Correctly Diagnosing and Repairing 98' S70 GLT

[harrmed]

Hello Forum. I am new to car repair and could use some of your advice. I have a 1998 Volvo s70 GLT, and recently i had the car repaired for a leaking heater core. the mechanic said it was too late a day after when i told him the cars check engine light was blinking, the car had been overheated. he ran the engine codes, and told me 1) relay/fuel pump problem 2) cylinder 1,2,3 misfire & catalytic converter damage 3) water in oil.

Now he said the repair would cost around $1500 dollars, but stressed that i should sell the car. I LOVE THIS CAR, and would rather fix it on my own. I have access to VOLVO VADIS 2005, if that helps anyone to help me.

My question is how i can diagnose and repair the problems indicated above. I regularly start the car, the car drives, but eventually stalls, and loses power. Take about 6 hours for the car to gain power and start up again, so i am guessing the alternator is still good?

Thank You for Your Time
Ben

[wooz797]

i would check the fuel pressure with a guage while running and see if it drops when the vehicle stalls out. that could explain the missfire codes if the fuel pump is dying off

[JDS60R]

Its time to stop driving the car and do (or have) a diagnosis.
If you have water in your oil you are hurting the motor as water and oil mixed do not provide the lubrication your motor needs.

What did the mechanic diagnose the $1500 problem as?