I have a 2.5 liter that started knocking (rattling almost) and shortly thereafter stopped running. And after checking out the top end, we think it might have been a timing gear mishap. My question is, could this have damaged parts of the engine like valves, etc? so I dont get into a project of fixing the timing just to realize the rest of the engine is shot. any help is greatly appreciated

Jon

I believe the 2.5 timing is direct drive gear.....meaning there is no timing chain. So it's very unlikely that the timing gear slipped.....notice i didn't say impossible. However, if by some chance that it did slip and throw things out of wack, then yes, some valve-train components would more then likey be damaged. It's usually bent rods and a bent valves though. But sometimes it's worse, like rounded off cam lobes, or craked or busted pistons.

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1984 2M4 SE Auto *stock*
1997 Covette 6-speed *slighty modified* ;)
My main squeeze!

The 2.5 is a direct drive system. No chain is involved. Without hearing the "rattling sound" It could be many things. If the distributor was loose or broke the timing could have caused hard pinging. This will crack valves and pistons. All GM pushrod engines are not "interference engines". Intereference engines are engines that if the cam and crank changed timing with each other, the valves and pistons could actually contact (touch) each other.

quote Originally posted by Oreif: All GM pushrod engines are not "interference engines". Intereference engines are engines that if the cam and crank changed timing with each other, the valves and pistons could actually contact (touch) each other.

So you're saying that all GM pushrod motors will never have a valve to piston contact? If so, you need to go do some homework. No flames intended.....i'm just speaking from first hand experience and i know for a fact that valve to piston contact can occur with a GM pushrod motor. Not to mention i know of other people with LS1 based motors that have also had valve to piston contact....all due to either timing chain failure, timing chain tensioner failure or over revving.

[This message has been edited by 97C5ENVY (edited 08-08-2002).]

I can say from first hand experience that the 2.5 engine will not be hurt if the timing gear fails. I've had it happen 3 times over the years, twice at over 70 mph. Usually the cam gear sheds some teeth and will either jump time or, more likely, cease turning altogether. There is no chain on the 2.5.

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Rod Schneider, Woodstock, Ga.
White 88 GT :)

hmmmm, hehe thx guys, well my father an i are going to check out the timing gears today, and if they're bad, ill just hope there's no other problems. thx Rod, i needed something a little encouraging.

Jon

The 2.5 maybe a non-interfence motor.....but Oreif stated that "All GM Motors were non-interference"....which simply isn't true.

quote Originally posted by 97C5ENVY: I believe the 2.5 timing is direct drive gear.....meaning there is no timing chain. So it's very unlikely that the timing gear slipped.....notice i didn't say impossible. However, if by some chance that it did slip and throw things out of wack, then yes, some valve-train components would more then likey be damaged. It's usually bent rods and a bent valves though. But sometimes it's worse, like rounded off cam lobes, or craked or busted pistons.

If they were METAL gears... Maybe it couldn't slip...

But our fieros were blessed with "quiet" PLASTIC timing gears...

They can chip a tooth and jump time!

quote Originally posted by Mach10: If they were METAL gears... Maybe it couldn't slip... But our fieros were blessed with "quiet" PLASTIC timing gears... They can chip a tooth and jump time!

Your's may have a plastic timing gears, but my '84 has a METAL timing gear. Which may explain why i never had any timing issues with it.

quote Originally posted by 97C5ENVY: So you're saying that all GM pushrod motors will never have a valve to piston contact? If so, you need to go do some homework. No flames intended.....i'm just speaking from first hand experience and i know for a fact that valve to piston contact can occur with a GM pushrod motor. Not to mention i know of other people with LS1 based motors that have also had valve to piston contact....all due to either timing chain failure, timing chain tensioner failure or over revving. The 2.5 maybe a non-interfence motor.....but Oreif stated that "All GM Motors were non-interference"....which simply isn't true. [This message has been edited by 97C5ENVY (edited 08-08-2002).]

Sorry, I was unaware the LS1 was an interference engine. So all stock GM pushrod engines except the LS1 are not interference engines.

BTW ~ I said all pushrod engines were not interference engines. I didn't say they would never have contact. A broken valve lock will send the valve into the piston.

