ok, inexpensive head gasket fix. take packet of ground black pepper from your kitchen and add to radiator. top off radiator with coolant. drive round for about 15 minutes to circulate pepper. if the head gasket is leaking this will fix it until such time as you dump the coolant.
as for your car looseing heat over 45 mph, i am going to say this is not caused by a faulty head gasket
this is more likely a faulty temperature thermostat or the timing in engine is not automatically advancing or retarding under load
take your vehicle to a mechanic
but not the mechanic that said the problem is head gasket
he doesnt seem to know what he is talking about
Normally they blow due to engine overheating. They can sometimes blow for no apparent reason.
Losing coolant with no apparent leaks, White smoke out the exhaust that has a sweet smell to it,
bad intake manifold gasket or a blown head gasket, check your oil level and see if the oil looks milky colored.
The gasket alone is actually a very inexpensive part (approximately $10-30), however the job itself is labor intensive - expect to spend $1-2k, depending upon whether the gasket replacement is preventative maintenance or a repair.
Bad plugs, or plug wires. Blown head gasket, or burnt valve. If you are loosing coolant with no apparent leak you may have a blown head gasket. Sweet smell at the exhaust is another sign of blown gasket. If none of that applies, replace the plugs and go from there.
The gasket is very inexpensive at around 2 dollars. I believe it is about a one hour job by book hours. The price should be around 75-100 dollars.
White smoke from the exhaust is a sure sign of a blown head gasket. You will also be loosing coolant with no apparent leak. A compression test will verify this. A rod will knock if the bearings are worn.
If you are referring to a head gasket the symptoms of a blown head gasket are.Engine overheatingLoss of coolant with no apparent leakEngine oil level overfullWhite sweet smelling smoke from the exhaust especially at startupPossible engine missA white or grey substance on the underside of the oil fill cap
Coolant in the oil, low compression on the cylinder where the gasket is blown, air bubbles in the radiator, sweet smell at the tailpipe, white smoke at the tailpipe, especially at startup, & loosing coolant with no apparent leak.
Moisture is getting into the oil pan. If you are loosing coolant with no apparent leak then you may have a blown head gasket.
External or internal leak. If there is no apparent external leak and you see white smoke then you have a blown head gasket.
I assume you mean head gasket. Symptoms are: White smoke from exhaust, loosing coolant with no apparent leak, oil level overfull, a white foamy substance on the underside of the oil fill cap, air bubbles escaping from the radiator, and sometimes an engine misfire. A compression test will verify if the gasket is blown.