Coolant Temp Running High

[DearbornDave]

Ok, since I've reinstalled the engine in my Marauder, I get some weird coolant temp swings. It doesn't happen all the time, maybe a couple times a week. What happens is the engine will come up to temp just fine, but after a few minutes the gauge will creep up to the very top of the normal range (it never goes into the red) and hang there for about a minute, then it will fall back down to normal temp. I check under the hood after this happens and there is always a little coolant around the overflow tank fill cap. Does anyone know what is causing this? Do I have an air bubble in the system? Or is it something else, like maybe a themostat? If it's an air bubble, how do I "burp" it? Any help woulg be greatly appreciated! :help:

[babbage]

When the engine is cool, take a small socket drive extension and put it into the square hole in the round opening in the top front of the metal coolant tube. It's right there front and center. Remove him and top off with 50/50 premix coolant. Run car for 1 minute and repeat procedure until the system is full. Verify coolant reserve is filled with 50/50 to the high cold mark.

Replace your Thermostat with a Motorcraft 180 or Hi-Tech. T-stat is driver side vertical tube halfway down. (Easy to do and will eliminate a bad T-stat)

Also you can remove fan shroud assy and blast from in to out with hose to remove all the 'clag'

[DearbornDave]

I just got back in the house from trying to "burp" the system. I removed the cap in the crossover tube and filled it until it started to raise the level in the overflow tank. I than started the car and ran the engine with the cap off until it warmed up and the coolant started moving. At this time the coolant started to "spit" out of the opening in the crossover tube. I quickly reinstalled the crossover tube cap, and shut the car off. The coolant level in the overflow tank was now way above the marks on the side. Did I do it right?

[ctrlraven]

Make sure also that the front end of the car is sitting on an incline so the air will want to travel towards the front of the engine to escape when burping the system. It may take a few times of burping it to get most of the air out. I would also replace the t-stat with a 180 degree especially if you are reusing t-stat from before.

[babbage]

I just got back in the house from trying to "burp" the system. I removed the cap in the crossover tube and filled it until it started to raise the level in the overflow tank. I than started the car and ran the engine with the cap off until it warmed up and the coolant started moving. At this time the coolant started to "spit" out of the opening in the crossover tube. I quickly reinstalled the crossover tube cap, and shut the car off. The coolant level in the overflow tank was now way above the marks on the side. Did I do it right?

Um, no. When I did mine - I topped off (poored 50/50) into the metal coolant tube 3 times and the reserve level never raised up. Use a pump or old turkey baster to lower the levels in the coolant reserve.

Secure the metal tube plug, start car for 1 min, shut off car, remove metal tube plug, pour in coolant slowly stop when its about to overflow the metal coolant tube. REPEAT until all air gaps are out of tube. Leave the coolant reserve cap ON tight during this procedure.

[RF Overlord]

Dave, try leaving the crossover cap loose, like just enough that it won't fall off, and run the car until it starts fizzing and spitting. When it stops doing that, tighten the cap. Others have had success by putting a funnel in the crossover bung large enough to allow the coolant to raise and lower while the air is being expelled, without spilling overboard.

[ctrlraven]

Dave, try leaving the crossover cap loose, like just enough that it won't fall off, and run the car until it starts fizzing and spitting. When it stops doing that, tighten the cap. Others have had success by putting a funnel in the crossover bung large enough to allow the coolant to raise and lower while the air is being expelled, without spilling overboard.
That's a good idea, I'll have to remember the funnel next time I flush my coolant.

[DearbornDave]

Thanks for the replies, it was a help, and I will definitely use the funnel trick next time I need to do this. Apparently what I did worked because I haven't had a problem in over a week. I asked the question because I had burped the system a couple times and I still had the problem, and I began to wonder if there was some trick to doing it, but I guess there's no trick, you just have to do it three times.