2.4 SOHC Engine Damaged ??

[pcbiker]

"2.4 TWIN CAM" engine has been fluttering a bit the past week, but I thought it just needed a tuneup. This morning it would not start. Good battery and very strong response from the starter, but it seemed that the flywheel just would not turn. I could hear the starter straining but the engine shaft would not turn. Oil was low but still showing on the stick, and there was never any low oil light, so I do not suspect frozen main bearings. I fear that a valve may have fallen into the cylinder and is blocking a piston from moving. On a different car a timing belt lost its teeth and slipped so much that a piston slammed into a valve in a zero clearance engine and bent the valve. But this Grand Am 2.4L timing is a chain timing and so I would not expect there to have been so much slip that it could result in valve damage (unless maybe the chain broke). I do not know if the 2.4L TWIN CAM is a zero clearance design. I cannot think of anything else that could be the problem besides frozen crankshaft bearings or valve interference with piston. I have no way to tear the machine apart myself and so I must have it towed. It would be nice to hear any ideas that I might talk with the mechanic about, before he tells me that I need $$$$$$$$ work.

An acquaintance suggests that if the timing chain breaks, then it will fall to the bottom and get wedged between the timing gear and the timing chain cover, jamming in such that the starter may not be able to turn the crankshaft. I am beginning to suspect that this is the most logical assumption of what has happened. Just strange that it should occur in the morning when I tried to start the car, but was ok the night before.
Opinions/experience with such a failure??

[Ridenour]

Welcome to the forum. Sorry to tell you, but it sounds to me like you do in fact have a broke timing chain. I have heard of it happening before on 2.4's, and it sounds like you might've been one of the unfortunate people to have it happen to. There's a couple knowledgeable 2.4 guys on here ( i'm a 3.4 myself ) - I would wait to see what they think.

[pcbiker]

Originally Posted by Ridenour

Welcome to the forum. Sorry to tell you, but it sounds to me like you do in fact have a broke timing chain. I have heard of it happening before on 2.4's, and it sounds like you might've been one of the unfortunate people to have it happen to. There's a couple knowledgeable 2.4 guys on here ( i'm a 3.4 myself ) - I would wait to see what they think.

Eek !
Thanks for the reply and the opinion.
I cannot think of any other explanation other than water leaking into and filling the cylinder such that the piston cannot move up due to incompressibility of water; some kind of head gasket leak while the engine is hot and coolant pressurized overnight might do this but it would have to force the air in the cylinder out somewhere (slowly past the cylinder rings lf or through partly open valve overnight?) ... I have not removed the plugs to see if any cylinder is full of water ...... anyways, this is a bit far fetched and I have never heard of it happening.
At this point I am hoping that it is some weird problem with the starter itself, but I am not optimistic because of the poor and lightly noisey engine this past week.

[GTP Dad]

With the plugs removed attempt to turn the engine over with a breaker bar and a socket on the harmonic balancer crank bolt. If you can't turn it that way the engine is probably locked up for some reason. If it turns easily then the starter would be the next item to check.

If the timing chain broke it should have happened when the engine was running not when you tried it the next morning. Your theory on the water in the cylinders is a viable one but once you remove the plugs the engine should turn over and pump the water out. The other possible scenerio is a dropped valve that has wedged itself between a piston and the head. Good Luck!

[skibum1111]

I have a 2.3 in mine and when the head gasket was failing it would fill a cylinder up with coolant and wouldn't turn over the next morning at all, or it would turn until that cylinder was compressed and would stop with a thump. Pulling a plug and cranking the motor resulted in a shot of coolant going about 30 feet in the air (neat to watch, expensive to fix), then put the plug back in and start the car. The way I avoided this was to open the pressure cap when I shut the car off, this would remove all pressure from the system and the car would start the next morning. The 2.4 dohc is an interference fit, meaning that if the timing chain breaks the valves do hit the pistons, but its unusual for a chain to break when the car is off.

[Werm9]

Originally Posted by skibum1111

I have a 2.3 in mine and when the head gasket was failing it would fill a cylinder up with coolant and wouldn't turn over the next morning at all, or it would turn until that cylinder was compressed and would stop with a thump. Pulling a plug and cranking the motor resulted in a shot of coolant going about 30 feet in the air (neat to watch, expensive to fix), then put the plug back in and start the car. The way I avoided this was to open the pressure cap when I shut the car off, this would remove all pressure from the system and the car would start the next morning. The 2.4 dohc is an interference fit, meaning that if the timing chain breaks the valves do hit the pistons, but its unusual for a chain to break when the car is off.

hey ridenour. did your GA come / the sunroom or did you havaae it custom installed? im trying to find a place where i can buy one and have it custom installed but i dontk now if its legal, since your modifying the roof for safety purposes

[Ridenour]

Originally Posted by Werm9

hey ridenour. did your GA come / the sunroom or did you havaae it custom installed? im trying to find a place where i can buy one and have it custom installed but i dontk now if its legal, since your modifying the roof for safety purposes

It came stock. If you want to have one installed, I would go for it. As far as the legality is concerned, it shouldn't be an issue; even if it was how would anyone know. I can speak from 1st hand experience - my sunroof actually helped to save my life. The sunroof assembly in my 01 GT is a huge assembly that spreads out underneath the roof, and when I had it out must've weighed at least 50 pounds. When I rolled my car twice going 70, the roof was actually strengthened by the sunroof. It pushed the sunroof assembly in a little bit, and that was it. By essentially adding a structurally-enhancing hole (the sunroof) in the roof, it added to the rigidity of the roof and helped it hold up when the car was upside down. So by all means, if you find a place that will do a sunroof install, I would go for it. But try to find one that's lighter then 50 pounds - It's a lot of weight to have at the worse possible point on the car. Good luck.