Engine beauty cover

[mmarinov]

Greetings, all:

I'm just curious - someone told me that the '93-'94 N* had a metal intake beauty cover. I have a '94 and it is indeed plastic.

Specifically, he said: "I also wanted to let you know that this is NOT a cover from a 1993 (nor a 1994) Northstar. 1993 and 1994 had a metal cover, and the engine would actually not operate without that cover."

Could someone set me straight please??

Thanks!

Mark

[PAUL T]

I have a 94 Concours and I can tell you beyond a shadow of doubt the cover is metal. It is a part of the intake on the 93 & 94 and if the car is started up with the cover off it will run wide open. If yours is plastic someone has changed out the motor or intake. I do not know what year it became just a beauty cover, I am thinking maybe in 96. If someone changed out the motor they would also have to change out the computer and wiring.

[Ranger]

I do not know what year it became just a beauty cover,

1995.

The '93/'94 cover is an integral part of the intake. '95+ it is nothing more than a cover to make the engine look clean (and silence the injectors a bit). Does it only have 4 plastic acorn nuts holding it down? If so, I would agree with Paul, there was an engine or intake swap done.

[9000rpm]

I've noticed when searching information about parts and what not for the 1994 eldorado, there are two different engines, one is a code 9 and the other a code Y, both are 4.6L northstar engines. I haven't found out what the differences are or if they are mechanical or cosmetic, but after seeing this thread I think I figured it out, but which is which.

[Cadillac Jim]

The 1995-1999 model year engines have a plastic intake manifold and beauty cover. The beauty cover has a layer of foam under it, and serves a purpose too -- it keeps the very high under-hood temperatures from affecting the intake gas temperature any more than necessary.

So far as I can tell, the only difference between the VIN Y and VIN 9 engines from 1993-1999 are the intake cams. The long block has all the same parts, according to the FSM. I don't see any references to engine VIN in the air cleaner, throttle body, or exhaust. Someone with a parts manual may know of other differences.

Others will have data on the 2000+ engines; there were three, all with roller lifters and lower compression than the 1993-1999 engines: 300 hp, 320 hp, and 443/469 hp turbo. For some reason, they put a 6.0 litre in the CTS-V, probably for all-around world-class instant performance as a road racing prototype GT car.

[Ranger]

I've noticed when searching information about parts and what not for the 1994 eldorado, there are two different engines, one is a code 9 and the other a code Y, both are 4.6L northstar engines. I haven't found out what the differences are or if they are mechanical or cosmetic, but after seeing this thread I think I figured it out, but which is which.

VIN Y = 275 HP

VIN 9 = 300 HP

Difference is as Jim said, in the intake cams.

The beauty cover has a layer of foam under it, and serves a purpose too -- it keeps the very high under-hood temperatures from affecting the intake gas temperature any more than necessary.

Jim, where did you hear that from? I have never heard that before, It would seem that the cover would trap engine heat around the fuel rail if anything, not that I would think that would make much difference.

[9000rpm]

ah so thats what it is.

[mmarinov]

Jim, where did you hear that from? I have never heard that before, It would seem that the cover would trap engine heat around the fuel rail if anything, not that I would think that would make much difference.

Uhh...wow, guys.

Maybe my engine/intake was a swap after all. I am totally dumbfounded as I have found no evidence that this is anything other than the OEM engine. If it was swapped out it was done very well as all of the OBDC/computer functions work perfectly. Not to belabor the point, but how can I tell what I have (physically, not by VIN code as that is now invalid)?? Would pictures help? I have the cover with (12?) screws that was later updated to (4?) for removal. I can tell you for a fact that my Caddy is more powerful (well, it puts the driver into the seat more) than my '95 Impala SS which is (under)rated at 265 HP.

It's not often that I feel this dumbstruck. Good thing I haven't had to purchase many parts for the engine as I'm sure there would be some confusion eventually

This is the second car I've owned where I've been told the engine was one thing but was actually another. Thanks for straightening this out, all. I look forward to any responses I get in this thread.

