: Head gasket blown? Help!



SplitSlim
11-17-04, 05:20 PM
Hi,

I just returned from the dealership for a full diagnosis and injector flush. My 93 STS N* was idling a little rough, and stalling at times during idle. While at the shop, the mechanic saw a small puddle of oil on the power steering pump side, underneath where the head connects to the block. He is now telling me that the gasket needs to be replaced.

Here is my question. My car does not overheat, the highest the temp has ever been is 106. I am wrong in thinking if the head gasket was blown, the leak would be coolant and not a puddle of oil, the size of a couple of quarters? The oil level is constant, and does not seem to fall drastically. From this information do you think I need to replace my head gasket? He did not do a compression test (funny thing is, before seeing the puddle he said he did not have to, he could "see and feel" that the compression was fine).

Any help would be greatly appreciated

Thanks,

SS

No More Cadillac's
11-17-04, 06:32 PM
I would get a second opinion. When my head gasket blew there was no oil leakage, rather the primary indication was water in the exhaust. There are several threads herein that suggest ways to check for a blown head gasket.

BeelzeBob
11-17-04, 08:59 PM
Hi,

I just returned from the dealership for a full diagnosis and injector flush. My 93 STS N* was idling a little rough, and stalling at times during idle. While at the shop, the mechanic saw a small puddle of oil on the power steering pump side, underneath where the head connects to the block. He is now telling me that the gasket needs to be replaced.

Here is my question. My car does not overheat, the highest the temp has ever been is 106. I am wrong in thinking if the head gasket was blown, the leak would be coolant and not a puddle of oil, the size of a couple of quarters? The oil level is constant, and does not seem to fall drastically. From this information do you think I need to replace my head gasket? He did not do a compression test (funny thing is, before seeing the puddle he said he did not have to, he could "see and feel" that the compression was fine).

Any help would be greatly appreciated

Thanks,

SS



Now let's see....this is a 12 year old car with 180,000 km on it. Any you are worried about a tiny bit of oil in the valley....???

Drive it and forget about it.

Keep fresh coolant in the engine and use the coolant supplement.

I hate to break it to you but this car has a lot of miles and time on it...It is not a new car. It is a used car. That is why you didn't pay much for it. You can expect to see some leaks and oil puddles and things like that with a 12 year old car. If you are expecting perfection I would get in the market for a newer car.

Not trying to be mean, just realistic.

If the puddle of oil in the valley is engine oil.....so what? It could be a little bit of oil seeping from the head gasket interface at the front as there are oil passages from the block to the head for the overhead oil feed near the area you describe. So what...?? If oil was running out the back of the block or there was a lake under there it would be one thing. A little bit of oil is nothing to get upset over in my opinion. If the head gasket ever starts to leak oil badly or the engine starts to overheat due to a head gasket then have it replaced then. Until then, forget about it and drive the car. It would be insane to take the heads off for the problem you describe. Absolutely insane. Replace the head gasket if the oil puddle in the valley turns to a river or the engine starts to consume coolant faster than you can pour it in...until then drive it and forget about it.

Too many people buy an old car and expect it to be a new car or treat the experience as what a new car (Cadillac in this case...) would be like. It isn't. That car has been rode hard and put away wet for all you know. The fact that it still runs pretty good and is reasonably clean and solid is a testament to the quality of the vehicle originally.

You happened to buy a Northstar that is of the most vulnerable vintage due to the original factory coolant fill of the green silicated coolant. The 93/94/95 engines needed to have the coolant changed frequently to keep the corrosion inhibitors from becoming depleted. Depleted corrosion inhibitors allow internal corrosion that ultimately leads to cracked heads or failed head gaskets. If it happens it happens. Fix it then. Until then, keep the coolant fresh and forget about it.


See the post on "Paranoid effects of the forum" on the caddyinfo forum.....LOL

growe3
11-18-04, 12:45 PM
The temperature of 106 C (223 F) is normal. A little oil seepage is not a big deal, it is however a real money maker for the dealer to call them to your attention for repair. If the head gaskets are seeping oil, it could mean that a head gasket failure is in the future, but I wouldn't worry about it until you start losing coolant and overheating. It could be a long time away.

SPARK PLUGS
You have enough miles on the engine to likely need to replace the spark plugs. This is a simple straight forward job.

Use dual platinum, AC Delco or Champion spark plugs. The dual platinum style is important, due to how the Northstar fires its plugs. Other plugs styles are not recommended.

Using a 1/2" drive ratchet will make it easy to break the spark plugs loose. Use a 3/8" ratchet drive to install, to avoid over tightening.

The rear plugs are a little close but not that bad to get at. Just use an extension with a flex joint.

Some people like to remove the coil pack (4 connections and 4 bolts), to access the rear spark plugs, but I do not feel it is necessary.

