Prelude 4th losing power, noisy

[feizor]

Hey guys,

I've got a '96 4th gen prelude.
125,000kms

After about 20mins driving or 15mins in peak hour, as the temperature gauge reaches half way, it starts losing power.

The engine becomes noisy/rough. The temperature gauge never goes past halfway though.

Although it's annoying, it doesn't bother me TOO much but could this be a sign that some bigger problem might happen in the future?

After this symptom started occurring I have:
Flushed the coolant
Changed engine oil (Honda FEO)
Changed spark plugs + leads (Bosch)

Still not solved.

I've also posted this in preludeaustralia.com but I think more people use this forum.

Cheers

[thepope1986]

engine seems to be cooking. hows your water pump? is it pushing water properly. whats the condition of the head gasket might not be a bad thing to check for leaks there.

[feizor]

I'm not sure if the water pump is pushing the water properly, how can I find out? Coolant doesnt seem to be mixing with engine oil, is there another way I can check for leaks in the head gasket?

[UR34DY]

are you losing water? before you take it for a drive, check the water in your radiator if your losing water that means there is a leak some where. if your engine oil is fine your head gasket is fine.

[aaronng]

Is it a VTIR? Are you using 91 or 95 RON petrol?