Posted by Matt Wilson on Monday, February 23, 2004 at 2:05PM :
In Reply to: Replacing head gasket on an M37 230ci. posted by Doug Boeve on Monday, February 23, 2004 at 1:04PM :
If the bolts are in good shape (i.e., minimal rust, threads not stripped or worn), then you can re-use them. If they have been in the engine for 50 years, it might not be a bad idea to replace them, as they can stretch over time. Particularly if the threads or shaft or underside of the head show a lot of rust, then they should be replaced.
The torque is 65 - 70 ft-lbs for a cast iron head. They should be torqued in stages, starting with about 25 ft-lbs, followed by about 45 ft-lbs, then finally ending up in the 65-70 ft-lbs range. For each torque stage, you should start with the bolts in the center of the head, working your way outward in a spiral fashion. Use a thread sealant on the bolts, to prevent coolant from working its way past the threads and seeping out of the engine. I've been told that using teflon tape is not recommended, because it "lubricates" the threads too much, so that 65-70 ft-lbs of torque results in a much higher tensile load in the bolt and much higher stress on the threads than if you just use a sealer on the threads.
The use of sealant on a head gasket is the subject of some debate, I've noticed. I bought my gaskent from NAPA, and I contacted a technical representative from Victor (the company that makes the gasket), and he recommended against the use of any kind of sealant. However, I know of at least one person on this forum who experienced chronic head gasket failure until he did use sealant, based upon the recommendation of a shop that deals a lot with flathead engines. After that, he had no troubles with it. He used Copper Coat, and the gasket was a NAPA gasket. I have used Copper Coat on all of the heads I've installed on 230 flathead 6 engines, and I've never had any trouble with leaky gaskets in the few thousand miles I've driven with these engines. Of course, you should NOT use a sealant such as blue RTV or black RTV, etc. These are NOT made for head gaskets.
The Dodge flathead 6 repair manuals all recommend performing a hot re-torque of the bolts after the engine has come to operating temperature for the first time after the head gasket installation. This is also an area of some debate, as the tech rep from Victor recommended against a hot re-torque. I have always done the hot re-torque and I've not had any trouble yet, but that is up to you.
Then after 500 miles, perform another re-torque. The tech rep recommends that this be done with the engine at room temperature, while other people have done it with the engine hot. In the end, I don't know if it makes much difference.
Good luck!
Matt
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