Long time reader 1st time posting. This is going to be a long post to get all the details in.
I have a 1998 firebird trans am 5.7 bone stock 114k miles. Yesterday we cranked it up it started then immediatly died, when it was turning over it seemed slow turning like weak battery or out of time. After it died the starter would just click. Checked battery and it is fine, pulled starter and the nose was broke off and case was split down the side. No mounting damage. Pulled out broken pieces of starter from bellhousing then I installed the new starter, engine cranked right up but there was a loud knock. The knock sounds like it is coming from the top of the motor. Any recomendations on what it could be or what I should check first. I was going to start with pulling valve covers and checking that area out. Any ideas will be appreciated, Thanks in advance.

 

You sure its not piston slap? The two can be confused to the untrained ear.

 

I am not sure. This is a brand new knock, I have never heard it this loud, this is nothing like the normal or even a little exagerated "lifter tap". I had thought I may have missed some of the starter nose and it was rattling around. So I pulled starter again and any cover I could get to access bellhousing and found nothing. Then I matched what I had pulled out with the old starter and looks like I got it all the first time. I listened from under the car as it was started and definetly sounds like it is coming from the top end. Also it sounds like it is coming from the passenger side of the motor. The first time I started after the starter change I immediatly shut it down due to the loud knock I was hearing while sitting in the driver seat.

 

This is the starter

 

Unfortunately what you describe in a hydro lock situation. Has the car been sitting outside in the rain? What can happen is the rain leaks past the windshield cowling down on top of the engine. The water finds a way into the intake manifold through the gaskets and slowly collects in the intake. Then you try to start it and that water goes straight into a cylinder hydro locking it and either breaks the starter OFF completely or it breaks the housing and sometimes does internal damage. Bending a connecting rod, broken piston etc.

I think if you close your hood and run water over the windshield then open the hood you will be very surprised how much water is leaking onto the engine. When the car is new and gaskets and intake manifold bolts are tight you can get way with it, but with time the gaskets shrink and bolts loosen then water can get in quite easily.

I'll give you a good example over time the gaskets shrink and bolts corrode in the threads. The bolts feel tight but only the threads are tight, the manifold itself is loose. Its hard to get this through peoples heads when I tell them I'll bet the intake is loose but they say no the bolts are tight.............................

At this point you need a good mechanic to pull it apart, find the damage and have it repaired.


1st thing I do to every fbody I buy is seal the windshield cowling and loosen all the intake bolts. Lube the threads and bolts then tighten to proper torque. I had a few close calls in the rain before I discovered why. My 02 Formula always started funny like you described above after sitting overnight in the rain,until I opened the hood and seen the water dripping over everything. After I sealed the cowling and tightened the intake never had a problem again.

Good Luck to you

 

Thanks RockinWs6
That sounds like what could have happened. It was sitting in the driveway and it rained all day before we went out to move it. We had multiple inches of rain.

 

Yep that's exactly what happened, I seen it over and over. Gm should be ashamed for making such a obvious hidden issue just to make dealer work. See they get away with it for a bunch of reasons. 1st the intake gaskets don't leak until its out of warranty and most people just never think of looking if rain water is dripping on the engine. 2nd its a performance car, the engine tosses a rod and most people think it was from beating on it.

GM tests these cars to an extreme, They know what is going to happen to them and when! Just like the ORING for the oil pickup, they know the acids in the engine oil are going to eat it over time but only offer a acid resistant oring over the parts counter.<planned to make your wallet ALOT lighter!

Once you get it fixed be sure to seal that cowling and test it in the rain. There is about 40 places along that cowling where it leaks water. Its a real pain in the azz to seal up.

 

Good info here

 

Dropped the motor and found #6 connecting rod bent. Everything else looks fine so far. I will definetly be sealing the cowl before I put everything back together.

 

Be sure to test it carefully with the hood closed using a garden hose. Also for a few rain events pop the hood and be sure nothing is getting onto the engine. You need to seal every little hole, there is a bunch of them.

I put gloves on and take the silicone with my fingers and coat every hole using a mirror. Takes some time to get it all sealed.

Another good way to completely seal it is to remove the wiper arms and cowling then pre seal everything then reinstall the cowling.

I've dodged this bullet a few times, I keep the cowling sealed and the intake bolts tight.