2001 F=250 Super Duty, 5.4l, 120K.

Noticed a smell of hot coolant, but it doesn't seem to be losing much from reservoir, and on inspection cannot see obvious leak.

I am guessing there is a pinhole in radiato?

How to test ... ?

 

Check the bottom left and right corners of the radiator. Pin holes are common from my experience.

 

Also take a look under the intake manifold in the engine "valley", bypass tube leak. and feel the carpet under your dashboard, heater core leak.

 

OK, will check, but I should have clarified: the smell is not in the passenger compartment, it is in the engine bay.

If I still cannot see anything obvious, would it make sense to take it to a radiator shop?

Are there tests they can do (without disassembly) that I cannot?

Thanks.

 

They should have the adapters to perform a pressure test on the coolant system. A close eye on all your hose connections might reveal where the leak is.

 

The coolant can also be coming from the water crossover on the passenger side with the heater hose where it mates with a cracked intake man leaking down into the engine valley. But as Dyno said, take a look under the intake for coolant coming from either or....

 

Follow up: A radiator shop did a pressure test.

At about 15 psi, tech said saw coolant begin to well up and drip from rear corner of head on passenger side.

Hopefully it is leaking from somewhere else and running down and pooling there.

A Ford mechanic I know said it is not likely that the head gasket would leak there.

Comments / suggestions as to how to best zero in on the problem?

 

Heater bypass tube? Intake man. gasket? Theres 2 coolant ports at the rear of each head (1 on each head) as well as the front.