1994 Olds 88 3.8 V6

A while back I posted about loud banging while starting, and after attending to a couple of other matters, I am back with more information.

I am still trying to figure out why after starting sometimes something knocks REALLY badly 2-3 times (like a rod is about to punch through the block). Once the engine is at idling speed, all is well, and it doesn't do it every start-maybe 1 out of 5.

It'* LOUD and dramatic enough it sounds and feels like someone is striking the engine block w/ a BIG hammer, and the engine mechanically pulses each instant it knocks (as if it is hanging up on something mechanically for a brief instant). Once the engine is running, it sounds smooth like a Swiss watch as well it should w/ 60k original miles on it.

My feeling was that it was a loose bolt in the bell housing that occasionally flips and gets caught between the torque converter or the flex plate and the housing itself, then flips out of the way again.

Yesterday, the starter quit, giving me the opportunity to examine. Odd that at 60k miles since new, the solenoid quit (no click, but there is voltage at the solenoid terminal, so it'* a dead solenoid for sure).

I dropped the starter, and it looks fine, with the starter shaft and teeth, and the teeth on the ring gear in perfect condition all around (though obviously I am going to replace the unit).

I carefully examined inside the bell housing as best I could with the inspection cover (where you get at the flexplate-to-torque converter bolts), and I can clearly see an area around the T/C shiny steel (outboard of the ring gear teeth) where something has been rubbing, and there are some shallow "dents" as well that I imagine are caused when it "bangs" loudly. The dents look like someone took a punch and hammered some shallow (maybe 0.005") divots into the T/C.

I inspected carefully w/ a flashlight, and probed around w/ a magnet wand, and had someone turn the crankshaft while I looked and probed in the bell housing as well as I could, and I could find absolutely NOTHING down there at the bottom where one would expect to find something loose like a nut or bolt floating around that could sometimes pop up and into the way.

Any ideas what it could be causing this, or what could be loose and getting into harm'* way at times?

The rub marks are all around the radius shown with a RED arrow in the photograph that is at this Link: 2013-06-29_0929 - bobinyelm'* library The photo is taken looking up and slightly back into the inspection area (big plastic cover removed).

The narrow rub/scratch mark all around the T/C is not that shiny in the photo, and the small shiny indentations (divots) are on the other side of the T/C (but in the same area the arrow points to). They are all in the radius of the T/C right at the arrow-point.

Any ideas or suggestions most welcome as I am sure that at SOME point, whatever it is may do some actual damage to the T/C or something else.

Any other way to get at that area to inspect w/o pulling the engine/tranny?

Bob

Check to make sure you still have 3 bolts on the flywheel/TC.

Yep-
First thing I did w/ the cover off was to have a helper rotate the crankshaft so I could check the T/C bolts for presence and torque.

I would have thought that if there WERE a loose bolt in there, it would have been at the bottom where it could have been felt, seen, or snagged by the extension magnet I fished around with.

So far, with the new starter in place, in about 1/2 doz starts it hasn't banged, so maybe (hopefully) it was just the starter, though that doesn't explain the scratches and divots, but I'll give it a while.

Thanks-

Have you had your vehicle serviced by anyone besides you? Like a quick time lube or something?

It'* possible that the old starter solenoid'* bendix was sticking in the out position and making contact with the flex disc. I've had that happen before on a Mercedes Benz I used to own. It literally sounded like the engine was blown.

We just purchased the vehicle for a young man staying with us recently.

When we started it for the test drive, it did the "bang-bang" routine, but the seller wisely said it was the exhaust pipe banging when the engine started, and my wife (standing at the rear bumper concurred). To me (inside) it didn't sound that way (in fact inside it isn't lound at all-sounds like a cold misfire), but I (stupidly) didn't question.

It didn't do it on subsequent starts when I was outside, so I didn't hear it until the next day (after purchase) when I WAS outside and it was a "Holy CRAP" moment. Seems to not do it every day, but when it does it the engine is almost always cold (first start of the day).

The car is low miles (verified by seats, pedals, and inspection ticket mileages for years) but wasn't "loved" for a while by its elderly owner, so I don't know what servicing it'* really had. For instance the passenger window, which was taped closed and supposedly just needed a switch turned out being a broken regulator linkage (that I was able to MIG weld to restore the spot welds that had broken long ago inside the door).

I'm trying to get it to excellent reliability for the gent, and may even put a "Maaco" paint job on it to repair the Texas sun-damaged clearcoat on the top surfaces of the vehicle. Other than that, it has not a single door ding or spot of rust, so I think it HAS potential as long as nothing self-destructs badly.