: Help



jammin
04-16-08, 04:54 PM
My 98 Eldorado overheated a month ago. Took it to the shop and they ran tests everything seemed to still be ok. Replaced thermostat. They did a final road test and when they came back the exaust check showed there was a leak in the head gasket. Ok I have them mill the heads and as they put it back together the last bolt strips. They helicoil(sp) the head and 3 bolts strip. Apparently this wasn't the first time its overheated. I'm already into them for over 3000 and now with a used motor and install I'm looking at $6200 for everything. The car is in excellent condition with 117k. Any advice will be greatly appreciated. Thanks. Javin.

Krashed989
04-16-08, 05:59 PM
Never, I repeat, NEVER use helicoils on a northstar engine! Why, well you just described why. Use only GM approved Timeserts or Norms Inserts for the headbolts. Norms inserts are not GM approved, but they look like they're better quality than the timeserts.

Timeserts: http://www.timesert.com/

Norms Inserts (AKA: NS300L): http://cgi.ebay.com/ebaymotors/NORTHSTAR-ENGINE-NS300L-HEAD-BOLT-THREAD-INSERT-KIT_W0QQitemZ150237256280QQcmdZViewItem

Some interesting reading: http://www.cadillacforums.com/forums/northstar-performance-technical-discussion/133429-root-cause-head-gasket-failure-fix.html

misfit6794
04-16-08, 05:59 PM
The reason the threads got screwed up is that the helicoil is the improper way to repair the northstar headgaskets. The proper fix is to put new, larger threads into the block, they are called timeserts. The threads actually pull out of the block, so when you replace the ruined ones, with the same size, you are going to have the same exact problem. Don't buy a used motor, have them timesert te block you already have and you will never have to deal with hg issues again.

Submariner409
04-16-08, 07:10 PM
Actually, a helicoil does use a larger hole which is newly threaded to accept the insert, BUT a helicoil is like a wound spring while Timeserts and Norm's units are in fact solid metal which is threaded both externally and internally. A helicoil MUST use the same thread pitch and spacing (not diameter) both inside and outside, while a full machined insert can use any combination which will guarantee maximum physical integrity. (Helicoils work perfectly well in iron blocks, however.....) A Timesert could be made to adapt a 2" threaded hole to a 1/2" bolt. A Helicoil cannot do that.

jammin
04-16-08, 07:58 PM
I called my mechanic and he had not heard of timeserts. He had called the local cadillac dealer and was told by them thats what he needed to use. Hes going to check into them tommorow. I really hope this works and if it does you guys are the greatest and this is the best forum ever! Thanks again. Javin.

krimson_cardnal
04-16-08, 08:17 PM
If you've ever worked with wood it all makes sense, only way to go. K_C

zonie77
04-16-08, 08:32 PM
It's cheaper and quicker to go directly to timesert.com

They have a short video showing how to install an insert.

Ranger
04-17-08, 09:38 AM
Too bad you did not check here first. We could have save you some time and money probably. Helicoils will fail and timeserts will work. That's just a fact. Too bad your mechanic didn't know about them. Hope he is not going to charge you for his mistake.

AJxtcman
04-17-08, 10:15 AM
Actually, a helicoil does use a larger hole which is newly threaded to accept the insert, BUT a helicoil is like a wound spring while Timeserts and Norm's units are in fact solid metal which is threaded both externally and internally. A helicoil MUST use the same thread pitch and spacing (not diameter) both inside and outside, while a full machined insert can use any combination which will guarantee maximum physical integrity. (Helicoils work perfectly well in iron blocks, however.....) A Timesert could be made to adapt a 2" threaded hole to a 1/2" bolt. A Helicoil cannot do that.


I found a tool in the tool room buried. I have to post a picture. :yawn:

The # is J39345
See if you can find it someplace in a search. It states on the box 4.0L & 4.6L