1st time ever leakdown test - are these results normal?
10-26-2014, 11:13 AM
#1
1st time ever leakdown test - are these results normal? I've never done this before, so I'd like advice from those that know more than I do.
LS6 forged 383 shortblock from Texas Speed, with~1500 miles.
F1 Procharged with ~12 PSI boost, 660 RWHP.
Cold engine. All leakage was from the oil fill hole, none from tailpipe, intake, or radiator.
1: 10%
2: 10%
3: 22% -- I did this one again after I finished the others to be sure.
4: 9%
5: 15%
6: 12%
7: 25% -- I did this one again also, after I finished the others to be sure.
8: 6%
Pulled the valve covers, no broken springs or anything obvious.
Symptoms: 3rd gear pull that felt great, engine died at the next stoplight. I started it back up but had to stay in the car and give it gas to keep it from dying. Fuel pressure was 58PSI. Lots of white smoke from the tailpipes that looked more like coolant smoke than it did oil smoke. I decided to try and limp it home, and after 400 yards it cleared up and ran fine all the way home, although I did not get back into boost... I just tried to limp it home.
By the time I got home I could rev it up in the drive way and nothing sounded weird, and there was no smoke. Idled perfectly.
LS6 forged 383 shortblock from Texas Speed, with~1500 miles.
F1 Procharged with ~12 PSI boost, 660 RWHP.
Cold engine. All leakage was from the oil fill hole, none from tailpipe, intake, or radiator.
1: 10%
2: 10%
3: 22% -- I did this one again after I finished the others to be sure.
4: 9%
5: 15%
6: 12%
7: 25% -- I did this one again also, after I finished the others to be sure.
8: 6%
Pulled the valve covers, no broken springs or anything obvious.
Symptoms: 3rd gear pull that felt great, engine died at the next stoplight. I started it back up but had to stay in the car and give it gas to keep it from dying. Fuel pressure was 58PSI. Lots of white smoke from the tailpipes that looked more like coolant smoke than it did oil smoke. I decided to try and limp it home, and after 400 yards it cleared up and ran fine all the way home, although I did not get back into boost... I just tried to limp it home.
By the time I got home I could rev it up in the drive way and nothing sounded weird, and there was no smoke. Idled perfectly.
10-26-2014, 11:19 AM
#2
Forgot to mention I had to pull the radiator to get to the crank bolt (my radiator is literally millimeters from the front of the procharger pulley).
So I was putting my hand over the water pump inlet, and had my ear placed on the outlet. I wasn't checking for bubbles like I've read in other posts. (Yes I did do a search before this post!)
So I was putting my hand over the water pump inlet, and had my ear placed on the outlet. I wasn't checking for bubbles like I've read in other posts. (Yes I did do a search before this post!)
10-26-2014, 02:50 PM
#3
Update:
After talking to a few people, I put it back together and went for a test ride. Everything was smooth, no smoke, misfires, or anything else. But I know there has to be a problem... I'm pretty sure it was coolant in the engine. Somebody suggested the heads lifting under boost but at 12 lbs with ARP bolts I wouldn't expect that?
After talking to a few people, I put it back together and went for a test ride. Everything was smooth, no smoke, misfires, or anything else. But I know there has to be a problem... I'm pretty sure it was coolant in the engine. Somebody suggested the heads lifting under boost but at 12 lbs with ARP bolts I wouldn't expect that?
10-26-2014, 03:59 PM
#4
Since there was white smoke & coolant in engine (oil), it does sound like a head gasket leak while in boost. If it continues to happen, I'd pull the heads & install new head gaskets sprayed w/copper. Re-torque the head bolts after first couple of drives.
May want to check head bolt torque now. Tightening won't fix an already leaking gasket, but may confirm an under torqued bolt(s).