UIM crack...GM techs...

I'm curious how common or uncommon this is with the 3.1

I've never seen it happen before. Just noticed it yesterday. So far it's not bothering it, but that won't last long...

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If the proper torque/sequence was not used when installing that would do it

If the proper torque/sequence was not used when installing that would do it

I did the LIM last year but I was incredibly particular about cleaning gasket surfaces, straight-edging, and torque and sequence...still there it is....I musta done something wrong...

I did the LIM last year but I was incredibly particular about cleaning gasket surfaces, straight-edging, and torque and sequence...still there it is....I musta done something wrong...


when torquing any bolts there is wet torque and dry torque. with oil on the threads this would then be wet torque which would apply a higher torque then dry. so if it is stated not to use any lube on the threads and oil was on the threads this would occur.

with metals like this a 3 pass torquing is best where you at each pass slightly increase the torque at each sequence .

sure you did not mess up with ft lbs and inch lbs ? the torque with this is quite low.

start at the middle and criss cross to the ends is the usual method.

I did the LIM last year but I was incredibly particular about cleaning gasket surfaces, straight-edging, and torque and sequence...still there it is....I musta done something wrong...


looked this up found that the center bolts are torqued at a lower torque than the corner bolts . I got 10 ft lbs on the center bolts and 18 ft lbs on the corner bolts. torquecenter bolts first at 50 % then corner 50%. then center 100% then corner 100%.

when torquing any bolts there is wet torque and dry torque. with oil on the threads this would then be wet torque which would apply a higher torque then dry. so if it is stated not to use any lube on the threads and oil was on the threads this would occur.

with metals like this a 3 pass torquing is best where you at each pass slightly increase the torque at each sequence .

sure you did not mess up with ft lbs and inch lbs ? the torque with this is quite low.

start at the middle and criss cross to the ends is the usual method.

I did have to transpose the inch pounds for foot I didn't have an inch pounds wrench. I remember it was very low in ft lbs, like 22 or something. Possible the pound wrench didn't take to the low values reliably....my pattern was correct and I did do an incremental torquing...

If no unmetered air leaks, clean and try a Metal bonding & adhesive for a quick patch.

If no unmetered air leaks, clean and try a Metal bonding & adhesive for a quick patch.

I do not think that would be the correct way to go. the distortion is quite large. leaks are going to be there or very soon.

scrap yard get a good one and anything else and replace it. this is very low cost repair.

I have used epoxy to repair leaks/holes in metal but this is a structural failure and gaskets will not be properly compressed..the part is distorted.

This looks like the plenum that is cracked. Am I correct. That is an even easier replacement job.