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Changing the Headgasket of a 97 Seville SLS


AliRaza

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Anyone know how to disengage fuel Quick Connect connections to input manifold without the special tool?? i am in the process of removing stuff and will be posting pictures as things progress.

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Quick update on the status of removal of head

Last night

Removed the radiator, the AC condenser, the cam cover for the front. Removed some of the rear cover bolts too

Took the timing chain out as Guru suggested in one of his messages by taking the sprocket out. Took the front head bolts out. Out of ten, two were badly stripped. I will post the pictues soon. I may create a website and will have pictures of different stages of removal and installation.

Still have to remove the exhaust manifold from the front.

There is a shield in front of the exhaust manifold and I believe I have to get under the car in order to get it loose. Then the exhaust manifold will come out.

Oh by the way, Following Guru's advise, and since he did it already, I am changing the headgasket by haivng the engine inside the car. I can see it will be challenging once I willl be working on the rear head.

Any suggestions wll be appreciated.

Ali

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Oh by the way, Following Guru's advise, and since he did it already, I am changing the headgasket by haivng the engine inside the car. I can see it will be challenging once I willl be working on the rear head.

Any suggestions will be appreciated.

Regarding the rear head....

No need to remove the exhaust manifold. Just undo the crossover & exhaust connections and the head + manifold can be lifted out together.

By loosening the frame bolts, (that connect the frame to the body), in the front portion, this will cause the engine to rock forward and provide better access to the rear head. (Remove the "dog bones" first)

You will need a right angle drill or air ratchet to tap the rear head bolt holes.

If I think of anything else, I'll let you know.

Barry

2008 STS V8
2016 Colorado Z71
1970 Corvette LT-1 Coupe

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You will of course need to remove the crankshaft pulley, front cover, and oil pump to realign the cam sprockets and cam chains. Then retighten the crankshaft pulley (approximately 350 ft. lbs.).

You will find this very difficult to do with the engine in the car.

The drilling and tapping necessary to Timsert the head bolt holes is very messy, tedious and time consuming; especially when hanging over a fender.

While it has been said that you can do the headgasket repair with the engine in the car, I think that it is a big mistake to encourage someone to try it that way.

I have many years of working on cars and building custom engines. I have only done two Northstar headgasket replacements, on my personal cars, and knowing what the job entails, I would never reccommend trying to do this repair, with the engine in the car.

Pull it out he top or the bottom, but pull it out.

I wish you good luck in your efforts.

-George

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

DTS_Signature.jpg

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Vince,

Thanks for yor suggestion. I am taking the pictures as I am going through and keeping some notes as well. Trying to be very orderly as I am removing the bolts and parts and keeping the bolts specially in separate ziplocks with marked details.

Hopefully with a sucesful completion, I will be able to share the experience.

Last night I worked a little and remove the fuel lines and removed the intake manifold.

Regarding the exhast manifold, I went inside the car and remove two nuts holding the bolts to the rubber seat where that exhaust manifold sheild is staying. Still have to remove two bolts from behind the shield and not much room to do anything there. Still trying.

Guru, I found the crossover bolts and those were a bit tight. So put some WD40 on them last night and today will remove those. I am not sure I still need to remove the shield first in order to slide the head with manifold out or can it slide out without removing the shield.

Bary,

i need to ask you for more details about rolling the engine to get more room on working on the rear head.

Again thanks a log for everyones input as always

Best Regards

Ali

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Barry,

i need to ask you for more details about rolling the engine to get more room on working on the rear head.

Remove the "dog bones" first.

The sub frame is connected to the body with 4 or 5 bolts on each side. To make the process a bit easier, remove each bolt (one at a time), grease/oil and replace.

Procedure:

If you back off the front sub frame bolts to only being held by about two turns, then the next pair of bolts (left & right), back those off, not as much as the front pair.

Then the third pair, and so on, until the last pair (rear) is mostly tight.

This will cause the frame to "slope" down in the front, and cause the engine to rock forward about 2 inches. This gives improved access to the rear head.

(Also great for changing the heater fan)

Reverse the procedure to rock the engine to the rear. I needed to do this to have better access to the cross "over/under" exhaust bolts on the rear.

Also:

As Bill mentioned, don't turn the engine over during the repair.

I made a "U" shaped device from a piece of 3/4" wide x 1/8" thick flat bar and used this to "lock" the flywheel.

I removed the plate (under the flywheel) that looks like a bow tie, and put this device up in to engage with the teeth on the flywheel and used the plate to retain it securely.

Now you can remove the front pulley with ease, as the engine is locked.

