Donor Help - Cobalt SS wont start but cranks - Thoughts?

PHerder

Well-Known Member
Tilt one side up (i.e. exhaust side) and pour solvent into the port. If the valves are leaking, the solvent will run out. Do it for the intake side also.

No leakage, valves are good.
 

BaltimoreHokie

Goblin Guru
Tilt one side up (i.e. exhaust side) and pour solvent into the port. If the valves are leaking, the solvent will run out. Do it for the intake side also.

No leakage, valves are good.
Thanks. I had thought of some type of test like this but was not positive how I was going to test it. This makes the most sense. Any suggestions on what liquid to use?
 

Lonny

Administrator
Staff member
If you find one leaking, pop the top of the valve with a rubber mallet a couple of times on the spring side. This will cause the valve lift of the seat and resettle in a better spot.

Valves seat themselves while while the engine is at running temperature and with the cylinder head torqued down. When you remove the head from the block the head will have a slight distortion.

Popping the valves open to let them resettle on their seats will give you a more accurate test.
 

Briann1177

Goblin Guru
The service manual doesn't call for replacing the bolts when reinstalling the head. Just says clean with a nylon brush and blow out the bolt holes.

As far as going with studs, I wouldn't worry about it. I'd just stick with bolts.
 

Karter2026

Goblin Guru
The service manual doesn't call for replacing the bolts when reinstalling the head. Just says clean with a nylon brush and blow out the bolt holes.

As far as going with studs, I wouldn't worry about it. I'd just stick with bolts.
I replaced mine. After I found out what the total torque was on them I would not do it again. I don't believe that they are stretched all that much to the point of needing replacement.
 

Briann1177

Goblin Guru
My reading comprehension is a fail this early. It does call for new bolts. Main head bolts are 22 ft-lbs + 155 degrees and the four front bolts are 26 ft-lbs.
 

BAR-AIR

Well-Known Member
If you go with a ARP stud kit I believe that they are reusable. OEM bolts / replacement bolts are torque to yield so technically scrap after used. (Not that people don't reuse them).
 

Karter2026

Goblin Guru
If you check after Your done with the 22 ft-lb and the 155 Degree angle It comes out to about 90 to 95 ft-lb I seriously doubt that it stretches those bolts much. I have done heads where the final was up over 150 to 175 ft lb That may stretch the bolts.
 

SliderR1

Well-Known Member
I just can't image the stretch on steel bolts when bolting them to cast aluminum. There better be a lot of thread in the block.
You know - I was surprised when I found out out the LS engines are the same way. Most of the builders I've talked to are VERY adamant about using new head bolts. Stock type sets are not too expensive, so I guess it's cheap insurance...
 

dperkins

Well-Known Member
I would replace those bolts and either get OEMS or ARP head studs, which do have pretty much unlimited uses. The head bolts NEED to be replaced. You can not replace them, but you would risk snapping the bolts, and that isn’t fun. I’ve looked on forums for this and it seems to be surprising common...
 
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