6669charger

high mileage 94 sts

14 posts in this topic

I everyone, First post here.

Bought a 94 STS with 190000 miles. Does driving style have anything to do with the head gaskets going out or is it mostly not keeping the antifreeze changed? With the high mileage I'm worried  that high rpms will blow the gaskets. Any opinions would be appreciated.

 

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:welcomesmiley:

 

Ya know what they say about opinions......

My feeling is driving style or "high rpms" Within Reason, do not affect head gasket longevity.

During extended highway driving the engine reaches operating temp and all the components ( heads - head bolts - gaskets - cylinder liners etc.. ) reach operating temp and don't fluctuate a great deal. By contrast the numerous "starting, stopping, short local runs" generate numerous engine "temp cycles" causing expansion and contraction cycles of the components that can lead to head bolt stretch and gasket compression failures that lead to head gasket leakage.

Coolant change intervals should not exceed 30,000 regardless of advertising hype and regardless of coolant chemistry (silicate or acid based)... We spend $10 dollars a quart for oil and change it at 3000, 7500, 10000 why not change the coolant too? Why didn't Cadillac put a Coolant Life Monitor alongside the Engine oil and Transmission Fluid Life indexes. ??? I have my own theory why GM didn't but that's another story altogether. I also, don't like to get involved in engine oil discussions and that is not what I'm trying to get started either.

You buy a vehicle to take you where you want to go and get you back. Cadillacs do it with "Style" and safety. When they're new, Cadillacs are cutting edge technology. Drive it like you want. Drive it like you need to drive it. Whether you bought the vehicle new, used or built it from the ground up EVENTUALLY it will break. You never know what the magical mileage number is until you get there.  

BUT, take care of it like you would a loved one.

That is my 2 cents worth :excl::scenic:

 


THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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I will concur with @OldCadTech that if you drive the car reasonably you should be fine. 

To wit, I blew the headgasket on my 96 at 127K miles by pushing the engine way too hard, I was late for an appointment, got on to the expressway and from the entrance ramp floored the accelerator to 90, the next time I came to a stop, I had a misfire and she began to overheat.   While this type of driving if fine if the engine is new or rebuilt, at 127K miles, I believe I was being abusive and caused the head gasket to fail.   Now......maybe it would have blow anyway in time and I just sped the process along quicker, but in fact, my romp to 90 and about 5,500 to 6,000 rpm did it in.    I had changed my coolant often from when I got the car at 57K miles and at about 97K miles, drove from Virginia Beach to the Poconos in Pa with 4 big guys in the car averaging about 80 in high outside temps with no problems. As a matter of fact, over the years, I had done crazy stuff like race an Audi S5 to 95 with no problems.   I just think that at 127K miles, pushing the engine as hard as I did, was more than it could take.  Don't baby it, but don't go out and race it. 

One interesting note, when the engine is validated when new it is run at varying half to full throttle for 175 hours. 


Pre-1995 - DTC codes OBD1  >> http://z-cut.de/US/dtcobd1.html

1996 and newer - DTC codes OBD2 >> http://carprogrammer.com/Z28/PCM/OBD2/On-BoardDiagnosticTroubleCodes(OBD-II).mht

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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That's exactly the situation I worry about. I don't go around racing, But I worry about if I floor it passing someone, there goes the motor

With 190000 miles I doubt if I would fix the motor. Too bad such a nice car with a fragile engine.

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Its not a fragile engine but its like anything else as it gets older the frequency of problems naturally rise.  When I was a kid, when cars got to 100k they were junk rust buckets and they went tothe junk yard.  These cars look amazing, just renovate the engine as you would your kitchen or bath and you are good 

It really depends on what you pay for it and how.much you enjoy driving the car.

You can have the engine rebuilt by a place like Northstar Performance.  They are from Canada but are planning to open a US shop.

 

 


Pre-1995 - DTC codes OBD1  >> http://z-cut.de/US/dtcobd1.html

1996 and newer - DTC codes OBD2 >> http://carprogrammer.com/Z28/PCM/OBD2/On-BoardDiagnosticTroubleCodes(OBD-II).mht

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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It's not a fragile engine at all.

Do you have any idea of the service history? Any records?


THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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Didn't want to ruffle any feather. 

Got the carfax, it shows it was regularly serviced at the Cadillac dealer up until 157000 mi. The last 30000 must have been rough on it. Bought it on ebay for 230.00 put radiator, ecm,and tps to make it drivable. Runs great now maybe the head gasket problem isn't as wide spread as the internet makes it seem. Would post a pic but don't know how.

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You didnt ruffle anyone's feathers, we just don't like to leave ill informed disparaging statements left unchallenged.

You are speaking about engines that have in excess of 125,000 miles.  You will find aluminum engine problems on BMWs, Mercedes, Toyota and Ford.  The internet is the focus of BAD news you don't get owners running to the internet with 325,000 miles to let everyone know how happy they are.

I trust you tested the head gaskets before you bought the car which should always be done given the age and mileage.

That said, given that it was serviced by the dealer to about 150k is good news, good luck


Pre-1995 - DTC codes OBD1  >> http://z-cut.de/US/dtcobd1.html

1996 and newer - DTC codes OBD2 >> http://carprogrammer.com/Z28/PCM/OBD2/On-BoardDiagnosticTroubleCodes(OBD-II).mht

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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Welcome to the forum.

To start miles mean nothing with these cars. I bought my 1996 Deville with 180k on the odometer, and I put 40k on it. To date it was still the best car I ever had. It ran and drove excellent. I did not baby it at all and  it loved every bit of it. I meticulously maintained it. 

