after cold start and driving 3 to 4 miles in town stop and go the brakes wont fully release and top speed is 20mph. after sitting and cooling the brakes work fine until the next drive. Also I can crack open a brake line fitting at the master cyl and get instant brakes. I’m thinking masrer cyl or por portioning valve?? fluid contamination don’t seem to apply here. Help
I’d guess a failing brake hose. Hoses fail like check valves and hold pressure against the brake calipers. You release that pressure by cracking the bleeder. If your 19 year old car has never had them replaced, start there! If one has gone bad, expect the rest to be close behind.
If you still have the problem afterwards, suspect the master cylinder but at least your brake hoses will be safe.
Concur, failing rubber brake hose somewhere is the first suspect. There’s various rubber brake hoses involved. If one of the four wheels is much hotter than the others, that’s a clue which hose it is. However, if one has failed, that’s a canary in the mine situation, so good idea to replace all the other rubber brake hoses.