Northstar headgaskets...

[winterset]

On really hot summer days, when I drive home from any type of long trip, I open the hood to let the car cool off. I know the temp rises after the car shuts down. If I am at 220 and it's hotter than 90 degrees out, I pull into the garage pop the hood, and leave the bays open to let the heat out. my twisted thinking is that it'sprobably a few of these really "extreme" temperature spikes that can cause damage. I started doing this to keep the battery from baking after I park (esp. Since car Batteries & Me have had many issues). Maybe this ritual can have some additional benefits for my sensitive N* HG's.

[winterset]

As far as heat, I wonder if removing the foam insulation from under the back of the hood will help transfer the heat from under the hood up out the back towards the windshield. I remember when I was a kid seeing some 70's & 80's cars removed the plastic back filler on the bumpers/rear fenders to allow the rear end of the car get some air circulation because the chrome bumper sections used to rot out at the seams. sometimes it really is the simple things that can make a big difference.

[Ranger]

On really hot summer days, when I drive home from any type of long trip, I open the hood to let the car cool off.

I do this every time I pull in the garage.

As far as heat, I wonder if removing the foam insulation from under the back of the hood will help transfer the heat from under the hood up out the back towards the windshield.

I have thought about that as well, but I think that would just allow any air to flow over the engine and out the hood rather than over the engine and down between the firewall and the engine.

[Jan Olsson]

When the head gasket leaks the clamping force is reduced. Because of that the bolts becomes loose...The dynamical load gets a much higher variation because the pre-tension in the joint is gone.

I think the reasons for blowing a head gasket (when maintainance of the colant system has been done) are due to production variations such as gasket defects, surfaces beeing uneven, porous blocks etc

Besides that it seems that the gaskets are subjects to fatigue. I believe that the number of complete driving cykles makes a bigger difference than accumulated miles (when everything else is "perfect")

The right cylinder bank is warmer than the left one. Thats why a defect shows earlier on that one. I don't believe the right bank gets too hot, just that problems show earlier.

Anyway, the RWD ones should be easier to work on if the worst ever should happen, right?

[KHE]

I don't buy the theory that the hot air or low air circulation is the cause of the headbolts pulling. The areas around each head bolt hole are surrounded by the water jacket.

[Cadillac Jim]

I think that making small changes, like raising the hood when you park or removing hood insulation, will have no discernible effect on the engine because they will have no effect on the engine internal temperatures. I think that the rear head runs hotter is because the water pump is on the front head and the water is fed to the rear head through the crossover, not because of any external heat transfer, and that this is known and accounted for in the design, which is why the ECT sensor is on the rear head.

Raising the hood when you park the car can't do any harm, assuming that a herd of kittens doesn't ensconce itself in your fan shrouds before you start the car again. I've heard of people with attached garages that leave the garage door open and open the car hood to minimize warming of the house when they come home from work. Whatever floats your boat, and maybe reduces your electric bill and is easier on your house HVAC system is just fine, of course. The underhood temperatures may come down quicker after you park but everything is designed for the very high underhood temperatures that do exist. Any additional heat flow from removing the hood insulation would be dwarfed by the cooling system heat flow, which is massive -- and in fact the cooling system would likely compensate by very slightly reducing its heat flow to maintain engine temperature.

I definitely recommend that you do NOT remove the hood insulation. The one predictable effect will be a much higher hood surface temperature. The most drastic effect will be reduced paint life and reduced resistance to scratching and pitting from road debris. The most visible effect will be much more visible heat refraction along the hood line, like watching the horizon waver in the mid-day desert. Another likely effect is increased engine noise, and such things as more audible cooling fans when stopped at traffic lights and such.

[MrEldo97]

I don't buy the theory that the hot air or low air circulation is the cause of the headbolts pulling. The areas around each head bolt hole are surrounded by the water jacket.

Never said it was THE cause only a contributing factor. IMO there are several issues that contribute to head bolts pulling and hot underhood temps could be/are one.

[manowar77]

What about these sealant tabs that you put in the system...could there be any possibility that these can have a negative impact on the gaskets? For example my dads 96 VW Passat have an all aluminum engine also but it doesnt say that you should put sealant tabs in it during a coolant change!

[Bruce Nunnally]

The tablets are basically fibers that expand and act to 'cork up' porosity in the aluminum if any. An expert once suggested that I add extra tablets to my STS that was overheating, with the argument that it would not hurt but could help -- still some chance that the fibers would clog up the gaps.

[BodybyFisher]

Can we discuss, the merits of spending $150 per headgasket for these

http://www.cometic.com/est.aspx

Verses spending $25 per head gasket for say Fel Pro. Anyone know how much the OEM head gasket is?

