mfg Posted January 15, 2022 Report Share Posted January 15, 2022 Here's a question I'd like to toss out to the mechanically minded out there...its got me scratching my head! I use an '83 Avanti for everyday transportation...It's basically bone stock. The braking system on this Avanti is in good condition, and, I believe, well maintained. Here's the issue....It gets COLD here in the Boston area...and whenever the temp drops below, say 15' F., I COMPLETELY lose assist from the power brake unit..UNTIL..heat from the warming up engine migrates into the unit..which then works completely normally. (when warm the power brake booster operates just fine.) Bear in mind I do have brakes!...however with much greater pedal effort until the booster warms up....SOUNDS CRAZY HUH??......But unfortunately true. THOUGHTS ABOUT THIS ARE WELCOME!!.....Ed Link to comment Share on other sites More sharing options...
adamderosa Posted January 15, 2022 Report Share Posted January 15, 2022 I have experienced this in my Avanti as well when it's really cold. I believe what may be happening is that the diaphragm and seals inside the brake booster become stiff at cold temps and cannot function properly until it warms up a bit. Link to comment Share on other sites More sharing options...
studegary Posted January 15, 2022 Report Share Posted January 15, 2022 Hopefully, you do not have some moisture/water trapped in the system. Link to comment Share on other sites More sharing options...
mfg Posted January 15, 2022 Author Report Share Posted January 15, 2022 32 minutes ago, adamderosa said: I have experienced this in my Avanti as well when it's really cold. I believe what may be happening is that the diaphragm and seals inside the brake booster become stiff at cold temps and cannot function properly until it warms up a bit. Sorry to hear you've experienced the same issue....however, on the other hand I'm kind of happy to hear the problem isn't unique to only my car! Link to comment Share on other sites More sharing options...
mfg Posted January 15, 2022 Author Report Share Posted January 15, 2022 14 minutes ago, studegary said: Hopefully, you do not have some moisture/water trapped in the system. Yes, I've thought about moisture freezing inside the booster or supply hose...BUT WHERE??...It does have a new factory one way valve in the vacuum supply hose which prevents booster damage in case of an engine backfire through the manifold. Link to comment Share on other sites More sharing options...
pantera928 Posted January 15, 2022 Report Share Posted January 15, 2022 Sounds like a stiff diaphragm to me and if that is happening, it may not be long before you have a cracked and leaking diaphragm. Not sure about the availability of replacements but I am sure they must be out there. Link to comment Share on other sites More sharing options...
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