CarTalk.com Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

Re-Torquing Head Bolts

I’m getting ready to start up a completely rebuilt 1.9L Saturn engine. It is in a 95 Saturn SC2 DOHC. Torqued down the head as per the specs in the Haynes manual. Followed the sequence and used the CopperCoat on the gasket. When retorquing the head bolts after a couple hundred miles, do you just torque until there is some movement and you feel the head bolt seat? The reason I ask is at the last torque, the bolt moves another 1/4 turn so it’s obviously not a given spec. If I use the last highest setting from the sequence, it won’t move the bolt.

I’m assuming I just wrench it down till you feel so movement and call it a day. Will that work or is there some other technique?

I’d check the official service manual for that sort of thing because it tends to be quite specific:

For insance, on some cars you torque in a very specific sequence to a primary torque, then repeat the sequence to a secondary torque to then crank it one more time to a specific degree on top of that. Then drive it 500 miles and torque it again.
The bolts your torquing are likely stretch bolts so you can only do it once. You don’t want to screw it up by guessing at it.

Are you using new bolts or re-using the old ones?

I assumed they were new but that’s a really good thing to point out, Caddy.

Yes…New head bolts going into a clean block. The assembly steps were followed to the letter. I’m looking for the re-torque procedure which is not in the manual. (at least this one)

You may want to look on line for the factory service manual for info like that.
The Haynes manual is good for superficial stuff but sometimes cut/paste gets away from them. They’ve been known to be wrong or stuff is missing. You want to do that right.

I’ve gotten FSMs in PDF form off ebay on CD for $5 shipped but no doubt you can find a download for one somewhere, sometimes for free.

Okay, this site has what looks like a FSM on your car:
http://www.powerlibrary.net/Remote/Remote.asp?ID=Monroe
To get in, enter barcode 02378001078755

Under “engine overhaul”/“cylinder head”, it contains a section on the sequence and torque settings of those bolts.

I have not seen a factory recommended retorq in 40 years. Did Saturn specify retorquing?

No, I don’t see one. Here’s the procedure as it relates to installation. It has pictures as well.

If removed, install the intake manifold and/or the exhaust manifold and new gasket(s). Tighten to specification in the proper sequence. Clean the gasket mating surfaces. Be careful not to damage the aluminum components. Make sure the block bolt holes are clean of any residual sealer, oil or foreign matter. Using a dial gauge at 4 points around each cylinder, check that the cylinder liners are flush or do not deviate more than 0.0005 in. (0.013mm). Make sure the crankshaft is still 90 degrees past TDC and that the camshaft(s) are properly positioned with the dowel pin(s) at the 12 o'clock position to prevent valve damage. Install the cylinder head gasket and carefully guide the head into place over the dowels. If the head bolts and/or the block were replaced, install the bolts and tighten in sequence to 48 ft. lbs. (65 Nm) to insure proper clamp load, then remove the bolts. Coat the cylinder head bolts with clean engine oil and thread the bolts by hand until finger-tight. Tighten the bolts in sequence to 22 ft. lbs. (30 Nm). Tighten the cylinder head bolts again, in sequence to 33 ft. lbs. (45 Nm) for SOHC engines or to 37 ft. lbs. (50 Nm) for DOHC engines. Install Snap-on® torque angle gauge tool 360, or equivalent, and calibrate the tool to zero. In sequence, tighten each cylinder head bolt an additional 90 degrees. Install the timing chain, sprockets, guides and tensioner. Then install the front cover assembly. Refer to the appropriate procedures in this section. Position a new gasket, then connect the exhaust pipe to the manifold. Install and tighten the fasteners to 23 ft. lbs. (31 Nm). If not already done, remove the crankshaft sprocket retainer tool. Apply a thin film of RTV sealant to the damper/pulley assembly flange and washer only. Install the crankshaft damper/pulley assembly and tighten the bolt to 158 ft. lbs. (214 Nm) while holding the pulley with a strap wrench or block of wood. For DOHC vehicles, install the intake manifold support brace bolts next to the alternator, then tighten the block bolt to 33 ft. lbs. (45 Nm) and tighten the manifold bolt to 22 ft. lbs. (30 Nm). Apply a small drop of RTV across the cylinder head and front cover T-joints. Inspect the old camshaft cover gasket and replace if damaged. Install the gasket and the camshaft cover. Tighten the fasteners uniformly to 22 ft. lbs. (30 Nm) for SOHC vehicles or in proper sequence to 89 inch lbs. (10 Nm) for DOHC vehicles. Install the drive belt tensioner and tighten the bolt to 22 ft. lbs. (30 Nm). For 1992–98 vehicles, install the idler pulley and tighten the fasteners to 20 ft. lbs. (27 Nm). If not done during removal, drain the engine oil and change the filter, then install the drain plug and tighten to 26 ft. lbs. (35 Nm). If removed, verify the gaps on all spark plugs and install. Tighten to 20 ft. lbs. (27 Nm). For SOHC TBI engines, install a new gasket and the throttle body assembly. Tighten the assembly retainers to 24 ft. lbs. (33 Nm). Install the power steering pump assembly to the bracket, then tighten the bolts to 22 ft. lbs. (30 Nm). If equipped, install the air conditioning compressor and bolts. Tighten the rear bracket bolts to 19 ft. lbs. (25 Nm), then tighten the front bracket bolts to 35 ft. lbs. (47 Nm).

It has that dual torque procedure and one angle procedure. From what I’ve seen, lots of cars require that at least.

@RemcoW Great reference…This Is the exact same procedure as in the Haynes manual and followed. The head is on and all is good. As you can see, I changed the title of the topic as that is the information I’m looking for. It is not in there ^ either. I have seen talk of this “go back and re-torque the head bolts” here on the forum.

Nice. You should be good to go, then. Good luck with it.

Don’t worry about retorqueing the head bolts. And do NOT just crank on them some more. Unless there’s a specified procedure, you’d likely do more harm than good.

I agree.
I’ve seen it on older cars but don’t think you need to do that anymore, with most newer cars having stretch bolts. On most older cars you’d often have to retain the bolts and put them in the exact same position. They could walk loose so would require retorquing or at least checking.

These are called stretch bolts or torque to yield bolts. Once you turn them that last 90 degrees past the original 37 ft pounds, that’s it…There is no re-torquing them later on…You will notice you don’t use a torque wrench in that final tightening step, it’s done by measuring the number of degrees turned, in this case 90 degrees or a quarter turn. This procedure “stretches” the bolts, putting them under great tension…If you attempt to re-torque them, you are likely to snap them off or greatly weaken them…

Caddyman is right, if you try to re-torque these bolts, the head gasket will fail. The bolts are intentionally stretched to the center of their modulus of elasticity, this allows them to expand and contract with the head through its thermal cycles. If you re-torque them, they will lose this ability, the head will over compress the head gasket and it will blow. This is why the head bolts are not re-useable.

I think we all agree on that.

Sometimes a retorque may be beneficial or even necessary as shown by the example cut and paste below.

http://www.genuinesaab.com/psi/files/headretorque.htm

That maybe OK for saab, but not for all cars. If Saab is using torque to yield bolts and they are recommending this, that may explain some things about Saab engineering in general.

Subaru.

Your link is for Saab.