I have a 1999 Blazer and what started out to be a mild issue turned into a very large issue. I bought it just shy of 6 months ago and the place I bought it off of must have had the check engine light code shut off. To make a long story short the radiator was replaced and after that a lot of issues happened. It started to miss and idle badly. so we replaced the plugs and wires, the distrubutor cap and rotor, the sensor, the thermostat etc.Needless to say now it loses oil pressure and randomly overheats. We think its the heads but any insight would be greatly appreciated.

 

Are you losing coolant, is your oil milky any steam from exhaust. Head gaskets are uncommon but not unheard of.

Did you put a new radiator cap on when you did the other stuff?

 

If you spend some time searching through the postings here you will read that the 4.3L engine seems to only like Delco ignition parts (cap/rotor/plugs), wires...not so much.

If you did not use Delco parts, first thing to do will be to do so.

What sensor did you replace?

Have you checked the oil for coolant or the coolant for oil?

If you suspect the heads, suggest a compresson check and/or a leak-down test to determine head health. Loss of oil pressure may just be the oil pressure sensor near the distributor.
Ramdon overheating could just be trapped air in the cooling system.

Good luck...and let us know what you find.

 

Ive spent some time looking thru postings that were just related to my issues that i have been having. There is no oil in the coolant or vice versa but it is burning oil. I did replace the rad cap and I'm not sure if the parts are from that company. I am supposed to take it Thursday for compression testing. It only has 80k on it. The lot that I bought it from isn't taking blame for it's issues so I'm going to try and figure out the issue. It's just frustrating

 

hello good evening my name is rey, i have a 1998 chevy blazer it was running perfectly the only problem was the ignition swicth i could turn on the vehicle and when i turned it off it would not shut off i had to pull the ignition fuses in the engine compartment, so today i finally replaced the ignition swicth and the blazer does not want to start it cranks perfect the fuel presure is perfect 55 to 65 or something like that lol, i have spark fuel pump is running , but the blazer just starts and in a couple of seconds it shut off and if i press on the accelarator it shuts off even quicker and sugestion or help you can give me please some one its my only way of transportation im very mechanical incline but for some reason this one is eating me up please help . Thanks.

 

hello good evening my name is rey, i have a 1998 chevy blazer it was running perfectly the only problem was the ignition swicth i could turn on the vehicle and when i turned it off it would not shut off i had to pull the ignition fuses in the engine compartment, so today i finally replaced the ignition swicth and the blazer does not want to start it cranks perfect the fuel presure is perfect 55 to 65 or something like that lol, i have spark fuel pump is running , but the blazer just starts and in a couple of seconds it shut off and if i press on the accelarator it shuts off even quicker and sugestion or help you can give me please some one its my only way of transportation im very mechanical incline but for some reason this one is eating me up please help . Thanks.

 

If your fuel pressure is ok and you have good spark is the security light on? Which means u could have to do the relearn which is detailed here on forum