tinbanger84

alright this has kinda got me stumped, it will more often than not on the first cold start of the day as it is getting up to temp.. while driving..spike to almost 230 and then drop back down and never have an issue for the rest of the day regardless of load or how many times i shut it off and restart, i can tow 30,000lbs over MT Hood with zero issues foot to the wood.

last week i replaced the thermostat to see if that was the issue but no luck same problem. i did notice tho that the coolant in the reservoir was higher than it had been for the last year, but would return to normal at times

whats been replaced in the last year due to a head gasket failure caused by a stuck factory thermostat at 221,000 miles

it was deleted with a smarty jr at 67,000
LAST YEAR\/
head gasket
arp head studs
water pump
thermostat
fan witch clutch
serpentine belt
radiator

just a few days ago i did the chemical test fro exhaust gases in the coolant, and could not get it to change color with multiple tests

then i did a leak down test, and it held 14 psi without moving for over an hour
then i did a warm up pressure test and it took 30 min at idle get to 11 ish then dropped to 7 when the thermostat opened up.

so im fairly convinced the head gasket is OK

is it air in the system??? thats the next thing im going to check

brattboy

did you purge the air in the cooling system?