Engine temp at speed

[Frank Bruegger]

Hi Folks,

Ok, my 45 MB engine is freshly rebuilt (150miles) and seems to run well. At idle and around town the water temp stays at 180 degrees +- a little.

This evening I took the Jeep up into the foothills to a car show and this was about a 20 mile ride.
I had to run up hills and almost wide open in third gear. So, I had to run the engine that hardest since it's rebuild and the water temp hovered around 200 to 205 degrees. The air temp while driving to the show was 85 to 90 degrees, relativly hot. Am I overreacting on this or was this a little too hot. By the way, I got a new repro radiator from Ron and a new themostat as well.

What is the general opinion on this? What do most of your Jeeps temps run at in these conditions?

Thanks

[Ben Dover]

Do you know what the thermostat is rated at? Try a 160F Thermostat.

[Frank Bruegger]

I have always heard pros and cons about running a thermostat. I have one in it now and was going to check what temp it was made for. I was considering taking it out. Here in Calif, we dont have that much cold weather where I am so I figured maybe I can do without it. Thanks Joel for the suggestion, I am going to check it.

How bout anyone elses operating temps based on the conditions I mentioned in the first post.

[dkwkid]

When you put a load on an engine the by product is heat. Many things decide how much heat the cooling system can dissapate. Different motors require certain temps to run correctly. Running an engine without a thermostat will not in many cases allow optimum fuel atomization for proper operation. in addition, running a lower rated thermostat will not prevent overheating if the load exceeds the capacity of the cooling system.That is why modern vehicles run 195 thermostats for economy and fuel efficiency as well as aluminum core radiators to dissapate heat. If you are seeing the temp climb pull over and run it in neutral at a high idle for a bit until it cools off. I would have dropped into 2nd, slowed down until it went normal again-this will get the coolant flowing faster as well as taking the load off of the engine.

[echelon1]

When you put a load on an engine the by product is heat. Many things decide how much heat the cooling system can dissapate. Different motors require certain temps to run correctly. Running an engine without a thermostat will not in many cases allow optimum fuel atomization for proper operation. in addition, running a lower rated thermostat will not prevent overheating if the load exceeds the capacity of the cooling system.That is why modern vehicles run 195 thermostats for economy and fuel efficiency as well as aluminum core radiators to dissapate heat. If you are seeing the temp climb pull over and run it in neutral at a high idle for a bit until it cools off. I would have dropped into 2nd, slowed down until it went normal again-this will get the coolant flowing faster as well as taking the load off of the engine.

That is 100% correct.
The temperatures indicated are good in the assumption the temp gauge works properly.
Keep an eye on the radiator overflow, if the coolant does not burst when the temp is peaking, nothing is wrong.

Gindi.

[artificer]

Following on from the others:
Many things effect running temperature not just cooling system components & be in perfect operating condition.
No do not remove the thermostat no matter where you live & there is no need for a very low temp 160* thermostat.
Other things you can do is check the point dwell using your auto multimeter. Adjust if needed.
Then check your ignition timing, I would do & adjust using a vacuum gauge for better accuracy.
The gauge may indicate you have a vacuum leak which can cause lean mixture & elevated running temperture.
Also fine tune your carburettor settings.
Running @ elevation & low humidity conditions can contribute to higher than expected operating temperatures.
If you are not loosing coolant you are not boiling & thus not overheating.

[Ben Dover]

Since when have all Jeeps had to slow down on a drive from point A to point B while driving a Jeep in order to cool down? Remember, the MB/GPW was designed with a heavy duty cooling system designed to operate in year round in all climates.
Best place to start is to check the temperature rating of the thermostat that is installed. Right now that is an unknown. It might just be a thermostat rated 180F or greater. The thermostat controls the operating temperature. My MB has an OEM 160F Bellows thermostat, the operating temperature is a steady 160F year round even during 90F summer days. Remember, a thermostat insures quick warmup and prevents overcooling and overheating by automatically controlling coolant flow from the engine to the radiator. It is necessary in order to ensure the operating temperature is uniform thruout the engine block. The OEM thermostat in the MB was fully open @ 170F.
Hopefully the issue is simply the thermostat or even a loose fan belt.
There are other contributing factors, but they are more remote such as timing, faulty pressure cap, restricted exhaust system, etc.
If you can, post a pic of your thermostat.

