Still with the overheating problem.

[regularman]

I still have this problem and its driving me nuts. I have a brand new radiator, and extra heater core back near the differential plumbed with copper pipe back there, plus I have the heater valved on. New Thermostat, waterpump, electric fan. Here is how it goes. I can start out from the house with it topped up with water and climb mountains up and down and the heat hand will rise and fall a bit but generally stay around the N mark on the gauge, just as it should. After driving about 50 miles the heat hand starts to gradually ease on up until it gets hot. I stop the car before it boils over and let it cool and top it up and it settles right in again at the N mark for another 50 miles or so. Each time the radiator is low on water. I have a pressure tester and pressurized the system several times at 20 psi with no leaks. I even pressure tested the cap.
Today I drove it until it started getting hot and this time noticed a bit of frothy, oily substance come to the top when I started filling the radiator. I wonder if the engine is using water?
I have had this same problem since I have had the car. I had the head off and cleaned it good and checked for cracks when I had the car and engine all apart and put new rings and all in it. I wonder what it could be? Its a new head gasket, and certainly a different one than 10 years ago when I got the car and had the same problem. There is not any water showing up in the oil. I got no fogging out the back to indicate water in the combustion. This is perplexing.

 

[Biff]

"frothy, oily substance" , loss of water without boiling over are signs of bad head gasket, cracked head or block. No water in the oil says that it is not a water/oil leak but a water leak only, somewhere. Cracked head would be my guess.

 

[Trevor Jessie]

Didn't you also say the radiator was holding pressure after the engine had cooled?

This sounds (like Biff said) to be a crack. If you are 100% positive the head has no cracks, then you have to look to the block. :frown:

 

[texas_bugeye]

If its a cracked head, block or gasket leak from the combustion side to the water the pressure from the comustion is higher than the water pump capacity stopping circulation causing over heating. This can raise the pressure to the point were you blow hoses and or the radiator cap will bypass. This can also happen between oil galley and water jacket. foamy light brown residue (oil ) in the radiator. Also could be dumping water in the block area same resiude color on the under side of the oil filler cap. This only takes a very small leak.
If its in the block it will destory the bearings.

 

[regularman]

Didn't you also say the radiator was holding pressure after the engine had cooled?

This sounds (like Biff said) to be a crack. If you are 100% positive the head has no cracks, then you have to look to the block. :frown:

I am never 100% positive of anything, trevor. It could still be a cracked head. I need to look for another used head to play around with and get ready to swap. The think is that it is a very very small leak. I have put several thousand miles on the motor like this and did so back before I restored it. The usual sign of water getting into the cylinder is fogging out the pipe, but I don't see that at all. Yes it does retain pressure once the engine has gotten hot. I could wait a month and unscrew the plug and there would be pressure. It could be either the head or a crack in a cylinder wall. I just saw an Idea here on the internet for a check. Pressurize the cooling system again and then start removing the spark plugs and see if it leaks down. I could get no leak down last time. I put 20psi on it and left it and it kept the pressure. Thing is that all the spark plugs look about the same, you would think that the one getting water would be clean.

 

[aeronca65t]

Just a guess here (I always try to think of the simple, easy things first).

Look at your lower radiator hose. It is under suction (from the pump) and will sometimes collapse at higher speeds.
Rev the engine up and observe the hose.
Some loler hoses have a spring in them (to prevent collapsing). Others are molded thick so they are pretty stiff, but will get soft and collapse over time.

Also, check your ignition timing. If it is retarded, it will cause overheating.

Too much anti-freese and not enough water will cause overheating (water is much better at rejecting heat). You should have about a 50/50 ratio.

Try removing the thermostat and running the car without one. Won't hurt anything and worth a shot (might be defective).
I run a 165F thermostat in my MGB.

 

[tweety]

Simple... She's a hot Brit who likes to drink

 

[regularman]

Just a guess here (I always try to think of the simple, easy things first).

Look at your lower radiator hose. It is under suction (from the pump) and will sometimes collapse at higher speeds.
Rev the engine up and observe the hose.
Some loler hoses have a spring in them (to prevent collapsing). Others are molded thick so they are pretty stiff, but will get soft and collapse over time.

Also, check your ignition timing. If it is retarded, it will cause overheating.

Too much anti-freese and not enough water will cause overheating (water is much better at rejecting heat). You should have about a 50/50 ratio.

Try removing the thermostat and running the car without one. Won't hurt anything and worth a shot (might be defective).
I run a 165F thermostat in my MGB.

It got pure water right now for the most part, new t stat, same with the old one. Lower hose has the spring in it. I still think I need to pull the head and see if something is plugged or there is a crack or something. I don't know of any explanations that fit. Unless its something crazy like some blockage in the head and not letting the system fill up good with water and when it gets hot it boils.

 

[tweety]

I've heard that even the best engine (solid block, good head gasket) can still have very small imperfections that cause the symptoms of a blown gasket or cracked block.

You might want to give the K&W head gasket sealer stuff a try..... Again, I've heard that is solves some of these unidentifiable overheating gremlins you describe.

The directions call for the flushing of all coolant, run the car with the K&W solution for 20-30 min, then empty and let the car sit for 24 hours. Then flush and refill the system with 50/50.

