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MG Midget and Sprite Technical - Overheating Sprite

Looking for some guidance: ....Yes, I read archives this AM :0)

1275 midget motor in 67' Sprite. All new parts (total rebuild.)

Car overheated after idling on a VERY hot day despite letting it cool off and then running it around, it still overheated. I realized one of my problems was a major lack of oil (I felt very dumb on that one.)

So 2 days later...

I just replaced thermostat and radiator cap (insurance)

I ran the car, checked for leaks so far so good....

Some questions:

#1 I am running the original fan with no electric fan. I am 95 % sure the fan is oriented correctly. However I feel alot of blow-back off of the radiator. Is that normal???

#2 The radiator (that has been re-cored) is really hot on top and not so hot on the bottom. Is that a good thing or a bad thing? Does this mean a blockage or is this normal as the fan cools the water.

#3 I know if it goes haywire again, I will look at timing, and mixtures...any other thoughts?


Sorry for the long thread, just looking to be thorough.

-Steve


Steven Conant

go with the flow ;-) the hot water comes out of the head into the top hose into the rad. It falls down the rad as it cools and cold water is taken from the bottom and pumped into the engine, so your findings sound perfect. The oil plays a far greater part on keeping the engine cool than a lot of people realise, so I'd be confident you won't get a reoccurrence.
David (davidDOTsmithAT stonesDOTcom)



what are the spec of the rebuild, pure stock or hi performance....hi performance means more heat.

what is your water to coolent ratio....No more then 50/50 but I personally use 70% water to 30% coolant in all my vehicals, the less coolant the cooler the engine runs...But I live in missouri where the temps with humidity can be off the charts. Seriuosly Ive never had a Deep frozen ice cold engine that made the frezze plugs pop out during july and august...But I dont live in the north east. I guess thats why its called anti-frezze and not anti-heat.

Heres a tip to protect your engine during over heating

drill 1/8th inch hole into the stat housing face, that way it will elevate the pressure/heat build up and reduce the the chances of a blown head gasket or a cracked head...and it will also drop some temp as well

Also try water wetter, agian a small amount is all thats needed...2 table spoons IIRC

Prop
Prop

Okay,

Standard engine...no high performance gear except for a header.

I refilled the car with 50/50 coolant, Oil looks good, and car ran around the block several times at 50 mph.

Upon return from test run... Temp said 175 at idle, temp climbed up to 190..steadied and then spiked up to 212 and boiled over into overflow (currently the washer bottle). The car was idling for 20 minutes or less.

BTW it is a cool day in the North east 70 degrees.

No other leaks, all looks well, is it time to check timing and richen the motor a bit? Or is the fan back-ass-wards?

A Frustrated and confuised Steve

Steven Conant

Okay,

Standard engine...no high performance gear except for a header.

I refilled the car with 50/50 coolant, Oil looks good, and car ran around the block several times at 50 mph. Temp said 175 at idle, temp climbed up to 190..steadied and then spiked up to 212 and boiled over into overflow (currently the washer bottle).

BTW it is a cool day in the North east 70 degrees.

No other leaks, all looks well, is it time to check timing and richen the motor a bit? Or is the fan back-ass-wards?

-Steve
Steven Conant

Steve:
"boiled over into overflow (currently the washer bottle)"

Not sure what you mean by this. maybe I am misunderstanding you but it suggests that you don't have the system assembled properly.

The overflow should be connected to the expansion bottle. This is part of the pressurised cooling system. The pressurised system raises the boiling point of the water allowing it to run at above 212 without actually boiling (which drastically reduces the ability of the water to convey excess heat from the engine.

The "0verflow" from the radiator isn't really meant to overflow and waste water. It allows for expansion into the sealed and pressurised expansion tank and then, when you stop and the system cools, it draws that water back into the radiator. This is important to prevent air locks and also loss of coolant which would prevent the system from operating properly.

Guy
Guy Weller

Agree with Guy, the system has to be assembled correctly to work.
Robert (Bob) Midget Turbo

Guy,

That makes perfect sense. This car was a 10,000 parts in a box project. It did not have an overflow tank, like a modern car.

