please dont be head gasket!!

[Pablo 94STS]

Cadillac made a mistake in production of the early Northstar engines. This is from a guy I met in Dallas who used to be a Service Mgr. for Cad. but now has his own shop where he works exclusively on Cad's..

The stock engine for some years (I can't remember which years, but since mine's a '94 it occurs at lease in '94 and maybe other years) have a factory defect. At about 100,000 miles or sooner, one or more of the studs in the block give way, blowing the head gasket on that particular side of the engine. Mine was blowing a huge amount of steam out the tailpipe and boiling the overflow over too.

Well I didn't know about the defect, so I sought out and paid a guy to put a junkyard Northstar in to the tune of 3800 bucks... (at least the replacement has worked out nicely.. very tight engine so far)

The real fix is to have the heads pulled, all studs removed, redrilled and install Helicoils in the block, reinstall the studs...etc...

Cadillac will not admit this defect, but it happens A LOT !

This guy said he generally charges about $1,500 bucks to do the job.

[Pablo 94STS]

Cadillac made a mistake in production of the early Northstar engines. This is from a guy I met in Dallas who used to be a Service Mgr. for Cad. but now has his own shop where he works exclusively on Cad's..

The stock engine for some years (I can't remember which years, but since mine's a '94 it occurs at lease in '94 and maybe other years) have a factory defect. At about 100,000 miles or sooner, the studs in the block give way, blowing the head gasket on that particular side of the engine. Mine was blowing a huge amount of steam out the tailpipe.

Well I didn't know about the defect, and paid a guy to put a junkyard Northstar in to the tune of 3800 bucks...(Luckily, the replacement has worked out nicely, except my "check ride control" now always comes on....)

The real fix is to have the heads pulled, all studs removed, redrilled and install Helicoils in the block, reinstall the studs...etc...

Cadillac will not admit this defect, but it happens A LOT !

This guy said he generally charges about $1,500 bucks to do the job.

[BeelzeBob]

Originally Posted by Pablo 94STS

Cadillac made a mistake in production of the early Northstar engines. This is from a guy I met in Dallas who used to be a Service Mgr. for Cad. but now has his own shop where he works exclusively on Cad's..



The real fix is to have the heads pulled, all studs removed, redrilled and install Helicoils in the block, reinstall the studs...etc...

.

That is a BS story....

Hopefully he is using timeserts, NOT helicoils, to repair the head bolt holes. Timeserts at the only apporved repair and the helicoils, as often mentioned on this forum, will fail as a repair.

The Northstar uses head bolts...not studs.

By the way....this post and this section of the forum is about 4.1/4.5/4.9 engines...NOT Northstars....LOL LOL LOL The engine in question being discussed in this thread is a 92 4.9 not a Northstar.

[chuckles_100]

Well Bbob I took your advice and pressure tested my cylinders with air. on the 3rd cyl. on the bank closest to the firewall it bubbles in the rad when shop air is applied. So I thought what the hell Im going to r&r the heads myself. I do have a couple questions if you dont mind. #1 how much is it approx. for a kit to do timeserts? #2 If helicoils will work on my 4.9.? #3 Is it feasable to stud the heads on a 4.9 as opposed to using bolt as I know most race engines are studed. If there is an engineering problem with that idea. I really dont have the coin to replace the engine, living on a fixed income like I am. I planned on helicoiling all 20 of the head bolt holes. Thanks for the advice.
chucky

[91TexasSeville]

Chuckels_100

Chances are that you do not need timeserts or any other block work done.

bbob was posting a response to the 4.6 NorthStar not the 4.9L that you have.

If you pushed shop air through #3 cylinder and bubbles resulted in the radiator, it means that the head gasket is leaking into the water jacket.

DIY (Doing it yourself )

Since the first gasket set did not last....
It is time to pull the heads (both). Take them to a machine shop and have them micro blocked (checked for true flat) and all valves checked. DO NOT USE 3M SCOTCHBRITE to clean any surfaces because it contains aluminum oxide (an abrasive) which WILL damage your engine.

It is most economical to buy a rebuilder gasket set as opposed to individual gaskets, plus you will have on hand all that you may have overlooked.

Exhaust studs tend to get stubborn after a time, so expect to break at least one in the process of removing the exhaust manifolds. Make allowances for that.

While the intake is off it would be a good idea to remove everthing and have it professionally cleaned. You can clean the throttle body yourself. If you happen to have an extra $30, I would replace the throttle position sensor on the throttle body before re-installing especially if your car has over 100K miles on the odometer. This will save you from having to remove the throttle body just to perform that task.

Let us know how you make out.

[BeelzeBob]

Unlikely that a head bolt hole in the 4.9 will need repairing. The 4.9 engines do not stress the headbolts like the Northstar does so they rarely have a problem.

If there is a need to repair the head bolt holes then only use the timeserts specifically for the 4.9 engine. Helicoils are NOT an acceptable repair.

I would do both head gaskets as lone as you are in there.

I would personally forget having the heads touched. Just clean them up and reinstall with the new OEM gaskets.

