Timing chain/timing chain tensioner gone. [Archive] - GrandAmGT.com Forum

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JFleury8469
07-24-2009, 07:52 PM
Well, I'm a little sore that my first post on this forum involves serious damage to my GA but here goes.

So I was cruising down the interstate headed back to VT from NH and I gassed it a little to pass someone, and the whole car lost all power, revs dropped to ~1000 and shortly after that the engine died. Pulled over and tried to start it again and nothing, plus the engine sounds different while cranking.

Had it towed to a nearby repair shop and they said the timing chain and/or tensioner is shot. I would just like some clarification/confirmation about whether the engine is damaged and in what way and maybe what it would cost to fix.

Thanks

Mike Jung
07-24-2009, 10:10 PM
6-hours book labour rate, IIRC...for a timing chain & water pump change service.

Don't you love the 2.4L Twin Cam 4-cylinder engine ?

Also, while you have it opened up:
Change the water pump, & flush & re-fill your engine coolant.

So, maybe minimum $600+

But since the timing chain broke on you, more.
Since you probable have to fix some values too (?).


PS: Why did you wait so long to get it serviced ?
The timing chain must of been noisy at cold start-ups.

JFleury8469
07-24-2009, 10:17 PM
Probably should have clarified, this is the 3400 v6. The chain was making no noise, this was basically a no-warning situation. At this point is it worth going to pick it up and bring it back ~150 miles (one-way)? I was also told the piston may have smashed the valves, is this true?

cardude007617
07-24-2009, 10:28 PM
hmmm i thought the timing chain never was really an issue on the V6s....

lone_wolf025
07-24-2009, 11:35 PM
For a timing chain to fail is extremely rare unless its way past the recommended change. As for engine damage, that depends. I don't know if the 3400 is an interference engine or not, but what it boils down to is that if it is and your chain did fail, chances are good you're gonna have major engine work done. Interference engines are ones where when valves are down and pistons are at top dead center they can smash and "interfere" with each other. I'll see if I can find the info before someone else chimes in.

Edit:

Can't find anything specific but someone with a 3.1 had the bent valves to show its an interference engine and that's basically the same engine for the most part as the 3.4. So I'm thinking yea you'll be lucky if you don't wind up with cracked heads if it is one.

cardude007617
07-25-2009, 12:42 AM
at this point he would be better off getting a low mileage junk yard motor or something to put in instead of trying to fix his own of there is extensive motor damage. :/ quite the ****ty deal

AaronGTR
07-25-2009, 08:31 AM
Are you sure they didn't mean the serpentine belt and tensioner? The timing chain is under the front cover and it doesn't have a tensioner. It has a damper, and it controls the rotation of hte camshaft relative to the crank. When a timing chain goes the engine does not just quietly shut off. It's usually accompanied by lots of broken valves and pistons. ;)

There is a much better chance though that the belt tensioner broke since that's a common problem, and losing the serpentine belt would make the engine shut off since all your accessories wouldn't be turning anymore (alternator, water pump, power steering, A/C).

stewartfn18
07-25-2009, 08:41 AM
Are you sure they didn't mean the serpentine belt and tensioner? The timing chain is under the front cover and it doesn't have a tensioner. It has a damper, and it controls the rotation of hte camshaft relative to the crank. When a timing chain goes the engine does not just quietly shut off. It's usually accompanied by lots of broken valves and pistons. ;)

There is a much better chance though that the belt tensioner broke since that's a common problem, and losing the serpentine belt would make the engine shut off since all your accessories wouldn't be turning anymore (alternator, water pump, power steering, A/C).

wellllll, the car COULD still run without a serp, belt, but like you said all of the acc. are not spinning, so you would lose PS, power would be pulled from the bat instead of the alt, no more ac...you get the point OP. but like everyone else has said the timing chain on the 3400 is very robust and is not prone to failure. how many miles are on the car?

JFleury8469
07-25-2009, 09:21 AM
Well when I bought the car the engine was supposedly blown so I had a new (used) engine dropped in for $1300 (~700-800 for the engine, the rest was labor) . It had around 100k miles less than the car (or so my mechanic told me) so now its probably around 48k on the engine.