[Frank Bruegger]

I did a quick search but couldnt find the answer. Since, for me the timing marks are next to impossible to see when trying to time my engine, what is the amount of vacuum I should be pulling? Artificer, I think you answered this before.

[Frank Bruegger]

Also, I have a brand new radiator cap and I am losing coolant when I stop and shut off the motor. The cap is the Napa correct replacment. I was losing coolant with the original as well. I figured it had a warn spring, so it was replaced.

[artificer]

Stop filling up the cooling system when it has cooled down & found its own level.
You just wasted money buying new parts to replace already good parts.
If when hot the hoses are taught when you squeeze them there is pressure in the system & all is good.
As for vacuum 17-21 in.hg move distributor till best reading then back off about 1/8 to 1/4" @ the outside of the distributor body, tighten & road test to ensure not pinging.

[Ben Dover]

"After boil" is also an indication of a faulty pressure cap or thermostat with to high an operating temperature.

[artificer]

"After boil" is also an indication of a faulty pressure cap or thermostat with to high an operating temperature.

Are we ready for an engine overhaul yet? Why turn something quite simple into a drama which suits your hypothesis?

[Ben Dover]

[quote="artificer"][quote="Ben Dover"]"After boil" is also an indication of a faulty pressure cap or thermostat with to high an operating temperature.[/quote] Are we ready for an engine overhaul yet? Why turn something quite simple into a drama?[/quote]
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The engine is too hot, what causes "hot", normally a thermostat. Good place to start, don't you think? :wink:

[Chuck Lutz]

Things to help keep op temps in a good range:
1) Correct 4 lb radiator cap
2) Cooling system that will hold pressure
3) Proper timing
4) 50-50 mix of anti-freeze/water
5) Correct thermostat...that works and isn't plugged up
6) Reliable temp guage
7) Tight fan belt
Radiator with no obstructions in it (bugs, etc.)

None of these simple things to check off the list cost money and as suggested above are the first things to look at. With a rebuilt motor, new radiator and thermostat I am leaning towards the timing as suggested....FIRST.

[dkwkid]

Since when have all Jeeps had to slow down on a drive from point A to point B while driving a Jeep in order to cool down? Remember, the MB/GPW was designed with a heavy duty cooling system designed to operate in year round in all climates.
Best place to start is to check the temperature rating of the thermostat that is installed. Right now that is an unknown. It might just be a thermostat rated 180F or greater. The thermostat controls the operating temperature. My MB has an OEM 160F Bellows thermostat, the operating temperature is a steady 160F year round even during 90F summer days. Remember, a thermostat insures quick warmup and prevents overcooling and overheating by automatically controlling coolant flow from the engine to the radiator. It is necessary in order to ensure the operating temperature is uniform thruout the engine block. The OEM thermostat in the MB was fully open @ 170F.
Hopefully the issue is simply the thermostat or even a loose fan belt.
There are other contributing factors, but they are more remote such as timing, faulty pressure cap, restricted exhaust system, etc.
If you can, post a pic of your thermostat.

In this post the writer stated that he was wide open in 3rd gear going uphill on a hot day. Maximum load on the engine with lower rpm "lugging" will cause the temp to climb.If you drop into 2nd the load drops as well as the rpm goes up causing better coolant flow. You see- it depends on your point a to point b destination. I live in Southern California and I drive in the desert all the time so I do have some hot driving conditions experience. I am new to this forum but I see lots of hooey about thermostats, engine heat and whatnot. Most likely nothing is wrong with the posters cooling system although it never hurts to check.