318 Correct operating temperature?

[VistaCruzr]

Sent: 7/27/2005 5:06 PM

I just tuned up my "71" 318 and she seems to be running great...but, she is running on the high end of the heat gauge (ran hotter than I would like since I bought it) and actually steamed a bit on our last trip to the Kenai River. In my efforts to save time and money I thought I would tap you guys with 318's to see if there was a  little more info available other than what was on the overheating posts. Posts are kinda general. Is there a starting point that is better (clutch fan replace) for example. Any help would be great.

Dan/  Vistacruz

[heynnema]

Sent: 7/27/2005 8:35 PM

Dan,

The 318 has a "hot" thermostat in it. 190 degress, if memory serves me correctly... so the temp gauge will normally be at the 3/4 mark... however, you probably won't find a 190 thermostat at the auto parts store, but 185 is readily available, and that's what I've got in mine.

Cheers, Al

[Slantsixness]

Sent: 7/28/2005 7:18 AM

My '72 318 has a 185° thermostat, and I didn't bother with the correct "shouldered" one either (just be careful to center the thermostat when you install it and  Silicone it in place).

My Temperature guage reads:

C \___/__/ H

under normal driving at 99° & 90%R.H. outside temperatures (typical VA summer...)

When climbing a 15% grade, she got up to here:

C \_____// H

The manual states that there is no cause for concern until the tempperature guage hits the H, or this:

C \_____/ H/

And, yes.. IT CAN GO THAT FAR UP! this is approximately 300°, and that's too hot for even a pressurized system. over 320° and your head gasket will blow.

The reason this happens is because of the position of the temperature sensor in the M300 chassis, it's located on the test port on the rear of the right head bank. If you hooked the sensor back up to the intake manifold Water inlet crossover at the thermostat, the temperature readings are considerably lower there, because you would be measuring the coolest part of the cooling system.

M300's use coolant at the carb base and the offset mounted water pump, both of which prohibit using the sensor in it's traditional location (on the intake manifold). The part of the head where the M300 sensor is located is typically a higher temperature than your average "non-motorhome" 318.

As for your coolant gurgling or loss, do you use a recovery tank? Or do you just let it drain out? Further, if you don't use a tank and have replaced the 16 pound radiator caps (both of them), then you have "closed system" caps with the large gasket at the top, not just the small gasket at the bottom spring portion of the cap.

If you don't have a coolant recovery system, you can get one from Interdynamics for under 20 bucks from a discount place like Advance Auto parts or AutoZone, and it'll mount behind the grille very easily. If you have the old "open" system caps (no upper gasket) then replace both radiator caps.

The mounting of the Interdynamics recovery tank is pretty straightforward, however, be sure you use the recovery nipple on the Main radiator, not the extension fill tube! If you don't have ports at both points, then it's ok to use the extension nipple, but the coolant will stay about 14 oz . low, which shouldn't be a problem.

You can still get the 190° thermostats at NAPA, but I wouldn't use it. Go for the 185°...

I'm going to repost this in another discussion so people can find this with the message search.

Under "Temperature Guage Reads High"

Hope I helped,

Tom

[VistaCruzr]

Sent: 7/28/2005 4:48 PM

Tom,
Thanks for the feed back. That is a relief. I tested the temp when I bought the rig with a infra temp gun and it was under 200 degrees at any given location on the block. I was still uneasy about it. The coolant did have to be replenished during the trip back, so the overflow jug is next on my list of add ons. One of the "R" caps looked pretty shot when I got the rig and has already been replaced. New thermostat replaced at the same time (190 I think). Once again CWM to the rescue. Thanks alot Tom. Let you know how she pans out after repairs are done.

Dan/Vistacruzr

[heynnema]

Sent: 8/5/2005 6:03 PM

Tom,

Ouch, my 72 Brave D20 w/318 never gets THAT hot with my 185 degree thermostat.

It normally runs at half mast, and will creep up to 3/4 going up tedious long hills.

I've got a brand new radiator, new hoses, new thermostat... and maybe that radiator makes the diff(?).

