Why does the front of my block keep cracking?

[WH23G3G]

I cracked one area around the top water pump housing bolt where the upper alternator bracket goes yesterday. I switched all the water pump housing bolts to grade 5 and grade 5 washers. I built up the cracked area with JB weld putty which says it can be sanded and tapped. Luckily I didn't have to tap it, the bolt still went in and torqued down. Now today I cracked the front of the block around the power steering bracket. I wasn't even at the full 30lbs-ft of torque yet. I had the bracket against the block and the bolt and washer on the outside of the bracket. It looks like either the bolts are to big, but they go in just right and they are the same size as OEM. 3/8 -16. Or either 30lbs-ft is too much torque. I read the instructions on my Craftsman torque wrench and it says to put the dial on the top of the line for 30lbs-ft not the lower line like I use to do before I read the instructions. So I've cracked two places on the front of the  block not the water pump housing, this is the actual casting of the block that's breaking real easy it seems. All I can do now is leave it how it is hope the water pump housing gaskets don't start leaking. I think when I tightened it down it cracked one of the gaskets too. I hope I've been setting the torque wrench right otherwise I may have overtightened everything inside the motor.

[WH23G3G]

I may have seriously messed up the whole engine. I think I had been overtightening everything I've tightened so far. Including the timing set, timing cover, oil pan, cylinder heads, and most importantly rod/main caps. I had a friend show me the torque wrench and where I had it set and he said it was over by 10lbs-ft that's why I kept cracking the front of the block. That's also why I split the timing cover gasket at the top. My worst concern is the main and rod bearing caps. Where I had the torque wrench set it would've been 55lbs-ft instead of 45 and 95lbs-ft instead of 85. This is a new Craftsman torque wrench too so it's probably right on. I was using .010 oversize bearings and the old main bolts, old rod bolts, and new rod nuts. Now with the heads on the engine turns smooth but it's tighter now because it's got compression on it with the plugs in. Will I have to start all over again or could I get away with running it?

[maxwellwedge]

I don't know what to tell you but I can tell you what I would do. Take it all apart and by god - please use new rod bolts and nuts (ARP) and start from scratch with a torque wrench you can trust.

[c00nhunterjoe]

i cant see 10 ft lbs cracking a cylinder block. and seeing as how you "upgraded to grade 5? that would tell me you used standard bolts before, if so a standard bolt will snap long before the block cracks. if there was dirt in the threads that can crack a hole open.  what kind of gasket is the timing cover? cork? if so scrap it for rubber, you will be happier

[WH23G3G]

I'm most worried about the main and rod bearings being overtorqued now. The block cracked because I had the torque wrench set to 40lbs-ft instead of 30lbs-ft and it cracked in a place where it's not very thick. But still even that I was surprised that the block could only take that much more torque there. It may have had something to do with not using the correct bolts and washers. It cracked only at the beginning of the threads on the front of the block where the water pump housing bolts to. I was originally using grade 8 and I thought maybe they were too hard so I switched to grade 5 and they still cracked so I knew I was overtightening. The gasket split because they are cheap. They are paper that came in the gasket kit. If it's safe to keep going with the rod and main caps tightened potentially 8-10lbs ft over the specified torque I will continue on and see what happens. If not I'm going to have to remove the lifters and hopefully be able to turn the engine over on the stand and loosen and retighten the main and rod caps again. I was trying too hard. Before I bought a new torque wrench just to use on the engine I had been tightening everything else on the car the correct way with the dial set on the first line of the number I was setting the wrench to instead of doing it on the second line of the number like what appeared in the Craftsman instructions. The damn example in the Craftsman instructions is so small you could be confused if you had never used a torque wrench before which I had and I should've continued the same way and I wouldn't be worried about this.

[Sublime69]

What kind of engine are you building?

The torque specs you mentioned for the pump housing should not crack the block. What kind of Craftsman torque wrench do you have? Is it a beam style or click type?

If your building an engine, a click type is one of the best investments you can make. Is the engine in the car or still out of it? If it's still out of it I would take it apart if you have any doubts and definitely add the ARP rod bolts one of the other members mentioned for cheap insurance.

Your block may have been damaged to start with. Maybe it was in the beginning stages of cracking in that area and you just finished the process. Do you know the history of the block?

[flyinlow]

Torque wrench calabration is important. I live near a Jegs store and they have a test stand. I took a three of mine ,two click type and a beam one and checked them at a couple of setting ( head bolt / rod bolt). All where within 2-3 pounds.

Machine shops probably can help with one.

