What does it mean when my car is knocking in the head and blowing white smoke but not overheating?

Answer 1

If the vehicle is knocking it depends on where the location of the knocking sound is coming from if it is coming and what type of engine it is in other words

1) Is it a (DOHC) Double Over Head Camshaft Engine.

2) Is it a (SOHC) Single OVer Head Camshaft Engine.

These two choices are the topend of your engine

3) Is it a In Block Camshaft Engine.

This choice is the bottom end of your engine

If your engine is one of the first two choices listed above the problem can be either a valve has bent or broken off and is being tossed around in the combustion chamber or what is known as the TopEnd

If your engine is number three choice a push rod has been broken

(These are the most common problems)

Now if the engine is inblock cam a push rod may be bent or a valve might also be broken.

But to give some better direction if your engine is blowing whit smoke and making a knocking noise you might have burnt or sticking valves along with a blown head gasket

a cracked engine block or cracked cylinder head.

There are several ways to test and diagnose your problem one check your spark plugs and look for several things as in

Is the Spark Plug covered in oil

Is the spark Plug Rusty Looking

Checking the Compression on all cylinders

Checking cylinder Leakage on all cylinders

Pressure test the block with a radiator pressure tester

Check the color of the coolant/AntiFreeze see if it is brown or looks like chocolate milk

You can also test the Exhaust fumes from the tail pipe with a special tester

But if you do not want to perform all of these tests then the simplest thing that you can do to make sure all of the cooling ststems work properly.

1)Remove the thermostat and put it in hot water and visually inspect to see if it opens if it does it works fine

2) This is going to sound stupid but it works turn your heater on and watch your temp gauge it will rise for a little bit but then the guage will go back down to a lower temp. because you are heating up the coolant witch will heat the thermostat and cause it to open and allow flow of coolant

3) Visually inspect radiator for leaks rust spots cracks and repair as needed

4) Inspect Hoses Replace as needed

5) Inspect water pump if leaking from pump replace

Now with all this being said check all connection points as in the radiator necks for cracks, breaks, softness check the water pump contact areas on the pump and block same goes if the problem is a head gasket if replacing but check for burrows, chips, frays, cracks, rust, any imperfection that will not allow the gasket to seat properly

Another diagnosis is check to see if any previous repairs in these areas might be the cause as in look for spots where silicone and RTV are visible if so you will need a new radiator and the block will most likely need to flushed.

Also one neglected area is the freeze plugs they might be rusted and leaking coolant replace as needed.

I hope this information will help you in your repairs.