We have recently discussed the potential of the piston to move due to its unsupported upper end. That to me, if that is possible would damage/burnish the head gaskets or mating surfaces over time, no?

If you go to the above site and click

Cometic MLS (multi-layer-steel) Head Gaskets are ideal for any combination of head and cylinder materials. MLS Head Gaskets are comprised of two embossed viton coated stainless steel outer layers and a variable stainless center layer. The variable center layer allows us to create multiple gasket thickness options. No re-torque is required after initial torque set

Why is this worth $125 more than the FEL Pro or OEM head gaskets?

[manowar77]

Ok, but can we determine that,like JimD said, the bolt threads protecting coating suffers no damage until it gets in contact with coolant and the bolt pulls? In that case you can say its a sealing question!

And then the gasket hasnt been doing its job, due to maybe corrosion caused by old coolant..!

So if,like Jan Olsson said, cange coolant on a regular basis,24 month, with the right type coolant,distilled water and sealant tabs you can say that you are keeping the gaskets happy..?

And also try to keep your Northstar as cool as possible..!

Then you have done what you can to avoid gasketleaks!

[MrEldo97]

I remember paying about $246.00 for my headgasket set (Felpro) from NAPA. At the time I thought the headgaskets looked pretty "chintzy"...

[Cadillac Jim]

At this point I would add only that underhood temperatures are not a likely cause of anything internal to any Northstar. I like the MLS idea, but the MLS finds its best application in ultra high performance engines that are pulled down a lot more often than most Northstars. Only one thing bothers me about the MLS gasket: It's steel, and the head and block are aluminum. If any trace of coolant gets in contact with both metals, there will be some etching of the aluminum surface. I would be interested in recommendations from GM and experience with MLS head gaskets in engines that are not pulled down for many years. They might be the best thing ever for Nothstars if, for example, they have non-galvanic seals at the water jacket holes; most head gaskets have rings around the cylinders or other special treatment for compression sealing but nothing special at the water jacket holes, some have special treatment at the water jacket holes. In any engine with an aluminum head or block I would want a head gasket that has special sealing around the water jacket holes.

We have discussed the fact that nearly all 1993-1999 Northstars that have had a head gasket failure do so after about 7 years with no coolant change, and that a pulled head bolt is identified that is separate from the head gasket failure and thus probably preceded and caused the head gasket failure. We have theorized that traces of old, conductive and expired coolant in the head bolt wells settles at the bottom and there is galvanic corrosion at the threads that eventually causes the head bolts to pull. However, we have information from the guru to the effect that the head bolt wells are sealed specifically to prevent just exactly that problem. My car, however, showed coolant seepage on the outside corner of the rear head on the driver's side, which was the cylinder that had the head gasket problem, which was into the coolant and not between cylinders. I had 7+ years on my coolant. I think that this case is typical of most 1993-1999 Northstar head gasket failures.

MrEldo97 and possibly a few others have reported Northstar head gasket failures when there was a history of coolant changes. This mystifies me, but with the tens of thousands of people who have come to Caddyinfo over the years we will have exposure to more problems than the average large dealer, and certainly more than the average experienced Cadillac tech -- a few of which contribute regularly here. Thus, sooner or later, we will see everything. If the coolant was kept fresh, perhaps we can identify tap water instead of distilled water, one or more significant overheating incidents, running for long periods with low coolant or low oil, or a car history event not known to the owner such as an engine swap or skipped coolant change, or, perhaps something peculiar to that car.

As long as I'm in a thoughtful mood about high mileage Northstars and their care and feeding, I would *never* put heavy or high-mileage dino oil in a Northstar, or oil thickeners like STP Oil Treatment. These are for cars with excessive piston clearance and lots of blowby and I've never heard of that happening to a Northstar of any mileage. We have one member here, again MrEldo97 who ran dino high mileage oil and ended up with a severe case of stuck rings, not unexpected in a tight-clearance high-performance engine that is not driven hard very often when you use dino oil that is too thick for too long.

[BodybyFisher]

I remember paying about $246.00 for my headgasket set (Felpro) from NAPA. At the time I thought the headgaskets looked pretty "chintzy"...

