Below is an old post I've saved from Pauli on this matter of head bolt torque.

The only part I wonder about is the sanding with 400 grit paper, but that's what his experience led him to.

There's some great stuff in this old post from Pauli.

************CLIPPED**************

Hello Steve and fellow Volvo owners.

I have had my share of problems with the repair of these engines, ie. cracked blocks, warped blocks, headbolts that never get to the torque value, Threaded holes in block that need tapping for proper torque of the bolts, leaking headgaskets at the oil passage, bolts breaking. All the above and more. I have found that to do the best job of retorquing the headgasket, the following is required:

1. You must make sure you have new bolts.

2. The holes for the bolts must also have been chased with a thread tap.

3. The block surface, with the dowel pins removed, needs to be sanded with a 400 grit emery cloth.

4. The cylinder head resurfaced or sanded again with the 400 grit emery cloth. (To keep everything straight I use a 1/4 inch piece steel attached to a 2x4 and wrap the emery cloth around that)

Torquing:

When I torque the bolts I start in the center and move outward. I like to coat the threads of the bolts with a white lithium base grease to prevent binding.

The first torque is 25 foot pounds.

The second torque is 45 foot pounds.

The third torque is 45 degrees.

The fourth torque is another 45 degrees.

The final torque is another 45 degrees.

I use this torque sequence for all the 4, 5 and 6 cylinder aluminum engines. I have only had one comeback and that was my own wagon parts runner. I dented the gasket when I installed the head at the rear oil passage. I was in a hurry.

I have saved 2 blocks that have cracked and the cracks on the others have been almost identical to the ones I have saved. The crack starts just below the headbolt threadhole and travels the length of the block (on the exhaust side). I hope this helps anyone tackling the head replacement or gasket replacement. I love the engine when it runs with no leaks, but it can really try your patience when it doesn't want to seal properly.


I don't know where this porous block issue came up. I have never seen one. I have about 24 cracked engine blocks on the back scrap pile and they range from 92 to 97. They all cracked in the same place. I also cracked one when I did a headgasket.

I have tried welding, but with very little success. The aluminum is a casting, so it makes it difficult to weld a nice pretty bead, but with much cleaning and grinding the third pass came out great. I heated the block in a outdoor grill at high for 25 minutes before I tackled the welding on the second time, but I only got about 8000 miles out of the engine before the oil and water started mixing. I would not weld another one. You would be wasting your time and money. The engine blocks are hard to find, but not impossible. Look for a 6304s block instead of the 6304f block. The s has a beefier web and a better breather box. The only bad part is the main bearings are different from the f on the lower half of the block. Look for a block with less than .006 of wear in the cylinder. Try to find a c marked on the piston, or an A. These are the smaller pistons. Then you can use the f or k pistons and will be able to hone and fit pistons to new tolerance. A new set of oversize pistons and rings will set you back 800.00, plus the cost of machining. By looking in the different core piles, you will be able to piece together a great engine for less than 300.00 with no cracks. Soak the old pistons in carb cleaner with the rings still on, wash in warm water and then dry, wipe them down with a transmission oil soaked rag so they won't rust.

A steam cleaner works perfect to get all the old gasket material off the engine mating pieces, otherwise you will spend hours scraping. Resurface the cylinder head and torque the new head bolts, then only 45 degrees at a time; do each headbolt three times. Don't torque the bolts to the final factory spec. It is too tight and tends to crack the blocks. I have a customer that has my first 960 engine job. It is still going strong with 109,000 miles on it since the rebuild with a 100.00 core from Muse Core Suppliers. That was 5 years ago. I do about 1 every 2 months now and so far have only cracked one block. I am always amazed how little these engines wear with the proper oil changes. I hope this helps you decide what to do.