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jcatnite

jcatnite

Jedi Knight
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I've done nothing to correct this yet but just wanted to know how well other midgets out there perform in the cooling department. My 76 has a 160 degree thermostat and does pretty well as long as I keep the speed down around 45 miles an hour. If I get much past that for very long it starts to heat up and I've let it go as high as 210 to see how far it will climb... Got nervous and backed off a little. The PO put an electric fan on so it obviously has had issues in the past. So I guess my question is will the cooling systems on these little cars actually maintain the temp around 160 or are they doomed to heat up? I have learned that flipping on the heater seems to help control the temp a bit so looks like a new radiator is in the future at the very least. One of the supports is broken on the existing one anyways...
JC
 
good question...i just installed a temp gage in mine, been a year without one (yea i know DUMB) anyway mine gets to about 180 and stays there unless i am running about 55-60 then it drops...yes drops to about 165-170. as soon as i slow back down it comes back up. also note the temps around here have been running a pretty cool 50ish or so. This morning 25F it barely broke 160 on the 10 mile ride to work.


mark
 
First things first. The cross flow radiator in your Midget needs to be kept clean. They work well when maintained, but tend to gunk up and constict coolant flow (or so I was told by the mechanic I brought beer /ubbthreads/images/graemlins/thirsty.gif to each weekend). A fan is good, and an oil cooler couldn't hurt.
 
I am not a specialist on Midgets but on MGB I have seen quite a few heat up.

Generally make sure of the following:

Really good radiator
Really good water pump
Engine and radiator flush out if required
Fan runnning in the proper direction (my DPO mounted mine backwards)
Timing properly set (yes timing as an impact on temperature)
Good anti-freeze (50-50)
Proper thermostat (not clogged)

and so on...
 
My 1500 Spridget racer has a completely stock cooling system and stays cool under the most demanding conditions (including some 3 hour enduros).
As far as I can see, the cross-flow design on the newer Spridgets is quite good.
I had my rad boiled and cleaned and I replaced the hoses two years ago.
Our friend from Montreal (above) has made many good observations. Be especially sure that you do not have too much anti-freeze and too little water in your mix, since this combination will impede heat rejection.
 
I run a 160 thermostat and I run 160 degrees whether it is freeway speeds or freeway gridlock.

MYTH: Midgets will run cooler if you remove the thermostat
FACT: You need a thermostat to reduce flow so that the water spends enough time in the radiator to be cooled.
TIP: Anytime you have either the head or the water pump removed, replace the bypass hose. If it is the head you've removed, take a moment and clean the water journals.

JACK
 
Thanks everyone! That was just the info I was looking for. So Jack, or anyone who knows, which hose is the bypass hose? I get a little lost when I get to looking at the hoses that go to the heater box. I have what looks like an inlet and an outlet but then another smaller one that seems to bypass it. Is that the hose you are talking about? Also what is the valve that is mounted to the left of the heater box. I thought it might be a manual shutoff for the heater but when I tried to operate it coolant poured out of it so I put it back like I found it. The heater works so if it is a shutoff then it must be open...lol Thanks for the info.
JC
 
In most cases, when people talk about the bypass hose on Spridgets, they are referring to the one between the head and the water pump on the 1275 (and older) engines. A picture of this hose (#23) can be seen here:
https://www.mossmotors.com/Graphics/Products/Schematics/SPM-008.gif

Your 1500 also has a water line that is somewhat similar but I do not think it's normally referred to as a bypass hose. This hose (it's actually a metal line) comes from the back of the water pump and is under the exhaust manifold. It comes up at the rear of the engine and connects the heater valve control. This valve is #43 in this picture:
https://www.mossmotors.com/Graphics/Products/Schematics/SPM-012.gif

My car hasn't had a heater in a long time, but I think it should have only two lines going to it. One is direct to the engine and the other is routed through the heater control valve.
If your heater valve leaks when it's moved, it's obviously bad. As an emergency-fix, you could replace it with a short length of small, straight-though copper pipe (but you would have heat "on" all the time).
By the way, be really sure that your system is "full" and does not have air pockets. Use the plug in the thermostat housing to fill the car (when cold) and squeeze the hoses to "burp" all the air out....otherwise you can get some trapped air in the system.
 
Great! I know exactly which pipe you are talking about. I only noticed it last night. I've been working on rough idle, weird timing issues since I bought the car so haven't dove into the cooling yet. I figured the "heater valve" was installed to either allow or prevent water from going into the heater core but like I said when I decided to turn it coolant came out of what would be the stem packing on most valves. If I'm not so concerned with originality can I just replace it with a ball valve rated with for that temp or is there a bypass orifice in there that I should be concerned with?
JC
 
JC, the valve is a stock item, and it does control the heater flow. I leave mine on all the time just in case I'm sitting in traffic and the temperature starts creeping up. Even though nobody carries parts to repair the valve, it can be repaired. If you disassemble the two screws holding everything together and scrape off the old gasket, there is a small screw holding the valve packing in, and you can slide it apart. The O-ring has probably given up the ghost, but if you peruse the Autozone (or other part store) shelves, you should be able to find an O-ring to fit it, and if you find some gasket paper you can make new gaskets.

To answer your other question, mine had a LOT of gunk in the old radiator, heater core, and engine block, so I ran through several rounds of flushing and got gobs of rusty crud out of it. I also had the radiator recored because it was damaged, but for the most part, things stay around 185 (I have a 180 degree thermostat), but can creep up around 190-200 if I'm sitting bumper to bumper with the car in front of me.

Hope this helps!
-Dave
 
That sounds pretty simple. I might save that little gem of a rebuild for a rainy Sunday afternoon. As it is right now the heat is always on and it does come in handy. As uncomfortable as it is. I can turn the heat on full blast and get about 10 degrees of "extra" cooling if I have to climb a big hill or one of those 18 wheelers gets too close for comfort...lol. Thanks for the advice Dave I'll put it to good use.
JC
 
Also,
I know that I probably need to flush the cooling system but the antifreeze that is in there is prettier than the coolant that is in my 6 year old pickup. It looks like someone before me flushed it already trying to combat an overheating problem. That's probably why the electric fan is mounted on the front of it. I don't like the electric but I guess it can come in handy sitting in traffic. The fan shroud on these engines don't seem very comprehensive.
JC
 
I run an un-thermostat controlled (i.e. just the hoses to and from) oil cooler and a 165 or so degree thermostat. Regular position is at about 1/3 of the total range (no numbers on my '76) and it never gets past half (normal) in traffic. At speed, it never wavers from 1/3. I'm going to take some measurements to determine whether I should add a thermostat to keep tempterature up, but that's a future project ...
 
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