I have a 2004 Chevy Impala with the 3400 series V6 engine. The car currently has around 172,000 miles on it. I have been driving this car all over the place for the past 7-8 months or so with absolutely no problems. Due to its age, mileage, and lack of maintenance from previous owner(s) when I bought the car, I have already had to replace a lot of parts on this car to keep it running and improve the ride and handling on this car. I have already replaced the following on this car: Front and rear strut assemblies with new coil springs, front and rear sway bars and end links, front and rear brakes (including new rotors and ceramic pads), new rear parking brake cables and adjuster, replaced all O2 sensors, complete engine tune-up (including B&B Platinum Class Laser Mag 8mm spark plug wires, Bosch Platinum spark plugs, new WIX air filter and cabin filter, PCV valve, etc.), new Idle Air Control Valve (IACV), new Throttle Position Sensor (TPS - since the engine had problems idling properly and once it warmed up, it would "idle" around 1,800-2,000 RPMs), replaced heater blend door actuator motor (which was a B-ITCH to get to, but necessary as it was blowing cold air out of the driver's side vents with the heat cranked up all the way!), and, most recently, I just replaced all of the subframe mount bushings on the car as it was making creaking and popping noises when going around corners. (PHEW!!) So, obviously, I have more than a few bucks invested into this car at this point... It rides like a new Cadillac now though after all of the suspension upgrades I've done to it.
However, on Thursday evening (March 5th) while driving it back home from work, as I was pulling into my driveway, the engine suddenly started puking its guts out all over my driveway! After I shut the engine off, I noticed there was already a pretty large coolant puddle underneath the front of the car. I took a quick peek under the car and could see coolant dripping down from the back of the engine and down the oil pan. On Friday morning, I tried to put some radiator and engine block stop leak pellets in the radiator and topping it off with some fresh coolant to see if I could band-aid it for now just to get me to work. I started it up and let it idle for about 15-20 minutes in my driveway to warm up and circulate the stop leak. However, this did not work as it was still dumping out coolant from the back of the engine and the temperature gauge in the car started heading towards the overheating mark (around 260 degrees). I'm pretty sure this means that the lower intake manifold gasket is blown, especially since these GM engines are known for this problem. I can see that it is pouring out coolant from the back passenger's side of the engine and steam and coolant is coming out from in-between the alternator and the power steering pump.
So, if I have to replace the lower intake manifold gasket on the engine, that's pretty involved as I'd have to take everything off from the top of the engine. I'm sure that everything I remove will need new gaskets and/or O-rings as they will be all brittle and destroyed from age. It is a cheap job, relatively speaking, in that the gaskets to repair it are pretty cheap (under $100), however it is a very labor-intensive job. I'm sure if I had to take it to a repair shop to have it fixed, they would probably charge me anywhere between $600-$1,000 to replace the intake manifold gasket, which would be pretty much all labor.
Given all the other work I have done to this car already, I'm kind of already into it beyond the point of no return, I think. I hate to have to throw in the towel and junk the car with so many new parts installed on it. However, it is not exactly the prettiest car by any stretch of the imagination! The car suffers from the bad GM paint problem and most of the clear coat has blown off of the car, making the paint on the car look horrible. There is typical New York rust all over the car, especially on the rocker panels and over the rear wheel arches. (In fact, especially on the passenger's side, the rocker panels are pretty much completely rusted away...) At least for now, thankfully the floor pan in the car is still intact though. I also recently hit a deer that was standing right in the middle of the road with the front passenger's side of the car. Amazingly enough, all it did was break the headlight assembly and dent the front fender a bit! So, now I have new headlights in the car too. Still, this car certainly ain't winning no beauty pageants in the shape it's in!
I'm wondering if it is worth it to fix the engine in this car to keep it going or if I should cut my losses and just get another car? I hate to throw away all the new parts that I have installed on this car, but even if I fixed it and got it running again, I'm sure I would have a hard time selling the car for much more than maybe $1,000 as it is, if for no other reason than the body is pretty shot on the car! (It's sad that a pretty looking car with no rust that mechanically needs everything replaced will still sell for more money than a mechanically sound car that looks like a rusted POS...) It's probably not the most difficult job to replace the intake manifold gasket, but it would take me probably a weekend to do the job in my driveway. (I'd also need to invest in a torque wrench to be able to properly torque down all the engine bolts as I do not own one right now...)
Also, if I have to tear the engine all apart anyways just to replace the intake manifold gasket, I'm wondering if I should also swap out the stock camshaft and lifters that are in it? I have heard stories of people having broken the camshaft in their engine after they had the same issue of the lower intake manifold gasket blowing. Coolant can leak into the oil and the cam bearings seize up and the cam gets destroyed. But can I actually remove the cam from the engine with the engine still in the car or do you have to pull the engine (or, conversely, drop the cradle) in order to do that? How difficult is it to replace a camshaft, cam bearings, and lifters in one of these 3400 series V6 engines anyways? (Plus, I figured if I'm going this far with the engine anyways, I could upgrade the cam to one of these to make this Impala a bit more fun to drive: https://www.wot-tech.com/street/strip-performance-camshaft.html Not really sure if there are any other options for a performance camshaft for the 3400 V6 or not?)
I'd appreciate any help or suggestions with how to go forward with my Impala at this point. Thanks!