't imagine a hollow, assembled camshaft, but apparently that's a reality... Who knows what happened. He needs a new engine.

Most cars have assembled camshafts now.

I've seen it happen twice. I've also seen the rear belt-side (arg, is it #2 or #1?) exhaust rocker pull out of the head a few times. It's always the exhaust, and it's always that cylinder, and it's always the 01?-up 3100/3400.

Here's the breakdown of what happens. That cylinder gets shortchanged for coolant especially if the engine's allowed to run low enough that an air pocket develops. There's no way for the engine to self-flush the air out of that area, so that cylinder gets hot. The exhaust valve, which runs the hottest, starts to stick in its guide. Sometime around that timeframe, GM went from 10mm rocker bolts to 8mm. The threads are the weakest point in the assembly...

The torque spec for the rockers is remarkably low. Very easy to overtorque. Not sure if this is a contributing factor or not. At any rate, when we do the intake, when we remove the pushrods to get the gasket out, we use the fancy prybar-looking tool to lift the rocker off of the pushrod instead of loosening the bolt, which would necessitate retightening it. Can't ruin what you never touched in the first place...

stan_d wrote: since the zink was removed from the engine oil it has doomed all flat tappet engines to death unless you add some.

i think every 60 degree V6 made since they started calling them a 3100 instead of a 3.1 has had a roller cam in them.. this was sometime in the early 90's..