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Hello Everyone.. My sister is putting another motor in her 1998 Deville. It has the n* motor in it. The car is in great shape with only 67000 on it. I have read on here, but can't find it now, that some recommend changing some under the hood parts while the motor is out. Can anyone give me a list to give her. Thanks for all the input in advance.

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When the motor is out I've read it's a good time to replace the oil pan gasket.

Also the material on the firewall that gets brittle and cracks and breaks off would be easy to replace with the motor out.

That's what I've gathered from reading posts on the forum, I'm sure there's more that I'm forgetting and I'll let others chime in with suggestions.

WARNING: I'm a total car newbie, don't be surprised if I ask a stupid question! Just trying to learn.

Cheers!

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If it were me, I would change the following

pan gasket

ISS sensor (in side pan if tranny is out)

Pressure Solenoid (in side pan if tranny is out)

TCC Solenoid (in side pan if tranny is out)

Side pan seal (in side pan if tranny is out)

heater pipes

HVAC cover referred to above

torque converter seal

output shaft seals

inspect engine mounts

crossover seals while the engine it out

inspect oil pump for clearances

That list might be overkill, but while the engine is out

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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Good list.

I agree and it would eliminate the....

"I wish I had replaced (insert name of part here) while the engine was out of the car."

Which WILL most probably happen. :D At least it would to me. :D

Just my 2 cents.

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Thanks for all the great input. Sorry but I left some info out that might change your advice. The new motor going in is out of a 05 Deville with 42 k. The numbers match. Knowing this now,again sorry about that,would you still relace all that was listed?

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Thanks for all the great input. Sorry but I left some info out that might change your advice. The new motor going in is out of a 05 Deville with 42 k. The numbers match. Knowing this now,again sorry about that,would you still relace all that was listed?

Someone is in for a big surprise. There are so many differences between a '98 and a '05 engine that it might as well be a totally different engine altogether.

The short list of differences includes;

intake manifold and air control

integrated MAF and IAT sensors

ignition type

PCM calibration to accomodate internal differences and lower compression ratio

Not sure what "the numbers match" means in this case.

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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dang, sorry again. The numbers mean there is a "y" in the vin and the engine code is the same, LD8. Not totally stupid here but I though if those were the same, you could swap out the motors without a problem. Please help before my sister kills me. She hasn't purchased the motor yet. Should we stay closer to the year of the original?

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.... Should we stay closer to the year of the original?

Yes. It should be safe to limit the engine donor Deville to 1997 through 1999.

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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If the mechanic is COMPETENT it is best to Timesert the original block. Of corse, the key word here is "COMPETENT"... :rolleyes:

Ancil, I think that we can rule out "competent" if your mechanic thinks that an '05 Y engine would be a direct swap out for a '98 Y engine.

Possibly he is just ill informed.

I agree with MrEldo97 that the best course of action would be to "timesert" your existing engine.

Installing a used engine with an unknown maintenance history is asking for a repeat of the pulled head bolts, leaking head gasket problem that you now have.

If the engine is otherwise OK, then do the research and get it "timeserted".

If you must replace the engine, consider "timeserting" the replacement engine before you have it installed.

An addition to BBF's list would be to replace the lower crankcase seals.

These seals are notorious for seeping oil on the early Northstars.

The lower crankcase bolts directly to the cylinder block (upper crankcase) and holds the lower half of the main bearing shells.

The engine MUST be out of the car for the replacement of these seals.

The oil sump (pan) bolts to the lower crankcase.

When I changed the engine in my 94 SLS, I didn't replace those seals and regret it daily.

Take Care,

Britt

Britt
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Britt, when the case half seal is replaced, do the main bearings need replacing?

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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Britt, when the case half seal is replaced, do the main bearings need replacing?

BBF,

I have been told that it is not an absolute necessity, depending on their condition.

But, personally, I would change them.

Bearing shells are built with a "crush" which is a slight protrusion above "flush" when placed in their saddles. When the lower crankcase is assembled to the upper, the bearings in the upper crankcase and the opposing ones in the lower crankcase contact each other slightly before the case halves meet. This is where the term "crush" comes from. When the lower crankcase is torqued down, this "crush" seats the bearings firmly in their saddles.

It is my opinion that bearings, once assembled will lose some of the "crush" and be more prone to movement. Any movement can eventually lead to a "spun" bearing.

I want to emphasize that this is MY opinion. Even some aircraft engines allow bearings to be reused under certain situations.

Take Care,

Britt

Britt
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Britt, when the case half seal is replaced, do the main bearings need replacing?

BBF,

I have been told that it is not an absolute necessity, depending on their condition.

But, personally, I would change them.

Bearing shells are built with a "crush" which is a slight protrusion above "flush" when placed in their saddles. When the lower crankcase is assembled to the upper, the bearings in the upper crankcase and the opposing ones in the lower crankcase contact each other slightly before the case halves meet. This is where the term "crush" comes from. When the lower crankcase is torqued down, this "crush" seats the bearings firmly in their saddles.

It is my opinion that bearings, once assembled will lose some of the "crush" and be more prone to movement. Any movement can eventually lead to a "spun" bearing.

I want to emphasize that this is MY opinion. Even some aircraft engines allow bearings to be reused under certain situations.

Take Care,

Britt

Britt, I agree, and wanted you to elaborate on this issue. You know me, while I am there why not replace them. The CRUSH issue for me would be enough for me to replace them. (I'd replace the oil pump also while I was there, why not) Thanks

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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I agree with everything you fellows have said. I never opened a motor without replacing mains and rods because of the crush issue.

To be sure if the motor had a lot of miles then a complete rebuild was done...

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Why would timesert the new donor motor? or replace the case seals? After 2000 they took care of those issues.

He needs to use a 1999 and older engine, he can't use a newer engine

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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Why would timesert the new donor motor? or replace the case seals? After 2000 they took care of those issues.

First of all; not really, second of all since the motor is on the floor and and you (your sister) is planning on driving it for quite some time spend a little extra loot and cure future problems. All Northstars with mileage leak at the case half seals and many Northstars pull headbolts.

This is not the time to be C-H-E-A-P.

I'm not convinced an '05 motor will work in '97.

I'd cut down my chances of having these two problems a few years down the road...

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