VW Golf Mk2 Owners Club

Technical => Technical => Engine & Gearbox => Topic started by: BristolGolfmk2 on November 04, 2020, 11:42:59 PM

Title: Brake pedal causes engine to bog
Post by: BristolGolfmk2 on November 04, 2020, 11:42:59 PM
Hey guys

As the title suggest I have a weird issue where if I press the brake on my carb auto 1.8 during the Dow press it directly causes the idle to drop a bit. Once fully depressed idle rises again.

I’m thinking two things - electrical draw on alternator ?? Or vacuum leak on brake servo being exposed during the down press.

I’m guessing it’s not normal and it only drops by 100rpm but thought you lot might know!
Title: Re: Brake pedal causes engine to bog
Post by: Monkey on November 05, 2020, 08:05:51 AM
It does sound very much like a vacuum issue.
Try (carefully) spraying a little clutch/brake cleaner over the vacuum lines while running and see if the idle picks up.
Title: Re: Brake pedal causes engine to bog
Post by: BristolGolfmk2 on November 05, 2020, 10:27:02 AM
It does sound very much like a vacuum issue.
Try (carefully) spraying a little clutch/brake cleaner over the vacuum lines while running and see if the idle picks up.

Will give this a try! Any main ones to look for?
Title: Re: Brake pedal causes engine to bog
Post by: Monkey on November 05, 2020, 11:26:56 AM
Yeah, trace the main vacuum hose from the brake servo back to the engine, chances are, it'll be along that one.
Title: Re: Brake pedal causes engine to bog
Post by: BristolGolfmk2 on November 07, 2020, 10:38:36 PM
Yeah, trace the main vacuum hose from the brake servo back to the engine, chances are, it'll be along that one.

Will give it a crack tomorrow !