1997 STS head gasket replacement next week

[mudweiser]

I bought a 1997 STS with 163,000. I bought the car from Virginia, had it shipped here and 2 months later the head gasket went out. I'm the 3rd owner, very, very clean car. When i bought the car you could smell coolant when running, i would have to add every week or so from in-town running. Once you would hit the interstate after about 50 miles it would overheat. Found a leaky radiator to blame and replaced that. All was good for about a month. I started the car after it sat while i gassed up and it ran rough right away. As soon as i hit the hi-way it was blowing white smoke. I knew about the head gasket/block treads so i continued home watching the gauge. It ran hot and about 3 blocks from home it told me to stop the engine. The car still runs, but rough and it smokes.

Now, i'm going to do the headgasket replacement and timesert the block. I'm not an auto tech, but i'm very capable, replaced many headgaskets, tranny's etc. The N* is new to me but my friend was a GM tech. I'm doing this repair in my garage which is equiped with everything but a hoist. I plan to lift the front of the car over the motor for removal with a chain hoist or engine lift. Once the motor is out i will remove and timsert the block. replace the upper gasket set, replace the H2O pump, replace the lower case gaskets What i really need to know, is there anything else i should do while the N* is out?

Also, is ther any special tools i need that are specific to the N*?

Please work with me here, i have read many posts about people saying you can't do it at home. I'm not your average shadetree guy. It's getting this servicing done no matter what. I'm layed off and i need this car going. Oh ya, i have an, umm Haynes manual.

[JimD]

....Oh ya, i have an, umm Haynes manual.

Before you remove the first bolt on that engine, find and purchase a GM Service Manual; eBay will be your friend.

Camshaft timing is critical! And Haynes will NOT provide the details.

While you are looking for a GM Service Manual, it would be a good idea to rotate the crankshaft to put #1 cylinder at TDC.

[mudweiser]

Just ordered the 1997 OEM EK Platform books. $47.50 from Ebay for books 1 and 2. I was planning to go TDC with #1 cly. Take a few pics and paint/scribe things. It looks like i had the Chilton manual, not the Haynes. Either way, OEM books are always good.

I'm not looking to keep the car for another 100k. It's getting fixed and sold. However i might have to drive it a month or 2 before it sells. I do not want to put any more money into it once this is done. Thats why i asked if there was any other prone issues with the N* that i should do while the powertrain is out. Also is there any speciality tools needed to do this service?

[KHE]

If the blower motor housing is brittle and falling apart, I would suggest you replace that. Very easy to do with the engine out of the car. Also, if the blower motor is the original design with the 1/2" thick steel plate on the face, replace it with the newer design with the foil/fiberglass heat shield.

If the oil manifold plate (1/8" plate between the oil pan and the lower crankcase) is leaking, it would be a good idea to replace it while the engine is out as well as the rear main seal. It would be a good idea to re-seal the upper and lower crankcase halves while the engine is out of the car also. The rear main seal requires a special tool to install. Unless you can find a deal on one off ebay, a Cadillac dealer should be able to install the new rear main seal for you for 1/2 hour of labor if you bring them the engine.

Replace the graphite donut exhaust seals at each end of the exhaust crossover pipe while the engine is out.

I realize you said you were going to sell the car when you got it repaired - in that case, you might not want to replace the blower motor and re-seal the lower half of the engine but I would replace the exhaust seals so you don't have an exhaust leak upon reassembly. You might just want to keep the car after you drive it awhile...

[BodybyFisher]

Just ordered the 1997 OEM EK Platform books. $47.50 from Ebay for books 1 and 2. I was planning to go TDC with #1 cly. Take a few pics and paint/scribe things. It looks like i had the Chilton manual, not the Haynes. Either way, OEM books are always good.

I'm not looking to keep the car for another 100k. It's getting fixed and sold. However i might have to drive it a month or 2 before it sells. I do not want to put any more money into it once this is done. Thats why i asked if there was any other prone issues with the N* that i should do while the powertrain is out. Also is there any speciality tools needed to do this service?

