It's been awhile since I have posted here, and I need some serious advice here on our LS1 motor.
2000 Pontiac Firehawk

No check engine light
No drop in oil pressure
No nothing.
I don't have a video of the sound either, but just imagine a large heavy chain going through a metal tube, almost like a ships anchor being pulled up, but on a smaller scale of course.

Husband went to start the car last week, and there was this horrible clunking/grinding sound. He did not allow the motor to turn over.
Brought it to the shop, and they said that the starter had cracked right by where it is supposed to be bolted on.

New starter was replaced, got the car back Wed.
Drove the car Thurs. and Fri. Started and ran great, then it sat for two days.
Monday, I went to start the car and same thing. Sounded like a metal chain clunking, and I did not let the motor turn over either.

Car was towed to the shop again, and they bench tested the new starter and another new one and they said it was fine.
Flywheel teeth are in great shape.

Then I get a phone call later yesterday stating that something is up with the valve train and #2 and another cylinder is bad. I believe he said the two on the passenger side are bad.

What are my options now?
We are taking the car home, taking it off the road for the time being because the way the mechanics are talking, this is going to cost a lot of money to repair.

Any suggestions on what to look for when taking the valve covers off? Some said to take the spark plugs out and do a compression test. Doesn't the car have to run in order to do a compression test? I am afraid to start the car in fear that if I let it run, it may do more damage.

WHY did this all happen and no warning?!

 

For compression test you remove all the spark plugs and turn the engine over on the starter. However in this case a leak down test would be a safer option. See
http://en.wikipedia.org/wiki/Leak-down_tester

Essentially you test each cylinder at its TDC.

Remove the valve covers and inspect of any broken valve springs, rockers and rocker bearings.

I am wondering if the timing chain has failed, that is slipped. If you know your cam specs check your valve timing before removing the timing cover.

Let us know how you get on.

 

Well I'll sum it up for you, windshield cowling leaks water onto intake manifold. Intake manifold bolts are loose. Water leaks past intake gaskets and into the engine. You go to start the engine and slug a cylinder with water. STARTER BREAKS OFF. Starter gets replaced and no one ever considers why it broke off in the 1st place......... Good Luck

 

Tear it apart and look for the broken pieces. If it truly sounds like a chain in a metal tube something broke.

 

You must have missed the part where they drove it for two days after the first starter replacement.

 

No I didn't, damage was done or more water got in the intake because NO ONE TIGHTENED THE INTAKE BOLTS. I seen this happen so many times its insane, GM should have sealed the windshield cowlings.

The new Camaros have the intakes covered completely so this can't happen.


!st thing every Ls1 car I buy gets is the windshield cowling sealed and the intake bolts tightened. I've never seen a factory LS1 car that the intake bolts were NOT loose. After about 30k miles you can turn them out with your fingers.


If you read between the lines on this site you see this at least once a month on here someone posting up the engine suddenly broke after rain at start up. Either the starter breaks off or the block cracks etc.

 

Well, my husband took the valve cover off, and now there is not clunking sound.

 

I am wondering if the timing chain has failed, that is slipped.

 

"at least once a month"

Hmmm, I haven't see this posted at all. My car's intake manifold at like 180,000 miles did NOT have loose manifold bolts-and it's lived outside most of it's life.

Could you tell us more about this phenomenon? Tell us what it takes to seal the cowl.

 

I doubt this. The chain would break before it jumped. And the car wouldn't have been drivable if it did (due to the cam sensor being off).

 

Have a good look inside the valve covers. Any signs of metal on metal contact, rubbing or wear?

I think you should do a leak-down AND compression test. Inspect the rocker arms, valve springs and push rods thoroughly. Any excessive wear to the rocker arm to valve tip? Any on the valve tip?

How many miles on this car? Any modifications?

 

Last months winner https://ls1tech.com/forums/generatio...-start-up.html

 

Alright, I suppose it's possible but in the thread you linked to this issue was your suggestion, it's not yet proven by the OP. Thanks for posting it.

If an engine had a loose intake manifold, it should exhibit signs of false air (vacuum leak). The suction of engine vacuum is far greater than water leaching in by gravity.

Tell us about sealing the cowl-it sounds like a good idea regardless of any other problem.

 

Next time it rains open your hood and see how much rain water is dripping down on to the intake and running back along the heads back towards the transmission.

I've owned 5 LS1 fbodies and every one suffered from loose intake bolts ANd the stock GM intake seals are notorious for leaking even when tight.............

Don't believe me?
I don't care......

 

We believe you-it's just that I haven't experienced this and didn't know it was a common problem.

Share with us what it takes to seal the cowl.

 

I found this problem the hard way on my 1st LS1 TA, came out after a rain storm and the car started funny. I thought to myself WTH just happened? Started fine every time after that UNTIL it rained overnight and the car sat. Started funny again like it started to lock up then started.

So I popped the hood and sure enough the intake was wet along the edges. I took a water hose and wetted down the area around the windshield cowling, Christ water dripped through at about 40 different places. I pulled the cowl and sure enough its not sealed in any way. I also found ALL my intake bolts were loose, car had about 30k on it.

I use black silicone and seal the plastic push fasteners and then all along the plastic cowl and the under rubber seal. It takes a lot of time to get it completely sealed to the point that NO WATER drips through onto the engine.

My wifes 02 Formula with 31k on it when I bought it, I tightened the intake but never sealed the cowl because I didn't get around it time wise. At about 65k she goes to start her car after it rained the night before and the engine locked for a second then started.

I about ****, sure enough those effin intake bolts were loose again. Now i'm an experienced engineer, I tightened those bolts with a proper torque wrench the 1st time around. The heat cycles these engines goes through every time you run them causes these bolts to loosen and I suspect the nylon intake itself moves around and shrinks a bit over time. Lock tighting the bolts is a poor solution because this just locks the thread, it doesn't do anything for the changes the seals and intake bolts go through from heat cycles.

I check the bolts every 30k and they ALWAYS need proper tightening.

If you look at the new Camaros they have a complete engine cover to be sure no water gets onto the intake.

To the OP of this thread, If you dodged a bullet and engines runs ok seal cowling and tighten the intake with the proper tools.

 

Thanks for posting all that. Sorry you had to go through it so many times.

It sounds like a worthwile thing to do-easy for me as I'm about to pull my engine and the hood's off.

 

the thing i don't get is, if the intake manifold bolts are loose and if water gets on top of the motor and is able to leak in... then shouldn't you have problems starting the car when dry? wouldn't you have a vacuum leak, poor running motor, and a bunch of related DTC's and a check engine light?

you simply need to use thread locker on the intake manifold bolts. a plastic intake manifold with soft gasket material you're not suppose to crush, you can't get sufficient torque on the bolts to prevent them from loosening without breaking the plastic intake manifold or crushing/distorting the gasket.
I ended up putting new intake gaskets on my truck which has the cast iron 8.1L engine and an aluminum intake manifold, those were reported or has a TSB about oem gasket leaking and needing replacement and that stated to use threadlocker on the bolts since they only get tightened down in inch-pounds..

 

I would agree that a nylon manifold could expand & contract with heating & cooling cycles but any dimensional changes or movement should be easily compensated by the silicone O-ring style intake port gaskets.

Regardless, Rockinws6, who appears to have a good grasp of the componants involved, has had this happen several times. It won't hurt to seal the cowl and occasionally check the manifold bolts. I don't think the bolts are turning out but perhaps the gaskets are ''relaxing'' over time.

 

What's a good way to seal the cowl