slmnn

1995 Pontiac Firebird Trans am LT1 5.7 sitting for 3 years with 10 liter oil for rust proof. When i tried to start after temporarily oil change with 20w50(4-5 mm high then max line) didn't crank cause of oil compression in cumbustion chamber. It had cranked after spark plug removal and spark plugs changed with new.
There was too much burnt oil smoke in first start and it smells like oil burnt. It cuts oil smoke after 5-10 startups&warmups. But it still blows smoke after warm up(approximately after 170 F). Also exhaust popped. But smoke doesn't smell like oil(i think oil completely burnt which was in cumbustion chamber).
Low coolant level on dashboard(It had 3 years before) but there is no air in coolant or any leaks, same level.
After 10 mins drive(no power loss) and total 45 mins idling oil became black and same level.
Today i tried to start engine when it warmed up and i stopped, dont turn, After i tried again click or knock sound come from engine. I was wait 1 hours and try starting then it works normally.

Normally cold start without smoke;

Smoke after warmed up;

Hard crank when hot and knock sound;

I didn't find answers for these question.
1- Why engine smokes and popped after warm up? Intake manifold gasket, throttle body coolant leakage, EGR valve, PCV valve, o2 sensor or cat? I dont think cause of blown gasket, engine didn't overheating.
2- Why oil turn black too quick?
3- Why engine don't turn or hard turn when hot? Is it heat soaked starter problem or about crank bearings? There was knock sound.
4- It s '95 Canada made and have 16 pin connector. How can i scan? Does Mini ELM327 OBD2 works?

Injuneer

All 4th Gen F-Bodies were built in St. Therese, Canada.

The PCM is OBD-1, not OBD-2. The 16-pin OBD-2 style connector was added in 1995 in anticipation of an OBD-1.5 system, as used in the Corvette LT1, but the PCM was never changed in the F-Body.

- Find an old OBD-1 basic scanner, like the ones from Auto Xray.

- There are some current scanners that have OBD-1 and OBD-2 capabilities, but only some of them will work, and often need a cigarette lighter adapter to pick up the required 12 volts. There is no 12 volt pin in the 95 connectors. And avoid Innova brand at all costs. Some models have a faulty data base for the LT1 engine, and give you an long list of codes in error, many of which do not even exist.

- Up to 1993 you could short the ALDL pins and flash the codes on the SES light. Will not work an anything newer than 1993.

- Best bet is Scan9495 software. Free donwload from a link on this site, build or buy a 16-pin cable:

https://www.camaroz28.com/forums/com...95-lt1-874306/

Why did you use 20W-50 oil.... way too heavy for an LT1 engine. You want a low viscosity oil that will start circulating quickly in a cold engine. Use factory recommended 10W-30 as long as you do not expect any temperatures below 0-degF (-18-degC).

Low coolant light, when the radiator is completely filled, is a very common problem. Coolant penetrates the printed circuit board in the level sensor and corrodes it. As long as you verified the radiator is full, to the very top of the fill neck on the radiator, and the air has been correctly bled from the cooling system, you are OK. If the light is a problem, unplug the sensor.

If you had oil in the combustion chambers, even though most of it was forced out of the plug holes, compression in the cylinders was significantly increased. I would suspect the this forced carbon from the burned oil past the rings, contaminating the oil, turning it black. Just a guess though.

slmnn

Thanks for your explanatory answers. Well, what do you think about blows smoke after warm up?

shoebox

Perhaps some of that oil that was in the combustion chambers is now in the pipes and has not burned out.