The set up reminded me of my MGB that just had an overflow tube that ran down the side of the radiator and drained to the ground.

I was using the washer bottle as an expansion tank but it certainly wasn't sealed up tight.

There was a pretty good surge coming from the overflow pipe back into the washer resevoir when car climbed up to 212 ish.

-Steve


Steven Conant

A vertical flow radiator doesn't have an expansion tank like the later crossflow rad system so when it boils it just dumps the coolant onto the floor (usually via a pipe).

However, if you don't have a pressurised radiator cap it boils at atmospheric pressure rather than quite a bit hotter - enough to prevent boiling over when standing still and idling.

Daniel Thirteen-Twelve

I am using a pressurized cap but at idle from cold start it creeps right up to 212 and shoots out a ton of coolant.

Is it possible that the radiator is just purging out excess??

But why so darn hot at idle???

Steve
Steven Conant

Okay,

Is it possible I have the wrong Water pump?

I will check to see if there is flow after the car cools off to see if I can see the coolant flow when thermostat opens.

-Steve
Steven Conant

Sorry, I saw that it was a 1275 and assumed a cross flow rad, but Daniel is right, the early 1275's used a vertical flow rad in 1967.

Even so, it shouldn't be boiling over at 212 degrees. Maybe you have the wrong radiator pressure cap?

Re-reading the symptoms: leaving the car stationary to idle for 20 minutes on a hot day is quite a long time and it may not be surprising that it boiled over. Although the fan will circulate air, the real cooling of the radiator - and around the engine bay generally - is from the air flow from the forward motion of the car. This is far more effective than the engine fan.

Maybe, now with the oil level properly topped up, there is no actual problem. Just don't expect it to stand with the engine idling for that length of time. Drive it! ;-)

Guy
Guy Weller

Guy,

My latest thinking is exactly that! Drive it and don't sit.

I am debating an electric fan for I believe that this car may have been a 1098 car with a 1275 added after the 1098 unit died.

I like the way the car is running currently and don't want to tamper with timing and mixture.

Thank you Prop and Guy and everyone else for your input.

-Steve on "beverage" break.




Steven Conant

I was thinking cross flow also

Back to your fan...can you post a pic. that would help alot...Im guessing you have the 2 blade that makes an "X" is that correct, if so Id upgrade to the plastic yellow 6 blade fan...I dont think thos "X" blade fans where vary effectve.

When you filled the rad, and started did you leave the car sitting at idle for 20 minutes with the cap off...I have to always do this on the midget to help purge out the air..other wise it turns into a gyser blowing steam and fluid 6 ft. into the air

In the northeast where your at...With idleing in place I dont think you will have a problem due to ambiant air temp...I doulbt you see too many 100+ F degree days

Prop
Prop

Instead of getting a different engine fan, ditch it altogether in favor of an electric, that way it only runs when it has to and doesn't sap energy from the engine all the time and lessens engine noise. I put one on my 1098 and it works great, comes on only once things are good and warm and I stop at a light, goes off again shortly after I start moving. Car maintains 185 all the time. Perfect.
J Van Dyke

Prop it is a metal 6 blade fan.

Would your 6ft geiser happen at about 200 degrees?

I did not do that on the last coolant re-fill. But I will give it a shot!

Thanks So Much!

-Steve AND his wife!
Steven Conant

Well,

There was an improvement.

I "bled" the radiator at idle, as Prop suggested. It did not overheat.

I then capped the radiator and idled it for 10 minutes, warmed up a little, drove it around the block parked it and idled it for 30 minutes and it just started to get hot and steam out of the overflow pipe a little bit.....I turned on my box fan and it settled back down.

So what do we think just go and get an electric fan to "help" the situation?

Should I get a thermostatically controlled unit or a switched unit???

I feel somewhat better on this situation.

