Evan_in_CA
NAXJA Forum User
- Location
- Los Banos, CA
OK so had some weirdness with engine temps today and wanted to get some opinions. FWIW I did a cylinder pressure test on this engine when I bought the jeep and all cylinders were 175-185 with no pressure loss. It has a supposedly rebuilt head within the past year. Apologies for the long post, I want to give as much info as possible.
Some background - To refresh the cooling system I did the following - I flushed the heater core since it was clogged, using a garden hose and flushing both directions until the water ran clear. I then put in a coolant flushing solution and let it sit for a week. I then did 4 complete flushes of the whole cooling system, filling then running the engine for 10-15 seconds with no thermostat installed. The first flush was with regular hose water, then with distilled on the next 3 flushes. I drained the system each time by pulling the radiator hose on the bottom of the block to get as much from the block and radiator as possible. After the last flush the water drained from the radiator and block was clean and clear. I then replaced the water pump, thermostat (Stant superstat which is supposed to bleed air without drilling a hole in it), thermostat housing, and heater hoses. I refilled the system with half dexcool (pink) and half distilled water.
Up until today I have put about 50 miles on it just driving around town and temps have been rock solid, though I had noticed that it gurgles (from I think the radiator, but I never really tried to totally nail it down) when I shut it down and it’s at temperature.
Today I took it on it’s first highway trip since the cooling system refresh. It ran at 210 indicated for the first 20 miles, then randomly the temp gauge shot up to 250, like instantly, and on a slight downhill section. I pulled over and popped the hood and everything looked fine, it was not boiling over or gurgling. I left it running while I checked things and literally a minute later the temps were back to 210. I said F it, and even though I was at the base of a significant hill I decided to go for it. Temps shot back to 250 (instantly again) pretty soon after getting back on the road for about 5 minutes, then to 260. It was not steaming or driving any different than usual, it ran completely fine and normal. I got to the top of the hill 10 minutes later and on the way down temps dropped back to 210 and remained there for the next 30 miles, which included another hill.
I got to my destination and popped the hood. There was no gurgling in the radiator like there has been. The overflow tank was just above the hot full line, coolant looked clean and pink. Engine oil was recently changed and still looks brand new, no milkshake, level was normal. There was some coolant on the hood and air box that appears to have been purged from the radiator cap. 10 minutes of shutdown and I turned around and came back home, over the same mountain pass. On the way home engine temp never got over 215 or so, even though the climb on the return trip is steeper and continuous, unlike the rolling hills on the initial trip when it ran hot. When I got home there was again no gurgling coming from the radiator and fluid levels were the same as when I had started the return trip.
Did the cooling system burp itself? I’m a bit confused, I’d convinced myself that i have a blown headgasket but none of the symptoms are there. Thank you for reading my novel.
Some background - To refresh the cooling system I did the following - I flushed the heater core since it was clogged, using a garden hose and flushing both directions until the water ran clear. I then put in a coolant flushing solution and let it sit for a week. I then did 4 complete flushes of the whole cooling system, filling then running the engine for 10-15 seconds with no thermostat installed. The first flush was with regular hose water, then with distilled on the next 3 flushes. I drained the system each time by pulling the radiator hose on the bottom of the block to get as much from the block and radiator as possible. After the last flush the water drained from the radiator and block was clean and clear. I then replaced the water pump, thermostat (Stant superstat which is supposed to bleed air without drilling a hole in it), thermostat housing, and heater hoses. I refilled the system with half dexcool (pink) and half distilled water.
Up until today I have put about 50 miles on it just driving around town and temps have been rock solid, though I had noticed that it gurgles (from I think the radiator, but I never really tried to totally nail it down) when I shut it down and it’s at temperature.
Today I took it on it’s first highway trip since the cooling system refresh. It ran at 210 indicated for the first 20 miles, then randomly the temp gauge shot up to 250, like instantly, and on a slight downhill section. I pulled over and popped the hood and everything looked fine, it was not boiling over or gurgling. I left it running while I checked things and literally a minute later the temps were back to 210. I said F it, and even though I was at the base of a significant hill I decided to go for it. Temps shot back to 250 (instantly again) pretty soon after getting back on the road for about 5 minutes, then to 260. It was not steaming or driving any different than usual, it ran completely fine and normal. I got to the top of the hill 10 minutes later and on the way down temps dropped back to 210 and remained there for the next 30 miles, which included another hill.
I got to my destination and popped the hood. There was no gurgling in the radiator like there has been. The overflow tank was just above the hot full line, coolant looked clean and pink. Engine oil was recently changed and still looks brand new, no milkshake, level was normal. There was some coolant on the hood and air box that appears to have been purged from the radiator cap. 10 minutes of shutdown and I turned around and came back home, over the same mountain pass. On the way home engine temp never got over 215 or so, even though the climb on the return trip is steeper and continuous, unlike the rolling hills on the initial trip when it ran hot. When I got home there was again no gurgling coming from the radiator and fluid levels were the same as when I had started the return trip.
Did the cooling system burp itself? I’m a bit confused, I’d convinced myself that i have a blown headgasket but none of the symptoms are there. Thank you for reading my novel.