Wipe out any moisture that may be in the spark plug tubes!

Before putting the spark plugs in, verify that they are gapped at .050"!

When reconnecting the spark plug boots, be sure each one is fully pressed on, and snaps to the spark plug!

The spark plug wire ends that connect to the coils can get corroded. If so just use a small brass parts brush to clean, them until they are bright metal.

THROTTLE BODY CLEANING
Spraying out the throttle body would also be a good idea.

Loosen the upper strut bolt and remove the lower strut bolt, swing out of the way of the air filter box.

Remove the air filter and intake tube, run the engine and spray into the throttle body taking care to keep from killing the engine. After a few sprays this way, stop the engine and carefully hold the throttle plate open and finish spraying to remove the oil deposits from around the plate and shaft area. Use a soft tooth brush if necessary to help.

Start the car and allow to clear from the excess vapors. Replace the air filter, if needed, then reinstall the intake tube and air filter box. Swing strut back in place, thread bolt in lower strut connection, then tighten both ends securely.

EGR VALVE
The EGR Valve most likely needs cleaning. It is very good design and the valve itself is probably fine, just sticky. The phenolic plates under the intake manifold are probably plugged.

Do a site search for more information on how to clean the spacers. If you need more information on this send me an e-mail, I can elaborate on this cleaning.

-George

SplitSlim
11-19-04, 11:08 AM
UPDATE!

Good news. My intake manifold gasket was leaking a fuel/oil combination. The dealer had the valley visibile, and the intake off. You could clearly see that gunk was built up in the intake channels and this caused the gaskets to fail and leak slightly into the left half of the valley. Upon closer inspection of the headgaskets, they look flawless. This, I guess, would also explain my rough idling.

The dealer will clean the intake channels, replace the gaskets and off I go. Thanks again for your advice and suggestions.

Relieved,
SS

growe3
11-20-04, 10:42 AM
UPDATE!

Good news. My intake manifold gasket was leaking a fuel/oil combination. The dealer had the valley visibile, and the intake off. You could clearly see that gunk was built up in the intake channels and this caused the gaskets to fail and leak slightly into the left half of the valley. Upon closer inspection of the headgaskets, they look flawless. This, I guess, would also explain my rough idling.

The dealer will clean the intake channels, replace the gaskets and off I go. Thanks again for your advice and suggestions.

Relieved,
SS

Great! Those "intake channels" under the intake manifold are the phenolic spacers and the accompanying "mouse holes", you will hear them mentioned occasionally, that need cleaning when servicing the EGR valve.

-George

SplitSlim
11-23-04, 08:27 PM
Well the stalling is back and here's some more info.

Ok, I'm learning more and more here

I've run some diagnostics on the car via the PCM Overrides and also found out that P095 creates a PCM Snapshot automatically. Here are the numbers from the snapshot

PD01 (ED01) TPS (Throttle Position Sensor) in degrees - 3.3
PD02 (ED02) Manifold Absolute Pressure Sensor in Kilo Pascals (kPa) - 92
PD03 (ED03) Barometric Pressure in kPa - 101
PD04 (ED04) Engine Coolant Temperature (ECT) sensor in degrees Celsius - 103
PD05 (ED05) Intake Air Temperature (IAT) sensor in degrees Celsius - 39
PD07 (ED07) EGR Pintle Position - 42
PD08 (ED08) Spark Advance in degrees Before Top Dead Center (BTDC) - 7
PD09 (ED09) Ignition Ground Voltage - 2.437
PD10 (ED10) Fuel Pump Feedback Voltage (battery voltage) - Not Shown
PD11 (ED11) Engine Speed in revolutions per minute (rpm) - 0
PD12 (ED12) Vehicle Speed in miles per hour (mph) - 0
PD13 (ED13) Pintle Position - 0

Can someone please decipher these numbers?

Also, in the service manual I ran a diagnostic for the code P095, and it's saying if my snapshot parameter for PD02 is less then or equal to 95Kpa, to refer to a section on Hesitation , sag and stumble. I am doing this now.

Another diagnostic I ran was the Exhaust Gas Recirculation System Check. In this test you shut the engine off when the coolant is greater then 90 degrees celsius, override the EGR to 0 ( in PCM overrides), then note the EGR pintle position (PCM Data PD07). In my case it was 41. If less then 103, it says to override the EGR to 99, then check PD07 again. In my case it was 214. At this point you turn the engine on, note the rear bank block learn value (PD39), in my case 118, then slowly start increasing the EGR override to 30% while making sure the engine keeps running. At EGR of 30, I checked my PD39 again after 60 seconds, and it was at 98. You subtract the two values, and if you have a difference of greater then 10, the EGR system has no fault. A difference of 10 or less means there is a fault in the EGR system.

So next steps and any help?

Thanks,

SS