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Good afternoon all, I have a '99 Deville with 69,750 miles and she runs great. My question is by doing the WOT excersise is there any adverse affects on the head gasket? So far I have no signs of head gasket problems and I don't want to be doing something to speed up what seems to be inevitable. I just had her painted at a cost of $5,300 and plan on keeping her. Any comments? Thanks Craig.

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years ago, I asked the same question of the guru, who was a Northstar Powertrain Engineer. He said no, that WOTs would not cause a head gasket problem.

I would say this, if your bolts are going to pull, they are going to pull regardless of whether or not you do WOTs

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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years ago, I asked the same question of the guru, who was a Northstar Powertrain Engineer. He said no, that WOTs would not cause a head gasket problem.

I would say this, if your bolts are going to pull, they are going to pull regardless of whether or not you do WOTs

Mike, how do you feel about repeated WOT's stress on an 11yr old transmission? Also, do you feel WOT's will hasten

the deterioration of motor mounts?

On my "new to me" STS, I really haven't run WOT's yet.

1989 FWD Fleetwood, Silver

1995 STS Crimson Pearl on Black leather

1997 STS Diamond White

1999 STS Crimson Pearl

2001 STS Silver

2003 STS, Crimson Pearl

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Good afternoon all, I have a '99 Deville with 69,750 miles and she runs great. My question is by doing the WOT excersise is there any adverse affects on the head gasket?

I fail to understand how using the engine as it was designed to be used might have any adverse affect on head gasket life.

...I don't want to be doing something to speed up what seems to be inevitable.

Inevtiable is what it is (unavoidable). But WOT therapy is not a factor with modern technology, testing, and metallurgy. In the 1960's, you could bank on replacing a vehicle or a major engine rebuild before reaching 100,000 miles. Not so today (1990+).

My '98 model continues to survive heavy/frequent doses of WOT therapy at 191,xxx miles.+

I just had her painted at a cost of $5,300 and plan on keeping her. Any comments? Thanks Craig.

Yes. Drive it like you stole it!

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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The Northstar was designed to be driven hard, it thrives on being run hard, long trips rejuvinate it, new platforms can be run hard all day long. The transmissions are strong. However, I agree that WOTs can be stressful to older high mileage drivetrains. as they would any drivetrain, unless they are done smart. When I do them I don't wind out to the red line, I don't do them at low speed. I do them getting on to expressways but I don't overdo them, I do them to clean out the combustion chamber

I got an email from a member who reminded me that the head bolts don't just pull out of the block, they pull because coolant leaks into the threads and corrodes the threads weakening them, then they pull. That was the guru's contention after doing many teardowns.

Recent reading that I have done has shown me that head gaskets can compress. Can overheating, heat soak, and cycling compress head gaskets and start the cooling leaking into the threads? The guru used to say that coolant that is not changed turns acidic and can eat the gasket allowing coolant to get into the threads. I know the history of my Northstar and the coolant was changed regularly, so if my coolant did not get acidic, how did the coolant get into the threads to weaken them?

I had a long discussion recently with someone (I wish to keep his identity a secret), he said that he felt that from 93 to 99, the NS aluminum alloy was soft. The reason we see the rear head gasket go bad more often is because of increased temps due to higher temps by the firewall softening the aluminum causing the bolts to pull. I am not a metalurgist, so I don't know how true that is, but the fellow I spoke to had rebuilt hundreds of NSs and has lots of experience. We as a group are familiar with his company.

If the aluminum material has been overheated, it will be gritty, powdery, and soft and a timesert will pull right out like it was butter. We have seen timeserts fail, and I have had dealer mechanics say that timeserts don't always save a block. That could be because the block aluminum is junk or because they rushed the job. Anyone who followed AJ's thread saw the gritty aluminum in his photos

I do know this, the engine head bolts changed in 2000 and 2004, but I don't know if the aluminum alloy was changed, anyone know? I do wish that the guru was still around to see some of the things we are seeing.

I don't know the bottom line answer, maybe its all of the above, maybe not. I love this engine, its a marvel, its hard to be objective, given the allegiance I have to the guru and to GM. I do believe that aluminum blocks are challenging. My first experience as a child was our first car, a 54 Packard Carabbean Convertible that had an aluminum head and my Dad had negative things to say about aluminum heads when it cracked.

I currently drive a 2002 3.4 Monte Carlo weakling, and just today I said, I miss the power of my Northstar, I can not get out of trouble with a 3.4, not enough power. The Northstar is an amazing engine

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Do you mean current northstars? Is there an all aluminum LS engine?, excuse the dumb question, but I dont follow them closely. Are there head bolt failures in the those?

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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Do the engines in nowadays Cadillacs run as hot as Northstar has been doing?

How hot is hot?

Modern engines (the Northstar qualifies) operate in the 19x to 22x degree F range. The driver might not ever be aware of the acutal moment to moment coolant temperature flucation due to the damping of the coolant temperature indicator inside the car.

One (of many) reason for coolant temperatures reaching and exceeding 212 degrees F is to promote evaporation of nasty unwanted by-products from the crankcase oil supply.

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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years ago, I asked the same question of the guru, who was a Northstar Powertrain Engineer. He said no, that WOTs would not cause a head gasket problem.

I would say this, if your bolts are going to pull, they are going to pull regardless of whether or not you do WOTs

Mike, how do you feel about repeated WOT's stress on an 11yr old transmission? Also, do you feel WOT's will hasten

the deterioration of motor mounts?

On my "new to me" STS, I really haven't run WOT's yet.

Yes. WOT torques the engine back and pulls on the front mount, stressing and eventually tearing it since GM id away with the torque struts. That's why I fabricated a set for my car.

http://www.cadillacforums.com/forums/northstar-performance-technical-discussion/175113-fabricated-torque-strut-2000-norhtstar.html

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The first time I did a WOT with my car, I was scared half to death that it was going to break something. 5 or 6 good WOT runs later, and she's running the best she ever has. My car is a 1994 with just over 155,000 miles on it.

If you are really concerned about it, check your motor mounts out ahead of time to be sure they are still in good shape. Assuming those and the transmission are in good shape, I don't think you will have any issues. There is actually a procedure on here somewhere for doing the WOT, though I'm unsure if it pertains to your year car or not. I'll see if I can find it and post it here.

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