Thanks guys
In answer to the following:
"When was the last time you fully bled your brakes replacing all fluid? How old are your flexible brake hoses at each caliper?"
Have not done full brake flush but that is something I will be doing. Not sure thats where the problem is as none of the brakes are binding when the problem surfaces, although I guess if the brake fluid was boiling at at some point in one of the lines ...but again the substantial increase in pedal effort may nullify that.
"hmmm....good one. I suspect booster/servo or check valve at the very least. "
I have checked the check valve and it tests ok. Have done the brake booster check . Turned the engine off and continued holding the pedal for another 30 seconds and brake pedal stays. Then also with engine off did the
Pump the brakes five to six times then started the engine, and pedal drops like it should. Albeit both tests done while cold. Today I will try them again hot and see the results.
IT HAS TO BE THE BOOSTER as that is the only control for the braking pressure the bleeding will be deeper pedal movement
I pretty much agree but the normal tests (at least cold) don't confirm. I just don't get why it only gets weird after sitting hot....As long as I am driving at normal operating temperature it's fine...it only malfunctions on a restart after sitting hot for 20-30 min continues to malfunction when driving.
Any Additional input appreciated.
Today's Troubleshoot To Do List
Run booster tests when hot...Do the brake cleaner spray test for vacuum leaks when hot....check all lines for proximity to heat source ...replace check valve (just in case)....open a Newcastle
Stay tuned....Cheers