I don't know if this makes any difference but when I cranked the engine to try to start it, it sounded entirely different than the other 1000 times I've started it and one of the guys I work with said that it was def. the timing chain so I'm still not 100% sure.

I think I'm just gonna go down there with a car dolly and bring it back up here for my mechanic to take a look at it. Thanks for all the answers/advice, I appreciate it.

lone_wolf025
07-25-2009, 11:17 AM
Well when I bought the car the engine was supposedly blown so I had a new (used) engine dropped in for $1300 (~700-800 for the engine, the rest was labor) . It had around 100k miles less than the car (or so my mechanic told me) so now its probably around 48k on the engine.

I don't know if this makes any difference but when I cranked the engine to try to start it, it sounded entirely different than the other 1000 times I've started it and one of the guys I work with said that it was def. the timing chain so I'm still not 100% sure.

I think I'm just gonna go down there with a car dolly and bring it back up here for my mechanic to take a look at it. Thanks for all the answers/advice, I appreciate it.

There's one easy way to see if this isn't a case of belt gone bad vs chain failure. Pop the hood and see if you still have a belt tight against the pulleys. If you do, chances are your coworker might be right.

Anyone find out for sure if the 3400 is an interference engine or not?

JFleury8469
07-25-2009, 12:40 PM
Yeah, the serpentine belt is definitely still there. That was one of my first thoughts while I was coasting "Did my serpentine belt just snap???" hahaha. My biggest problem now is trying to find a truck that I can use with a U-Haul car dolly to get the car and where to come up with the money for gas and the rental. FML

lone_wolf025
07-25-2009, 12:58 PM
Sorry to hear that but maybe you'll get lucky and have minimal damage if any. It might not be likely but until you open the engine or someone knowledge says for sure its non-interference, you still got a shot.

Malaclypse
07-25-2009, 03:11 PM
The 3400 is an interference engine as far as I know.

The only non-interference engine GM has used in recent memory was the 3.4 DOHC that was phased out in '97.

juanvan
07-27-2009, 08:24 AM
There was a list somewhere on google with the mechanic list of all the interference engines. I can't find it now though. I was searching for a Honda B21A1 - the timing belt went in that car 4yrs premature - have to replace the head on it, but its not making any noise and one of the cylinders is at 15psi. still running though :)

JFleury8469
07-27-2009, 12:18 PM
Not sure if this is true for the chain equipped engines as well, but this is a chart for belt equipped engines.

GM Timing Belt Tech Data and Replacement Intervals (http://autorepair.about.com/od/glossary/ss/timin-belt-info_8.htm)

lone_wolf025
07-27-2009, 12:27 PM
Chains last much longer than belts. I just flipped through my owners manual and there is no mention of checking the timing chain. Granted the service recommendations are one step short of useless, if it was a timing belt it'd be mentioned. If I recall correctly chains should be checked every 100,000 miles.

I just heard a quick and easy way to check. Take out a spark plug, ground it, and put you finger over the hole and have someone bump the engine over with the starter. If you feel it sucking at your finger and blowing out you have some compression. You could also pull off one of the valve covers and see if the rockers move when you turn it over. If it passes both tests the chain is intact still. To confirm without a doubt do compression tests on a couple of cylinders. If you have compression on both timing chain is not the issue.

JFleury8469
07-27-2009, 12:42 PM
Well the part I was concerned about was the "Interference" column, it says "No" but I'm not sure if this applies to the chain-equipped engine as well.

Just got off the phone with U-Haul too, they said the Jeep I was gonna use ('98 Grand Cherokee Laredo) is not heavy enough to tow the trailer/car combination. This is turning into more of a headache than I though it was going to be. ;crap

lone_wolf025
07-27-2009, 01:18 PM
Well the part I was concerned about was the "Interference" column, it says "No" but I'm not sure if this applies to the chain-equipped engine as well.

Just got off the phone with U-Haul too, they said the Jeep I was gonna use ('98 Grand Cherokee Laredo) is not heavy enough to tow the trailer/car combination. This is turning into more of a headache than I though it was going to be. ;crap

It could go either way. If it is interference, not much more damage you could do than is already done. If not then you'll be alright.