[This message has been edited by Oreif (edited 08-08-2002).]

quote Originally posted by Oreif: Sorry, I was unaware the LS1 was an interference engine. So all stock GM pushrod engines except the LS1 are not interference engines.

UnTrue!

I have a '94 Cavalier 2.2/4 cyl (with 174K miles) that had broken the timing chain tensioner causing too much slack in the chain and allowed the gears to slip. The result was scarred pistons, bent valves, bent rods and a rounded off cam lobe. So, the LS1/LS6 isn't the only interference motor in the GM line-up.

I'm not trying to start a flame war here, but rather help provide accurate information to my fellow Fiero brethern.

This will be my final post on topic....sorry Bizquik for taking the thread into a different direction

[This message has been edited by 97C5ENVY (edited 08-08-2002).]

heh...I think was was meant by the non-interference term, was that the engines are meant (meant being the operative word) to all be non-interference, when something fails (like the timing chain/blet/gears) it now becomes an interference engine and thus causing a problem...

Metal gears can also chip or break a tooth, and there really isn't anything wrong with having plastic gears as long as you keep up with the proper maintenance and stay away from crankcase additives that are petroleum based as it causes the plastic to break down (this I have seen).

Tim

quote Originally posted by Mickey_Moose: heh...I think was was meant by the non-interference term, was that the engines are meant (meant being the operative word) to all be non-interference,

No, what is meant by "non-interference engine" is that if the cam stops moving and the crank continues to move (or vice-versa) then the valves and piston will not come into contact.

Just like Oreif said.

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Doug Chase
Duvall, WA
'88 Fiero Formula 5-spd (autocrosser)
'88 Fiero GT 5-spd (daily driver)
'85 Fiero GT 4-spd (rally car)

quote Originally posted by 97C5ENVY: UnTrue! I have a '94 Cavalier 2.2/4 cyl (with 174K miles) that had broken the timing chain tensioner causing too much slack in the chain and allowed the gears to slip. The result was scarred pistons, bent valves, bent rods and a rounded off cam lobe. So, the LS1/LS6 isn't the only interference motor in the GM line-up. I'm not trying to start a flame war here, but rather help provide accurate information to my fellow Fiero brethern. This will be my final post on topic....sorry [b]Bizquik for taking the thread into a different direction [This message has been edited by 97C5ENVY (edited 08-08-2002).][/B]

The chevy 2.2L isn't a pushrod it's an overhead cam! I said PUSHROD engine! Most overhead cam engines are interference engines. If I remember correctly all multi-valve engines are interference engines. They do not use pushrods. The last 4-cyl GM had that was pushrod was the 2.5L.

This is the second time you thought I said ALL GM engines. Which I did not. I said all PUSHROD engines. As soon as I hear back from a friend at a Chevy dealership, I'll find out if the LS1/LS6 is in fact an interference engine.

wow, well reading this i see you're all prolly correct, just about different engines lol. anyway i took out the spark plugs and hooked up a freshly charged battery and it turned over good, after it also turned good by way of the harmonic balancer, so i think this engine has a chance! besides, an easy timing gear replacement will give me at least a running car and the time to do the v6 swap correctly and thouroghly (can't wait!) thx for the insight guys. beleive it or not, im glad others piped in to check against each other so i get the right info, you guys are great! just yeah dont get upset. thx again guys

Jon

The early 3.0l and 3300 series V6 engines are interference fit, and have a plastic cam gear.

That design was changed to a steel timing gear with the 3800 series. These are interference fit also.

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quote Originally posted by Oreif: The chevy 2.2L isn't a pushrod it's an overhead cam! I said PUSHROD engine!

OK, so what part of this sentence was unlear "The result was scarred pistons, bent valves, bent rods and a rounded off cam lobe."? I guess i was dreaming when i pulled out lifters and push rods from my 2.2L motor....PLEASE!

I just replace the timing gear, no interference or damage on 2.5 iron duke. Fastest way to verify if it is a timing gear failure is to remove distributor cap, crank engine and see if distributor turns. If not, most likly a cam gear failure. Don't crank any more than you need to however, cause if distributor is not turning, the camsshaft is not turning. If the camshaft is not turning, the oil pump is not turning. Always like that oil flowing when cranking or running.