Cant find coolant leak
 

Been wrestling with this issue for the past week on my 92 fd. Coolant drips from the engine, but it only happens after the car is fully warmed up, driven a few times around the block, then turned off. The coolant doesn't drip on startup or when turned off. So far I've replaced the rad and checked the upper and lower rad hoses and everything is fine there. I hooked up the coolant pressure tester when the car was cool, and also no leaks. The car only loses about 500ml of coolant each time its warmed up and driven, but its becoming a nuisance. Anybody experience this problem before?

My next step is to remove the UIM and check the lines behind. Thanks in advance.

If coolant drips from the engine, then you have a leak somewhere. Make sure you check ALL the hoses. There is a coolant line that goes to the throttle body from the block that is between the firewall and the UIM. There is also a return line for it that goes from the throttle body into a hardline that then returns to the filler next area if memory serves. There is a supply and return coolant line to the turbos that is known to get old and split from the heat of the turbos. Don't forget heater hoses and AST hoses.

Matt

Thanks Matt, will do! Fyi I have the AST deleted. Ill grab a diagram of the coolant hoses in the shop manual and go from there

Pressure test the system.

System was pressure tested, the psi drops very slowly and can hear a hissing noise. I got in to removing the UIM today, and the line coming off the throttle body looks in decent shape.

If the pressure is dropping and you hear a hiss, then it is without a doubt leaking. Dried coolant typically turns white in color. If you can find white spots, that might hint where the leak is. When you said coolant drips from the engine, is it the front side? Back side? Driver or passenger side? This might give you more of a hint as to where to look.

the drip is coming from the drivers side (car is RHD), and lands on the steering rack. When i look up from the bottom it appears to be coming from a higher point on the engine. No white drips in sight

Get your self a stethoscope and start searching.

My 1st guess would be the water pump itself/pulley seal or the water pump to engine gasket

I'd put it on jack stands drop the lower duct/cover and let it run and drip until you find the leak

There is typically a "weep" hole on water pumps. When coolant leaks from this hole, it signifies the seal on the water pump is failing or has failed [requires replacement of the water pump]. Make sure that your coolant lines are clamped TIGHT as well. I had a small coolant leak from the lower line of my AST because the factory clamp had loosened up [was old and reused]. A new worm style clamp got it to quit leaking. Fritz has a good suggestion to run it and check for leaks if you can't pin point it with just pressurizing it.

Matt