We have a 95 buick riviera with the supercharge 3800 v6 engine. It overheated, usually runs at 200 degrees and blew the oil dipstick up and oil splattered on the engine. Oil level is ok and oil doesn't spell burnt. The radiator is full. Nothing leaking. It runs fine until around 45 mph but starts to hesitate, shake and won't go any faster. ?????????

it can take upto 30 starts for the engine light to go out but if there is still a code active it will stay on. have the code read and then see if its still active.

Superchargered, Yes. Regular engine, 95 to 99.

the oil level sensor in the oil pan is probably going bad.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

Hello lysiphlebus2,

((My thoughts: cold START valve IAC at very bottom))

Plenty of places will do FREE diagnostic code reads.

I would rather suggest it be a muffler shop than
AUTOZONE... but either is better than guessing.

AUTOZONE will likely make you buy OXYGEN
sensors... (but that makes about as much sense as
buying a new THERMOMETER every-time you
have a FEVER.

What you are describing sounds (from an old
mechanic's perspective) like a collapsing
catalytic convertor or rotted muffler baffle
(a slightly better blockage will halt operation
completely)...

((again speculation... get your codes read))...

Do not buy OXYGEN SENSORS....

Know your prices before waltzing into any
exhaust shop.

AMAZON
1 24 of 108 results for Automotive 1995 riviera catalytic 1995 riviera...

rockauto
1995 BUICK RIVIERA 3 8L V6 Supercharged Catalytic Converter RockAuto

IAC (cold start valve)
1995 BUICK RIVIERA 3 8L V6 Supercharged Idle Air Control IAC Valve RockAuto

Hope this helps

Carnac the Magnificent

Drain and flush the cooling system...more than once if needed.
Replace the thermostat with a 180 degree...the OE stat. is 200 degree.
Clean the outside of the radiator and a/c condensor, make sure there is no debris in the cooling fins and they flow air freely.
Fill system with 50/50 mixture.
If it still attempts to overheat...check your cat convertor, it's clogged and creating too much back-pressure
Hope this helps...

if your supercharger sounds like tumbling rocks, it is the plastic coupler between the nose cone and the charger body; take off your serpentine belt; chances are the pulley has some play in it but it turns freely; the replacement coupler is a cheap fix; what gets a lil pricey is the labor to replace it... the buick has an alternator bracket that has to come off before you can take the nose off of the supercharger... dont forget to drain the oil from the nose cone with a spray bottle nozzle

unplug the cam sensor behind the water pump pulley; see if it starts; if it does, shut off engine; replace both cam and crank sensors because crank sensors go out in these engines

Good engine 28 mpg+ hwy. These 3800 engines had upper intake problems and would leak coolant into the combustion chamber. The new ones were re-designed and do not give any trouble. My 90 buick 3800 has 295000 miles on it. If yours is supercharged it does not have that intake problem.

In A chilton repair manual at the library.

you can not put a regular 3800 intake in place of the 3800 super charged engine,the compression ratio is lower than the regular 3800 engine.......!