: Is this head gasket, or ? ? ?



norway548
12-31-04, 10:48 PM
just bought my first caddy- 93 sts, with 212 big ones on the odometer.
test drove it thru the city for about 45 minutes last night, rode and drove like new, watched the temp on the message board the whole time, stayed around 200-214 got up to 221 once in rush hour. OK so Im thinking this car has been pampered or totally gone thru - SOLD. come back this morning. paid for it, hopped on the freeway, made it about 30 mins running about 75 with the cruise on, then almost on cue, " STOP MOTOR - ENGINE OVERHEATED " and of course it was, parked it , come back to load it on the trailer and it starts and runs fine like it was never hot. FRUSTRATING. Id appreciate any input you have. or if youd like the newest looking pearl white 93 sts in existence (no joke, Im a wholesaler and I usually never touch these things at any miles, but this car is truly gorgeous, see what happens when you fall in love. :disappoin ) let me know.

Spyder
12-31-04, 11:24 PM
search through this forum for the telltale signs...I don't remember exactly what they were, but the one I do remember is to watch for bubbles in the coolant surge tank upon startup...tons and tons of info on here, use the search button and you'll likely find your answer! Hopefully its good news...

mcowden
01-01-05, 05:27 PM
That depends. Why did it overheat? Is the coolant level low? If not, look for a pump, thermostat, or plugged/collapsed hose. If so, where did it go? Is there a pinhole leak in a hose? Is there coolant dripping off the oil pan or running down the block? Is it coming out of the radiator or the water pump housing? What does the engine oil look like? Is it normal color, or slightly milky-looking? How does it smell? Is there an oil slick on top of the coolant? Bubbles coming up through the coolant when it's cold and running?

If any signs are pointing toward head gasket, get the compression test done (pressurized cylinders) and go with those results.

Good luck...

M C
:cheers:

BeelzeBob
01-01-05, 10:31 PM
just bought my first caddy- 93 sts, with 212 big ones on the odometer.
test drove it thru the city for about 45 minutes last night, rode and drove like new, watched the temp on the message board the whole time, stayed around 200-214 got up to 221 once in rush hour. OK so Im thinking this car has been pampered or totally gone thru - SOLD. come back this morning. paid for it, hopped on the freeway, made it about 30 mins running about 75 with the cruise on, then almost on cue, " STOP MOTOR - ENGINE OVERHEATED " and of course it was, parked it , come back to load it on the trailer and it starts and runs fine like it was never hot. FRUSTRATING. Id appreciate any input you have. or if youd like the newest looking pearl white 93 sts in existence (no joke, Im a wholesaler and I usually never touch these things at any miles, but this car is truly gorgeous, see what happens when you fall in love. :disappoin ) let me know.


Well, there are several things that will make the engine overheat...not just a head gasket.

Is it full of coolant..?? Is the level in the surge tank about 1.5 inches from the cap when cold??

What is the condition of the water pump drive belt/pulley/tensioner?? The water pump is at the rear of the engine and is driven by a separate belt drive from a pulley on the right hand intake camshaft. If the belt is failing or the spring loaded tensioner is stuck/corroded in place the belt may be slipping severely at higher speeds causing the overheat.

Did you check the coolant concentration. If the system is not filled with fresh 50/50 coolant/water it can boil prematurely.

If the wrong thermostat (or no thermostat) has been installed in the engine it will not cool correctly.

A plugged radiator can also restrict cooling at higher speeds.

With that many miles on the engine it could be in great shape inside if it was maintained correctly or it could be in serious trouble from internal corrosion if the coolant was not changed frequently (every 24-32K miles/2-3 years) as was required on the 93/94/95 Northstars. The all aluminum engines will suffer severe damage internally to head gaskets and cylinder heads due to corrosion if the coolant is not changed and the corrosion inhibitors replenished frequently..... The 93/94/95 engines had the green conventional silicated coolant in them that required frequent refreshing. From 96 on the systems were filled with the long life DexCool that does not require the frequent maintenance.

Search the archives using the search feature. Try "coolant" "overheating" "coolant supplement" "head gasket" etc...as there is much info in the archives to reference.