I went to www.rockauto.com and the head gasket (Felpro) was about $21 each or $42 total, maybe you are talking about the whole kit for $184, see below? I am only talking about the top two items below

FEL-PRO Part # 26150PT

DOHC engine; Loc. L.H.; Head bolts not incl.; Head bolt replacement recommended $20.79

FEL-PRO Part # 26151PT

DOHC engine; Loc. R.H.; Head bolts not incl.; Head bolt replacement recommended $20.79

ROCK PRODUCTS Part # HG3154L

DOHC; Left Hand $23.89

ROCK PRODUCTS Part # HG3154R

DOHC; Right Hand $23.89

FEL-PRO Part # HS26150PT1 {HEAD SETS (HS) are used for upper engine repair only, typically on a valve grind.}

DOHC engine; Head bolts & exh. pipe packing not incl.; Head bolt replacement recommended; PermaDry® molded rubber valve cover gskts. incl.; Premium valve stem seals incl. $184.79

ROCK PRODUCTS Part # HGS3154

DOHC $232.89

[BodybyFisher]

Jim you are saying that if you had low oil pressure at idle you would not use 15W40 as it may potentially clog the rings?

Keep in mind that many of us have oil light flickering at idle and case half leaks that are bad, unless an engine reseal is done the only option is a thicker oil, to date I have not had serious smoking or oil consumption, but if and when I do this job, I will have my pistons out and inspect the rings

[MrEldo97]

I remember feeling as if I'd been gouged at the time. Of course I could have taken my wallet elsewhere...

I will be changing the oil in my Eldorado this weekend - switching to Mobil 1 10-30.

I'm also changing to Mobil 1 in Junior's '03 Seville and my '95 XJS. I'm finished with Castrol High Mileage.

This should be an interesting experiment...

[Cadillac Jim]

I am saying that I would not use 15W-40 dino oil in my Northstar to lessen oil seepage in the half case or oil pan. To me stuck rings are a major item, second only to head gasket failure in a Northstar -- and possibly worse, because once done, the damage is so hard to reverse without a pulldown that includes removing and cleaning the piston ring grooves.

If you have a flickering oil light and a new oil pressure switch doesn't fix it, and a pressure check does indeed show that the oil pressure is low, then yes, run 10W-30 in it. If that doesn't do it, then fix the low oil pressure problem. This might be done with an O-ring change if an oil gallery through the half-case is leaking through the O-ring seal, or it might require re-torquing the damper wheel, or a new oil pump. If you have a problem with leaks and run for a period of time, say three to six months, with oil additives that limber up the seals, and that doesn't do it for you, then either live with it or fix it.

But no, I would never use thick dino oil in my Northstar because a really bad case of stuck rings might put me in an existential crisis like we have seen with MrEldo97. If I really wanted to do that, I would use synthetic 15W-40 high mileage oil because it won't form shellac like dino oil will. I think that 5W-30 Mobil 1 with a quart or so of MMO for an oil change or two might be the first thing that I tried. My fear is that a really intractable case of stuck rings might require a pulldown that dwarfs a Timesert job or force an engine exchange. And, if an engine needs an O-ring or oil pan gasket, then, it needs an O-ring or an oil pan gasket, and these are a lot simpler than pulling the pistons and cleaning them.

[BodybyFisher]

Well, the problem is that the case half seal is bad, and the engine leaks internally, short of taking the engine out, and breaking it down at the case half to replace the case half seal, that is the only repair, so, the 15W40 works fine unless I want to spend an arm and a leg to fix it, and it was sanctioned by the guru himself.

[MrEldo97]

"existential crisis like we have seen with MrEldo97" very accurate dsecription...LOL!

I'm switching my three cars to synthetic oil because of the stuck rings problem in my Eldo. Food for thought...

[Jan Olsson]

Ok, but can we determine that,like JimD said, the bolt threads protecting coating suffers no damage until it gets in contact with coolant and the bolt pulls? In that case you can say its a sealing question!

And then the gasket hasnt been doing its job, due to maybe corrosion caused by old coolant..!

So if,like Jan Olsson said, cange coolant on a regular basis,24 month, with the right type coolant,distilled water and sealant tabs you can say that you are keeping the gaskets happy..?

And also try to keep your Northstar as cool as possible..!

Then you have done what you can to avoid gasketleaks!

The tabs don't harm anything. In fact they are recommended to stop nuisance leaks. You don't have a VW..You’ve got a Cadillac.

Volvo didn't use to put anything extra in their cooling systems for their earlier Volvos. Don’t know if they have come to their senses or if they still insist on not doing it. This is why my father had to refill the cooling system with a couple of gallons per month... They never recommend changing the fluid either. I remember when I had to pull the head on my Volvo 740. There was plenty of space (lots of cast iron) between the cylinders. The gasket was rotted half way through but still sealed up. Not because the corrosion doesn’t apply on a Volvo just simply because of the large distance between the cylinders. The gasket was just some copper gasket, nothing fancy. But it was a cast iron block (with an aluminium head).