It might be cheaper to just arrange to have a towtruck pick up your car and take you back. I assume you've looked into that already?

JFleury8469
07-27-2009, 01:48 PM
Well the trailer I was going to use is about $45 for the day, and depending on what vehicle I use it'd be around $50-75 for fuel VS. 100 miles at $3/mile or more calling a tow truck. I'm pretty much at a dead end here unless I hear from some of the people I've talked to about a truck.

lone_wolf025
07-27-2009, 02:40 PM
Whats the cost of renting a uhaul truck one way?

alerored04
07-27-2009, 02:57 PM
It is definitely an interference motor. I had my crank gear keyway shear off last summer. There was carnage. All the exhaust valves were bent and the pistons while not destroyed had deep enough dents to make me worry about crack or deformation so I replaced the whole short block. Mine did the same thing on the first attempted restart after the problem. You can hear the starter spinning but not even a cranking noise since there is zero compression. If you can find a cheap short block and do the work yourself and have a cheap machine shop check the heads and swap the valves you could get off for less than $500. Otherwise you will be better off with a new engine. I have pics of the dented pistons, they are not very visible but enough to cause concern.

lone_wolf025
07-27-2009, 03:02 PM
Ouch.

AaronGTR
07-27-2009, 04:38 PM
Yeah, I remember the one guy in california that had the built motor and rsm SC, was revving it to like 7000rpm and broke the pin on the cam gear so he lost all valve action and he had broken valves sticking out of his piston faces.

alerored04
07-28-2009, 02:47 PM
Mine were not that bad luckily but I ended up replacing it all just to be safe anyway. His was traumatic to look at, funny though cause everyone told him to get a MAF on it and when he did not listen and torched it he tried to blame you guys for not helping him enough.

JFleury8469
09-18-2009, 09:35 PM
Well it seems I'm reviving an old-ish thread, heres the damage on the engine since my mechanic looked at it.

http://i29.photobucket.com/albums/c284/TheRuiner84690/FrontPistons.jpg
http://i29.photobucket.com/albums/c284/TheRuiner84690/RearPistons.jpg
http://i29.photobucket.com/albums/c284/TheRuiner84690/Head1.jpg
http://i29.photobucket.com/albums/c284/TheRuiner84690/Head2.jpg

Pulled the front cover off, the lower timing gear stripped off of the shaft.
Bought a new gear and put it all back together, little-to-no compression on the front 3 cylinders (at least, didnt check the back 3).
Pulled the heads off to find that all 6 (exhaust?) valves were bent and each piston has a nice little ding in it.
All but one of the pushrods are ok according to my mechanic. Looking for some cheap valves (first estimate was $30 ea.) or heads (not the slightest clue on price).

Again, FML

*EDIT*

Also, after he gets the valves/heads he's gonna slap it all back together AGAIN and do another compression test to see if the rings on the pistons are shot.

AaronGTR
09-18-2009, 09:51 PM
Oh yeah... you definitely had some valves bouncing off the pistons there. I'd definitely suspect bent valves and that's what I would blame for loss of compression. They probably aren't moving/sealing right. If the valve is bent it won't seat in the head properly so it won't hold any pressure. ;) The rings I wouldn't think are damaged, and those pistons might still work... but I'd replace 'em anyway since they have dings in the quench area now and I wouldn't want there to be a chance of a crack in them. Not sure if you'd need to replace them for a non-performance build or not.

PhantomLover007
09-18-2009, 10:01 PM
OUCH!! G/L fixing it man.

alerored04
09-19-2009, 08:33 PM
That is identical to my damage. I replaced the pistons just to be safe. For the same reason as aaron stated.

JFleury8469
10-24-2009, 03:16 PM
$900 later and she's running, new SES light reads DTC P0336 Crankshaft Position Sensor A Circuit Range/Performance. Gonna have my mechanic look at that, hopefully just a bad sensor.

Also there is a strange jerking while cruising at or around 40mph, tach reads ~1500rpm, surges to ~1700rpm back down to ~1300rpm and back to normal, only while cruising (caused by CKP sensor??). Accelerating seems fine so far, might replace pistons down the road but everything else seems fine.