SM105K

iTrader: (3)

I have a 2001 SS with a 99 4.8, APS TT, with a powerglide. The 4.8 has some worked 862 heads, LS9. eadgaskets, pro comp studs, LS6 cam, br 7 plugs.

Put it on the dyno for the final tune, first pull it knocked the damn freeze plug out of the head. 14 psi, with only 9 degrees of timing netted me 568 hp with 505 ft lbs of torque. Have any of you FI guys ever seen anything like that?

My head guy said he didnt touch the freeze plugs. I am pretty sure it didnt lift the head, and if it did wouldnt it have crushed the radiator cap? Maybe it cracked the head.....I am pulling the head off today to check it. Maybe it was just a weak freeze plug.......

rwb

At least it didn't happen on the street and leave you stranded somewhere.

nxfirebird

iTrader: (1)

pin the plug back in!! don't just blow it off if you don't find anything, make it so it can't come back out.
I have a freeze plug bore in a block that was a little over sized. it never moved during it's service as a stock 140k motor. it fell out on a burn out, I put another one in. 2 passes later I hit the wall head on at 125 when it popped out again, shortened the car up 3 feet.

Wicked69

Yes, I have done that before. I thought I blew a head gasket and pulled the head and then realized I blew the plug out. I didn't even know it had a plug in the head at the time. lol Put a new one in and ran like a charm. Mine blew out running above 20lbs of boost and it was at the track.

SM105K

iTrader: (3)

I got the head off. It doesnt look cracked. However I will get it tested, and I will make sure that it doesnt come out again.

c0ncEpT

iTrader: (4)

Epoxy the next one in.

BottleFedZ346

iTrader: (17)

Same thing happened to one of our car's, pulled the head and had it back on after a $3.00 fix lol.....

Blown06

iTrader: (32)

fixed it for ya

stock48

iTrader: (17)

You would think it would take some kind of psi in the cooling system to push them out but still a bad deal on the track. Has me thinking about putting some kind of guards across mine.

SM105K

iTrader: (3)

The more I think about it, it probably did lift the head. The boost spiked the maf, and after 15 psi we couldn't read it. Pretty sure it was my error with the boost controller. I haven't confirmed but, I have a feeling. Hell it could have seen 25+ psi for all I know. I ordered a new head gasket and it should be here later today. I am also taking the head in today to get it checked out. Then tomorrow I will strap it back on and go back to work putting her together again.

SM105K

iTrader: (3)

The head is fine. Looks to be faultly freeze plug installed by gm. Should have the motor rebuttoned up today.

Heavy H.P.

Might seem like a dumb question but what happened on the dyno with the car when this happened?

ssfast99

iTrader: (3)

Hey Easton you didn't tell me it might have seen 25psi lol.

ssfast99

iTrader: (3)

Well what's the news? Get it running again or what?

SM105K

iTrader: (3)

I think my manual boost controller didn't control the boost. It only has 9 lb wastegate springs in it, so I am thinking it only saw maybe 18 lbs of boost. The run was normal, the tuner did some street tuning and the we strapped her down and made the first pull, and it popped the freeze plug.

SM105K

iTrader: (3)

I should have the head torqued down and the turbo manifold back on today. Tomorrow all the little crap should be back on the car (intake, coils, plugs ect). I am hoping it will be ready by noon on Saturday. I did take care of the oil leak from the front main seal as well.

NicD

iTrader: (7)

Just saw this thread, yeah it saw nowhere near 25 psi. On the dyno we let out as soon as it came up into boost because that's when the spray started and it only registered approximately 14-15 psi and the map sensor didn't flatline indicating that it went any higher, the sensor reading was still going up at the point that I let out. Remember, this all happened within a second or two after boost hit so it made nowhere near a full pull.

SM105K

iTrader: (3)

Yeah, I was venting. I rethought about it. Bill said I had a bad freeze plug, and it possibly lifted the head. The head is back on, going to see I can get her fired up tonight for the Cruise tomorrow. Since it has very little timing in it, I will beat on it a little bit, and if she doesn't **** herself again, I will see you again on the dyno and see if this little motor can touch 700. lol.