L86 Head Bolt Torque Sequence
Mette Florida
I've got a friend with an 806 that he's running on an auger. It's been rebuilt with about 100hrs and now the head gaskets seeping a bit. He thinks it needs to be re-torqued and he may be right. Anyways would somebody know what the specs for torquing the head and which order to do the head bolts?
Allmost all 407 and 361 engines seep out the head gasket. When we bought our 856 custom the dealer put a new head gasket in and it seeped. I overhauled it and it still seeps. We surfaced the block and head on our 1456 and it seeps until it is warmed up.
Thanks guys, I think it was Nebraska 1206 who said his 1206 or 1256 seeped too so I suspected it may just be the nature of the beast. I know he ought to buy the book but we just wanted to do it while he couldn't get in the fields. We've had a couple inches of rain out of those storms that passed through this week. Not as bad as a lot of guys but bad enough to slow us down.
Well, ever since I had the head gasket put in the 1256, it hasn't leaked yet. There's only about 25 hours on the engine since then. I plan on retorquing the head bolts at about 50 hours, just to stay safe. I do know they used some Permatex on both sides of the gasket around the oil & water passages.
The 1206's isn't too bad, but if you push it too hard before its warmed up, it might seep just enough to let you know that was a bad move. Otherwise, it didn't seep any at all this summer while pulling. Mainly, it just slobbered black slime down the block. Made a guy think a head gasket went! A bottle of Power Service into the fuel tank, and getting it pulled good & hard w/ wagonloads of beans took care of that problem!
Now, even if you don't know the actual pattern of the bolts, I'd say starting in the center, and working your way out would be the best. I've done this on a few other engines, and most manufacturers used a pattern very similar, starting in the center & working your way out.
generic body of text, insert fsm diagram. Read one subaru specific caption, followed by vague general info. Haynes has been good to me for ea82's but i find it lacking with the legacy, it doesnt go into the 2.5 in good detail, although it covers 2.2 well enough
otherwise, if i am looking at the head, i would consider the top left #1 bottom left #2 and the bottom right #6, tops are odd and bottoms are even, and keep track of my sequences based on that. let me know if that assumption is wrong
clean the head and block surfaces well and use NO sealant of any kind. I have done at least a dozen of these and have had none fail. Subaru cautions against any of those sprays and be sure to use only a subaru OEM gasket. Do not be fooled by other manufacturers telling you that they are equivalent, I have tried one other manufacturer and had to redo the heads within 500 miles.
I'll take in your considerations. I already have a felpro set, so i am stuck with that. I had to stop my install when the haynes book turned up blank. the head and gasket are already mated, just waiting to do the torque
I hope you aren't pulling the engine too soon. Many of the board members have made the same suggestion and others have not used the subie gaskets. Maybe you eill dodge the bullett, but the engine is out of the car and it will only take a few minutes to replace the gaskets. If it were me I'd wait and get the subie gaskets, but that is because I had to redo three engines when I used a different gasket manufacturer and the seller claimed that he had never had any trouble before. These were the only gaskets that failed. Never had a subie gasket fail. I just hate haveing to redo the same work. For me it is another day wasted. I hope the felpro works out for you.
I'd suggest buying OEM and only doing it one time. Unless you wanna get good at it by possibly doing it twice. I don't care how broke you are. Max 100.00 while the engine is out versus an unplanned failure and possibly doing it again seems like a no brainer.
Cometic is among one of the best head gasket makers, however, with all of the non-subaru head gasket failures I would be very hard pressed to use anything but a Subaru head gasket on a 2.5 DOHC. It just isn't worth the time of haveing to pull the engine again if it fails. As I said earlier, I did that in the past and I won't do it again.
Now i have gone ahead and torqued everything up. I felt better after completing the task. Everything went together very well. The signs of failure on this example are consistent with photos i found online(skip's 2.5 headgasket page)
I'd also use the FSM to find out the torque values for the exhaust manifold and in take manifold mountring fasteners. Or you may overtorque the mounting fasteners and cause them to pull out of the aluminum head. Or you may under torque 'em and have exhaust/intake manifold leaks.
If you are using ARP Moly Lube or any moly lube on the fastener threads and under the nut or bolt head use 80 Ft LBS as the head fastener torque value. Cuz moly lubes much better than 30 Wt engine oil. If you lessen the fastener's friction coefficient you can achieve the required joint clamping force with a lesser torque value See the below link.
