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1993 STS Head gasket or something else, hopefully???


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Also I noticed a couple of the vacuum fittings were really "rotten" one of them was falling apart on a little deal that seemed to be an electrically controlled "vacuum valve relay" just behind the air intake butterfly in fact one of the lines lead to the rubber boot that wraps around the butterfly. I patched it with little pieces of rubber hose but noticed no apparent vacuum leak. Have no idea what this thing does.

This sounds like the EVAP harness. Its a tangle of plastic vacuum lines that includes the EVAP solenoid that's attached to the rear valve cover. Does it include the triangular rubber vacuum port that goes into the top of the throttle body? If so, that's it.

The complete EVAP harness, including the solenoid, is available from the dealer.

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I've never cleaned it or the "mouse holes" or the throttle body.....does anyone happen to have a photo of these "mouse holes" and a location?

The mouseholes are the EGR passages and they're cast into the heads under the "feet" of the intake manifold. To really get to them for cleaning, you have to remove the intake. You'll notice the passages when you get in there. Mine were about half blocked by carbon buildup at 98K miles a couple of months ago. The EGR valve is mounted on the crossover right next to the throttle body / throttle linkage.

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Try lifting the fuel rail, turn the key on to pressurize it and see if any injectors leak (don't turn the key to start, just to on).

I wish there was a way to do this on a 93, but with everything being inside the manifold and covered by the gasket that integral to the fuel rail, its hard to see whats going on.

If you pressurize the fuel system by turning on the key, be ready for injectors to blow-off of the fuel rail. The clamping force applied by the cover is what holds the injectors and fuel rail in place.

Visual diagnosis of injector problems is alot easier on the 95-up models where they took all of the fuel outside of the intake manifold.

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Try running the engine with the beauty cover off

You can't do this on a 93. The "beauty cover" the top of the intake manifold. Never start it with the top off.

True, and I know that... Someone smack me... I need to buy a mint 94 so I can learn about it...

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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Try lifting the fuel rail, turn the key on to pressurize it and see if any injectors leak (don't turn the key to start, just to on).

I wish there was a way to do this on a 93, but with everything being inside the manifold and covered by the gasket that integral to the fuel rail, its hard to see whats going on.

If you pressurize the fuel system by turning on the key, be ready for injectors to blow-off of the fuel rail. The clamping force applied by the cover is what holds the injectors and fuel rail in place.

Visual diagnosis of injector problems is alot easier on the 95-up models where they took all of the fuel outside of the intake manifold.

The 93 - 94 are somewhat foreign to me, that is why I said this above "Your engine it too different from mine for me to be able to help you in detail. We have users that are familiar with the 93 and 94. I need to buy a manual for that vintage NS, so that I can learn more about them".

Thanks for chiming in here Jack and TDK, keep an eye on this thread if you would.

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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The 93 - 94 are somewhat foreign to me, that is why I said this above "Your engine it too different from mine for me to be able to help you in detail. We have users that are familiar with the 93 and 94. I need to buy a manual for that vintage NS, so that I can learn more about them".

Thanks for chiming in here Jack and TDK, keep an eye on this thread if you would.

Understood. Will do......

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It seems all your questions have been answered except for the manual. Get a FSM (Factory Service Manual) by Helm Inc. Forget Haynes or Chiltons. Ebay is your friend.

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ok. this got my attention and my curiosity is overflowing.

can someone enlighten me on the where the highlighted information came from, regarding both issues .. ?

1) impregnation and 2) arching and mis-fires

I'll update after I change plug wires and thermostat (if I can find it). These engines run great but I must say they are a little different animal...thanks

Good observation. You need to throw away everything you know from cast iron engines. I had to relearn everything. Go to www.helpinc.com or ebay to find the FSM (factory service manual), you can not work on this engine without it. I am in the process of doing two big jobs right now and it has saved me a bunch of times..

By the way, if you buy the

OEM wires (ac delco) they are impregnated with dialectic (? spelling) grease, using additional grease can create arching and mis-fires.

Mike

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See this thread,

http://caddyinfo.ipbhost.com/index.php?sho...;hl=impregnated

this clip is out of the factory service manual:

Dielectricgrease.jpg

Its amazing how the old habits die hard, there is a lot to relearn. Here is another oddity, don't smoke while you are doing the plugs, the coating can cause flu like symptoms for smokers

Spark Plug Removal Procedure

Notice

Twist the spark plug boot one-half turn in order to release the boot. Pull on the spark plug boot only. Do not pull on the spark plug wire or the wire could be damaged.

Remove the spark plug wires from the spark plug.

Caution

Wash your hands after handling coated spark plugs and before smoking. The coating is a non-hazardous material and incidental contact will not cause any adverse effects. However, exposure to polymer vapors - the result of contamination of cigarette products and subsequent burning of the polymer - may result in flu-like symptoms and should be avoided.

Important

Do not remove spark plugs when the engine is warm. Clean dirt and debris from the spark plug recess area.

Remove the spark plug from the cylinder head.

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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this is new to me. it does change things as even non-OEM may have

be pre-greased.

thanks

See this thread,

http://caddyinfo.ipbhost.com/index.php?sho...;hl=impregnated

this clip is out of the factory service manual:

Dielectricgrease.jpg

Its amazing how the old habits die hard, there is a lot to relearn. Here is another oddity, don't smoke while you are doing the plugs, the coating can cause flu like symptoms for smokers

Spark Plug Removal Procedure

Notice

Twist the spark plug boot one-half turn in order to release the boot. Pull on the spark plug boot only. Do not pull on the spark plug wire or the wire could be damaged.

Remove the spark plug wires from the spark plug.

Caution

Wash your hands after handling coated spark plugs and before smoking. The coating is a non-hazardous material and incidental contact will not cause any adverse effects. However, exposure to polymer vapors - the result of contamination of cigarette products and subsequent burning of the polymer - may result in flu-like symptoms and should be avoided.

Important

Do not remove spark plugs when the engine is warm. Clean dirt and debris from the spark plug recess area.

Remove the spark plug from the cylinder head.

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