this engine was over heated due to cracked rad. tank. was driven hot til the head gaskets started leaking. pulled engine checked heads time serted all head bolt holes, rear head felt like it pulled down fine, front head felt like the time serts are pulling out. any one else have this problem.sts96 (97 deville base )
09-13-05, 01:15 AM
While I didn't have the problem I did think the bolts felt "funny" torqueing. But you say one head felt OK.
What I can tell you is that it is OK to pull the head off and check before you start it. We got interrupted on one we did and weren't sure which bolt we stopped on. The MIA engr said you can remove and reinstall without a problem as long as you havn't thermal cycled the engine. (He actually said they sometimes reuse them in testing after running but I think that was on dyno.)
09-13-05, 12:38 PM
When I tightened my head bolts two felt a little odd during the last ten degrees of torque-angle rotation. I used the 30lb/ft-70-60-60 degrees torque, torque angle for the head bolt installation after time-serting the block. Anyway I stopped tightening those two bolts as soon as I felt the lack of additional resistance. In other words each of the other head bolts had a linear increase in the amount of resistance on the torque wrench as the additional steps on the torque angle was applied but two did not. After all of the head bolts had been tensioned I returned to the two head bolts in question and applied the last ten degrees of rotation and the time-serts held and are still holding today about 14 months and thousands of miles later. I though maybe the loctite coating on the threads of those two bolts could have been different of possibly those two time-serts were not cleaned on their inside diameter as well as the remaining 18. If I ever time-sert another N* I will revert to the original torque, torque angle (22lb/ft 60-60-60 degrees or 22lb/ft 90-90 degrees) and never look back.
I have read one or two other threads in which the person(s) had a problem with some of the time-serts pulling out during the head bolt tensioning process. In one of the threads I think the person was using a very high torque, torque angle (30 lb/ft 70-70-60 degrees) during the head bolt tensioning. Based on these threads I would say the application of a little too much torque, torque angle during the head bolt tensioning could cause the failure of the time-serts.
Four of the 10 on the front head did feel funny on the third pass. (30ft lbs 70 60 60) on the fourth pass gave way and could turn the bolts with 6" wrench. the serts did indeed pull out with the threads full of block metal. not sure about trying big serts @ 600.00 for the kit. this is my second engine to try time serts and fail. the N* just may be a disposable engine. sad! sts96
While I have never had the "pleasure", this is the first time I have heard of this. I do not mean to insult you, but is it possible that you did not install them correctly, that is, seat them deeply enough? The reason I have to ask is that I would suspect the odds of that happening twice in a row have to be extremely small. Feeling them give after all that work has to be a terrible feeling.
Time-sert nor myself have control or knowledge of the abuse the engines have taken before my repair attempt and I did follow the instructions to the letter. It would seem the engines were over heated more than I knew about some folks wont tell what the truth when they have used poor judgement . I think the block has been degraded past the point of repair and will not try any further repairs on this engine. Have found a 98 N* for 1400.00 with 64k miles will slide it in later this week. So I continue with my education. Thanks for your feedback. sts96
Best of luck. Hope your luck turns around. You are over due.
Think I may have a knack for picking the best looking dogs in cars. Thanks sts96