-Steve
Steven Conant

Steve,

I think you got it, If it ran that long almost an hour before it got overly warm...your there.

id say give it another run and see what happens. BTW did you drill the 1/8th inch hole in the stat face, I know that made a big differance on my car when I did that. but nothing to thinning down the coolent to 2/3 water and 1/3 antifresse...besides when it gets cold, you can always add more antifresse

Most likely it was just a traped air bubble...trust me the A-series blocks and heads have got a lot of hiding places in the water gallies for air to hang out in

Id still recommend the plastic yellow fan instead of the metal one...(I didnt even know there was a metal 6 blade)

on the electric fans, it seems alot of guys here make there own set-ups, out of salvage yards but Ive seen a few nice little kits with everything included from a couple of companys called "Kenlowe" and "Hayden"

Try mossmotors.com...they got hayden, or Advance auto parts store they got a universal kenlow or vic brit...they got one for around $130 with the add on thermo kit, Im guessing the quick connect system for 5 dollars is just a few zip ties and acouple pieces of foam ... frankly Id buy a $5 footlong if it where me. LOL(see the link below)...I think the avg. cost is under $150

My guess (If Im wrong someone please tell me) you will need a 10 inch fan...a push or pull fan who knows that seems to be a popular debate around here, Id get one thats Bi...goes both ways. (Yeah Arie Im into Bi fans..SO Sexy..LOL) Known as a pusher/puller fan. as it can be mounted ither way.

http://www.victoriabritish.com/icatalog/sm/full.aspx?Page=75

Prop....Was my 6 ft. gyser 200+ degrees...HUH, Like Im going to stick my hand in to find out...Prop
Prop

My gyser occured when I put new coolent in after having the engine out for a week. the engine/radiator was completely empty, I put the coolent in put the plug back in the rad, and fired it up, about 15 minutes later the temp gauge was off the charts steam was pouring out the expansion bottle I screwed out the raD. PLUG and Whola...a gyser in my driveway...Luckly Ive been there and seen that before on a old mazda truck i had, so I knew what it was...so I always fill the midget rad, run it for 20 minutes un-caped, then cap the rad, run it another 20 minutes ...no problems

on the cross flow rad it has a screw-in plug in the rad, not a rad cap. the rad cap is on the expansion bottle...yeah its wierd

Prop
Prop

The thing I always found intreguing after a gyser erruption out of the rad is finihed. A steam vortex forms...like a spinning tornado, I can understand the steam, but why a vortex, how does that form, and why is it always in the same direction (left to right) there is nothing that I can see that would cause that...Anyone know, just a question that has always been in the back of my mind...

Prop
Prop

My fan is a 10" flexa lite, (http://www.flex-a-lite.com/auto/html/auxiliary-electric.html second one on page) scavanged off my previous car, it has a sensor and I rigged a toggle switch under the dash so I can turn it on and bypass the sensor or off, I also put a little LED near it so I know if it kicks in (can't hear it at speed and barely at idle). I have it on switched source so it turns off with the key, no need for it to be running after the engine is off, I wired it off a relay. I did have to shave the fan's cowling a bit to fit it in front of the cross member and behind the rad. It is a tight fit but that's good. It is also great to not have a fan in the way when turning the engine over to find TDC when setting valve lash or timing. I've had it on most of this summer and it's all good other than I put the sensor in the top rad hose and it sometimes leaks coolant there now, you can stick the sensor in the rad fins too otherwise. I paid nothing of course. Some get them out of wrecking yards from cars that have electrics stock. It seems to me though that you're fine and I don't know that I'd buy one if didn't need one, although you do get 1 or 2 more horse power because the engine isn't spinning a fan anymore, that's worth a bit too I guess. Personally I'd just drive your car an enjoy it. You're good to go.
J Van Dyke

Don't forget that on some models, there is a spacer between the pulley and the fan blades so that they are nearer the raditor to be more effective at upulling through the cold air.

What is distance between fan and rad?

A
Anthony Cutler

I have an electric fan on mine, but don't believe they actually improove the cooling - it is just that they are more controllable so that they don't have top be running continuously. They also sap less power from the engine.

But the mechanical one, properly fitted as Anthony points out, will cool it just as well as an electric one.