Many of the Japanese auto makers have additives to their cooling systems just to stop the engines in their cars from soaking coolant.

Use the tabs and the correct fluid. Change when recommended. It is the best and only way to protect your engine.

Don’t worry about the temperature on the engine until you get warnings or unusually high temperatures. The difference in flowing direction compared to other engines is to keep an even temperature in the engine, but the temp. gauge reading will vary. Because of this the temp. gauge is slightly dampened around the “normal upright position” just to stop people from getting heart-attacks whenever the needle is moving… OVERHEATING might blow a bad gasket. Everything else will be fine.

The difference in work applied to the gasket, block and head due to the heat difference when the engine is 200F compared to 240-250F is nothing compared to the difference between 30-40F and 200F.

As the guru said “drive it and forget about it”

I personally would do exactly what Cadillac recommends if my STS ever blows a gasket. That is using OEM bolts, gaskets and Time-serts. This is because I believe that there is NOTHING to gain in using other types of inserts (or studs for that matter). Just a couple of years ago Cadillac was one of the very few who used Time-serts.

Today GM, Tesla, Audi, Nissan, BMW, Citroen, VW, AMG, Honda, Mitsubishi, Mercedes, Toyota, Porsche, Skoda, Subaru, Opel, Ford, Kawasaki, Volvo, Yamaha, Austin-Rover and Renault uses them. Can’t really say that using a Time-sert is a funny solution that only Cadillac uses.

I know that there are people here that claim that for instance Chevrolet doesn’t use them in the Corvette. I’m sure it’s true.

I’m also sure that there is a perfectly good reason for that. It’s not like they all suddenly decided to throw in Time-serts just for fun. Bolt length/diameter, temperature and gaskets define the connection. I believe that a quite different amount of work is done on a Corvette engine. Perhaps thermal expansion lengths differs, a greater distance between the cylinders and lesser movement between the head and block due to a conventional casting technique etc. all adds up to a need for a lesser torque on the bolts? I don’t know, just guessing here, but we can all be sure of that there are engines that need inserts and engines that don’t need them..the 4.9 needs them by the way

About loose bolts (implying that the bolt holes are weak)

Think of it this way. Let us say that the gasket blows early (after just 5 years). The bolts maybe come loose because of the collapsed gasket (it has to be collapsed to get a leak). Maybe even the threads will be damaged from the abuse of the shocks when the load on the bolt changes from 0% force to 100% working load instead of maybe an interval of 90%-100% working load (when the clamping force is still obtained). When doing the R and R the Time-sert has a much greater O.D than the original bolt. Nothing to worry about unless the block itself has become crystallized, and if that’s the case I’m not sure anything will work at all.

I’m confident that Cadillac has done anything in their power to fix the “problem” (remember that a Cadillac doesn’t suffer from bad gaskets any more than any other automobile) and no one would be more pleased than me if it was a permanent “fix”.

But I believe that the block design (defined by the casting technique) and the head design is the factor making the gaskets blow due to fatigue, can’t change that in a hurry. Changes have been made. Both joints and gaskets have been redesigned to the better. Use of pressure casting lessens the likeliness for porous blocks/leaks. I also believe that natural variations in the assembly of the engines can make them fail prematurely.

My bottom line is that about the only thing we ever hear about the Cadillacs is the “dreaded head-gasket problem”. I’m not sure it is a problem.. Of course I don’t want to change them and I keep my fingers crossed, but I don’t stay awake all night thinking of it either…

If the worst happens and you have to pay an authorized dealer to fix it? It is still a reliable car and you can’t get another car with the same reliability, luxury, gizmos and style for the same price and the likeliness for you to have to do it all again on the same car is just about zero…

[Jan Olsson]

At this point I would add only that underhood temperatures are not a likely cause of anything internal to any Northstar. I like the MLS idea, but the MLS finds its best application in ultra high performance engines that are pulled down a lot more often than most Northstars. Only one thing bothers me about the MLS gasket: It's steel, and the head and block are aluminum. If any trace of coolant gets in contact with both metals, there will be some etching of the aluminum surface. I would be interested in recommendations from GM and experience with MLS head gaskets in engines that are not pulled down for many years. They might be the best thing ever for Nothstars if, for example, they have non-galvanic seals at the water jacket holes; most head gaskets have rings around the cylinders or other special treatment for compression sealing but nothing special at the water jacket holes, some have special treatment at the water jacket holes. In any engine with an aluminum head or block I would want a head gasket that has special sealing around the water jacket holes.

