Thread: overheating 4.6

Probably still a cracked block. I wouldn't touch a used 4.6 without replacing the liners with top hat types. Too risky. Removing the thermostat just leaves a quick path for gases to vent via the pressure cap. Have you had the cooling system tested for combustion gases?

ihavent had cooling system checked for combustion gases.is it done with exp tank cap off and a gas meter that measures co2 and o2?

the block has stepped liners.

regards brett

It's a p38... Not really much more to say.


Haha

May not be relevant to your situation but make sure you dont have any blockages in the coolant header tank pipework. I had overheating issues some time ago and found the thin metal pipe in the header tank was blocked with crud. Can test by undoing small diameter hose from radiator top left that goes back to header tank and make sure airflows freely. Unblocked mine with a compressed air hose hooked up to it and cured the overheating.

The radiator was replaced 3weeks before i brought rangie and the fan is pushing heaps of air (gets harder to turn by hand as it gets hotter)

Does the radiator look NEW and can the seller provide a receipt or maybe the seller got one from the wreckers that is clogged inside. A quick coat of paint and Bob,s etc.
Regards Philip A

A radiator repairer should have a tester. I've not had it done because the signs of coolant blowing out are obvious enough on their own.

One mod I did to a cracked D1 engine was to replumb the 8mm hose from the top of the manifold (goes via the throttle heater) into the top of the expansion tank via a screwed in hose connector. This way the only path for combustion gases is to the vapour space under the pressure cap, and it blows off without losing much coolant.

Other than that I believe its possible to fit the thermostat the wrong way around on those engines with predictable results.

Originally Posted by RGD129

ihavent had cooling system checked for combustion gases.is it done with exp tank cap off and a gas meter that measures co2 and o2?

the block has stepped liners.

regards brett

Brett

Did you have the stepped liners installed? Or the previous owner?

When installing stepped liners, it is imperative to either clamp the liners down while the block is cooling, OR press them home after cooling. The thicker flanged bit at the top actually expands longitudinally by about 8 thou of an inch when dropped into the heated block. The engineering shop should machine the step in the block to be slightly less than the stepped flange height, record accurate measurements of both, then measure how proud the liners are from the block after everything is cool, to ensure they are fully home. Then the block can be decked and the engine built with confidence. Otherwise the liners will press home under the pressure of the head gasket when it reaches operating temperature.

The above summarizes my own 12 month drama, with me stripping the engine down twice during that time. The solution (touch wood because it is currently running fine) was facing the block AGAIN to the same level as the liners.

I hope your problem is simply a blocked radiator or pipe as suggested previously.

All the best
Andre

thanks for all the info

the small breather on the radiator is spitting out water when the rangie is running.i can see it dribbling out when the engine is running with exp cap off.

the 8mm hose from manifold is running to the bottom of the exp tank atm but ill try moving it up near cap.

the liners were put in before i got the radiator.

ihad tryed puting the termostate in the top hose and it ran fine for 2 day but over heated today after 86kms

thanks again for all the feedback and info

regards brett