This 1986 Sedan Deville is mint & when I say mint I mean perfect & loaded…it had the 4.1-liter motor & it ran fine until about 38,000 miles & then head gasket failure. When I went to remove the heads 3 bolts striped out & 1 broke. Even though I was new to Cadillac collecting I had read enough & herd enough horror stories to know that this motor was done. So I did what any Cadillac owner would do. I found what seemed to be a good donor car. A 1989 4.5 Fleetwood with 177,000 Km on it. That’s about 105,000 miles….not bad. Well that’s what the seller told me anyway. By the way it turned out this car had 377,000 km on it but I did not find this out until two years later. This was the Deville’s first swap & at first it was great but a donor motor with that much Km’s on did not hold up well after the swap. About a month & a half later it was all crap from there on. I had air sucking in from the intake manifold then about a week after that wile driving the cruse control shut down & the a/c-heating went nuts & I lost my breaks (F#*?ed up vacuum system??) After all those things were repaired about a month later when the weather got hotter I went to use the a/c but it caught on fire…..I swear I am not making this up. I had leaks from the oil pan like a screen door. Temp light went on every time I stopped until the top rad hose burst. Then when it got really hot outside like July hot I noticed a BIG KNOCK in the lower part of the motor & I mean a real hot torque knock. The more the car ran the louder it got. Then the STOP OIL light started to flash when the car was stopped & in drive like at a stoplight or in reverse. This was no doubt caused by a broken lifter rod. At that point I stopped driving this ticking time bomb & put the Cadillac away until I knew when I could fix it right. By the way I had a local mechanic do the swap for me…after all those problems that’s when I knew I would have to do my own work from now on if I wanted it to be done right!

So that brings us to the present, the Deville’s second swap. I now know a lot more about these Cadillac’s & had found a really good 1988 Sedan Deville 4.5 with about 120,000 Km (94,000 Miles) it has had regular oil & coolant changes with Stop Leak Tablets and I had been driving this car as a test for a month & it did run great. No problems with over heating, knocking, running rough, shifting, ticking clicking, leaking or what ever. It was all good. So I was ready to try this again but this time I would do the work my self with the help of a very good mechanic who is also a friend of mine & he really dose know what he’s doing.

 The swap from the 4.1 to 4.5 took 4 days to do & brakes down like this.

 Day 1. 8-hrs Removed engine & all necessary parts from 1988 4.5 engine bay.

1988 4.5 SedanDeville Engine Out

Day 2. 8-hrs Removed engine from 1986 4.1 

1986 4.1 SedanDeville Engine Coming Out

Day 3. 12-hrs Replaced water pump, plugs & wires, alternator, power steering pump, thermostat, accessory belt, out-put seals, rewired new 4.5 with old 4.1 wiring harness & removed 4.5 transmission & replaced with original 4.1 transmission & flywheel.

1986 4.1 & 1988 4.5 SedanDeville Engine's Out

Day 4. 12-hrs Replaced new 4.5 engine & transmission in to 1986 engine bay. Tweaking engine.

I did complete motor changeover & not just a 4.5 short-block with the 4.1 intake & its entire accessory’s. I rearranged the engine compartment of the 1986 to not just have an updated 4.5 but to also look like an 88 4.5 engine compartment. I knew this would be a lot of work but was ready to put in whatever time I had to. I read the GM Cadillac shop manuals for the 86 & the 88. I used 4.5 intake manifold & was able to get rid of the 4.1’s electric vacuum assist pump. I also used the 4.5 a/c system & air filter housing.

1986 SedanDeville with 1988 4.5 liter Engine 

The swap went very well, all & all it has worked out very well. I have been driving this 1986 Deville 4.5 since last October (but not in the winter) & it’s running perfect. The “service soon” light was coming on at about 90 Km’s but it tuned out to be a bad EGR valve, so I changed it out along with the EGR solenoid just to be safe & some times the “service air con” will come on but just for a minute or so. I checked the codes & I was only getting HVAC codes. I know this will be worked out when I get the vacuum rerouting as it should. I was getting really bad fuel mileage at first but the more I drove the better it got….not sure what was going on there but must have been a resetting of the computer?? Now I get about 9.5 liters to the 100 Km’s I think that’s great.

I have been detailing the engine bay this past winter as this was the most time consuming part of this project & will be posting more pics. I just wanted to make sure I would not have to do any more work on the engine or emissions system…..Stay Tuned More Pics To Come

MadCaddyMan out!