I still don't really understand why you expect the engine to run for so long at idle with the car parked. No air flow around the engine bay and it is bound to start to get warm in this situation. Cooling of the rad by the forced by air flow from forward motion of the car is far more effective than either a mechanical or an electric fan. They really only come into play at speeds less than 20mph. Above that they play little part in the process other than possibly to impede the air flow.
Guy Weller

My two pence worth. I can see the South Staffs chaps predicting what I might add! Is the fan the correct one for the car? Mine had a fan from a mini which meant it was pushing hot air into the rad rather than sucking cold air through. And no, turning it around won't change a pusher into a puller. The fan I had was from a mini and they push by design as the engine is the other way around. I swapped it for a puller and have had no problems since (excluding the scraped knuckles from teh rad fins when fitting it!)

I also agree with the others on needing a pressurised expansion tank in the system. Using a washer bottle means it's not pressurised and will boil at lower temperatures.

Ant
Ant Allen

I'm with Guy on this one, I have a Kenlowe and don't believe it adds to the cooling, one advantage is to stop the temperature skyrocketing when you come to a stop after a spirited drive, but for more consistant cooling I have left the mechanical one in place.

Also as others have stated, a midget was never designed to sit at idle for long periods, with no airflow and thinning oil lowering oil pressure all the time, this could end with serious trouble.

Also remember when stationary the ONLY cooling effect is the air provided by the mechanical fan, if your idle is set too low (600-700 or so)this reduces the amount of air passing through the radiator, as well as the efficency of the mechanical oil pump. If stuck in traffic for long periods you should rev the engine to 2000rpm for a few seconds intermitently, as this will help considerably.

I would be confident you seem to have a midget in good working order, so long as the temperature gauge is not being erratic and steam is not pouring out from under the hood, just drive it and enjoy!

Hope this is useful
Dave
D Prince

Thank you everyone.

I think I will throw in an electric, for peace of mind, but I do agree, don't let it sit...message recieved.

I will do a test with some cigar smoke to see if it is pulling or pushing...I believe it is pulling but I am not sure (Who knows where that fan blade came from.)

Thanks again for all of your responses, I have the 67 Sprit and a 74 Midget......The Adventure(s) Continue ;0)


Steve
Steven Conant

>> I will do a test with some cigar smoke to see if it
>> is pulling or pushing...I believe it is pulling but I
>> am not sure (Who knows where that fan blade came from.)

It's easier that that. Open the bonnet, stand in front of the car, and look down at the fan blades. One of the blades will be pointing almost vertically up at you. That blade should be angled from back left to front right as you look at it. The engine rotates clockwise so the blade moves from left to right as you look at it, and it should cut into the air and push it back towards the engine as it moves. If it goes the other way (front left to back right) then it's a pusher and you've found the problem.

> I have the 67 Sprit and a 74 Midget

In that case compare the angle of the fan blades. They should be the same!

Ant

Ant Allen

The cigar test works best if you have a pint of beer handy.

A
Anthony Cutler

After 6 pints you can dispense with the cigar and just put your hand into the fan and see which way the blood goes
Guy Weller

Hey steve,

I did some looking today...the "METAL" 6 blade is from the mini cooper, being thats from a side ways (transversed) engine, the radiator sits caddy wonk not at the front, so the pitch of the blades wont be correct...thus wont cool correctly, Also its designed to pull the air UP and partially push air over the rad. is this what it looks like see photo below ...Its got the nick name "Tropical" you want the plastic one made for the spridget...currently on ebay with hardware for 10 dollars besides the plastic is lighter weight

Prop

http://cgi.ebay.com/ebaymotors/MG-MIDGET-COOLING-FAN-RADIATOR-FAN-6-BLADE-MGB_W0QQitemZ140339766032QQcmdZViewItemQQptZMotors_Car_Truck_Parts_Accessories?hash=item20ace6e310&_trksid=p4506.c0.m245


Prop

My '63 got a test yesterday. Got stuck in a traffic jam, 90 degrees, dead stop for several minutes at a time for 40 minutes before I got clear. Never got hot (the car that is, I was dying) Electric fan kept up fine. A bit later, after stopping for gas the gearbox got stuck in 1st, is okay now.
J Van Dyke

Thanks Again guys,

I had to disappear for a week to go teach band camp (insert joke here).

But I am back now and electric fan does a great job.

-Steve
Steven Conant

This thread was discussed between 12/08/2009 and 24/08/2009

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