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1968 318 temp

calebkraft
calebkraft

Number of posts : 31
Location : Springfield, Mo
Registration date : 2018-07-31

1968 318 temp Empty 1968 318 temp

Post by calebkraft on Mon Aug 05, 2019 11:19 am

1968 family wagon (high top) with the 318 and a 727.
short : What temp should this engine be running at? (80+ degree weather, driving on country roads)


long: I got this beast running and didn't really worry too much about temp. Took it for a nice long drive with some highway to stretch its legs (after city driving for a few weeks). The overflow filled up and sprayed boiling coolant everywhere, so I pulled over and got towed.

After inspecting things, I see that my belt was slipping and pump wasn't spinning. this all makes perfect sense, but now I'm on edge. I replaced my alternator and belt and snugged it all tight.

I have no guages right now (trying to decide whether or not to go original or new). So I bought one of those caps that go on the radiator.

Driving on a hot day, I'll get a little bit of fluid into my overflow, but it doesn't fill up like that horrible day. The radiator cap will sit between 200-220.

Does that sound ok for temps? Seems hot to me from a bit of research, but people allso say these radiator cap guages show hotter. I have no idea.
vanny
vanny
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Number of posts : 11698
Location : Ashburnham, MA
Age : 60
Registration date : 2012-09-22

1968 318 temp Empty Re: 1968 318 temp

Post by vanny on Mon Aug 05, 2019 12:52 pm

Do you have a belly pan under the engine to direct the flow of air? I'm sure some of the Dodge guys will chime in.


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calebkraft
calebkraft

Number of posts : 31
Location : Springfield, Mo
Registration date : 2018-07-31

1968 318 temp Empty Re: 1968 318 temp

Post by calebkraft on Mon Aug 05, 2019 2:22 pm

I do have the belly pan in place.
OutofSight
OutofSight

Number of posts : 1281
Location : Lake Oroville, Ca.
Registration date : 2015-11-19

1968 318 temp Empty Re: 1968 318 temp

Post by OutofSight on Mon Aug 05, 2019 2:47 pm

I prefer 180*
calebkraft
calebkraft

Number of posts : 31
Location : Springfield, Mo
Registration date : 2018-07-31

1968 318 temp Empty Re: 1968 318 temp

Post by calebkraft on Tue Aug 06, 2019 8:28 am

when running to grab groceries and junk, it tends to sit closer to that 180 mark.
calebkraft
calebkraft

Number of posts : 31
Location : Springfield, Mo
Registration date : 2018-07-31

1968 318 temp Empty Re: 1968 318 temp

Post by calebkraft on Sun Aug 11, 2019 10:00 am

I installed a proper temp gauge and took it for some drives. Close to home, no problem, sits between 180-190 ish (gauge isn't super exact).

Then I took it down a stretch of highway and it crept up toward 210. The overflow filled up and foamy fluid gushed out of the overflow again. I'm suspecting a very slight head gasket leak or tiny crack in a head. That would make sense right? I have a test kit coming to test the antifreeze for exhaust.
OutofSight
OutofSight

Number of posts : 1281
Location : Lake Oroville, Ca.
Registration date : 2015-11-19

1968 318 temp Empty Re: 1968 318 temp

Post by OutofSight on Sun Aug 11, 2019 10:15 am

Interesting... let us know what the test reveals.
calebkraft
calebkraft

Number of posts : 31
Location : Springfield, Mo
Registration date : 2018-07-31

1968 318 temp Empty Re: 1968 318 temp

Post by calebkraft on Wed Aug 14, 2019 7:21 am

well, I did the fluid test thingy and it didn't show as having exhaust in the coolant.

with the cap off I can look down in there and see coolant moving after it gets warmed up, that means my thermostat is working, right?

I guess that leaves timing, fuel/air mixture, or exhaust leak right at the head. I'm no expert, but these are the things I'm considering. Does anyone have any more ideas why it would overheat when hitting the highway but be fine around town (more or less).
OutofSight
OutofSight

Number of posts : 1281
Location : Lake Oroville, Ca.
Registration date : 2015-11-19

1968 318 temp Empty Re: 1968 318 temp

Post by OutofSight on Wed Aug 14, 2019 7:31 am

You can remove your thermostat and test it in a pan of hot water to see if it opens up.
Keith D
Keith D

Number of posts : 189
Location : El Dorado Hills, Ca
Registration date : 2016-11-25

1968 318 temp Empty Re: 1968 318 temp

Post by Keith D on Wed Aug 14, 2019 7:50 pm

First I would put in a good quality 180 degree thermostat, yours may be stuck open, they are cheap.

Next I would check you hoses, if old the spring inside the hose maybe rusted out causing the hose to partially collapse at highway speed.

Lastly I would check the radiator and see if you see a bunch of buildup in the internal passages. It may be flowing enough for around town driving but not enough to cool it when you are generating more engine heat from freeway speeds. Does it also do it if you are going up a steep hill?

I don't think it is a timing, cracked head, or air mixture issue.

My opinion...

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1968 318 temp Empty Re: 1968 318 temp

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