When you take the rocker arms off the heads take the entire assembly off as one unit by loosening the 5 large nuts that hold the rocke arm support bar onto the stud headed head bolts. Take the 4 small bolts out first and then sequentially loosen the large nuts a couple of turns at a time to relieve the pressure on the rocker arms. Taking the rocker arm pivot bolts out indivicually will strip the holes and/or break the pivots. Leave that whole assmbly in one piece. Just take it off the head and put it back on with the 5 large nuts on the head bolts.

Good advice about staying away from the scotchbrite.

Forget the stud idea. The head bolts are fine. Just clean everything up and put it back together with new gaskets. I would highly recommend the OEM head gaskets as they are a premium compacted graphite gasket with stainless steel fire rings in it.

When you have the heads off the reason for the repeat head gasket problem may be evident and any corrective action obvious. If not, make sure that all the cylinder liners are seated correctly in the block. You may want to remove ALL the coolant from around the liners and clean and vacuum out that area to make sure the liners are seated correctly. The cylinder liners are loose fitted into the crank case and if someone dislodges one during working on the heads and some debris or something gets trapped under the bottom of the liner then that cylinder liner will sit a little high compared to the rest and possibly cause sealing problems with the head gasket... You can lift the liner up slightly when the head is off and clean around the bottom of it with air or something and make sure that all are seated correctly.

[john.ebbs]

its also apossibility that the head on that bank could have had a crack in it before the gaset was replaced,and that the G.M. sealant temporarily stopped the leak into #3cylinder.always magnaflux the heads as long as you have them out it could save a whole lot of misery later on

[chuckles_100]

When the fella had my motor apart last month he had to helicoil 2 head bolts as the threads pulled out of the block as soon as he started to torque them down. On the bank closest to the firewall one of the last bolts didnt seem right he said but then it seemed to hold. (thats what he told me antway). well now how do I get the old helicoil out so i can install timeserts? I've seen Bbob mention the bolt size and threads etc, anyone able to find those? I've searched and cant find em. I wonder how much timeserts would run? So if i lift the sleeve to clean it with shop air wont that let shit between the sleeves and let coolant leak into oil later on? I've seen bbob on some of his posts mention this. just wondering not second geussing. Now just for my edumacation why is helicoils not acceptible? Ive read timeserts web page an I can see why they are so good. Do the threads pull out or not grip? I really want to learn but I dont want people thinking Im qeustioning what they say.so thanks for your input.
chucky

Originally Posted by bbob

Unlikely that a head bolt hole in the 4.9 will need repairing. The 4.9 engines do not stress the headbolts like the Northstar does so they rarely have a problem.

If there is a need to repair the head bolt holes then only use the timeserts specifically for the 4.9 engine. Helicoils are NOT an acceptable repair.

I would do both head gaskets as lone as you are in there.

I would personally forget having the heads touched. Just clean them up and reinstall with the new OEM gaskets.

When you take the rocker arms off the heads take the entire assembly off as one unit by loosening the 5 large nuts that hold the rocke arm support bar onto the stud headed head bolts. Take the 4 small bolts out first and then sequentially loosen the large nuts a couple of turns at a time to relieve the pressure on the rocker arms. Taking the rocker arm pivot bolts out indivicually will strip the holes and/or break the pivots. Leave that whole assmbly in one piece. Just take it off the head and put it back on with the 5 large nuts on the head bolts.

Good advice about staying away from the scotchbrite.

Forget the stud idea. The head bolts are fine. Just clean everything up and put it back together with new gaskets. I would highly recommend the OEM head gaskets as they are a premium compacted graphite gasket with stainless steel fire rings in it.

When you have the heads off the reason for the repeat head gasket problem may be evident and any corrective action obvious. If not, make sure that all the cylinder liners are seated correctly in the block. You may want to remove ALL the coolant from around the liners and clean and vacuum out that area to make sure the liners are seated correctly. The cylinder liners are loose fitted into the crank case and if someone dislodges one during working on the heads and some debris or something gets trapped under the bottom of the liner then that cylinder liner will sit a little high compared to the rest and possibly cause sealing problems with the head gasket... You can lift the liner up slightly when the head is off and clean around the bottom of it with air or something and make sure that all are seated correctly.

[BeelzeBob]

There has been a lot posted on the timesert/helicoil comparison if you search on either timesert or helicoil....

Basically, the difference is that the timesert is a solid insert whereas the helicoil is a slinky of threads. The timesert transfers load from any given ID thread to the entire OD threads so as to not overload any given thread. The helicoil design transfers the load of each thread to the parent material of the repaired hole so it is much easier to overload any given thread and fail it and then start to fail the ones beside it...etc.

In addition, the timeserts for the 4.9 and Northstar headbolts are longer and allow for the complete thread engagement of the head bolts on the ID and OD of the repair insert.


If head bolt holes were repaired previously I would inspect them carefully to make sure the head bolts are not bottoming against the repair insert so as to take the load off the head bolt clamping....I have seen this happen on poor repairs. The bolt seems "tight" as indeed it is hard to turn but it is hard to turn because it is bottoming out not because it is tensioning properly against the head surface.