Great price.

I dont know if anyone brought it up, but check your HVAC cover they get brittle and crack. You might damage it doing this work also, it will crack like glass so be careful

Check your heater pipes out closely also, they rust and leak

Look over your engine mounts

Consider replacing the sensors and solenoids in the side pan of your tranny that will be easy to get to

Replace the torque converter seal and possibly the torque converter if you want to go nuts

Have your alternator rebuilt while its easy to get to

Look over your steering rack for leaks and retorque the bolts, replace it if its questionable

While the struts are loose have the springs replaced, and how are the struts?

Change the pan gasket you cant get at it while the engine is installed, replace the oil level sensor if its leaking

Replace the heater hoses if they look bad

Replace the by pass hose if it looks bad

Look at the crank balancer to see if its wobbling

Opps, I see you are selling it, forget what I said...

[mudweiser]

It could use front struts. I will have to replace them before the car sells. It's actually my wife's car. She's driving a S-10 Blazer for now. What a rocky box on wheels compaired to the STS. I'm afraid she will want to keep it once it's done. I have to question what else will go wrong after we fix it. I have to repair the lower case, it leaks bad.

The Alt. was replaced before we bought it.

Thanks for the heads up on the heater hoses and HVAC cover. I remember reading about those.

I'm thinking about having the starter rebuild as long as it's easy to get to.

Now, i have heard it takes about the same time to pull the motor as it does to pull the complete Powertrain? Is that corect? Again, i don't have a car hoist but i have a engine lift. So the question is, do i pull just the motor or find a way to lift the front of the car over the Powertrain?

[BodybyFisher]

I wouldnt worry about the starter, the difficulty of the job is overrated, its not hard at all to get to it. In addition, the starter is located in the middle of the engine, and its cooler than old starters that had muffler pipes running around them, they are not a significant source of trouble, but its your call.

We have members here that have done the job that will chime in on what method to use, but I have heard plus's and minus's for both methods.

I was going to build a custom dolly for it out of 4 by 4s with wheels lift it with floor jacks or something similar like 3/4" all-threads up under the carriage and then gently lower the carriage when its clear down to the dolly's wheels, but the body has to be pretty high for that. I was going to use my friends truck stands.

I suppose however using an engine lift with boom could be used to lift the body. I personally would like the entire powertrain out and on the ground so I can work around it easy.

Let our more experienced members chime in on getting it out.

[KHE]

If you need to reseal the lower crankcase, be sure to use the GM engine sealant. No other sealant will work. It is pricey but it works. Replace the oil manifold while you're in there also - it is the 1/8" thick plate between the oil pan and the lower crankcase half. They tend to leak a lot with aga and miles.

[mudweiser]

I guess the main question right now is; do i pull just the motor, or drop the powertrain? I have to do headgaskets/timesert and the case halfs for sure. I can work out the details on the rest later. Anyone have any insight as to pulling just the motor vs dropping the whole powertrain?

[KHE]

If you pull just the engine, there are a lot of bolts in awkward angles and limited clearance. The support that goes from the trans. inbetween the rear exhaust manifold pipes and to the rear head is a royal SOB to contend with upon reassembly... I had to lower the front of the engine cradle to gain enough clearance to install the bolt.

If I were doing the job over again, I would lift the body off the powertrain and then separate the engine from the trans. once the powertrain was out of the vehicle. The problem fasteners would not be an issue at that point.

[mudweiser]

I started the project a few hours ago. A friend was a GM tech, and he suggested to drop the whole subframe. So thats the way it's being done. I decided to order new headbolts, hopefully there is nothing else i have to wait on. Updates later.

[BodybyFisher]

You are timeserting this block correct?

www.timesert.com

[mudweiser]

You are timeserting this block correct?

www.timesert.com

Yep, The timesert kit was the first thing i bought. 20 holes to drill, tap and thread.

