: Upgrading and restoring a 4.9

05-28-12, 12:09 AM
I have my 93 Deville in the garage and this summer I plan to pull the engine out and fix it up.

The reason the car is in the garage now is it needs a little tender love and care. It blew the heater core and it started to run roughly in idle and got poor MPG and it's leaking tiny bit of oil.

I know that one fuel injector O ring is broken that might explain the bad idling and MPG but since it's also leaking a bit of oil I want to pull the engine out and fix it up real good.

If you had plans to rebuilt or fix your 4.9L engine, what would you do while the engine is not in the car? Easy access to everything and you're not on a rush since you have another car.

I want to fix up this car real good, have it up and running flawlessly and perhaps a little performance upgrade.
I plan on keeping the car.

And please don't lecture me on it's wiser to dump the car and spend the money on something newer or older (more classic). It's a hobby thing and I want this project.

Any and all ideas are well accepted.

This car is a project I plan on doing this summer and winter and have it ready by next summer.

I could even keep this post alive when I start and upgrade it every time something is done, post pictures and ask for advice for my next moves.

The first step is done, the car is in the garage and awaits it's fate.

Next step is getting a clue on what things I need to order and why, and in what order.
This post is that step.
Now the study and learning process begins.

05-28-12, 12:49 AM
If you don't have an FSM, get one before you start ebay is your friend. Iceland? How did that car get there and how long has it been there? One other thing, mileage.

05-28-12, 09:17 AM
Hi Dennis and thanks for the reply.
I have found a Service Manual on ebay and I'm going to order it with in the next few days.
Yup, Iceland. The car got here like any other car that comes to Iceland, it was imported :P We have all kind of cars in Iceland. I don't remember when the car got here but American cars are often bought used and imported.
If my memory serves me correctly the car has 86K miles on it.

But since I plan on pulling it, I want to replace all things that might be a good idea, even if it's not completly necessary right away. Also sensors like O2 sensors and stuff like that if it is a good idea.

I would like to put a new exhaust system under the car, perhaps dual (or at least with two ends).

05-28-12, 09:24 AM
Nothing too special about this engine. It's two biggest problem areas are main bearings and fuel injection, so be sure both are in perfect condition before reinstalling the engine. Else, everything is pretty standard

05-28-12, 11:39 AM
True dual exhaust will be a total pain in the ass to try and install, duals at the muffler is much easier. You should be able to find some video clips on You Tube that have had mufflers replaced with dual outlets. I don't know what emission standards you have to meet up there, I know that there were a lot of standards that were not required for Europe when your car was built. I think they, (european models) were built to run on leaded gas which will kill a lot of emission components and those were left off on the export models. Is your gas unleaded up there? The 4.9l was not built to take horsepower mods nor was the transmission, some have done it but can't say how the longevity experience was. Not all things are 100% correct in the FSM, but for the most part the best guide you will find for your DeVille. I would say for seals and gaskets on the engine the worst for leaks is the front main seal, valve covers and maybe the intake manifold on the ends. Before you pull the engine, it might be a wise idea to clean it up real good and drive it some to locate those worst leaks. If you want click on my profile, there are a couple of albums to look at for pictures. I have and am adding pictures to my photobucket account continuously, and there are some on my pbase account (I may take down someday just to keep them all in one spot).

05-28-12, 12:30 PM
Drew, thanks for pointing that out. I was looking on ebay the other day and found fuel injectors and thought it would be a good idea. Now I'm definitely going for new fuel injectors. Now main bearings have been added to my list. Thanks for that!

Dennis, Iceland, unlike other Europian contries have both CE and DOT standards, so anything car-related that goes in the States is also fine here. For example, amber rear turn signals are mandatory in Europe but here blinking brake lights are just fine.
Most American cars are imported from the States and are often used as well.

My Caddy is by no means a Europian version of some sort. It is as American as all of your U.S. located Caddies. Mine does not run on leaded gasoline. The rear turn signals are blinking brake lights.

The emission standards goes with the year the vehicles were built, along with all other safety standards. If you have a classic car you can have old license plates, that were standard when the car was built. So if you have a classic car you can keep it as original as you wish. If the car was manufactured with no seatbelts in the rear seats they are not mandatory - as long as it was not mandatory to have them when the car was manufactured.

Regarding tuning I know this engine and the transmission can't handle a massive tune-up, not a lot of things are avalible for the engine that are not stock ect. but I read on here somewhere if you put the timing on 14 degrees instead of 10 you might get a few extra HP. I was thinking if there were any other tricks you guys knew off. I'm not looking for a massive tune-up since the car is FWD and also the engine/tranny might not handle it. But just a little bit more if possible.

I thought I would buy a complete gasket set for the engine (I would probably not change head gaskets unless I would need to remove the heads).