SHERIFF
01-02-05, 12:43 PM
......... coolant was not changed frequently (every 24-32K miles/2-3 years). The all aluminum engines will suffer severe damage internally to head gaskets and cylinder heads due to corrosion if the coolant is not changed and the corrosion inhibitors replenished frequently.....


WoW! I didn't realize it was necessary that often! My DTS just turned 30,000 miles. Probably something I should consider doing pretty soon!

The little supplement tablets, and the discussions about puttting them in one of the radiator hoses....... one thing that has always puzzled me..... why can't they simply be dropped in the radiator cap?

BeelzeBob
01-02-05, 01:12 PM
WoW! I didn't realize it was necessary that often! My DTS just turned 30,000 miles. Probably something I should consider doing pretty soon!

The little supplement tablets, and the discussions about puttting them in one of the radiator hoses....... one thing that has always puzzled me..... why can't they simply be dropped in the radiator cap?


I think your DTS is a 2001...??? You don't need to change the coolant as often.

The 93-95 Northstars were factory filled with the conventional, green silicated coolants that required the system be refreshed every 2-3 years/24-32 miles to keep the silicate level high enough for adequate corrosion protection. In 1996 the coolant was switched to the DexCool longlife coolant that uses a completely different corrosion protection mechanism. The DexCool is good for 5 years/100K easily.

Your DTS has the DexCool (orange) coolant which is the long life variety that seldom needs changing.

There is no "radiator cap" on the radiator of a Northstar cooling system. The pressure cap is on the pressurized surge tank. You should never put the coolant supplement pellets into the pressurized surge tank since they will not get distibuted thru the system. The surge tank is, by design, an area of the system with very low flow so the coolant supplement particles will not get adequately dispersed thru the system if the pellets are just dumped in there. Always install them in one of the radiator hoses on a Northstar.

On a 4.1/4.5/4.9 engine the coolant supplement pellets can (and should) be installed at the radiator cap as the cap is on the radiator and there is no pressurized surge tank.

SHERIFF
01-02-05, 02:13 PM
I think your DTS is a 2001...??? You don't need to change the coolant as often. The DexCool is good for 5 years/100K easily.
Your DTS has the DexCool (orange) coolant which is the long life variety that seldom needs changing. There is no "radiator cap" on the radiator of a Northstar cooling system.


Ahh, once again, thanks! I forgot I have the orange Dexcool. And I have never noticed it doesn't have a radiator cap, learned something else new today! Never really had a reason to look for it yet though. :)

The Northstar is a pretty interesting engine. In design, and in discussions as well. Some of the Crown Victoria guys think it's pure unadulterated General Motors junk. They swear by the 4.6 modular Ford engine as if it's God's gift to America. :D

norway548
01-02-05, 06:09 PM
well, after starting the car again, it sounds horrible, so now my question is how many hours are involved in swapping one N* engine for another ? ?

BeelzeBob
01-03-05, 09:54 PM
well, after starting the car again, it sounds horrible, so now my question is how many hours are involved in swapping one N* engine for another ? ?


Uh...why don't you figure out what is wrong with it first....???

Grab a cooling sytem pressure tester and pump up the system to 15 PSI and let it sit. Pull the plugs in the mean time. Spin the engine over with the plugs out after the system sits for several hours pressurized and watch the spark plug ports for any sign of coolant. That would be a sure sign of head gaskets leaking....

No reason for it to "sound horrible" from overheating or anything like that. The engine control system has a very effective limp home protection system that automatically kicks in and disables cylinders alternately to keep the engine cool enough to avoid damage. So...even if it was overheated severely the engine should basically be OK.

The only obvious connection between overheating/coolant loss/noise would be a head gasket failure that allowed coolant to leak into the cylinders when shut down and then hydrostatcially locked the engine bending a rod on the next start up....but that is pretty unusual...possible but unusual.

Dooman
01-04-05, 12:12 PM
Bbob, When my waterpump failed at 125k miles, my engine went in to the "limp home" mode. It very soon, within one mile, went to "stop engine" mode and I kept going, beleiving I had a fighting chance to make the one mile left to my house. Coolant was gushing out at this point and I used lake water to refill the overflow bottle, with less than 1/2 mile left. After the waterpump replacement,I found out the headgasket was no good. I am assuming this was caused by the overheat because there were no other signs of gasket failure to this point. I have heard you say this engine is protected and I was wondering how it let me keep going to failure? Is there something here anyone else should learn as it is too late for me?

