95' 3.5L Interferance engine?

[MIKEL1965]

I have a 95' Intrepid with a 3.5L is this a Interference engine?. Also I had a waterpump installed, the mechanic never changed the timing belt. He said it looked in good shape. When i picked up the car after the work was done and when i started driving away the engine sounde like it was turbo charged. A wissing noise was coming from the engine. No more than 80 km later the engine died. When i brought back to the mechanic he had discovered that the cam gear was destoyed. i mean shattered destroyed. The mechanic looked at nme and said it would cost mega bucks to fix. My question to all is this. Is there anything that they could done to destroy that timing gear. 4 other mechanics have told me that they have never heard of a timing sprocket fall to pieces the way this one did.

P.S.
They claim the water pump was the right size.

[mopargrl]

I have a 97' and my mechanic changed my timing chain. I think your car has a chain not a belt. There is a huge difference. Ny mechanic said after about 100,000 you should have changed no matter what because once the chain goes it bends all the valves in the engine, unlike a belt, and your engine is toasted. It is an interference engine, and my timing chain was around 400$ w/o labor.

[AWP9521]

Yes the 3.5 is an interference engine. Why the mechanic didn't replace the Timing Belt is very questionable, since the front of the engine is already apart to do the water pump, the belt and/or Tensioner should have been replaced at that point just for cheap insurance, it's actually recommended by Chrysler that if the water pump is replaced the tensioner and belt should be replaced also. Honestly I would have never left the area if I noticed the odd noise from the engine that was never there before he "repaired" it, IMO it's plainly obvious that he messed something up and why should YOU have to pay for his mistake? I think I would talk with an attorney and go after the guy for either a free repair or a replacement engine. He worked on the car, he had to align the cam gears to reinstall the belt after changing the pump, if he used the wrong tools to do so and somehow damaged the cam gear and possibly ruining your engine, then he should be liable for repairing or replacing your engine at HIS cost, especially if the repair didn't last for 50 miles (80 km) since it was worked on by him.

[theFREAKnasty82]

The only way to destroy a cam gear is if you beat the hell out of it. I have worked on many of 3.5 liter intrepids and the only possible way that the cam gear got destroyed is that he was try to put the gear back on the camshaft itself (he took it off to probably replace the cam oil seal) and beat the hell out of it to get it on, thus cracking the gear in the process. That's mechanic error; in all the many times that I've done timing belts I have NEVER heard of a cam gear that was destroyed; not even if you dogged the engine, it wouldn't shear.

[LHSDriver01]

Originally Posted by mopargrl

I have a 97' and my mechanic changed my timing chain. I think your car has a chain not a belt. There is a huge difference. Ny mechanic said after about 100,000 you should have changed no matter what because once the chain goes it bends all the valves in the engine, unlike a belt, and your engine is toasted. It is an interference engine, and my timing chain was around 400$ w/o labor.

Both the the 3.3L and 3.5L are technically interference engines, but the likely hood of any damage occuring buy a timing belt or chain failure is unlikely. The valves and pistons can colide, but barely, the piston would have to be at top dead center with the valves fully open.

The 3.3L is a chain, the 3.5L is a belt.

3.5L's belt is recommended by the factory to be changed at 105K miles.

For a cam gear to be destoryed, i cannot even fathom what has the possibilty to cause that. That belt is tight yes, but how does a rubber belt destory an alumninum gear? Seems impossible to me. Sounds like perhaps the tensioner broke, something he should have replaced when the water pump was replaced. Whenever that timing cover is off, especially when your close to the service interval, the timing belt, tensioner, and water pump should all be changed. For those three the parts run only about $200.

[MIKEL1965]

I did'nt even think about the tensioner, i do remember that when i brought the car back in after the damage he showed me that the tensioner was still operatable by putting it a vice and slowly closing it he claims that is how they close them. Then they put in a pin through the holes once alligned. After it goes back in the engine they pull out the pin. For those of you that thought it was a timing chain...it is a timing belt in the 3.5L. Also the mechanic said tonight that seeing how this engine is a dual cam with 24 valves the travel on the valves is not as great as on a single cam engine, which makes this an non-interferance engine.
Does all this make sense to anybody?

[LHSDriver01]

The 3.5L is a Single overhead cam engine. There is only 1 cam over each cylinder head. But being a V6, it does have two cams total. If it was dual overhead cam there would be a total of 4 cams.

Heres a cross section of the 3.5L, its not much help, but fun to look at:

Being a 24 Valve v6 means it has 4 valves per cylinder, 2 intake, 2 exhaust. (Interestingly enough, the 3.5L heads are very similar to the new and old hemi engines)

Like i said, technically the 3.5L is classified as a interference engine, but the chances of any damage from a failed timing belt is highly unlikely due to the design of the engine.

I had the tensioner self-destruct in my concorde with the 3.5L, heres what i saw under the timing cover:


and the new tensioner next to the old one:



anyways, back on track to your problem. It is possible there is damage to a cam gear? Yes i suppose it's possible, but i can't imagine how... It sounds as if the mechanic is trying to scam you. Do some more research on the subject, check out www.allpar.com, lots of good info on the engine there.

btw, I replaced the timing belt in my car, took me about 10 hours in the driveway, but only because i didn't have some tools, and because the tensioner bolt was busted off into the front plate of the engine.