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frusterated.overheating.

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1975 midget Stan Beer
Newcastle, Ontario, Canada   CAN
My 75 midget mk4,1500cc. Is overheating.long story short,I've replaced everything.i have a cross flow rad (new). When i put antifreeze in,it only takes halg the jug.do i have to prime tne water pump amd how do you do this? I've flushed engine etc. I would appreciate help cause its getting to me.

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capnkx Avatar
capnkx nathan c
Albuquerque, New Mexico, USA   USA
The quick and dirty way I do it:
Remove thermostat and add coolant until almost overflowing.
Replace thermostat and fill through top of thermostat housing and bleed/turn on heater/engine running yada yada
Hopefully you haven't hurt the engine, because the coolant may not be even touching the sending unit!

1975 midget Stan Beer
Newcastle, Ontario, Canada   CAN
Thanks for quick response. I guess i have to empty anti-freeze and start over.if thats all i have to do ,that's a bonus . I'll let you no if this works. Oh, the sender unit and temp guage still work. Lucky.

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Colonel musturd 79 Avatar
Colonel musturd 79 Michael McKinney
Winchester, Virginia, USA   USA
1978 MG Midget 1500 "Colonel Mustard"
1987 Pontiac Fiero "SILVER BULLET"
In order to lessen the traped air in the system If your new thermostat has an air valve cut it off If not drill a 1/8th" hole in the flat part of the thermostat that centers it in the housing this will allow you to fill the system with the thermostat in place. once you have the cooling system full start the engine with the fill cap off and watch for bubbles If they are present you have combustion gas leaking in to the cooling system- a possible leaking head gasket.



Amore della Strada
For the love of the road

76lucas Avatar
76lucas Gold Member Josh L
Floyd, VA, USA   USA
Here is the directions for refilling the coolant system by the manual.
1) Check all hoses and drain plug and insure they are fitted properly
2) Fill the system with coolant through the thermostat elbow filler(the large large hex head bolt on the top of the housing) until the level is at the bottom of the threads refit filler plug.
3) Top up expansion tank to half full point and refit cap.
4) Run engine until it reaches normal operating temperature than switch engine off.
5) Allow the engine to cool than remove expansion tank cap.
6) Remove the filler plug and fill to bottom of threads again Refit filler plug
7) Top up expansion tank to half-full point and refit the cap.

You might have to do the fill run refill a few times before you get all the air out.



If you never try to do it You will never be able to do it

1975 midget Stan Beer
Newcastle, Ontario, Canada   CAN
Overheating. Okay,i have let cool down and topped up at thermostat hoesing and still overheating.its as if there is a blockage I've flushrd engine or my one year old water pump isn't working. Whar do you think and what should i try next. Its still only taking about 2 litres.

76lucas Avatar
76lucas Gold Member Josh L
Floyd, VA, USA   USA
How was the engine flushed? Given the results your having it could be a blockage somewhere. After you have run the engine is there a noticeable difference in the temperature of the upper and lower radiator hoses? In other words after you have shut it off is one hose hot and the other one cold? That would indicate either a blockage or bad flow. You should also check the thermostat for proper operation. Easiest way to do that is take it out place it in an old pot with water than boil the water. Use a thermometer for high heat cooking such has one for candy and see where the thing opens up at or if it even opens. What was the original reason for replacing the coolant system parts?



If you never try to do it You will never be able to do it

1975 midget Stan Beer
Newcastle, Ontario, Canada   CAN
Overheating. Original reason was it wes overheating. Regards to hoses being one hot and one cold. No. Not a bog difference. Right now 4here isn't a thermostat in it but it's new too.i flushed engine with hose (hard spray) through heater hose going to engine block. Im going to flush again tomorrow. What is the best possible way. I think there is a blockage that i didn't get first time. What else could i try at this point?

76lucas Avatar
76lucas Gold Member Josh L
Floyd, VA, USA   USA
Try doing it from the upper radiator hose. This might allow you to get a larger volume of water into the system. If you start getting a lot of gunk than you may need to have it done by a shop using a back-flow flushing system. Also it is important to install the thermostat. Not having one will allow the coolant to flow faster through the radiator than it can get rid of the excess heat. Which in turn allows it to go back in and pick up more heat. It's basically like dumping coolant that's already close to same temperature has the engine into it.



If you never try to do it You will never be able to do it

mgtonyditter Avatar
mgtonyditter Tony Ditter
Brookhaven, New York, USA   USA
Just so its not left off the check list I am assuming you saw the MG service bulletin about the license plate
in front of the grill causing airflow and therefor overheating problems.

1975 midget Stan Beer
Newcastle, Ontario, Canada   CAN
Overheating. No i didn't know so I'll take them off tpmorrow and see if that makes a difference. Thx for the info.

dlrhine Avatar
dlrhine Silver Member Dave Rhine
Columbia, SC, USA   USA
North American 1500s had fan clutches...
Does your engine have the clutch fan or the solid fan?

A faulty fan clutch can definitely cause overheating when all other systems are in proper order...

Living in Canada you shouldn't be fighting high ambient air temps like we face down South, so that shouldn't be a factor...

How high are the coolant temps getting?



If it ain't broke, I'll fix it 'til it is! winking smiley

1975 midget Stan Beer
Newcastle, Ontario, Canada   CAN
Theres no fan so it must be clutch fan. U mean the one with spindle on it?

dlrhine Avatar
dlrhine Silver Member Dave Rhine
Columbia, SC, USA   USA
No fan?
Best post a picture of your setup...



If it ain't broke, I'll fix it 'til it is! winking smiley

1975 midget Stan Beer
Newcastle, Ontario, Canada   CAN
Here's the fan belt. Hopefully everything is visible for you.


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