I've also heard of success with people driving the car for 100-500 miles with the K&K solution in the cooling system, then doing the drain, 24 hour dry, flush then refill.

Who knows if it will work but at this point it's worth a try.

 

[aeronca65t]

Another idea:

Look at the water pump vanes and see if they're rusted away or eroded with excess wear (usually from dirty, rusty coolant.

A tight fan belt can slip if it's polished and old.

You don't have a Mini fan in that car do you? (they are "backwards" and will cause overheating.....I've seen it)

 

[scubabatdan]

Did it do it with a 50/50 mix or have you been running straight water? Because the problem with running straight water is it can not dissapate the heat fast enough and has a lower boiling point. The Ethylene Glycol in say Prestone 50/50 mix can help dissapate the heat and increase the boiling temprature over straight water. Are you noticing a decrease in the anti freeze level After it has cooled down?
If so then there is a leak somewhere.
Dan

 

[regularman]

Did it do it with a 50/50 mix or have you been running straight water? Because the problem with running straight water is it can not dissapate the heat fast enough and has a lower boiling point. The Ethylene Glycol in say Prestone 50/50 mix can help dissapate the heat and increase the boiling temprature over straight water. Are you noticing a decrease in the anti freeze level After it has cooled down?
If so then there is a leak somewhere.
Dan

I have tried 50/50 and water. I am just using water right now because its cheaper. It is about a quart low after it finally cools down and I relived the pressure. The pressure is not high like compression going into the cooling system, just a few pounds that I let out with the plug and fill it up. The little coolant tank always stays full.

 

[aeronca65t]

I absolutley agree that Ethylene Glycol (anti-freeze) should added to water as part of a good engine coolant. As stated, it raises the boiling point and also has important anti-rust qualties.

But the Thermal Conductivity (W/m K) of Ethylene Glycol is not as good as water.

It does not dissipate heat as well.
Pure water "cools" better.

This makes no real difference is a modern, properly functioning car, but it might make a slight difference is older cars with less-than-perfect cooling systems.

For reference, the Thermol Conductivity of Ethylene Glycol is 0.258 W/m K (taken at a fixed temperature)

The Thermol Conductivity of ordinary fresh water (also taken at a fixed temperature) is 0.609 W/m K

Just striving for accuracy here.

 

[regularman]

I am going to look for a decent used 1275 head and go through it and then do a swap this fall if it all hangs together that long. I can leave the house and go for a nice 50 mile ride with the top down and have no problems. The water is going somewhere and it if ain't leaking it must be burning it, but really slowly. Which really kind of bites because I set this car up to be decent on the highway. Cruises along nicely at 65mph and 3000rpms nice and quiet like and good on gas to boot.

 

[livinginthepast]

I think that I may have an old 1275 head in my garage that you can have for the cost of shipping if you want it. I really don't know its condition - it's something I picked up along the way... but, if memory serves me, it came off a 71 Midget.

PM me if you're interested and I'll go digging for it.

 

[scubabatdan]

What was the compression in each cylinder when hot?

Try this, run the engine to full operating temperature, shut down, quickly remove the spark plugs and do a compression test at each cylinder while still hot. If one or more cylinders is low. That indicates a leaking cylinder via a blown head gasket, poorly seated or worn valves, or even possible a cracked head casting.

If indeed it is found cylinder pressure is entering the coolant while running, the explanation for the coolant pressure not bleeding off back thru the cylinder leak(s). It is not uncommon for the cylinder gas leaks to occur one-way into the coolant at operating temp only. At shutdown the coolant often will NOT leak back in the reverse direction to the cylinder(s) because compression leaks tend to close when cool, and the coolant pressure is lower than the operation cylinder gases.

Also make sure you have the correct radiator expansion cap rated at 15 psi for a 1275 engine.
Dan

 

[toysrrus]

Hi Nial,

I have one of those "MINI" fans in my `59 Bugeye. I`m ready to strip & paint it & then replace it.

After reading your post; I`m having my doubts about putting it back on.

What would you suggest for a "BETTER" fan on a 948cc engine?

Thanx, Russ

 

[Morris]

Blown head gasket. Every car I have owned that exhibited the symptoms you describe was a blown head gasket. Honda, Subaru, MG, Ford. All had the exact symptoms you describe and all where a blown head gasket.

On my own car. It took about 3 head gaskets before I finally solved the problem. This is with a shaved head and block, APT head studs and Payen gaskets. The thing that seems to have finally sealed the deal is head gasket sealer spray.

 

[aeronca65t]

Hi Nial,

I have one of those "MINI" fans in my `59 Bugeye.....

Russ:

The A-series Mini fan blows "backwards".
If you have it on your Bugeye, it will push air "forward" and not "draw in" air.

As a consequense, you car will run hot or overheat.

You'd probably be better off with no fan.

I would suggest the standard Sprite or Midget four-blade metal fan. Many folks eliminate one of the fan blades on these four-blade fans (they are "stacked" so this is easy to do)). They still seem to work fine with two-blades and it may save a bit of horsepower.

 

[leecreek]

Kim, a little pricey but might work. NAPA Item#: BK 7001006

https://www.napaonline.com/MasterPages/NO...+/+Engine+Block