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1997 ch613 e7


byrd auto
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Hey guys I am having serious problems with an engine. I did a complete rebuild last year after finding both heads cracked and all 6 liners cracked. I installed all new liners and new heads. Made approximately 6 loads with the truck last year and this year made two and it started blowing water from the coolant tank. Upon removing the heads I again found 2,3,4,5 cylinders with cracks. The cracks are not up and down. They are side ways in the liners. I need help to determine what could be causing this. Thanks for any input..

Edited by byrd auto
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Where are the cracks located in the liners. If they are where the line meets the counter bore and just above that area I have seen too much silicone used to seal the counter bore cause the cracked line. Have seen a couple trash the block because of too much silicone. All it takes is a very samll bead of silicone.

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Used a small bead of silicone when assembling the engine. I had no problem pressing the liners in and they were all flush with the block. I haven't removed the liners yet but will do so tomorrow. With this happening before it kinda throwing a red flag. I've built many engines and this is the first one I've ever seen with liners crack side ways. I've seen them cracked up and down because of scoring or heat but this is new to me. My first thought was maybe the owner or one of his employees used ether on it, locked it up, and kept trying to start it. But, that was when I thought only 3 and 4 were cracked. Being that they are companion cylinders and cracked in almost the same exact location. To much pressure in the cylinders was in my mind but I'm not sure. By the way thanks for your help...

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Did you cut the counter bores the last time? If you have a depth micrometer you can at least check the counter bore depth in 4 spots and see what the reading is. Factory is 4 inches. If they have been cut then the liners need to be shimmed. It is not too bad of a job just time consuming.

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Wheeler 73 I think you hit the nail on the head. I removed three of the liners today and found silicone pressed down the sides. the counter bores look fine. going back with another kit and making sure not to use but an 1/8 inch bead. Thanks... I also talked to a Mack shop in this area and with the cracks being side ways he said the same thing you did....don't know why in the world Mack would go from a seal to sealant... :thumbsdown:

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If they look good make sure you measure the depths. If they have been cut before the liners will need to be shimed. If you have to shim them make sure you put the shims on tye liners with the thinist first if you have to use a couple of shims and then apply a thin bead of silicone to the bottom shim and then install and use hold downs on the liners for about 30 min each to set the silicone. Mack says maximum counter bore cutting is 0.040. I have gone to 0.080 a couple of times as per customer request. Try to only use 2 shims per liner as any more cause issues.

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Ok guys, I've pulled all the liners, got a new kit and was about to install. I used a new liner just to see how it would fit into the holes. The liner will slide down into 2,3,4,5,&6 but #1 seems to be tight. Anyone know what the bore spec on the block should be? Don't want this thing to screw up again.

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