4AGE 16V engine overheat when at high speed

[chenfon]

Dear All, like to get advise for my 4AGE 16V. nowadays mine unit easily get overheat especially when i run at highway (start over heat within 5 minuite). but if run at normal speed 70-80kmh the temperature remain half (as per temp gauge).

1st i suspect the gasket issue but check radiator fluid condition is clean, no milky.
2nd suspect thermostat jam, dismantle check result OK.
3rd suspect cooling system piping scale, all check and replace new piping but result remain.
4th suspect water pump efficiency drop, dismantle the pump check condition OK (had replace new in 4 years back)
5th susepct radiator cap spring pressure drop and cause air into system, replace new result still the same.

did any advise for me to check futher? tqvm

[Dave W]

I would first do a compression check, even if you do not have milky coolant. About the only thing left is the actual radiator. You could try a coolant flush to see if that might help. Clean the rad surface, straighten out bent fins, or find a rad shop that can rod the radiator. But you probably looking at a new rad. You can confirm insufficient Flow thru the rad, by seeing if running the heater reduces the temp. You do have an over flow tank connected in your system? I know my cooling system takes 2 or 3 short runs, then topping off the over flow tank, after cool down, to be able to get all the air out of the 4AGE cooling system.
Dave W

[jondee86]

What has been known to happen is that the return hose from the radiator can get
"collapsed" by the suction of the water pump at higher rpm. This can only happen
if the hose is old and very soft, or if the hose has started to de-laminate internally.

Some radiator hoses have a coiled steel spring fitted inside the hose to prevent
the hose being sucked flat. But if the bottom radiator hose is very soft it may be
worth while putting a new one on to see if it solves the problem. If the top hose
is also very soft, maybe replace them both.

Cheers... jondee86

[Power_uP]

Before you chase your tail with cooling system checks, it might be worth checking the timing.

[chenfon]

(06-10-2020 12:16 PM)Dave W Wrote:  I would first do a compression check, even if you do not have milky coolant. About the only thing left is the actual radiator. You could try a coolant flush to see if that might help. Clean the rad surface, straighten out bent fins, or find a rad shop that can rod the radiator. But you probably looking at a new rad. You can confirm insufficient Flow thru the rad, by seeing if running the heater reduces the temp. You do have an over flow tank connected in your system? I know my cooling system takes 2 or 3 short runs, then topping off the over flow tank, after cool down, to be able to get all the air out of the 4AGE cooling system.
Dave W

Dear Dave, thanks on the suggestion. i have flush all the cooling system during my water pump service. Yes, i have the over flow tank on it. so far it never go empty after i had replace new radiator cap. now i suspect there will be minor leakage at piping when i at high speed = high pressure create. Did any have idea on how to check this minor leakage issue, due after i stop and engine is hot. minor water drip will direct condense and cant found any sign....tq

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(06-10-2020 12:41 PM)jondee86 Wrote:  What has been known to happen is that the return hose from the radiator can get
"collapsed" by the suction of the water pump at higher rpm. This can only happen
if the hose is old and very soft, or if the hose has started to de-laminate internally.

Some radiator hoses have a coiled steel spring fitted inside the hose to prevent
the hose being sucked flat. But if the bottom radiator hose is very soft it may be
worth while putting a new one on to see if it solves the problem. If the top hose
is also very soft, maybe replace them both.

Cheers... jondee86

Dear Jondee86, thanks on the suggestion. will the the radiator hose to replace, due current as per your mention is soft. will update the result soon after get the hose and test run. tq

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(06-10-2020 01:31 PM)Power_uP Wrote:  Before you chase your tail with cooling system checks, it might be worth checking the timing.

Dear PowerUp, i confuse now. will it be cooling system get overheat due to timing? please do explain more.... tqvm

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Dear Guys, below as some of the photo of the overhaul water cooling system parts. tq

[Dave W]

If you are not seeing any change in the water level of the over flow tank, that would lead me to think that it probably the radiator. [ you would have a very small leak with no level change ] You could try cleaning the fin area with compressed air or water, then straightening any bent fins, but you are more likely going to have to get the rad rodded at a radiator shop or replace it. Dave W

[totta Crolla]

Retarded ignition timing or incorrect valve timing can lead to overheating. In simple terms the fuel / air mix is being ignited late enough for it still to be burning when the exhaust valve is opening.

[Power_uP]

Damn, I was beaten to it. As totta Crolla explained, incorrect timing can cause overheating. Its not a common occurrence on modern cars, but with cars as old as the 86 you would be surprised how many I've seen.

[totta Crolla]

Gave you some positive reputation as an apology Power_uP!

[jondee86]

Having trouble getting my head around this ?? Retarded ignition can cause
combustion within the exhaust system and lead to a red hot header. I don't
have a problem with that. However, the cooling system picks up heat from
the block and head so fuel combusting in the exhaust would have little
effect on the amount of heat being picked up by the coolant.

Heat is a product of combustion, and the more fuel you burn the more heat
you get. So if some fuel is combusting external to the engine, by definition
there is less fuel being burned internal to the engine. Logic suggests that
this would lead to less heat entering the cooling system rather than more...
n'est-ce pas ?

Always willing to learn so quite happy to be proven wrong

Cheers... jondee86