QuestionGood afternoon Ben,
Is this Ben??? During my last Email I asked if we need to change the transmission keeping the 4.5 units together of course putting all in place of the 91 Seville 4.9?
I have checked out your sites & with the cost of a rebuild it is beyond the cars value. How about this, can the COMPUTER be 4.9 COMPUTER be reprogrammed to use with the 4.5 so that all the wiring does not need to be changed? If so, do you know of a company that can do this?
Sincerely, JLG@rocket7designinc.com
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Good evening & Merry Christmas as the hour is now after midnight. Thank you for you prompt reply. May I ask your name? Also, do you know of any remanufactured 4.9 or a used in good condition? Finally, do we need to switch transmission keeping the 4.5 together engine & tansmission?Sincerely, Jeff, jlg@rocket7designinc.com
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Good afternoon & Thank you for your first reply. Great news that we can move forward with my 91 Sedan Seville with this change over from the 4.9l to a 4.5l out of a 88 Sedan Deville. I had asked the following in my first set of questions. Is the wiring different or just the computer. I was told third hand that even the bulk head was different & ready one of your articles each & every wire needs to be traced? Is this the case & can we assume any of the wiring is the same, ie. all except the one going to the engine? Please explain? A thought I had was what about trying to find a 90 seville computer & wiring harness that used a 4.5 or are they different from the 4.5 in the above reference vehicle? Finally, I have intakes from two 4.9l, heads, etc, are they the same? Could the motor be changed over or are you better off to leave the 4.5 as is? Should we put the 4.5 transmission in the 91 Sedan Deville? Are all the hook-ups the same?
Sincere Thanks for helping us out, JLG@Rocket7Designinc.com
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Good evening, I have a 88 Cadillac Sedan Deville with a replaced motor about 35k on it, runs good. However, this car had a tree fall on the trunk lid so it is a savage title. My 91 Seville 4.9l was taken out & tried to put in a savage yard engine only to find water coming out of one of the spark plug hole, we believe it may have taken water in the intake & may have frozen. So I am now really in need to move forward & unlike most wanting to put the 4.5l in place of the 4.9l. I realize that the wiring may be diferent & need to know if this can be done. One question is how about a 90 seville computer & wiring harness?
Also, how about changing just the intake off the 4.9l & putting it on the 4.5l? What do we need to do to make it work? My final point is this, my Son & I at age 48 completely tore the original 4.9l down removing all to the heads, reworked all the values & the best of all but never did the rings on the pistons, was afraid of that stupid Cadillac design of O-rings. Put it back together with q-tips & scotch brite, looked like new but used a quart of oil every 25 miles after months & months of endless work so now I need to move forward with the 4.5 in place of the 4.9l, 88 Deville motor in the in the 91 Seville, help???
Sincere Thanks, JLG@Rocket7Designinc.com
p.s. Merry Christmas to you & your family. Looking to make the swap during the Holidays if we can get some direction?
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Yes its very possible. You need to use the 4.5 computer on the 4.5 engine, these should have the same adapters but the software is different, most of the engine components are the same, though the map sensor, some vacuum lines, and small things such as the windshield washer fluid resovoir and battery are just some of the obstacles you must overcome, if you can rebuild a cadillac motor you have my confidence in swapping a 4.9 to a 4.5.
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I cant predict whether every single wire is going to be identical, but to my knowledge most of the components if not all are the same for the motors, the main difference is the block design, the cylinder heads, intake manifold and transmission. Components should be the same. The wiring for the ECM should be the same as they are the same boards but different software. The wiring going to the engine will be different when things such as the MAP sensor or windshield washer resovoir are trying to be hooked up, also the battery is in a different location, you will probably have to extend the wiring for some components. This swap is very possible but in the same respect as doing any work on any car dont expect anything to be perfect.
p.s. caddis and most GMs are notorious for the ability to mix and match components and theyll still work 100% correct with one another.
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Jasper engines are IMO the best quality, but you will pay about twice as much as you would for all the other companys.
http://www.rebuiltcrateengines.com/ht4900-cadillac-p-1323.html
http://www.jasperengines.com
http://remanufactured.com/Cadillac_Engines.htm
http://www.theautochannel.com/autoparts/rebuiltpartscadillac/index.html
http://www.actionsalvage.com/Engine/UsedEngineCadillac.asp
AnswerIm sure this is possible but i have no idea who would do this, maybe a cadillac dealer has a solution for the comp. The transmission may or may not need to be replaced depending on which one you have as of now, and which one is designed to work with the 4.5, it SHOULD line up, but the performance and smoothness may be affected if its not designed to work with the 4.5.