Around 200k it started losing a little coolant into a cylinder or 2 and it was only really noticeable when the car sat for a few days as it would have a cold start misfire. I continued to  monitor and drive it normally. It had 230k on it when it finally blew. exhaust was spewing out of the surge cap.

Since that 1996 I still have 2 97s and recently let go of my 2001.

They are wonderful cars. My personal opinion is that changing the coolant normally has little to do with if or when the headbolts pull but not changing it doesnt help. 

Bf luck. Sounds like you got it for a steal.  Even if you replaced the engine you would still have a great car (given it is in good shape )

BodybyFisher likes this

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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On ‎2017‎-‎01‎-‎13 at 2:47 AM, rockfangd said:

Welcome to the forum.

To start miles mean nothing with these cars. I bought my 1996 Deville with 180k on the odometer, and I put 40k on it. To date it was still the best car I ever had. It ran and drove excellent. I did not baby it at all and  it loved every bit of it. I meticulously maintained it. 

Around 200k it started losing a little coolant into a cylinder or 2 and it was only really noticeable when the car sat for a few days as it would have a cold start misfire. I continued to  monitor and drive it normally. It had 230k on it when it finally blew. exhaust was spewing out of the surge cap.

Since that 1996 I still have 2 97s and recently let go of my 2001.

They are wonderful cars. My personal opinion is that changing the coolant normally has little to do with if or when the headbolts pull but not changing it doesnt help. 

Bf luck. Sounds like you got it for a steal.  Even if you replaced the engine you would still have a great car (given it is in good shape )

Just my two cents. I don´t believe that the bolts pull and the gaskets blow from that. If they ever come loose it is the other way around. I believe that when somebody renovates the engine and feels how easily the bolts comes loose and see aluminum left on the threads they wrongly assume that the bolts have come loose. It is also possible that the blown gasket collapses when it blows with the result that the bolt loosens a lot of the clamping force and eventually works itself loose.

My STS has 180 k miles on it and I believe that the single greatest thing one can do to prevent it from happen is to do regular coolant changes. Engines are individuals because of many things: natural variations in materials within factory specs, well done services, use, year by year changes in design and materials and so on. With time and miles the risk increases for something to happen. But hey, it is not the end of the world. It will probably cost a lot to have a shop do the job and do it right, but when it is done you can truly enjoy a great car for many more miles. What is interesting in the long run is (besides the big grin on your face every time you leave a "sporty" BMW or whatever in the dust after a WOT) is that the true cost to own these remarkable cars is very low. The parts are generally really inexpensive for a car with 300 hp, they are really reliable and repairs are rare and generally quite easy to do for a do-it-yourselfer.

Drive it like you stole it if you like. Of course a car on its way to blow a gasket will eventually break down but after a proper repair you'll not have to worry about it to happen again on a long long time. Head gaskets don't blow more easily or more often on a Northstar than on any other car, it is just harder to do a repair because of the transverse engine with FWD layout.

Do a research on WOT and coolant changes. There is a lot of information about that on the forum. I drive my STS about 25k a year and am aware of that something “big” is bond to break eventually. It still has its original starter engine, AC, alternator, water pump, shocks and many other things that other “premium car”-owners would have replaced a couple of times already.

I have changed the catalytic converter, AIR-pump, an AIR-valve, servo pump, front motor mount, front wheel bearings every 50 km miles or so (now THERE is a weak spot), an oxygen sensor, oil cooler lines, brake pipes, rear calipers and of course normal maintenance items like oil, brake pads and so on. It may seem as much but that is what has been done the 160k miles I have owned it! When you buy and own a high mileage car you’ll have to accept that things happen and be prepared to spend that money when it happens. But on the positive side I can honestly say that I wouldn’t be worried too much and remember that the true cost to own is much lower than many cars half the size, power and equipment!

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My three latest cars have been Cadillacs. A 1988 Eldorado, a 1993 STS and now my 2002 STS. There is a reason I drive them even when I have the option to drive a "luxury car" like a Volvo in the country that makes them. Before Cadillacs I drove Volvos and I since my first Cadillac I have never looked back! I also have a 2005 Jaguar Super V8 and shy of 90k miles it is crapping out on me BIG time. On my only 12k miles of ownership I have had to replace catalytic converters, mufflers, thermostat, coolant hose, wiper motor, SIR-sensor, park locking switch and still have a vibration from the drive line (probably a bad support bearing), and the rear suspension needs new bushings. I also have a strange electrical problem with the lights which cuts out in the dark when the automatic lighting system is on. That…thing is going as soon as I find someone willing to buy it.

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I agree that the cost of ownership for what they are is less than competitors.


GM FAN FOREVER

Nice, clean, luxury= fine automobile

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High RPMs aren't going to blow a headgasket.  If the headgasket is that weak, it's going to blow in short order regardless of the RPMs...LOL.

The most important thing is to keep the coolant changed.  5 years/100,000 miles for Dexcool and 2 years/24,000 miles for the green silicate coolant.  Keep in mind that only half of the coolant is able to be drained from these engines so unless you're flushing the system, a drain and refill is due yearly/12,000 miles for green coolant or 2-1/2 years with Dexcool.


Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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4 hours ago, KHE said:

High RPMs aren't going to blow a headgasket.  If the headgasket is that weak, it's going to blow in short order regardless of the RPMs...LOL.

The most important thing is to keep the coolant changed.  5 years/100,000 miles for Dexcool and 2 years/24,000 miles for the green silicate coolant.  Keep in mind that only half of the coolant is able to be drained from these engines so unless you're flushing the system, a drain and refill is due yearly/12,000 miles for green coolant or 2-1/2 years with Dexcool.

I totally agree! 

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