We have discussed the fact that nearly all 1993-1999 Northstars that have had a head gasket failure do so after about 7 years with no coolant change, and that a pulled head bolt is identified that is separate from the head gasket failure and thus probably preceded and caused the head gasket failure. We have theorized that traces of old, conductive and expired coolant in the head bolt wells settles at the bottom and there is galvanic corrosion at the threads that eventually causes the head bolts to pull. However, we have information from the guru to the effect that the head bolt wells are sealed specifically to prevent just exactly that problem. My car, however, showed coolant seepage on the outside corner of the rear head on the driver's side, which was the cylinder that had the head gasket problem, which was into the coolant and not between cylinders. I had 7+ years on my coolant. I think that this case is typical of most 1993-1999 Northstar head gasket failures.

MrEldo97 and possibly a few others have reported Northstar head gasket failures when there was a history of coolant changes. This mystifies me, but with the tens of thousands of people who have come to Caddyinfo over the years we will have exposure to more problems than the average large dealer, and certainly more than the average experienced Cadillac tech -- a few of which contribute regularly here. Thus, sooner or later, we will see everything. If the coolant was kept fresh, perhaps we can identify tap water instead of distilled water, one or more significant overheating incidents, running for long periods with low coolant or low oil, or a car history event not known to the owner such as an engine swap or skipped coolant change, or, perhaps something peculiar to that car.

As long as I'm in a thoughtful mood about high mileage Northstars and their care and feeding, I would *never* put heavy or high-mileage dino oil in a Northstar, or oil thickeners like STP Oil Treatment. These are for cars with excessive piston clearance and lots of blowby and I've never heard of that happening to a Northstar of any mileage. We have one member here, again MrEldo97 who ran dino high mileage oil and ended up with a severe case of stuck rings, not unexpected in a tight-clearance high-performance engine that is not driven hard very often when you use dino oil that is too thick for too long.

Ditto that.

I would only like to make a comment about dino oil. I believe that the use of an oil with the wrong viscosity is a bad thing. I also remember that the guru once said that the use of 15W-40 wasn't thick enough to hurt anything and recommended a 15W-40 oil if a 10W-30 was hard to get (for the older engines who needed higher ZDDP levels).

Dino, semi-synthetic or fully synthetic oils uses the same additives. I have used dino oils in all my cars since 1992...never had a problem with that. In fact my 2002 STS is the only car that I ever used a semi-synthetic oil in. My 1993 STS looked as good as new inside when I had to fix some burned exhaust valves (the car was running bad when I bought it)

[adallak]

Several courageous members of this board time-serted successfully their Northstar blocks, and thus entered into the caddyinfo.com Hall of Fame. Here is the door mat of the Hall.

[BodybyFisher]

Several courageous members of this board time-serted successfully their Northstar blocks, and thus entered into the caddyinfo.com Hall of Fame. Here is the door mat of the Hall.

I like that Adallak, thx

[JimD]

Mike:

It might be worth your effort to contact the folks below and ask them why they use whatever head gaskets they use.

http://www.chrfab.com/

Cheers....

Can we discuss, the merits of spending $150 per headgasket for these

http://www.cometic.com/est.aspx

Verses spending $25 per head gasket for say Fel Pro. Anyone know how much the OEM head gasket is?

We have recently discussed the potential of the piston to move due to its unsupported upper end. That to me, if that is possible would damage/burnish the head gaskets or mating surfaces over time, no?

If you go to the above site and click

Cometic MLS (multi-layer-steel) Head Gaskets are ideal for any combination of head and cylinder materials. MLS Head Gaskets are comprised of two embossed viton coated stainless steel outer layers and a variable stainless center layer. The variable center layer allows us to create multiple gasket thickness options. No re-torque is required after initial torque set

Why is this worth $125 more than the FEL Pro or OEM head gaskets?

[KHE]

Can we discuss, the merits of spending $150 per headgasket for these

http://www.cometic.com/est.aspx

Verses spending $25 per head gasket for say Fel Pro. Anyone know how much the OEM head gasket is?

We have recently discussed the potential of the piston to move due to its unsupported upper end. That to me, if that is possible would damage/burnish the head gaskets or mating surfaces over time, no?

If you go to the above site and click

Cometic MLS (multi-layer-steel) Head Gaskets are ideal for any combination of head and cylinder materials. MLS Head Gaskets are comprised of two embossed viton coated stainless steel outer layers and a variable stainless center layer. The variable center layer allows us to create multiple gasket thickness options. No re-torque is required after initial torque set

Why is this worth $125 more than the FEL Pro or OEM head gaskets?

OEM Headgaskets and bolts are $63.75 per side from gmotors.com. Probably $80.00 at the dealer parts counter.

I'm not convinced the MLS gaskets are worth $150.00...