230* ECT

[Blue Goose]

Pulling a 7-8K load at 60 mph, had already traveled about 150 miles with no issues when in about 20 seconds my ect went from 196-198 and jumped to 230 and I immediately backed off while trying to find a place to pull off of the road and in the next 20-30 seconds the ect went down to a low off 177 and then eased right back up to 196. This confuses me because the eot stayed at 202-204 the whole time that this happened. After stopping I checked the degas bottle and it had puked just a little around the cap, not everywhere, and I installed a new cap about 6 wks before. After temps returned to normal I came on home without any more hiccups. Yesterday I ran the same route again with the same load and everything was normal. Just wondering what is going on or about to happen.

[thomaslord84]

I seen a thread on here where this happen and it was headgaskets. I will try and find the thread and post a link. Hope this helps.

Have you replaced the thermostat lately? How many miles? The failsafe on the thermostat fails in the open position though. Also may be a bad sensor.

[Blue Goose]

64k miles, using insight to monitor engine, have not installed the new t-stat yet, planning on reflushing the system again soon and put it in then. I just dont know how or why the ect would spike that high that quick and not have any effect on the eot.

[HAM_RADIO_MAN]

Originally Posted by Blue Goose

64k miles, using insight to monitor engine, have not installed the new t-stat yet, planning on reflushing the system again soon and put it in then. I just dont know how or why the ect would spike that high that quick and not have any effect on the eot.

If it was puking it really did get that hot. Check out your Fan and harness. Could be a HG going away on you. As far as what your saying about EOT , It could be that this even happened so fast that there wasn’t time to transfer that heat to the oil. Especially if this was a localized event with combustion gasses entering the cooling system. See to troubleshooting guide in my signature for more answers to your questions.