I did the whole process with the engine locked.

Another tip:

I did NOT try to align all the timing marks for the cam chains before locking the engine.

Before removing any of the chains, (with engine locked) I placed a dab of paint on each gear/chain relationship. Then when re assembling, I just aligned all the paint marks together. (Chain & gears both had paint marks).

Since the engine was locked during the whole process, then this method will work.

I think, as well, if the chain/gears are marked, then you won't need to remove the oil pump to set the chain timing.

Barry

2008 STS V8
2016 Colorado Z71
1970 Corvette LT-1 Coupe

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Thanks Barry,

A quick question

As i removed all the head bolts from the front part, the timing chain is out and all other bolts are out too that are connected to the head including the cross over for the exhaust manifold, teh head is still stuck there.

The manual just says remove the 3 M6 bolts from the front of the head and remove teh ten M11 bolts and then pick the head up.

Now on teh head (as it is not moving at all right now) there is a bolt inside teh timing chain chamber that seems like connecting the head with the bolck and also between teh cam shafts, there are two other bolts going into the head and have inside grooves like the head bolts. Do I have to remove these three bolts too inorder to remove the head????

I will try to remove the head tonite. Atleast one from teh front.

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Did you remove the four bolts from the water crossover manifold attached to the driver's end of the head?

-George

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

DTS_Signature.jpg

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The manual just says remove the 3 M6 bolts from the front of the head and remove teh ten M11 bolts and then pick the head up

This is correct.

There are 10 head bolts, and the three "skinny" ones along the inside front end of the head. I don't recall any other bolts, other than the ones holding in the cams. (Which you do not remove).

George mentioned the water manifold.

Also, the alignment dowels (block to head) are rather large compared to a Chevy engine. (Chevy = 1/4", Northstar = 1/2")

These could be providing some resistance because of their size.

Barry

2008 STS V8
2016 Colorado Z71
1970 Corvette LT-1 Coupe

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Thanks George and Barry

I removed teh three M6 bolts from teh chain compartment. Removed three out of four water cross over bolts. The last one is kind of hiding behind the wire harness coming from the ABS system. I think once that will be removed, I should get some movement.

Any recommendations on how to easily remove teh last bolt under the harness? Also any tips on teh process for removing the head??

One more interesting thing

When I removed the intake manifold, the bottom portion where the intake manifold was sitting was half filled with oil... Kind of strange. I took some pictures of it and will post it with the overall journal once ready.....

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Any recommendations on how to easily remove teh last bolt under the harness?

Those bolts are a pain in butt to remove. I used a combination of boxed end wrenches, 1/4" drive ratchet set and "wobble" socket extensions.

These are extensions that allow a socket and extension to be at an angle, 10 - 20 degrees. Very nice for awkward places.

Also any tips on teh process for removing the head??

The head is not really that heavy. Just grab and lift.

Be careful of the extended valves.

The alignment dowels in the block need to be removed to do the timeserts.

I found mine very difficult to remove.

Anyone have any tips ?

Vise grips just would not hold.

I finally used a flaring tool and clamped it over the dowell and then pried it up.

Barry

2008 STS V8
2016 Colorado Z71
1970 Corvette LT-1 Coupe

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One more interesting thing

When I removed the intake manifold, the bottom portion where the intake manifold was sitting was half filled with oil... Kind of strange. I took some pictures of it and will post it with the overall journal once ready.....

That is pretty common, when you get the head off and look where the oil passage is that feeds oil up to the camshafts you'll understand.

That valley on mine was filled with coolant...

Dennis
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guys,

Here is the update....

I got all the bolts out and also everything that is holding the front head. The only thing left is the extension of the engine mound that also get connected to the head from the front. It is snuggling too tight to let the head being pulled out. I am affraid to do anything drastic (pulling too hard) and wanted to ask teh forum how to handle that part. To remove that part, it is like removing the engine mount. One way is to hold the upper part and pull it towards the fron to give enough room for the head along with exhaust manifold to slip out.

Barry,

How did you handle that part.

Sorry the progress is very slow as the last week was just crazy at work and also brought some work at home for the weekend.

Your help is always appreciated and I will keep you posted.

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I didn't remove or timesert the front head. I had intended to do this. I did the rear first (As it had the pulled threads) and when I unpacked the head gasket for the rear, it had one head bolt missing.

I robbed the bolt from the front gasket set. At that point I just kept putting the engine back together. I should have ordered another bolt, and did the front head as well, however, I didn't.

I eventually ordered the missing bolt and have the front head gasket on the shelf if I ever need it.

