4efte overheating under boost

[Fahim]

I have changed my radiator,radiator fan,head gasket,head bolts,removed thermostat,but car is still overheating under boost only...car doesnt overheat all day if i drive normally.
When i bought the engine,i rebuilt it using new piston rings,new valve seal,new headgasket.
One of my piston was bit cracked so i changed all my pistons using 5efe pistons
I polished top of the 5efe piston and installed them,the piston looks same as 4efte piston now.
Compression is good enough,getting 10bar-12bar in all of the cyclinder.
Now need help for the overheating issue.

 

[Calum122]

Not that this is the problem. But polishing the domes of pistons isn't always desired.

The polished surface, whilst better for dissipating the heat to the cylinder walls, can have minute adverse effect on the performance. As the heat/pressure is the driving force of the engine, carbon build up on the piston crown can maintain this heat better to increase the pressures inside the combustion chamber and thus increase the force actuated on the piston dome.

Whilst not addressing your problem, was food for thought.

Did you use a new water pump?

Maybe it's on its way out.

 

[dac69er]

crack in the head? its not common, but it can happen.

try a leak down test. this is a bit more specialist, but may give you a better idea of what is happening sealing wise within the combustion chambers.

 

[Jay]

You may find that under boost conditions the coolant system is being compromised by a weakness in the headgasket.

I've seen it before on failing headgaskets.

Jay

 

[Fahim]

Not that this is the problem. But polishing the domes of pistons isn't always desired.

The polished surface, whilst better for dissipating the heat to the cylinder walls, can have minute adverse effect on the performance. As the heat/pressure is the driving force of the engine, carbon build up on the piston crown can maintain this heat better to increase the pressures inside the combustion chamber and thus increase the force actuated on the piston dome.

Whilst not addressing your problem, was food for thought.

Did you use a new water pump?

Maybe it's on its way out.

No i didnt insytall new waterpump,as from garage they said my waterpump's circulation is really good

 

[Fahim]

No head and block is checked,no crack found

 

[Fahim]

You may find that under boost conditions the coolant system is being compromised by a weakness in the headgasket.

I've seen it before on failing headgaskets.

Jay

I have changed my gasket 4times,didnt work though...

 

[Fahim]

Whernever i boost my car a bit,car overheats

 

[Calum122]

Have you an AFR? Could be running lean causing the engine to detonate increasing temperature.

 

[Fahim]

These r my pistons

 

[Fahim]

No i dont have a afr....
Can using a narrowband say me whether its running lean or rich?

 

[Jay]

What boost are you running and which headbolts have you installed?

 

[dac69er]

your issues can only happen if you have a warped block or head, a cracked block or head or a bad headgasket. the only other issue it could be would be lifting of the head, but thats normally only under higher boost levels. have you installed the head to the correct torque specs?
as jay mentioned, are you using the correct headbolts? i cant remember 100%, but are they different lengths? are all the threads ok in bothe the block and the bolts? is there any crap in the bottom of the bolt holes as this could make them bottom out before they pull the head down properly?

 

[Fahim]

What boost are you running and which headbolts have you installed?

I am running with the stock actuator boost...mayb around 10psi.
And i dont know about the headbolts,headbolts are bought and installed by the workshop

 

[Fahim]

your issues can only happen if you have a warped block or head, a cracked block or head or a bad headgasket. the only other issue it could be would be lifting of the head, but thats normally only under higher boost levels. have you installed the head to the correct torque specs?
as jay mentioned, are you using the correct headbolts? i cant remember 100%, but are they different lengths? are all the threads ok in bothe the block and the bolts? is there any crap in the bottom of the bolt holes as this could make them bottom out before they pull the head down properly?

Brother everything is done by my mechanics,they said everything is ok,and headbolts are tightened correctly.
They are saying that the problem is with piston,and now suggesting me to change the engine.

 

[Fahim]

Brother everything is done by my mechanics,they said everything is ok,and headbolts are tightened correctly.
They are saying that the problem is with piston,and now suggesting me to change the engine.

Now i need a solution in my present engine,can anyone suggest me to do sth?

 

[dac69er]

i cant see how the piston specifically would cause overheating under boost unless they are damaged in some way, but this would cause other problems.

are you getting any oil blowby out of the breather at all? is the car just overheating (gone over halfway on the gauge) or is it overpressurising and blowing the coolant out? have you tried running with no thermostat?


is it definitely the boost that is causing the overheating or is it the rpm?

thanks
Duncan

 

[Fahim]

i cant see how the piston specifically would cause overheating under boost unless they are damaged in some way, but this would cause other problems.

are you getting any oil blowby out of the breather at all? is the car just overheating (gone over halfway on the gauge) or is it overpressurising and blowing the coolant out? have you tried running with no thermostat?


is it definitely the boost that is causing the overheating or is it the rpm?

thanks
Duncan

Brother no engine oil consumption and no white smoke from breather or exhaust.
Car is overheating only when rpm is over 3500 or when car starts to boost,and gauge is going over halfway when boosting or driving the car in high rpm.
And when car overheats,water is goes out through reservoir tank.
And i bought my engine without thermostat.and this engine was overheating from 1st.

 

[Fahim]

Need help,please anyone help me out from this mess

 

[dac69er]

If it is pressurising the cooling system you have a bad headgasket, a crack or warp in the block or head or the head isn't bolted down properly.

The only other unlikely thing it could be, is the water jacket of the turbo is cracked and boost pressure is pressurising the cooling system. This is very unlikely. Worth bypassing the coolant to the turbo to rule it out though.