Mark (or maybe it's really Mike or Fred). No. Definitely NOT Fred.

[PAUL T]

My guess is that it is a 95 engine or intake. In 1996 the cars became OBDII. Are your codes OBDI or OBDII? Give us an example of your codes. I think there were big changes in 1996 Northstars.

[Ranger]

Picture might help, but if there are only 4 acorn nuts, it is definitely not '94. The question is, was just the intake switched or the entire engine? '96 went to OBDII so it would have to be a '95 intake or engine most likely.

[Cadillac Jim]

mmarinov -- you can tell the 1993-1994 Northstar from the 1995-1999 Northstar by the EGR. The early Northstar had an internal EGR and the later Northstars all have external EGRs. Uh, now that I think about it, the EGR would have to be changed with the intake manifold.

Ranger -- I didn't read about the heat insulation function of the beauty cover. It's my opinion. Everyone is perfectly entitled to disagree with me.

My logic is that the intake air is at ambient. Typical June ambient in the Northern hemisphere is 20 C, while typical underhood temperature is more like 75 C for city driving, higher for stop-and-go. This 20 C air is fed to the intake manifold and is further cooled by expansion due to vaccum as it passes the throttle butterfly and by evaporation from the fuel as it passes into the ports. Heat passes into the manifold from the heads, "lifter valley" under the manifold, and through the top of the manifold through the beauty cover. All these paths are designed to minimize heat transfer in the 1994-1999 Northstar.

Another heat path is from underhood heat to the fuel lines. Fuel lines are routed to minimize exposure to heat. From the intake manifold, they are routed high on the firewall and down the left side of the car as far away from the engine, and particularly the exhaust system, as possible. The EVAP canister is at the rear of the car away from the exhaust system.

A point to note is that the intake manifold accounts for all of the 5 hp increase from the 1993-1994 and 1995-1999 Northstars. This is likely due at least in part to providing cooler engine charge. Compare the 1993-1994 metal intake manifold with integral top cover, with essentially no protection from engine heat from the engine compartment or the "lifter valley." I haven't seen the gaskets to the ports on the 1993-1994 Northstar.

As far as I know, the intake manifold assembly is interchangeable between the 1993-1994 and 1995-1999 Northstars. I don't know about the fuel injectors. If not, I suspect that the 1995-1999 fuel injectors are compatible with the 1993-1994 PCM. The true test of compatibility is doing the swap. Anyone?

Of course, the best case is someone with AP-22, G-Tech Pro, or diagnometer who has done the check and has before-and-after runs to compare the numbers.

[mmarinov]

My guess is that it is a 95 engine or intake. In 1996 the cars became OBDII. Are your codes OBDI or OBDII? Give us an example of your codes. I think there were big changes in 1996 Northstars.

Thanks, Paul and Ranger (Jim for pointing out the external EGR). My codes are similar to: P036, S044, etc. Here are photos from this evening:

Thanks for your input, all:

Mark

[acklac7]

That's not a 95' cover....Well I should say that it doesn't look anything like my 95' cover. My cover has 4 acorn nuts that fit into cavities on on the cover.

Your cover has these cavities, but also has 9 addtional rubber grommets that I DEFINITELY don't have! And that black bracket looking "thing" on the drivers side of the Engine...Yeah, I don't have one of those either!

However you do have an external EGR, so I guess you either have a 96+ N*...Or, for some reason, there were 2 distinctly different covers for the 95' model year. Maybe the ETC/STS (VIN 9) has a different cover?....If so im jealous!

[Cadillac Jim]

The front plug wires go around the front (driver's side) of the engine, not under the beauty cover like my 1997 ETC. The VIN number checks out as a 1994 ETC. I see eight cap nuts on the beauty cover. it looks like the PCV valve is right by the oil filler cap, but it's on the other cam cover on my 1997, back by the firewall. I couldn't make out the EGR valve in the front view of the engine.