SHERIFF
01-04-05, 01:39 PM
I have heard you say this engine is protected and I was wondering how it let me keep going to failure? Is there something here anyone else should learn as it is too late for me?

I certainly learned something..... turn the engine off when the "STOP ENGINE" warning light tells me to do so. I don't want a nightmare similar to yours.

I have thought about this limp mode thing quite a few times. Even if my limp mode warning comes on, I am stopping the engine and have it towed. A $35 to $75 tow bill is much cheaper than the head gasket repair, IMHO.

BeelzeBob
01-04-05, 03:27 PM
Bbob, When my waterpump failed at 125k miles, my engine went in to the "limp home" mode. It very soon, within one mile, went to "stop engine" mode and I kept going, beleiving I had a fighting chance to make the one mile left to my house. Coolant was gushing out at this point and I used lake water to refill the overflow bottle, with less than 1/2 mile left. After the waterpump replacement,I found out the headgasket was no good. I am assuming this was caused by the overheat because there were no other signs of gasket failure to this point. I have heard you say this engine is protected and I was wondering how it let me keep going to failure? Is there something here anyone else should learn as it is too late for me?


Your engine had 125K on it and it overheated and had coolant gushing out and you kept driving it....????.....it doesn't owe you a dime for doing that. When you say you had a "fighting chance" to make it home....you did...you made it home....LOL....no one promised the engine would be perfect...just that you would make it home....

The engine is protected with the limp home mode which turns off alternate cylinders to internally cool the engine in the event of loss of coolant and a severe overheat....but....there are limits to what it can do. With the many miles on the motor with the engine already subjected to several thousand thermal cycles and unknown corrosion or whatever...who knows. The fact that you made it home at all driving it with it severely overheated is a testimony to the fact that the limp home mode worked and extended your driving range in an emergency. It is an emergency item...not a convenience. And it carries no guarantee of "no engine damage no matter what you do". Especially with a high mileage engine.


I do not know if the head gasket failure was due to the severe overheat or not. undoubtably the engine's head gasket was compromised to some extent at those miles and years and the overheat may have just finished off what would have taken another 20K....or had already happened and was really your problem..not the water pump. Water pumps on the Northstar do not cause overheating. As long as that pulley was turning the impeller was turning and pumping. Water pumps will seize up and break the belt and make hidious noises and leak....but they never cause overheating. If it overeheated originally there was another , underlying reason.

Besides the overheating, you may have damaged the engine/headgasket when you poured lake water in it. Pouring relatively cold water into a severely overheating and dry engine (after the coolant gushed out) can damage it severely due to the heavy thermal shock of the cold water touching the hot metal inside the engine. That is why it is important to always allow an overheated engine to cool off before refilling with coolant or lake water and even then , keep the engine running so the cold add water can intermix with the flow of the hot coolant and pour the cold add water slowly so as to minimize the thermal shock to the aluminum parts and the gaskets.


More on this at http://www.cadillacforums.com/forums/showthread.php?p=220582#post220582

oldgamer
01-06-05, 11:08 AM
just bought my first caddy- 93 sts, with 212 big ones on the odometer.
test drove it thru the city for about 45 minutes last night, rode and drove like new, watched the temp on the message board the whole time, stayed around 200-214 got up to 221 once in rush hour. OK so Im thinking this car has been pampered or totally gone thru - SOLD. come back this morning. paid for it, hopped on the freeway, made it about 30 mins running about 75 with the cruise on, then almost on cue, " STOP MOTOR - ENGINE OVERHEATED " and of course it was, parked it , come back to load it on the trailer and it starts and runs fine like it was never hot. FRUSTRATING. Id appreciate any input you have. or if youd like the newest looking pearl white 93 sts in existence (no joke, Im a wholesaler and I usually never touch these things at any miles, but this car is truly gorgeous, see what happens when you fall in love. :disappoin ) let me know.

Are you sure that engine was really overheated? I have had a problem with this message coming out and engine wasn't overheated actually.
What do you mean "after starting the car again, it sounds horrible"? Limp mode?
Give some more info, may be problem is not so bad.