[mudweiser]

Got the powertrain out. Dropped it out the bottom. Overall, it was not that bad, so far anyways. I'm still waiting for the OEM manuals to show up, so the actual timeserting will have to wait until next week due to a busy schedule. I don't forsee us splitting the case. It looks more like a leaky timing chaincover gasket.

I can see why many people degrade this motor. The issues should not have taken Cadi this so long to correct. However, every build has it's issues, every model has it issues as well. Overall once yuo sit back and look at the N*, it's a piece of art.

Suddenly i feel like a little kid; waiting for the new bike to arrive!

[BodybyFisher]

It certainly is!

By the way, you said, you decided to replace the bolts, for what its worth, you NEEDED to replace the bolts, when the bolts are torqued, they 'stretch', when they are removed they must be replaced

Be sure to use the most current head bolt torque specs

[KHE]

It certainly is!

By the way, you said, you decided to replace the bolts, for what its worth, you NEEDED to replace the bolts, when the bolts are torqued, they 'stretch', when they are removed they must be replaced

Be sure to use the most current head bolt torque specs

The head bolts do not stretch. They need to be replaced due to the threadlocker on the threads - it is a special threadlocker on the head bolt threads as well as a sealer under the bolt head and on the washer that cannot be applied reliably in the field.

[BodybyFisher]

thanks Kevin, for some reason, I recall the guru saying that they stretch when properly torqued and that was the reason they needed replacing.

[BodybyFisher]

Here is a link to the GURU, talking about head bolt stretch, his name is beezlebob here, note how he is referred to as bbobynski

http://www.cadillacforums.com/forums/cadillac-forum/t-10272.html

[BodybyFisher]

Here is another article from the guru, he said they will stretch permanently

http://www.cadillacforums.com/forums/cadillac-forum/t-27009.html

[KHE]

Mike,

Yes - The head bolts will stretch a tiny bit but they are not torque to yield fasteners that would deform a lot. The tiny stretch is not the reason the headbolts are to be replaced.

[BodybyFisher]

Mike,

Yes - The head bolts will stretch a tiny bit but they are not torque to yield fasteners that would deform a lot. The tiny stretch is not the reason the headbolts are to be replaced.

No problem, in my mind I recalled the guru saying they stretch and that stuck in my mind, at least I know where I got it from and it was not my imagination.

[mudweiser]

It's not going too bad. No snapped bolts so far, just one on the cat. Heads are off, one bank is timeserted.

Does anyone have the latest torque steps for the cylinder head bolts? I have the 97 OEM books, but i was told to find the latest torque steps.

[KHE]

You might try the local Cadillac dealer for the latest torque specs. They can look up the bulletins for you. You will need a torque angle meter to do the job.

[mudweiser]

If i were to split the case, is it a prety straight forward task? Unbolt, clean and reseal?

Also, being the block is aluninum, if i do split the case is there any chance that the lower case treads will back out with the case bolts? I noticed this with the head bolts. Several head bolts that i removed had the blocks treads stuck in them. Obviously thats the reason for doing this project. However i don't want to have to repair the case 1/2 treads. The lower block is so covered with oil, i really can't even tell where it was leaking from but i figured this was the option to reseal the case.

If i do reseal it, can i use Loctite 5910 which is what i use on all my snowmobile and bike cases, or should i go with the GM sealant?

[mudweiser]

Update; the motor is back in. Everything went pretty good. I had a no-crank issue but some corroded fuses and breakers took care of that once they were cleaned up. I had the car running several times, each time i had to add about 1" of coolant in the resivor. Hope thats normal. The exhaust still smokes, but it seems to becone less and less each time. It does not smell like anit-Freeze athough. Tomorrow i have to tighten up the exhaust by the Cat and install a new gasket. Then give it a fresh tank of 91 OCT and take it for a spin. I do have the Anti-lock brake and ABS lights on though. Hmmm. I guess thats next.