And the below post, about 1/2 way down the first page of replies where DAD posts a copy of the ARP Instruction sheeet that came with the ARP Head fasteners. ARP - 30 Wt engine oil lube = 120 FT LB; ARP - ARP Moly Lube = 80 FT LBS.
I have had the head off of my Starion about 6 times during her 22 year life. I have reused the Original OEM head bolts each time. I initially torque the head bolts in in three sequential approx equal steps to the final torque of 70 FT LB. I have always used Permatex Anti-Seize lube on the head bolts threads and under the bolt head.
I have never blown a head gasket in the 22 years I've owned my Starion using the 70 FT LB head bolt torque. I'm only running stock boost pressure, with a clean and properly functioning engine coolant system.
I retorque the head bolts after the engine has just been initially started and warmed up after the head gasket replacement (engine rebuild), then I retorque the head bolts to 70 FT LBS. After 500 miles I retorque to 70 FT LBS; & 1000 miles retorque to 70 Ft LBS.
Yeah!!! The 3 retorquing's are a PITA :mad: but retorquing 3 times is a hade of a lot easier than having to go back and replace the head gasket cuz it was not initially properly broken in. Or ensuring the head bolts/stubs have not exceeded their 75% yield strenght
I might not have been clear enough on that. I meant in regards to using higher torque numbers like ARP states since they have seen OEM bolts and said theirs were no better, and I'm assuming he was talking about his old head bolts since he didn't mention ARP, to go far past what the service manual says. If a stock bolt just has oil under it and its using 72ftlbs, what I meant was to go ahead and twist it on until its to 100ftlbs. If you go back and look into the 70s at the torque numbers for head bolts they have increased but I've not seen any of those motors maybe their bolts weren't as good but the blocks and heads seem to be the same.
I had asked once if anyone had ideas or thought about using newer methods to tightening head bolts such as torque to 20ftlbs then quarter turn + quarter turn. Not sure what that ends up with and was going to experiment with different numbers so that it might result in more consistent torque numbers because it would be easier to get them to all match that way. It forces them to work in three stages instead of one.
Simple question today, what is recommended torque for fitting head on a '31 CD8 Chrysler engine (8cyl). I have a new head gasket and have cleaned the threads on all 27 head studs and secured them tightly in the block. I also note there were no washers on the head when I removed the nuts 3 weeks ago. Anyone know if they used plain washers or did nuts just go direct on block? I have the pattern for bolt tightening. Any other suggestions?
Thanks K31, I have the sequence diagram. This chart appears to say Chrysler Corp all 1933-54 headbolts 65-70 ft/lbs. It says Chrysler 6 1924-32 60-65 ft lbs. So no mention is specifically made of '31 8 cyl cars. As car is likely to be largely a Sunday driver, I'm inclined to go at 60-62 ft/lbs, and after a few drives re-check to see everything is still tight. I have 3 different engines here, this engine came with regular 3/4 hexagon head nuts, no washers. A second head from a '31 Deluxe CD8 car had 5/8" acorn nuts with thin stainless steel washers, and I plan to use these. BTW, 2 of the head bolts also secured the "Town&Country" horn bracket (3/16" thick steel with recessed holes for head nuts), based on it's thick base (about 3/32" bearing surface), I will likely use a 3/4 regular hexagonal nut there and no washers.
In my above August 17 post I mentioned that I was going to re-use the acorn nuts and stainless steel washers that came on one of the heads. Getting ready to proceed this week, an engine re-fitter friend cautioned me to never use stainless steel washers on a head, they are too soft, will distort under torque and gradually original torque setting will be lost. So I bought some grade 8 hard 3/8" washers and re-drilled the center holes (were 13/32) to 7/16" so they are a snug fit over the 7/16" studs, but not too large overall compared to the 5/8" hex nuts. So many lessons to learn, this one being for head torque situations always use "hard washers"!
Also, with the washer on, make sure the length of thread visible on the stud is sufficiently less than the depth of the acorn nut that the nut doesn't bottom on the end of the stud. You will break the stud before you reach torque. I know this because of experience on a motorcycle when I was .... a while ago.
Yes Spinneyhill, I checked acorn depth to confirm lots of room for stud. These are 7/16" fine thread and about 60 ft lbs should do. Today I made a new set of plug wires using the old ones as a pattern, they fit in a nice wiring loom, makes for a neat arrangement.
Don't know but I suspect the acorn nuts were somebody's attempt to dress up the engine. Generally on Chrysler built vehicles of that era I only seen nuts with no washers. But I have absolutely no documentation from that era to back up my suspicions.