blown 87

We found the problem
Let me start by saying that I have been a pro wrench for many years, started my first aid job when I was 14 and I am 50 now.

This is a little hard for me to admit that i got fooled by it.

When we had it in the shop on the lift a older man that works for me on the american cars (calls me kid) walked by and said "carbon can make one sound like that", one BG cleaning and it runs and sounds like it should.

I was about ready to pull the motor over carbon on the piston.

This may be a very bad sign of things to come, but it does not smoke or knock so I am a happy camper today.

Kevin Michael

" BG cleaning"??

928drvr86.5

BG cleaning? Please explain.

heinrich

This sounds very scary Blown ... where did the carbon hit that it knocked like that? INTERESTING though .... my ex-s S4 knocked like yours does. And she DEFINITELY had heavy carbon.

heinrich

I found http://www.bgprod.com/products/fuelair.html Personally this sounds a little scary.

blown 87

It is three of the BG products, a air intake cleaner, a fuel system cleaner and a injection cleaner.

We use it on a lot of cars, it cleans the intake tract (you know how gunky the back side of the throttle bodys can get) and the carbon out of the cylinders. it is good stuff.

I have seen what it can do with a borescope as far as cleaning the back of intake valves.

Almost all of the european car shops use it, even the dealers.

I guess that the carbon had built up while the PO had it and when I got it and started driving it hard a peice of it got wedged in between the piston and the head.
That is why it was making a noise at the crank because the piston was literaly touching the head at tdc and the sound traveled down the rod.

blown 87

Here is a pic of the three parts of the BG cleaning kit, it does take some special tools to use it.

Garth S

Congrats!
My Chev 350 suffered the identical fate once: following a general tune up, it started with a hammering that made children run for their mothers and dogs to hide. Baffled, local experts declared that the crank was fractured .... and the bright young guy ( not me, in this case ), said "carbon".

I slowly poured two cans of GM 'CLeens' into the intake of a running engine, hammering and shaking as it was - and stalled it out with the last 1/2 can to soak overnight. The stuff washed the cylinder walls so well that I had to squirt a little oil in a couple of plug holes in the AM to get enough compression to start.
When it started, it was pretty rough, still hammered a bit, and filled the area with billowly white clouds ..... but it smoothed out, and is running perfectly 8 years later .

Carbon it was - likely wedged in a valve seat: the hammering was truly awesome

blown 87

Yea Garth, this one really had me fooled.

This makes the third time I have seen it happen in almost 35 years of turning wrenches.

It really drives nice now with all of the new bearings and TT, and everything else we put in it.

Short list of the last project.
rear main seal
Three bearing torque tube
Constantine's TT shaft clamp
Convertor bearings
trans gaskets, stator seals, convertor seals, axle seals
reman axles
rear wheel bearings
repack front wheel bearings and seals (BTW, great idea of having to use a slide hammer to get the dust covers off, WTF were they thinking)
new foam that goes over TT and under shifter. (now I can ride with the window down and not have very hot air coming up around the shifter )
impulse sensor
most of the engine compartment fuel lines
drilled Zimmermans and Mintex street pads
bolts in rear flex plate
trans overtemp switch
I know there is some things that I am forgetting

I would like to thank all of the great suppliers out there for there service and support of the 928's

I promise overy one here that I am going to drive it hard, very hard.

Next project, intake and cam covers powder coated, new cam chains and tenisioners, MAS, IAC, all of the hoses under the intake, knock sensors, cam sensor, etc.

Then she is off for paint, some of Pauls great leather work, wheels and tires, and I hope a blower sometime next year.

Gretch

Now, THAT, you are gonna like!!!!!!!!!!!

blown 87

Yep, love it on the Corvette and I am saving $$ for a blower for the 928.

worf928

Greg, would you mind giving us (me) the basic steps for doing the BG cleaning? Carbon buildup removal is one of the things I need to do to my GTS that I've been putting off.

heinrich

Warning: removing carbon may lower compression

worf928

Yeah. I hope. That and lower pinging...

Fabio421

The 44k product works VERY well. Just wanted to second the opinion of Blown87 for some of the doubters.

Congrats Blown87, this could have been very expensive learning experience. You old that old timer lunch.