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replace head gasket questions


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1998 deville 4.6 engine.

we are replacing the head gaskets on our engine.

can both be done while leaving the engine in, or does it have to be completley removed?

why is the dampner not keyed?

are there any sites or books you recommend to find specifications ?

need timing marks for the cams.

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It is much easier to remove the engine to Timesert the block. It can be done with the engine in the car but there are so many fasteners that are in such difficult angles that it is easier to remove the engine.

When I Timeserted my '97 STS three years ago, I was going to do it with the block still in the car. I then decided to pull the block to make the Timeserting easier and had the block pulled and on a stand in 30 minutes. If I would have pulled the engine from the start, it probably would have taken less time.

The dampner is not keyed because it does not need to be. The damper bolt is torqued to a static torque value and then turned an additional 120 degrees. That results in a very high clamping load to the crankshaft.

You really need to buy a set of factory service manuals. I would not think of doing a major job such as Timeserting without the factory manual. Too many things that could go wrong.

'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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The factory service manuals are available from helminc.com for around $150 or you can often find them on ebay.


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Having done two complete head gasket Timesert repairs, I would absolutely recommend that you NOT try to do this job, with the engine in the car.

While the actual procedure to Timesert can be done by a reasonably skillful person, the methods to disassemble and reassemble the Northstar require knowledge from the manuals. You may of course just ask questions, for us to try and guide you through the procedures, but you will never quite get the whole picture without the factory service manuals.

The manuals cover many aspects of engine removal and fastener tightening methods that you will need to know. The manuals are well worth their cost in saving you from unintentionally damaging your engine, and will also help you in any other repairs that may come up.

Fastener tightening is very important, and changes with different year engines. Earlier Northstar engines used a large diameter crankshaft bolt. It had specific tightening torques and turns to angles that must be followed, or the oil pump will not work. Later Northstar engines used a smaller crankshaft bolt, and had different tightening specs. If you use the wrong specs, you will break the bolt and/or destroy your engine from lack of oil pressure.

Head bolt tightening methods changed, and must be carefully adhered to, or you will have failures.

These only a couple example of what could happen. There are many other procedures that you must follow to fix this engine. I urge you to get the Helms service manuals before you start this repair job, they will save you money in the short and long run.

I pulled the engines from the top; tight but it worked for me. It may be better to remove the engine from the bottom, depending on your mechanical experience. Each way has its advantages and disadvantages, neither is much fun.

Actually working on the engine in the open however, actually was kind of fun. It reminds me of the early Chrysler Hemis that I built, only smaller, lighter and with the dual cam action Chrysler should have developed, but I regress...

You will need lots of room for the parts that you remove, a place to clean everything, and keep things orderly to help you reassemble properly. Cleanliness is very important for a successful, and long lasting repair job.


Drive'em like you own 'em. - ....................04 DTS............................


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When I Timeserted my Northstar, I set the front of the car with cradle still mounted down on 4 jack stands, disconnected the cradle (FSM indispensable for this) lifted the front of the car body off the cradle using my engine hoist and Timeserted the block. Not easy, a helluvalotta work but doable. I'll never do it again.

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IMO studs are a far stronger repair. I ran Alfa 4s, 6s and Jaguar V12s for years. All with studs and I never had the problems with studded motors that I had with my Nortstar. I wish I studded my motor but I just didn't have the room to pull it from my car.

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