Hydroboost Head scratcher

[axisg]

Short story... lent my van to a friend for the week whilst his truck is in for repairs. Driving home in a snowstorm tonight he said brakes went to the floor in heavy traffic ( with his grand baby and son in the van with him). They pulled in to a parking lot and can find no leaks. Limped it home and with the help of another friend ( whom is a mobile tech ) they can find no leaks. Pumps up fine when in the driveway ( assuming not running ) but once he starts rolling he said the brakes go 7/8 to the floor before they start to grab. Brake fluid is not low

2003 Astro \ Safari with hydroboost. He's over an hour away , guess I will get it towed back to work to get a better look. First thing comes to mind would be Master Cyl. It just rolled over at 320000 kms ( 200k miles ) and other than wear items its all pretty stock.

Does a MC just fail " all of a sudden " ??

 

[Bonnewagon]

They sure can. I think you are correct if there are no tell-tale leaks.

 

[jlcustomz]

Mc's do frequently leak internally. They many times can grab double pumping the brake & holding it will drop to the floor.

 

[axisg]

Proof of my life update. Got it towed back to shop on Wed. Mobile Tech swapped in a new MC on Thursday and I drove it home. Drove it back to work Friday and in bumper to bumper traffic the pedal went to the floor gradually. I checked it and the front brake line is leaking now. ROFL

Its to be expected with S.Ont vehicles. Snow plus salt equals rot even if it gets undercoated every few years since new ! It is now parked until it learns it's lesson and meanwhile I am doing deliveries in a bucket truck !