Blown head gasket again

kwikt 911 · kwikt 911's Garage

Any input why #3 head nuts somehow come loose. The studs are not pulling out since they are timecerted by Ollies as well as resurfaced heads. Seems like it doesn't hold the torque! This is the 3rd time this has happened in the last 2 years. Cylinder 4-6 has no problem. I thought about loctite on 1-3 cylinder banks. Engine is a 2.4 with 9.5:1 compression. I'm in the process of disassembling the engine within the next few days..again. Any advice would be appreciated!

Steve@Rennsport · 10-16-2016, 04:22 PM

Love to help, but I'd need a LOT more details than what you provided.

What year engine?

What displacement?

What head studs?

kwikt 911 · kwikt 911's Garage

Hey Steve, 72 911T with 2,2E pistons and cylinders. 2,4 E mfi. I usually use the car for autox so always bouncing off the 7100 rpm limiter. I have own the car forever and do my own wrenching except when valve job is in order then I send them to Ollies. Btw they installed timecerts with stock head studs. Resurfaced the case spigots added thicker base gasket about 5 years ago. Maybe I need the heads resurfaced again!!!

Steve@Rennsport · 10-16-2016, 04:52 PM

I see no obvious issues,....what thickness base gaskets did you use?

Did you use more than one per cylinder?

What do you have for a torque wrench?

Please,...do NOT use any Loctite on these fasteners!!!!

kwikt 911 · kwikt 911's Garage

I use a single thick base gasket for each cylinder supplied by Ollies. Tried a few torque wrenches from Snap On to Craftsman. Strange thing is it only happens on #3 head. So maybe all 3 heads should be resurfaced or maybe the spigots aren't true!!!

Steve@Rennsport · 10-16-2016, 06:03 PM

It sound like either the heads were not uniformly resurfaced or the spigots are uneven. The other possibility is that the cylinders are not all the same height groups.

Time to take it apart and investigate.

kwikt 911 · kwikt 911's Garage

Agree Steve, I thought I checked cylinders this last time...but double check again. I'll pickup a machinist straight edge and check the spigots also. Thinking Ollies may have to remachine my case again..fun fun.

Maybe just throw ina 3.2 liter and call it done. Haha

Steve@Rennsport · 10-17-2016, 08:27 AM

Quote:

Originally Posted by kwikt 911

Agree Steve, I thought I checked cylinders this last time...but double check again. I'll pickup a machinist straight edge and check the spigots also. Thinking Ollies may have to remachine my case again..fun fun.

Maybe just throw ina 3.2 liter and call it done. Haha

Remember, if a mag case comes apart, you need to re-machine the main bearing centerlines so the crank will turn after reassembly.

kwikt 911 · kwikt 911's Garage

Yes, aligned bored once already with new mains along with oil bypass mod. I should have it disassembled this weekend.

Bobboloo · Bobboloo's Garage

When you get the motor apart mic your cylinders as Steve suggested and base gaskets. Also look for for any carbon burns on the sealing surface of #3 cylinder.

When you reassemble you might want to torque the heads to the cylinders separately to insure even torque. Just be sure to temporarily use the cam housing to keep the heads aligned. Then after torquing the heads you can install the cam housing with the sealer of your choice. Go easy on the housing torque.

Rusty 356 · 11-08-2016, 08:43 AM

Tensile strength of head stud. Check length against another stud.
Keep us up to date.

Jack Stands · Jack Stands's Garage

I had a timecerted case pull studs on a 2.7, so it can also happen. I had Henry Schmidt at Supertec install case savers this time, so I hope that will hold. I'm only running RS pistons/cylinders with 8.5 to 1 compression, so it's not as wild as some and will hopefully hold together.