Cheers, Al

[chip]

Sent: 8/7/2005 3:22 PM

a Flow Kooler water pump might help some. [cast iron pump#1701]. less anti-freeze and more water with Water-Wetter additive for better heat transfer might also be beneficial.

i also use a pusher fan in front with a flex-a-lite fan on the pump but, i'm not sure this would help in your situation.

when you work the old beasts that hard they are going to get hot--given the limited coolant available and the amount of air you can force thru the radiator of these things.
All the stuff I did to my system helped to some degree but she still gets warm when I'm slogging thru a sand dune at 3 mph.

Maybe I should put the radiator on the roof.   

[Frank M]

Sent: 8/11/2005 9:06 AM

My 73 - 318 runs nice and cool. I actually disconnected the heater and run the heater hose out and then right back into the engine creating a heater bypass. I did this because even with a brand new heater control valve I would still get some heat coming out and in 90+ degree weather that does not feel so good. I also removed the thermostat. In the fall I sometimes remove the heater bypass and hook the heater back up so the wife's tootsies don't get cold.

[ClydesdaleKevin]

Sent: 8/14/2005 4:13 PM

Frank:

NOOOOOOOOOOOOOO!!!!!!!!!!!!!  DO NOT REMOVE YOUR THERMOSTAT!!!!!!!!!

The thermostat does more than just let your engine warm up more quickly.  If that was all it did, then it wouldn't be a problem.  But the thermostat does so much more!

Not only does the thermostat let your engine warm up more quickly, but it also controls the water flow.  It does this in a couple of ways:

First, it keeps the water from moving through your engine TOO quickly.  In other words, heat induction from steel to water is more complicated than just shooting water past it.  Water has to be in contact for X amount of time for heat to fully transfer...then the water moves on at a controlled rate, a rate controlled by the THERMOSTAT, among other factors, through the radiator, where the heat dissipates, also at a controlled rate, which is also controlled by the thermostat, among other factors.

Secondly, the thermostat DIRECTS water to certain parts of the engine, such as the heads, which otherwise wouldn't get enough coolant.  This is especially true of skirted thermostats, but also applies to conventional ones.

The moral of the story?  Only take out your thermostat in extreme emergencies, and then only for a VERY short time!  In other words, if you break down because the thermostat fails:  Take it out so you can drive home...then replace it.

If you want it cooler, get a cooler thermostat.  I have a 160 in our rig.  BUT DO NOT DRIVE FOR PROLONGED PERIODS WITHOUT A THERMOSTAT.

Ok...the dead horse is beaten well enough...lol.

Kev

[Slantsixness]

I agree with Kevin.

I would also say that if you keep your cooling system maintained, the thermostat will almost never go bad.

Funny thing... so many people blame the thermostat on their overheating problems, but just exactly what is a thermostat? A bimetallic spring and a round plate that opens and closes with temperature... I can assure you that the spring will never wear out or stop responding to temperature change! Now sludgey antifreeze and water with high sediment or rust content could corrode the thermostat over time, but trust me.. the sediment and corrosion is doing more harm to your radiator,heater core and hoses then it is to the thermostat!

So, use distilled water, pure antifreeze (not the 50/50 crap they sell now) and stay away from the leak preventing and anticorosion, and "flush" additives.


Also, let me explain the "right "hot" mark" from above

C \       // H

not  C \        / H/


Chip,
LOL...
When I got my Winnie I thought a radiator WAS on the roof! I have dash AC and the Condensor was on the roof with a fan! I wonder whether putting a radiator on the roof would just cause roof leaks!But they did use to do it on water cooled dune buggies....!

These things always run hot, but a mechanical guage may show that it's not quite as hot as it seems, as ClydesdaleKevin found out.

Tom

[gadgetman]

Another option to removing the thermostat would be to just cut out the center. This way you still have the restriction the thermostat was ment to give it. Well most of that you still have with the plate removed.

Thermostats do fail. They usually fail by binding and sticking. Some fail because the wax/thermo bulb leaks out its wax. I carry a cut out stat just for a spare if needed and a new one. Why do I carry both ...hmmmmmmmm good question LOL, I carry way too many spare parts