Still Overheating.... any suggestions

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AlexxLush

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94
Ive changed the stat today and its not made the slightest bit of difference. I did notice that all the pipes where hot apart from the pipe between the heads to the top right hand corner of the radiator which was very warm at the end nearest the heads, and cold at the radiator end. I filled the system very slowly, and also filled the pipes to ensure no air locks.

Do you think I could have a knackered pump or radiator? Ive pretty much changed everything else bar the block.

Thanks for any advice offered :)
 
Alex, I had an overheating problem on my 4.0ltr 1999. I changed the thermostat and was advised by mechanic that the thermostat is working correctly if one side of the radiator is cooler than the other, ie - water flowing correctly and controlled by thermo stat. It still overheated, waterpump was ok, the pressure on the headetank was unbelievable. It was down to three things, Headgasket, slipped liner or cracked block. I stripped the enging ( my mechanic did) and the gaskets were ok - so one new engine later sourced at Turner Engineering in Surry (2300.00) and my Rangie is running perfectly. Sorry to be bearer of possble bad news, but if its not the Rad, Waterpump or Thermostat then start looking at the block
 
david.wade said:
Alex, I had an overheating problem on my 4.0ltr 1999. I changed the thermostat and was advised by mechanic that the thermostat is working correctly if one side of the radiator is cooler than the other, ie - water flowing correctly and controlled by thermo stat. It still overheated, waterpump was ok, the pressure on the headetank was unbelievable. It was down to three things, Headgasket, slipped liner or cracked block. I stripped the enging ( my mechanic did) and the gaskets were ok - so one new engine later sourced at Turner Engineering in Surry (2300.00) and my Rangie is running perfectly. Sorry to be bearer of possble bad news, but if its not the Rad, Waterpump or Thermostat then start looking at the block
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Thanks for the info David, I took my heads to Turners for skimming as thats what I first suspected. Putting the new head gasket in solved a few problems but not the overheating. My liners looked fine but Turners did advise my of a problem where the block cracks near the threads behind the pisons. I hope to god its not that as the only engine worth putting in is one with the ductile linings from Turners. How much did you pay for the full job including fitting of the new engine?
 
david.wade said:
Alex, I had an overheating problem on my 4.0ltr 1999. I changed the thermostat and was advised by mechanic that the thermostat is working correctly if one side of the radiator is cooler than the other, ie - water flowing correctly and controlled by thermo stat. It still overheated, waterpump was ok, the pressure on the headetank was unbelievable. It was down to three things, Headgasket, slipped liner or cracked block. I stripped the enging ( my mechanic did) and the gaskets were ok - so one new engine later sourced at Turner Engineering in Surry (2300.00) and my Rangie is running perfectly. Sorry to be bearer of possble bad news, but if its not the Rad, Waterpump or Thermostat then start looking at the block
Click to expand...

Water is not controlled by the thermostat in that sense. The thermostat is there to ensure the engine runs at it's optimum temperature and for no other reason. In normal use the thermostat opens once and once only, when engine has reached it's operation temp. The cooling is taken care of by water circulation by pump through the radiator. If there is a restricted flow through the rad the engine will over heat or if the water pump is not pumping well enough the engine will overheat. Any combination of these two things will cause problems. Running an engine WITH those problem over a period of time could cause what you list above that is certain, as you create hot spots around the engine which cause differing rates of expansion, which cause failure. The thermostat does not constantly open and close the control water flow. In effect when the engine is cold the thermostat creates a sealed compartment which is the cylinder block and heads to assist warm up. Only when this sealed compartment has reached operating temp does the thermostat open and allow flow through the radiator. If after warm up you have a pipe that is warm at one end and cold at the other you have a water flow problem. Simple as that. I get the impression from the first post that there is no water being forced out of system, at least they were not mentioned. So the only conclusion i can reach is that the temp gauge is running a little on the high side. A blocked rad or defective pump would cause that.
 