The code showing is

P036 (E036) ................................. EGR Valve Pintle Position Out of Range

and that is probably why the Check Engine light is on. At 107,019 miles, it's time to clean out the EGR valve. The EGR passages may also need cleaning; they are in the heads and can be cleaned by removing the intake manifold; that's a touchy job because there's lots of crusty stuff you don't want getting into the exposed intake ports.

Are you sure that the cover is plastic? It looks like a 1994 Northstar to me.

[PAUL T]

It sure looks like a 94 cover to me. Your codes are OBDI. Are you sure that the cover is not metal? Do a scratch test in a place that is not noticable on the gray area. The emblem is plastic but the cover should be metal.

Does your outside temperature sensor work? I noticed it hanging down in front of the radiator or is it made that way for a ETC.

[clarkz71]

Here's my 95.

[Dusty95]

That's what my '95 looks like too ^

Also on the beauty cover, I also believe its acting more as a thermo blanket as it is a cooling agent. Beauty cover- as it name implies- is just there to make the engine look cleaner/better. I'd think its making our intake charge and engine a few degrees warmer than if we had it off.

I was half tempted on keeping it removed last time I had it off. Those plastic nuts are starting to not work like they did 150,000 miles ago.

[JasonA]

That's weird. Except for the 8 nuts instead of 4, that looks exactly like my '97 cover. What are the four "empty" holes in the middle? Those are in the exact location of the holes of the 95+ plastic beauty cover. It almost looks to me like someone bolted a plastic cover to the top of a '94 engine.

[Ranger]

While I am not intimately familiar with the '93/'94, that does not look like my '97 did. The perimeter bolts are a give away. I suspect that is a '94, but I, like Jason, wondered about the holes.

It definitely has a plainly visible EGR valve. I do not recall ever hearing of an internal EGR. Perhaps Jim meant the EGR (mouse hole) passages inside the intake.

[clarkz71]

I have the 93 FSM. The EGR valve is in the same place as the later models. Looks the same in the book although the part # is different. The way the ignition wires are run, I'd say its a 94, but we'd know for sure if he pulls the cover and takes a pic. And the 4 holes where the later covers have the acorn nuts are access holes for the main intake bolts.

[Cadillac Jim]

The 1997 FSM doesn't call it a "beauty cover." It uses "sight cover" in the early pages and "sight shield." in later pages.

The hose that enters the left cam cover near the oil filler tube is an PCV feed tube, where breather air comes into the engine. It goes to the throttle body on the MAF sensor side of the throttle body. The PCV valve is on the right (rear) cam cover and controls air to the throttle body on the engine side of the throttle body. I thought that the front hose on the 1994 photo was the PCV valve hose; I was mistaken.

[GreenMachine]

I think everyone has a differant name for it The dealers I talked to call it an "acoustic cover". Clarks picture is the same as my 98's cover.

[Dusty95]

The dealers I talked to call it an "acoustic cover".

[JasonA]

I've actually had mine for a while. The slight burning smell that was apparently my fan motor I thought could have been some of the old foam on the underside of that cover hanging down and getting cinged. Anyway, the only real difference I notice is a slightly louder intake growl at full song, which isn't a bad thing in my book anyway.

[PAUL T]

That's weird. Except for the 8 nuts instead of 4, that looks exactly like my '97 cover. What are the four "empty" holes in the middle? Those are in the exact location of the holes of the 95+ plastic beauty cover. It almost looks to me like someone bolted a plastic cover to the top of a '94 engine.

The 4 "empty" holes in the center are the 4 long bolts that hold the intake down on top of the phenolic plates. There are 12 bolts that hold the cover down, the 8 that you see and 2 on each end, if you look closer. I would bet that the cover is metal, it looks like plastic but if you scratch the gray part you will find it is silver metal shining under the paint.