So I have a 04 sedan 6mt with 150k miles.I have invested money on the car when I bought it two years ago .The suspension is built complete after market parts.I tried to keep up with oil changes and maintenance.I also wrapped the car and bought aftermarket hood and headlights/tail lights.i bought the car without working AC and assumed it should be an easy fix.I filled it up with Freon and it blew cold for about 3 weeks until it started blowing hot again.

fast forward today I have the car back from storage.I changed the oil and took it to a Nissan dealership.The Nissan techs noticed the car had A very slow rear main leak.They also asked if I wanted a comp test and I agreed to do so.The results came back to 150psi on all cylinders and they mentioned that the numbers were very slow as a healthy DE is around 170-180psi.

the main question is that now im faced with a low comp engine plus a non working AC.I want to replace the engine when I get the funds or when it gives out.Is there any anyway to fix the AC leak while I’m in there when replacing the engine?

 

Ignore those technicians they're full of **** and just trying to sell you a new motor. FSM specs on an acceptable engine is 142psi. You're well above that so don't bother with shopping for a new motor yet, you'll probably hit 220k give that it's well maintained.

Focus on the AC leak, look up how to pressurize the system with nitrogen (or just add more refrigerant knowing it's going to leak out) and look for the leaking fitting. Use soap water and a spray bottle and spray down every single fitting. It will look like "white foam" after about 30-60 seconds when you spray the leaking fitting. What you have is a very SLOW leak so it will take a while before it starts to look like foam.

I'm sure there are plenty of videos and instructional stuff on the internet about how to find leaks. In a pinch you can even use compressed air but I really don't recommend it because you're pumping a lot of potential contaminates into the system. You can buy a manifold, a vacuum pump, and any other necessary fittings for around $100 and then you only need to purchase refrigerant. The most expensive part is buying a recovery pump, I don't recommend buying one but instead just go down to an auto AC shop and have them pump the refrigerant out. Don't just open a line and vent it off, future generations will be cursing your name. You can easily refill the system with cans of R134A, a scale, and the FSM specs for refrigerant weight / oil volume. Don't bother buying a fancy refrigerant scale, just use a cheapo kitchen scale since you will be working with small refill bottles probably.

Likely you just have a single o-ring fitting leaking, buying the tools and refrigerant you should be under $200. Sell all manifold and pump on craigslist to recoup a portion of that cost when you're done if you don't want to keep them.

 

If you can find a reputable engine builder they can probably just hone, re ring, replace bearings, check valve sealing, and replace all seals. I know a few places around here that charge about $800 for a freshen up. If you are a good mechanic you can DIY by the service manual for about $300-$400. It's a lot of work but it will save you a ton compared to buying a new motor.

 

unfortunately no good reputable Vq rebuilders in my area in Illinois.I check my oil everytime I drive the car now since I have a slow rear main leak.Im going to drive it for a good while now while saving up for another Vq if the worst happens

 

I think the dealership is trying to gyp you bud - maybe the tech wants to buy your car!
150psi is pretty healthy I'd say, considering the car is 16 years old with 150k miles on it. If it was below 140 (as the manual states) then I would be concerned, but not worried.
Since the car was in storage (how long??) perhaps the rings may be sticking a little. I would try adding Marvel Mystery Oil the cylinders through the spark plug hole and let it soak in overnight.
I've had good luck with using the UV leak detecting r134a refrigerant to find leaks with the A/C system.

 

yes it has 150k miles and has a slight rear main leak.I had the car stored since October last year and finally took it around the beginning of March this year.