Stumped on head gasket symptoms

Jay15857

Registered User
I have a 94 sc with an engine that has white smoke out the tailpipe. I've rebuilt the hg's twice now with the same result each time, white smoke with condensation and bubbles in the cooling system. The second time I had my heads decked but I haven't had the block resurfaced. I checked it for flatness with a straight edge and feeler gage and everything checked out. So unless I screwed up somewhere or overlooked something I can find no cause to this. My next step is to try a compression leak test to confirm it is combustion games coming out the cooling system.
 

35th

Registered User
When using the straight edge and feeler gauge the straight edge really should be a precision straight edge so hopefully that's the method your using also the 2nd time you rebuilt could you visually see damage in 1 or both hg's? And did you replace the head bolts? The original head bolts are one time use not trying to sound arrogant or cocky or deminish your skill whatsoever most of what I'm saying is based on what I've learned from this forum and hope you get it straighten out soon
 

Jay15857

Registered User
Yes, I ordered a precision straight edge specifically to check the block and head surfaces. Both times I used arp studs so that shouldn't be an issue. The second time I looked but didn't find any damage to the hg's.
 

KMT

Registered User
Same heads? Crack checked/inspected?

...try a compression leak test to confirm it is combustion games coming out the cooling system.
Just get your hands on a combustion tester...AutoZone, as an example, free-rents a kit you can use. Just fill the tube w/the test fluid, set it on the expansion tank, run the engine and squeeze the bulb to draw gases into the fluid. If it changes color, you know you have exhaust getting into the cooling system, but by your description, it sounds like you've already confirmed.

Which head gaskets are you using? What torque procedure?
 

Jay15857

Registered User
Same heads? Crack checked/inspected?


Just get your hands on a combustion tester...AutoZone, as an example, free-rents a kit you can use. Just fill the tube w/the test fluid, set it on the expansion tank, run the engine and squeeze the bulb to draw gases into the fluid. If it changes color, you know you have exhaust getting into the cooling system, but by your description, it sounds like you've already confirmed.

Which head gaskets are you using? What torque procedure?
I'm using felpros with the stock tightening sequence and the instructions supplied by ARP. Only thing different I did was torque the heads to 90 ft/lbs. Same heads that I took to a shop and had inspected and decked.
 

35th

Registered User
So it may be an issue with the block possibly I don't know if tighting to 90 instead of the torque angle method would cause that issue or not maybe some of the more experienced guys can answer that one
 

35th

Registered User
_flobird has a post up in the for sale section for a "fairly bare" 94 SC 3.8 motor....
 

Jay15857

Registered User
So it may be an issue with the block possibly I don't know if tighting to 90 instead of the torque angle method would cause that issue or not maybe some of the more experienced guys can answer that one
The way I read the instructions for studs you are supposed to torque the heads down in 3 increments up to 80. I went to 90 with mine. I've read on here some were going higher than 80, not sure if that would do it. Funny thing is I did a leak down test and couldn't hear any air escaping through the cooling system.
 

35th

Registered User
If my memory serves me correctly I belive 3 steps to 80 is for the none super charged 3.8 I'll look when I get home at the exact method I did on mine which worked for my situation but also my hg was blown a little different than yours mine was smoking just bubbling up to coolant tank but I know for certain I had to turn mine 90 degrees in the last step it wasn't a ft lb rating just said 90 degree turn
 

David Neibert

SCCoA Admin
Jay, when installing the stock style Felpro gaskets the part where some people screw up is with the coolant ports. It's super important to position the gaskets with the tab saying Front to the front of the motor. Since left and right gasket are the same, one side of engine will have stripped side of gasket up and it will be facing toward the block on the other side.

Using Felpro MLS gaskets with the rubber looking coating is the best way to go, even if block side isn't resurfaced. Torqueing to 90 ft lbs with studs shouldn't be an issue, I did same on mine.
 

Jay15857

Registered User
Jay, when installing the stock style Felpro gaskets the part where some people screw up is with the coolant ports. It's super important to position the gaskets with the tab saying Front to the front of the motor. Since left and right gasket are the same, one side of engine will have stripped side of gasket up and it will be facing toward the block on the other side.

Using Felpro MLS gaskets with the rubber looking coating is the best way to go, even if block side isn't resurfaced. Torqueing to 90 ft lbs with studs shouldn't be an issue, I did same on mine.
I'm pretty sure I placed the gaskets right with one facing the opposite way.
 

BLOWN38

SCCoA Member
Can you see which cylinder is getting coolant in it? Is possible the cylinder bore is cracked, not likely. Also maybe the intake gasket is leaking. do you have any pics of the cylinders?
 

Jay15857

Registered User
Can you see which cylinder is getting coolant in it? Is possible the cylinder bore is cracked, not likely. Also maybe the intake gasket is leaking. do you have any pics of the cylinders?
I can't I dont have it tore apart right now and I don't have a scope to look in the cylinders. Intake gasket leaking is a possibility although when I put the intake manifold on I used gasket sealer around the coolant ports.
 

DOUG H

SCCoA Member
Intake leak wouldn't put bubbles into the cooling system though? Definatly not on a N/A engine
but possible with supercharged, depending on boost level?
 

Jay15857

Registered User
I plan on running a battery of tests first: compression test, combustion leak test, cooling system pressure test...
 

DOUG H

SCCoA Member
As David said, it will be a advantage if your able to identify which cylinder(s) are
leaking before disassembly, so that you/machine shop can concentrate on that
area. Do you know which one(s) were leaking the previous 2 times?
 

Jay15857

Registered User
The last time I did them I couldn't identify any problem spots and just assumed I didn't torque the heads down right. The first time I could clearly see problem area.
 

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rura

Registered User
Try pressurizing each cyl. individually with compressed air with piston at BDC exh. stroke, and watch for bubbles in the radio. Depending on cam timing, you may have to use a long ratchet or breaker bar with a socket to turn the engine backwards slightly to close the exh. valve. This will give you the most available area in the cyl. and combustion chamber that could be cracked and infusing combustion gases with your coolant.
 
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