wammers said:
Water is not controlled by the thermostat in that sense. The thermostat is there to ensure the engine runs at it's optimum temperature and for no other reason. In normal use the thermostat opens once and once only, when engine has reached it's operation temp. The cooling is taken care of by water circulation by pump through the radiator. If there is a restricted flow through the rad the engine will over heat or if the water pump is not pumping well enough the engine will overheat. Any combination of these two things will cause problems. Running an engine WITH those problem over a period of time could cause what you list above that is certain, as you create hot spots around the engine which cause differing rates of expansion, which cause failure. The thermostat does not constantly open and close the control water flow. In effect when the engine is cold the thermostat creates a sealed compartment which is the cylinder block and heads to assist warm up. Only when this sealed compartment has reached operating temp does the thermostat open and allow flow through the radiator. If after warm up you have a pipe that is warm at one end and cold at the other you have a water flow problem. Simple as that. I get the impression from the first post that there is no water being forced out of system, at least they were not mentioned. So the only conclusion i can reach is that the temp gauge is running a little on the high side. A blocked rad or defective pump would cause that.
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Hi wammers thank you for that in such details thats a great help. I used to lose coolant before I did the heads but now; even though it overheats, I am not losing any coolant. The header tank boils up, and car overheats, I am also not getting any hot air through the BECM.

Is it know to be coming that the heater matrix pipes clog up; as when I tried to flush them out water did come through but it was very slow but because Im not sure what happens to the water after entering the bulkhead I didnt want to apply to much pressure.
 
AlexxLush said:
Hi wammers thank you for that in such details thats a great help. I used to lose coolant before I did the heads but now; even though it overheats, I am not losing any coolant. The header tank boils up, and car overheats, I am also not getting any hot air through the BECM.

Is it know to be coming that the heater matrix pipes clog up; as when I tried to flush them out water did come through but it was very slow but because Im not sure what happens to the water after entering the bulkhead I didnt want to apply to much pressure.
Click to expand...

Heater matrix's do get blocked as do radiators. Common problem with alloy units is if someone has used antifreeze not made specificlly for alloy rads or engines. Inhibitors are added to stop furring up of the internals. You can try one of the available rad flushes then back flush the units (flush them opposite to there normal flow). But usually on ally units once clogged by the fur that seems to grow within them, they are difficult if not impossible to clear, only thing to do is fit new ones.
 
I had problems a few years ago and did things like skimming heads, changing stats and the water pump etc first. Turned out to be a blocked radiator core which was about the easiest thing to replace!

Thats my bet

Regards,

Colin
 
Ive just ordered a new rad which should be here tomorrow! I agree with you magicol in that because of the nature/history of the V8 pople do just assume the worst and can be something simple; I guess though in too many cases its turned out to be something major and expensive!
 
I bought the engine with the upgraded linings. The dreaded VAT hurt a little and with the labour for engines out and in there was not much change from 4000 pounds.
 
just sorted my overheating problem out today..:) turned out to be the "Y" piece plastic thing, and narrow hose to top of thermostat was completely blocked!!, couldnt blow thru the hose so when i squeezed it, looked like dog ****e coming out, ha...finally cleared the hose, unblocked the "Y" piece and flushed the whole cooling system with a hose-pipe, filled back up, added coolant, bled and now sorted, phew!! also the heating now works from warm (which it did'nt before) needle staying in middle, very happy .....have u checked ur hoses?
 
jonb76 said:
just sorted my overheating problem out today..:) turned out to be the "Y" piece plastic thing, and narrow hose to top of thermostat was completely blocked!!, couldnt blow thru the hose so when i squeezed it, looked like dog ****e coming out, ha...finally cleared the hose, unblocked the "Y" piece and flushed the whole cooling system with a hose-pipe, filled back up, added coolant, bled and now sorted, phew!! also the heating now works from warm (which it did'nt before) needle staying in middle, very happy .....have u checked ur hoses?
Click to expand...

Hi jon thanks for that - its stories like yours that keeps me going! haha. I have had all the hoses off and flushed and backflushed the entire coolant system. What came out of the radiator was like a black cloudy water - didnt look good anyway. Im going to try changing the water pump and rad to see if that helps. After that the only thing I can think of is the matrix but ill try and bypass that to save buying one un-nessesarly.
 
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