Barry

2008 STS V8
2016 Colorado Z71
1970 Corvette LT-1 Coupe

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You should be able to remove the two engine mount bolts that are just below the cam cover mounting surface. There will still be two more bolts that attach the bracket to the engine block that need to remain in place.

-George

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

DTS_Signature.jpg

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The alignment dowels in the block need to be removed to do the timeserts.

I found mine very difficult to remove.

Anyone have any tips ?

My method is to use a fairly large punch and simply punch the dowel from three directions. Eventually, you distort the dowel enough that you can just pull

it out of the block.

Ian

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I got all the bolts out and also everything that is holding the front head. The only thing left is the extension of the engine mound that also get connected to the head from the front. It is snuggling too tight to let the head being pulled out. I am affraid to do anything drastic (pulling too hard) and wanted to ask teh forum how to handle that part. To remove that part, it is like removing the engine mount. One way is to hold the upper part and pull it towards the fron to give enough room for the head along with exhaust manifold to slip out.

Well, you are doing this the hard way. As another poster mentioned, it's really much simpler in the long run to pull the engine out the bottom. But since you

are into it....what I would suggest is that you loosen the two nuts/studs that

hold the front engine mount to the block at the bottom. You already have

the two bolts that attach the mount bracket to the cylinder head out, but what

is happening is that the weight of the engine will force the bracket against the head making it almost impossible to get the head up. Once you have loosened the bottom nuts, you will need to jack the engine up a bit so that the engine and front engine mount will move away from each other. You can jack on the engine oil pan provided that you use a block of wood. Hopefully, you can get the bracket and cylinder head to move away from each other and you might get the head off. If all else fails, you may need to completely remove the front engine mount assembly, but this will entail some more work.

Ian

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My method is to use a fairly large punch and simply punch the dowel from three directions. Eventually, you distort the dowel enough that you can just pull

it out of the block.

Ian

Thanks Ian, I hope I'll never have to use that tip.

Barry

2008 STS V8
2016 Colorado Z71
1970 Corvette LT-1 Coupe

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  • 1 month later...

Hello fellows,

Been a long time but I am back and with the news that both the heads are off and now I am ready to go for timesert operation.

Here is the detail

I tried to do the job by having the engine in the car but realized that it will be too challenging for me, so decided to pull the engine out. I however removed teh front head while I was working on it inside the car. I finally pulled the engine from the top "Thanks to one of the renowned members of this forum". He helped me out a lot at every stage and every step through. Previous posts on this forum were very helpful and I would like to say "What a wonderful forum it is"

I have taken some pictures and will be taking more as I will go through the process.

One thing that I noticed was in the rear head, some of the bolts came out very easily. I had two stripped bolts in the front head and four loose (not really but not as tight as the other ones) in the rear head. Cylinders were also had coolant in there, that explains how the coolant was seeping in and out of the cylinder and making the whole cooling system hot.

Once I will be done with this work, I am planning to post all the pictures and with my experience on a webpage and provide the link here.

Now the tasks to do are

timesert

timing chain and then getting the engine packed and back in the car.

As always, I will appreciate any and all help that I can possibly get. As a newbee and first time with an engine like that, I think the accomplishments are remarkable.

Thanks again to all the members and specially to "My Mentor"

Regards

Ali

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I don't know if the head dowels are out already, but I recall that Guru may have noted to clamp HARD with a vise-grip and hit the vise grip up from underneath (no twisting or dowell-defomation required !

The part about you deciding to leave the enignine in car, because Guru has changed heads that way - seemed a little humerous. Guru could probably change the heads with the da*m engine RUNNING for god's sake. :lol:

Add power to leave problems behind. Most braking is just - poor planning.
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Guys,

Any suggestions on removing teh alignment dowels from teh block surface??????

My method is to use a fairly large punch and simply punch the dowel from three directions. Eventually, you distort the dowel enough that you can just pull

it out of the block.

Ian

If you didn't like Ian's suggestion, this is what I did.

I would have purchased new ones, and done something like Ian suggested, however the dealer said they were not a replacable item.

Vise grips, (with a bolt inside the dowell - to keep it from collapsing) removed one only and I couldn't budge the others.

So, I used a pipe flaring tool clamp and tightened it securely on the dowell. Then used a small pry bar under the flaring tool to pry it out. It worked well.

Be sure to protect the block surface when prying. I used a flat putty knife.

Anything thin and strong should work.

Barry

2008 STS V8
2016 Colorado Z71
1970 Corvette LT-1 Coupe

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