Ok i picked up a 89 red late last fall after two day's put into winter sleep over the winter i got a manual & read ,the last month it FINALLY got warm enough to work on it so all fluid's changed, air & fuel filter all most all ground'a cleaned new battery and a lot of little thing's, now all system's go no codes it now even say's good morning to me .While doing this i found that the last owner wasn't a real maintenance type, so i thought i'd change the plug's.Well i wish the engineers who design
the car's should have to work on them i'm not a big man but i feel like i have the arm's of the hulk! i've read that you can tilt the motor to do the back plug's could you lift the motor up so you can get more room to do the front one's. now before you comment the motor was rebuilt by a dealership at 80 th it now has 150 on it should i just sit back have a beer and shine it
all's that is left to do is the radio that's next, but for now can't wait to drive with top down oh yea new soft top last year form last owner i think this car & i are going to have a great time hope to meet some of you soon
Just my perspective here. Really, I'd say it depends on the type plug installled in the engine. I have a '91 with 135 on the clock. It is still running the original plugs, which were indicated to go 100K I have had no issues to date, no issues that is that I can tell. I am sure that they need to be changed. I bought a new set of plugs, wires cap and rotor to install back at 90 K. When I realized what was involved I lost the giddyip to do it. Besides I'm getting decent enough economy, 15.4 average, 19 + if I take it easy.
There are basically three ways to do the job. The first is from the top, across the engine. That way will no doubt wreck your hands due to the difficulty in getting into the confined area where the rear plugs are. The second method is to tip the engine and do it that way. I understand that this is a viable method for doing it. I just hasve difficulty in accepting that no "other" problems would arise from that . In tipping I would think that the trans lines, exhaust connections and cooler lines all would be stressed. With my run of luck I am hesitant to go that route. With the third method going underneath when the car is up on a lift, I think might be the safest and least costly, injury wise. You do have to route the plug wires so there will be some work from above, but that could be worked through. I'd favor the last method. I, like you, have not done it yet.
In your case, if the engine was gone over at 80 K and you are only at 70 k on the plugs, I'd sit back and polish the car, unless you are noticing something.
Bring the car to local Cadillac dealer and hope that they indeed replace all 8 plugs .Saves hands and issues. Some jobs are just better off paying someone else to do it.
If local dealer has not done it in a while then get an estimate ahead of time and keep them to it when they come back with problems of access and extra time involved.
Don't take it to the dealer, that would be up among the worst places to take it.
Tilting the engine is the way to go. The whole engine tilts back and forth constantly while you drive, nothing's going to break. Disconnect the torque struts, and you can use a turnbuckle in place if one of them to tilt the engine forward.
Automobile(s): 1988 Allante' (sold), 1984 Eldorado, 84 Sedan DeVille
Re: any hints on changing plugs
Pull a plug on the front side and take a look at it. If its a platinum plug and looks good, leave them alone for now. I put DELCO platinum's from a 91 Eldo in my 88. Worked great. Went from 60,000 mile interval to 90,000 mile interval. If they are not DELCO, change them. I loosen the two front engine cradle (sub frame) bolts almost completely out and with a floor jack and a piece of wood under the oil pan. lower the engine gently. That requires the upper dog bone mount be removed. Just watch the exhaust coming down and forward in relation the the radiator.