Over heating.. just a thought

When I replaced a freeze plug awhile back, I happened to notice that my cylinder walls in the water jacket were white. I didn't think anything of it at the time but I just watched this (https://www.youtube.com/watch?v=u4bGiv2MD74) random video about this product that removes scaling from water ways on boat cooling parts. Well that is the same color as my cylinder walls.

Has anyone come across this before and if they have can scaling cause over heating if it is on the surface of the water jacket cylinder walls? How can I go about cleaning it off?

Scaling build-up on heat-exchangers is a common heat-transfer problem in engineering. The scale build-up is like a insulation that reduces the heat-transfer from the engine through the metal wall plus scaling and so less heat gets into the coolant in a given time. The heat, generated by the engine, that doesn't get into the coolant stays in the engine and then the engine starts to run at a higher temperature. In a bad scale build-up, the thermostat stays full open, while the engine temperature continues to increase and run hot. Some flushes can help reduce the scale build-up somewhat to improve the heat-transfer, but for large scale build-ups an acid/chemical cleaning or mechanical removal is required ($$$$). Easiest solution is to upgrade the radiator size, to remove more heat from the coolant at a faster rate. This will lower the coolant temperature, increase the temperature difference between engine and coolant and thereby increase the heat flow out of the engine block and in effect lower the operating temperature of the engine somewhat. Then on engine rebuild, have the engine block chemically "cooked-out" to remove the crud and scale build-up.

Best regards,

CJR

If your cooling system is neglected, a simple citric acid flush should remove most of the scale. Following the maintenance schedule, and using distilled water, the cooling system should have minimal to no scale at all.

The XJ Cherokee runs warm, and upgrading from the stock single row radiator to a stock Heavy Duty Cooling double row radiator, and routine maintenance, should be all that is necessary to keep the engine temps at or about 195°.

The PO neglected the hell out of this XJ. I have already upgraded to a 3 core all aluminum rad. I also installed a 160 thermostat. I've run 3 flushes through it and the water/coolant comes out clear now. I was still having over heating problems. I took out the original mechanical and electric fan and installed 3 new electric fans. I don't know if it wants to overheat now since it is cold out but with the 160 thermostat and the 3 fans it wont go over 200. I want to switch the thermo to a 180 and hopefully it gets back to normal op temp. I'm afraid that if I go back to the original 195 that it will run too hot.

Properly maintained, I find that the stock fans with a Heavy Duty Cooling radiator keeps engine temperatures normal.

YMMV.

In reality, a low temp thermostat will not cure an overheat condition. It only circulates coolant thru the radiator sooner. Eventually it will over heat again.

Tim_MN said:

Properly maintained, I find that the stock fans with a Heavy Duty Cooling radiator keeps engine temperatures normal.

YMMV.

Click to expand...

with my current rad and stock fans I would start to over heat in a drive thru. only reason I changed over to the 3 electric fans is because I got them for free.

chickenbot said:

with my current rad and stock fans I would start to over heat in a drive thru. only reason I changed over to the 3 electric fans is because I got them for free.

Click to expand...

Good chance that they don't pull enough air, most cheap fans don't!

BTW: a 160* stat could be part of the problem also!

chickenbot said:

with my current rad and stock fans I would start to over heat in a drive thru.

Click to expand...

This is typically caused by a weak mechanical fan clutch and low speed overheating is accelerated if the fan shrouds are not installed.

Tim_MN said:

This is typically caused by a weak mechanical fan clutch and low speed overheating is accelerated if the fan shrouds are not installed.

Click to expand...

This is still after I replaced the fan clutch and put a new fan shroud on