1999 bonneville changed the thermostat now it wont start

Asked by Nov 26, 2016 at 08:42 PM about the 1999 Pontiac Bonneville 4 Dr SE Sedan

Question type: Maintenance & Repair

ok so this site wont let me reply to anyones
responses and i need some help.  so ill start
from the begining..i was getting ready to leave
for the day and checked the oil.  it said it was
around a half a quart low so i added around
400 mls thinking i should be fine. i then drove
to town (20 miles) and the car started running
like crap and over heating. so i stopped and
had some lunch and checked the oil and it
seemed to be overfull. so i went straight home.
(i did not over heat the car at any point) and
changed the oil and filter and got it to the
correct level. it then continued to over heat and
run poorly. i then noticed it was out of coolant
and that the radiator hose to the thermostat
would vacuum shut while the car was running
so i changed the the thermostat and then the
car would not run anymore. i tried
disconnecting the battery to rest computor and
that didnt help and im pretty sure its not the
security system. also not leaking coolant. the
car started and drove fine (other than
overheating )before i changed the thermostat.
and i put the old one back in and tried to start it
just to make sure that wasnt the problem. any
help is appreciated but as i said for sone
reason i cany reply to responses to thankx in

1 Answer


Check for spark. The overheating may have burned out the ignition control module or the crankshaft position sensor. An easy way to check for spark is spray some starting fluid down the throttle body. If it runs a few seconds you have spark and it's a fuel problem. HTH. -Jim

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