I also read that O2 sensors are prone to go bad.

Things on my to buy list:
FSM (courtesy of dennis93coupe)
Complete gasket set
Main bearings (courtesy of drewsdeville)
Fuel injectors (courtesy of drewsdeville)
Water Pump

Please feel free to point out more stuff to buy.

05-28-12, 12:42 PM
I'd like to add that it might not be necessary to replace the injectors or mains - they are just the areas that should receive extra attention.

Plastigauge the mains to check for excessive clearance. The problem is located specifically on each end of the crank - #1 and #5 positions. There are special service-sized replacement bearings available to address this problem if yours is affected.

The injectors are probably either good or bad - no sense in throwing away your injectors if they work fine. Take out your VOM and probe the two blades on the injector connector. Resistance should be in the 12-16 ohm range, and all should be relatively close to each other (for example, if you have 7 injectors at 12 ohms and one at 16 ohms, you might want to consider replacing the one 16 ohm injector even though it's technically in spec.)

05-30-12, 08:52 AM
If you going to yank it to freshen it up then throw new rings and bearings in, or at least tear it down and spec every thing. Just a thought, as it will help identify future problems.

05-30-12, 10:30 AM
These engines can go 300k with good maintenance. No need to do that if it isn't using oil and has good compression.

05-31-12, 08:39 PM
Just about any relatively modern engine can go 300k with good maintenance. The 4.X is no miracle.

I do agree with Seville455...if your goal is to make a project out of making this car perfect, then by all means tear it down and spec everything. Is it necessary - probably not. However, it sounds like that's what'll make you happy.

the recluse
06-03-12, 02:51 PM
I don't know how much ability/tools you have, but one of the greatest performance mods I've done to this engine was porting the heads, doing a gasket match on the intake, and giving it a good valve job; also polishing the throttle body to a mirror shine.

The Multec injectors on these things SUCK, royally... Ohm them out as Drew suggested, but be leary they are always cause for problems...

06-07-12, 02:48 PM
Why isn't anyone recommending he totally get rid of the old horrible MULTEC's? This is a well know upgrade to the 4.9 Caddy Motor and any GM using these old MULTEC's. The original MULTEC injectors are known to have so many problems in all the GM motors of the the late 80's to early 90's and are 26yr old technology.

Upgrade to the Bosch III Injectors which are far superior. Better idle, no dead spot off idle, better fuel efficiency, and over-all better performance.
I got mine here: http://fuelinjectorconnection.com/shop/index.php?_a=viewProd&productId=187

I heard about this company on the Corvette Forums where all the guys use and recommend this company....his injectors are cleaned, flow balanced, have the extra o-ring for better sealing in the rail and port, and have a 3yr warranty.

I did a write up a while ago which included many of his videos as seen on his new website. Check out the video 6th from the top on this link below titled " LUCUS DISC vs. BOSCH III's vs. Gm MULTECS": The Lucus 3 hole design is being sold by Accel and some other performance aftermarket company's and has too heavy of a spray pattern which will most likely wash the cylinder walls and this guy says it really should only be used in a turbo application. Also check out the video titled "Fuel Injector Comparison" towards the bottom of this link:

Also, I, like many others are having problems with aftermarket water pumps. If you have your original OE. Water-Pump, don't change it if it's not leaking from the "weep holes" or making any sounds. Can you please take a close look at your pump for me and see if you see any stampings or identifying marks? If so, can you take a photo or post it here on the link I started below. I'm trying to i.d. original pumps so I can maybe go to the salvage yard to buy a used original because the after market pumps are not made as well as the original pump from what I'm now seeing. It looks like all aftermarket pumps are junk and they are sourcing from China!
See my 3pgs. of posts on a thread I started regarding a new A/C Delco Pump failure and now an A1 Cardone Pump Failure which both lasted for 1yr.

Hope this helps.

06-09-12, 01:18 PM
You're getting some good advice here. Just to reinforce some of the points made, I would do a leakdown test while the engine is still in the car to get a good idea about the compression and any leaking. If the numbers are all above 90% then you dont need to take it completely apart, but if there is anything in the 80s you should seriously consider working on the internals.

A gasket set is a good idea--leaking intake gasket is pretty common since its a steel head and aluminum intake. Replacing all of the sensors with good (preferably Delco) parts is also a good idea.

The 4.9 intake is already pretty well shaped so I dont know if you'll get much from that. You can polish it if you want, dunno if it will make any difference, some say yeah others say no.

The biggest performance gains I've had from my cars came from advancing the timing a few degrees and installing a Magnaflow cat.

06-09-12, 10:24 PM
I would replace the oil pump when you do the main bearings. More of a while your at it thing because its a pain to do drop the pan when your motor is still in.