I read somewhere that Head Studs leak on LT1s. I installed some head studs with high temp thread sealant on the studs. Each thread was cleaned with a chaser, not a tap. I haven't fired up the car yet but as I was putting in coolant, there was a leak. The car is raised from the front so the water was dripping from the back of the engine.

I checked the steam pipe seals and they are dry. I thought that studs were supposed to offer a tighter, more even seal. Then why do I have a leak back there?

Has anyone else had a leak with head studs? Why?

How can I remove the studs without having to rip apart the whole heads with new head gaskets? Can I pull one out at a time and replace the studs with bolts? Or will that warp the heads?

 

Are you absolutely positively sure it's coming from the head studs. It would seem if that's the case there is a much larger problem, like the heads not seating onto the block properly rather than just head studs since they are surrounded by gasket material.

 

Did you put in the coolant temp sensor and plug in the other side of the head?

 

The coolant temp sensor is on the driver's side with thread sealant. I'll double check around that to see if it is dry. It is between #1 and #3.

The head sat on the pins. It would seem kind of tough to thread the studs through the holes if they weren't centered.

I triple checked the pipe and the seals to the steam pipe and they are dry.

The leak is only on the driver's side, not the passengers. If I could get more water in there, then I can pressurize it to see if it streams out from somewhere.

 

Most stud problems I have read about were only after the system was under pressure. It would have to be a pretty good leak to come out when just filling the radiator. Hopefully, it is somewhere else.

 

Update - I just checked the ECT and it is dry... driver's side between #1 & #3.

I was able to grab my cooling system pressure tester even though there is a significant amount of air in the radiator. I pressurized the system up to 5 psi and the leak started from the back. I grabbed a dry towel and mopped around the steam pipe and seals... dry.

There is a small lip (or overhang) from the head onto the block. The seepage seems to be coming from the middle of the head on the back side. I pulled out the torque wrench and it is at 85 lb/ft as specified by ARP studs with 30w oil. I didn't check the lower one under the header or the ones between the rockers. All were tight and clicked the torque bar without movement.

I had the heads milled. Going with SSRRR's theory of not seating flat on the block. The gasket is clearly in the pins and the pins are in the head. Now, if the head was milled, how deep are the holes for the pins. Is it possible that the pins on the block could actually be lifting the head and thereby prohibiting the head from seating flat? Or is there enough depth on the head not to worry about pin depth.

That block is clean and prepped. There was very little gasket material from the OEM gaskets. 99% stayed intact to the gasket. I was going to dab a little permatex onto the gasket around the water jackets but I didn't... people were saying that is on old-school gaskets and is unnecessary on today's materials. FYI - I'm using the Impala Gaskets from GM Perf Parts.

 

What gaskets?
I know cometics do that alot....don't fill it all the way, make sure its not getting in a cylender.

Let it heat up and get hot a few times and cut it off let it cool all the way down. I had to do it with mine, I thought the steam pips were leaking too but I had to get it hot a few times and they sealed up

 

You mean you ran it with little coolant? Didn't it overheat?

I'm using the GM Performance Parts Impala Gaskets PN 12553160. So, run it for a bit then turn it off for a cold soak a few times. Did you retorque? What was your coolant level?

 

I didn't retorque it. I filled it as I started it and kept an eye on it. Let it get a little over 200 then cut it off. Let it sit til it was cold

 

Well... maybe your right. The head gaskets aren't sticking. I figured that the GM Perf Parts wouldn't need a "warm up" cycle to seal.

It went together smooth. I matched the gaskets with the earlier gaskets. I put thread sealant on the stud threads (not the block threads). I torqued the studs in 4 passes with 30w oil. I triple checked them at 85 lb/ft.

I'll try a small warm-up with a little radiator stop-leak to see if that works.

If not, then I'll have to pull the intake and the head again. I'll need to order another head gasket I suppose. Can I reuse the Intake & Exhaust manifold gaskets since they haven't been run? But they have been torqued.

 

I did not have a problem with mine. I did how ever use a cometic gasket. I am confussed though. You said that you put sealant on the stud thread not the block thread. Does this mean you did not seal the stud threads into the block when you torqued them in?

 

Oh and I did torque check mine after 100 miles.

 

Correct, I put the thread sealant on the threads of the studs that go into the block. I did not put the thread sealant in the block holes since it seems that it would squish into the water jacket.

There was a good amount that was put onto the stud threads that went into the block. The sealant went all around the stud for about 4 threads high.

Another option is to pull the studs out one-by-one (without removing the head) and putting more sealant on the stud threads. Then with a swab, stick it down the hole to get thread sealant on the block threads too. That way both would be covered with sealant. I'd be a bit worried about using a cotton swab since a fiber may fall into the threads and mess up the torque.

Also, removing a stud without removing the others... wouldn't that warp the head?

 

I dont think that is going to be your issue. It does not take a ton of sealant to get a good seal. Also if you tried to pull them back to reseal them your torque would be bad due to the sealant already on them hardening. Run a feeler gauge around your head to be sure it is seated correctly to the block. There should be no more gap then the compressed thickness of the gasket you put on.

 

My only other thought is that You missed on of the out bolts when you were torqueing your heads. The ones that face the fenderwells. They are the shorter ones that go directly into the water jacket. Missed sealant on one of these bolts may very well cause a leak.