[flyinlow]

I would buy arp rod bolts and torque properly 

I have sean dirt/grease in a bolt hole break a casting when torqued. Rare on cast iron.

[WH23G3G]

I've already started taking it all apart again. I don't want to put the engine in and have it spin a bearing right away because it being too tight. I'm going to just get another gasket kit and do it fresh again. I've asked several veteran mechanics with shops in the area that I know. They all said to just loosen up the rod and main bolts properly and then retorque them to the right specs. It's just a 400 and I guess the front cracked where the water pump housing bolts to with the added 10lbs-ft more plus maybe there was some pitting from water going through the ports there. Hopefully I'll be able to reseal the rear main seal and not mess it up because it will have to come out to retorque the number 5 main. I also hope I don't have to mess with the oil pump screen. I don't think it was in the way of just torquing the main and rods. My mechanic friend said he's going to help this time because this was just a major disappointment to me but it was my fault. So I'll correct and hope it works.

[maxwellwedge]

Your twice used rod bolts will be the weak link in your motor - go buy a set of ARP's and you will sleep a lot better.

[c00nhunterjoe]

worse case if the motor lets go you have the platform for a nice 451 stroker...... just kidding, swap the rod bolts and enjoy the motor, 400's are torky little motors, i had one in my car for a while.  also, i would have stuck with grade 8 bolts

[mauve66]

all automotive engine fasteners should be grade 8 or better (higher) not lower

[WH23G3G]

I already started breaking it down again to get this overwith. I was so close to getting it ready to put in. But I have to correct this. I'm going to buy a new gasket kit and reseal it all next week. I'm going to go ahead and break it all down clean the gasket surfaces again. Then loosen and reapply the proper torque this time with an experienced helper helping me out this time. Getting the damper off again will be a pain. What's the best tool to use to get this type of damper off? I don't even remember what I used when I took it apart originally it was so many years ago.

[flyinlow]

I would use arp rod bolts as good insurance on a rebuild. Over torquing the main caps by 10 ftlbs. should not have hurt anything. back them off and retorque correctly.

over torquing by 10 lbs on a 85 ft lbs bolt is not the end of the world. overtorquing by 10 lbs on a a 25 ftlb bolt could start to stress the fastener.

An over torque will not cause an engine to lock up or spin a bearing. It stresses the bolt and block threads.

If you are deforming the main caps or the connecting rod big end with a 10 lb. mistake ,they would not have survived normal operating loads anyway.
,
 

[tecmopar]

The problem now with all of your bolts is that by over-torquing used, already stretched stock bolts is that they are probably stretched to the max and good candidates for snaping. My motor---I would change them all, its not that expensive and costs less then a new motor should something break, good luck.

[mopar73]

Get the NEW bolts!!!!!!!!!!!!!!! Years ago when I used to work on helicopters we installed several transmission mounts 40 inch pounds over because of a faulty torque wrench and the teck inspector made us replace the hardware on all the birds. The torque wrench was only off by five pounds.  Just replace the hardware and drive in peace.

[WH23G3G]

I got all new hardware. I tore the motor back down, loosened and retorqued everything to the proper torque. It's a good thing I removed the rear main bearing seal retainer. I didn't trust it to not leak when I put it in and I know there's no way it would've sealed properly when I took off the retainer. In the new rear main seal instructions it says to fill the side seal cavities with black silicone until it oozes from the top, which it did. Then to dip the water absorbing inserts in water and stick them in the center of the main seal cavities. Well when I took out the rear main seal retainer the silicone was only about halfway down the retainer so it would've never sealed right. I've been reading nothing but nightmares about the Mopar rear main seal problems. I'm going to have my friend who's a long time mechanic redo the seal this time. He's done quite a few Mopar rear main seals without any problems. So I should have the engine sealed back up tomorrow. 

[oldkimmer]

............The last thing u want 2 do is loosen off a bolt thats over torked, then tork it 2 a lower setting....u r asking 4 a grenade, and believe me u will get a lesson u dont need or want.........u should have left them as is...........kim..........

[WH23G3G]

I don't know how many veteran mechanics I've asked in my area that I know well but they all said loosening up and retorquing everything was a good idea. They said I shouldn't have any problems. I guess I will see if this engine even runs because I'm almost finished, just waiting on rocker arms and the money to buy them with.

[Stretch]

You had better change the rod bolts like everyone has mentioned but it doesn't end there. When you change the rod bolts you must have the rod journal resized! Pressing the bolts into the rods will distort the shape of the rods main journal as will tourqing them to spec. This is way it is imperative to have them resized with the cap torqued to spec.