We win some and we lose some.

[L31MaxExpress]

I drove the van for 3-4 hours this afternoon. I parked it, then noticed a small coolant puddle forming. I looked up under it and had coolant dripping out of the starter. I cannot tell if its leaking from one of the two head bolts or the gasket itself. At the very least I am pulling a valve cover, adding some more sealent to the head bolts in the area and retorquing the gasket. More than likely the intake and head will have to come off. If the head is coming off, I will be porting the marine intake and installing it while I have it apart. I retorqued the heads on it after I had heat cycled it a couple of times on the stand. First time I have ever had a head gasket leak on a fresh SBC. The block was decked, the heads were milled and it has 0.028" thick GM head gaskets. I put thread sealer on the head bolts. Has me scratching my head for sure.

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[L31MaxExpress]

Well hopefully good news. I let it cool down some. Pressurized the cooling system. Dried the leak area with a paper towl and needle nose, was still pretty warm. It is leaking out of the top of the 2nd lower head bolt from the rear. Fingers crossed, I can pull that bolt without yanking the header, put some sealer on it and retorque it to stop the leak. I have not seen any coolant in the oil, so hopefully the head gasket is not leaking and no other bolts are leaking. It is running so well right now, I would hate to have to pull a head, and then mess with the valvetrain.

 

[GMCTRUCKS]

Check your freeze plugs

 

[Spareparts]

Hope it's a cheap easy fix!

 

[0xDEADBEEF]

Might explain why that electric fan couldn't do the job. Hope it's nothing major.

 

[L31MaxExpress]

Might explain why that electric fan couldn't do the job. Hope it's nothing major.

It was staying pressurized at that point.

 

[L31MaxExpress]

Check your freeze plugs

All the freeze plugs are below where it is leaking. Its a head bolt that is leaking. I held a small piece of paper towl directly to the head bolt and it became saturated with coolant pretty quickly. Going to try to pull it, reseal and retorque it and see what happens later today. Guess there is a first time for everything. First SBC head bolt I have had that leaked in this manner.

 

[stutaeng]

Sounds like a good plan to me. Hopefully that fixes it and you get it back on the road. Good thing you caught it early.

Where the bolts new? Maybe there's a little defect on the threads? Or maybe just the sealant started seeping? Can you use thread restorer to clean the threads into the block? Or does that require head removal?

 

[L31MaxExpress]

Sounds like a good plan to me. Hopefully that fixes it and you get it back on the road. Good thing you caught it early.

Where the bolts new? Maybe there's a little defect on the threads? Or maybe just the sealant started seeping? Can you use thread restorer to clean the threads into the block? Or does that require head removal?

I think a thread chase would require engine removal TBH. Not much room between the block and body in that area. They were new Jegs brand head bolts with washers for the aluminum heads. I think the sealer just started seeping. But I will clean the bolt and take a good look at it. I have a long gun cleaning brush with stainless wire brushes and a somewhat flexible shaft that I will chock up in a drill and clean the bolt hole the best I can.

 

[L31MaxExpress]

On a plus note, I found some more torque management nannies in the tune that were killing off torque on a heavy throttle transition. I did not realize it, but I found my rough running misfire feeling on a heavy throttle stomp at low speeds. The LS PCM used with a 350 can cut 2 or 4 cylinders by killing injectors to smooth out the torque delivery. It is now set to get all 8 all the time and since I do not use torque management shift torque reduction anyway, I zero'd out the torque reduction spark advance table to eliminate the PCM pulling timing for torque management. It was hauling butt before the coolant leak.