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Head Gasket


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Is it possible to replace a blown head gasket with out pulling/dropping the engine ? The service manual suggests it, but if possible, I'd like to avoid pulling the engine. Anyone with some much needed advice ? Scotty ?

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The preferred method by shops with all the necessary equipment (including a hoist) is to drop the powertrain cradle out the bottom of the car.

The engine can be pulled out the top but it is a tight squeeze. (A Northstar engine is way bigger than it looks sitting in the car!) Some have done the job without removing the engine from the car but the tight clearances make that approach very difficult - but not impossible.

I suggest you contact AliRaza who replaced his own head gaskets last fall. Ali planned to do the job with the engine in the car but ended up pulling the engine out the top. You can locate him and his posts on the subject by clicking the "Members" icon at the upper left of this page.

There are a number of members of this board who have done this job with the help of other members. Most of them would be glad to share their experience with you.

I replaced my head gaskets about a year and a half ago. I hired a mechanic, and long-time friend to do the work. He has a hoist so we dropped the cradle. I made all the decisions (with help from this board) and observed the progress on a daily basis, but didn't do the actual work.

If you'll network with Caddyinfo members, you'll find a wealth of help and support.

Good luck - and keep us posted.

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Happiness is owning a Cadillac with no codes.

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I have done both of my STS's. I pulled them from the top, yes it's a little tight, but with an engine leveler it is not that bad.

Actually the hardest part was removing the four exhaust flange to exhaust pipe bolts; due to their close proximity to the firewall. The rest was pretty much routine.

I preferred to pull from the top because I am more familiar with doing engine rebuilds that way and I didn't want to deal with a much heavier package by dropping from below.

In a FULLY equipped shop I would probably do it from below.

I have built many engines, including in-car head gasket repairs, to big block Chevy’s, Mopar, Hemi’s, etc. Each had a few challenges, but not any unusual problems.

However,....I would never advise anyone to attempt to do the Northstar head gasket repair in the car. While it is possible, it make it is VERY difficult to do it right that way. It is not just removing the heads and other parts necessary, it is the TimeSerting process and the need to keep the engine from getting any drilling/tapping debris into an area where the oil can circulate it and cause fatal damage later. The whole process goes pretty smooth with the engine mounted on an engine stand; plus you can do any additional cleanup and/or gasket replacements as needed.

Attached image shows engine, with engine leveler in use.

-George

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

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If I did this job, I would want to pull the engine out from the top also and put it on a stand. I would want to possibly do the case-half seal, pan gasket, valve cover seals, etc..

While I know that some have done the job with the engine in place, it has to be a rough job. Do a search on Jhall, he had totally disassembled his NS and is in the process of reassembling it.. Mike

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97LDough,

It's not too bad to pull the engine from the top assuming you are not in a hurry.

I worked on my '97 Deville 4.6L over a few days doing a little here and there and it made the work much easier than trying to knock it all off at once.

The first bolts I attempted to remove were the manifold to exhaust pipe bolts. I sprayed them with WD-40 and let them sit overnight. Long extensions are needed to reach up to the manifold connection and a long breaker bar is a big help. Get the front of the car on jack stands to provide some elbow room for this part.

I pulled the transmission and engine as one piece. I broke the engine down to the short-block on an engine stand (including removal of the lower case), but stopped short of pulling the piston rods, pistons and crankshaft. Engine is now back together with all new seals. I posted some pictures of the process. Do a search under jhall to find the pics.

If you're going to keep the car for a few more years, pull the engine / transmission and replace the rear main seal, valve cover seals, oil pan seal, transmission filters (and the axle, coverter seal and o-ring on the converter shaft).

Look carefully along the block split line. If you see any leaks, the block will need to be pulled down to replace the case seals.

If you're not keeping the car and want to try to do it without pulling the engine, you'll need to jockey the engine a bit to get the rear head off and will have to stand on you head to install the timersert inserts into the block (also, a 1/2" right angle drill will be needed).

See http://caddyinfo.ipbhost.com/index.php?showtopic=4796&hl= for a picture of the timesert process.

As of today, with new engine mounts, I'm into the project for about $2,000. In my case, I did not want two car payments, I have time to do the work without rushing and I plan to keep the car at least 2 years (body / interior are in great shape). ;)

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My 98 sls is currently in the shop for head gaskets. Mechanic was hopeful that job could be done without dropping engine. But once starting to take things apart realized that it must be dropped to replace both head gaskets. Its scheduled to come out tommorrow.

Good Luck

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growe3,

Looking at your engine leveler photos, I gather that turning the crank at the end of the orange bar moves the upper chain connection point along the bar. This shifts the balance causing the bar and the engine to precisely tilt one way or the other. I can see how, with this set-up, you could work the engine into a very tight space.

Interesting! ;)

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Happiness is owning a Cadillac with no codes.

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