218 Temperature question

[lelshaddai]

I have a 53 Plymouth with 218. I have been rebuilding it. I drove it on the freeway for the first time today. I am running straight water with flush in it right now. It has a new 160 stat in it. The expansion plugs, hoses and water pump were replaced. The radiator and engine have been flushed and have flow. It was 105 degrees outside today and I was going about 65. The temp on the gauge reached the edge of the line towards the H but never reached the H. I stopped and tested the temp while the engine was still running with a infrared gauge. The rad cap is 7lbs. It read 205 by the temp gauge sender and 207 at the front top of the head. It has never boiled over. Is this about normal for these conditions? I will finish the flush and replace with anti-free and water next week.

[55 Fargo]

Well this depends on a few things.

You state it was 105 outside, and your boogying down the freeway at 65mph, probably witha 3.90 rearend, to the tune of about 3000 RPM, so yes it is going to get good and warm.

What was your temp at say 55 mph, did it cool down, once you exited the freeway, and started driving at slower speeds?

Did you get all the water jackets thoroughly cleaned out, did you pull water tube, and clean that out too?

If not you should have. How is your timing, lat timing can cause higher engine temps.

But a heavy load on super hot day= more fire=more heat and higher coolant temps.

You are running straight water, with your 7 lb rad cap, your boiling point is about 230 degrees, so you were t least below that.

I would say a clean cooling system with stock gearing, no OD trans, going 65 mph on a 105 degree day= 185-200 temp ranges.

On cooler day temps below 80, you might run closer to 160-170 range or so.

How many miles or how long did you drive at those speeds?

Next time, see if you can get a temp of the coolant in the top of the rad, without burning yourself...

[lelshaddai]

The tube is the only thing I did not clean out. When I pulled the freeze plugs it was not very rusty. Also the temp is not really hotter in the back than the front. I hope I understand the posts correctly. I thought that indicates the tube may be working OK since the back is not real hot. When I checked the Rad water before it was around 150 when the engine was 200. The temp did not really change much when I was on the freeway or idle.

[lelshaddai]

I drove it about 5 miles under those conditions. The engine ran for about 20 minutes.

[Jerry Roberts]

" I have been rebuilding it . I drove it on the freeway for the first time " Newly rebuilt engines tend to run a little hot , it might settle down when it loosens up . Perhaps you were driving it a little too fast too , it depends on your gears . Some people report good results with ' water wetter ' to bring temperatures down some . Don't do anything drastic until you experiment with the easy and cheap stuff first . Is your bottom radiator hose collapsing at higher RPM s ? Is your thermostat opening completely ?

Edited August 30, 2012 by Jerry Roberts

[Niel Hoback]

Jerry Roberts may have hit on it there. Can you feel the big spring inside the lower hose? Are you sure its there?

[lelshaddai]

The lower hose has a spring inside. I will check it to see if it is collapsed. The engine is not a total rebuild. The guts have not been touched. It had not run in over 20 years. I boiled the stat and it worked. I do not see as much water movement in the radiator as I would like.

[55 Fargo]

The lower rad hose you might see collapse as you rev the engine rpm up, replace if needed.

You do not want your coolant running through the engine so fast that the rad does not have time to cool. 2 things are required, heat dissipation through rad, and the correct flow to allow the heated coolant the time to cool before re-entering the block.

You had temp along the head at 200-205,and temp of coolant in rad 150, something not right with that.

The 160 t/stat should begin to open at 155 and be fully open at 180....