Replaced spark plugs in 07 Dodge Grand Caravan and now brakes don't work
September 5, 2015 6:59 PM Subscribe
I was sort of proud of myself for replacing the spark plugs and wires in my 2007 Dodge Grand Caravan... until I drove it down the street and discovered the the brake pedal is rock hard and it's very hard to stop the think unless I virtually stand on the brake pedal.
I had to take off the air box and the large intake hose to get to the back of the engine but I put that back on. I haven't the faintest clue what I could have done. It almost feels like I have no power brakes now. I am thinking that when I got behind the engine maybe I knocked something loose? The engine actually runs better now with the new plugs and wires but man, this was an unintended complication. Anyone know what I could have busted in there?
I had to take off the air box and the large intake hose to get to the back of the engine but I put that back on. I haven't the faintest clue what I could have done. It almost feels like I have no power brakes now. I am thinking that when I got behind the engine maybe I knocked something loose? The engine actually runs better now with the new plugs and wires but man, this was an unintended complication. Anyone know what I could have busted in there?
Also, check hose for damage while you are in there, you might have bent the by now not so flexible hose enough to crack it.
posted by rudd135 at 7:16 PM on September 5, 2015 [2 favorites]
posted by rudd135 at 7:16 PM on September 5, 2015 [2 favorites]
There are a lot of websites that can give you solid troubleshooting advice. Search "hard brake pedal" and the first page of results will give you great troubleshooting tips. You can also do a youtube search with the terms "2007 Dodge Grand Caravan hard brake troubleshoot" to give you video instructions on how to fix what is wrong, once you have figured it out.
posted by Vigilant at 7:33 PM on September 5, 2015 [1 favorite]
posted by Vigilant at 7:33 PM on September 5, 2015 [1 favorite]
Best answer: It almost feels like I have no power brakes now.
This is precisely what has happened. The power brakes are 'powered' by vacuum from the engine intake manifold. It sounds like you have removed - but not refitted - or just knocked loose a hose from the engine vacuum system. If the problem was not there before the spark plug job and there directly afterwards? Then you knocked a hose loose.
Check the airbox and all the surrounding area. Follow the pipe from the brake booster (mounted on the bulkhead, usually directly-ish behind the brake pedal) back to the engine and see where that goes. Make sure it is not split. Then look at every pipe that comes from the intake system - start with the inlet manifold and check all over it (by sight and feel if you can't see) and look for rubber hoses or a fitting with no rubber hose.
It's likely just a hose hanging off. It's extremely unlikely to be a big deal, given the circumstances. Just diligent backtracking over the job you did should find it. Either replace the hose (if it is cracked or looks like it might) or just push it back into place if it looks to be ok. Check all the other hoses even if you find the right one straight away. It's good practice.
posted by Brockles at 7:54 PM on September 5, 2015 [3 favorites]
This is precisely what has happened. The power brakes are 'powered' by vacuum from the engine intake manifold. It sounds like you have removed - but not refitted - or just knocked loose a hose from the engine vacuum system. If the problem was not there before the spark plug job and there directly afterwards? Then you knocked a hose loose.
Check the airbox and all the surrounding area. Follow the pipe from the brake booster (mounted on the bulkhead, usually directly-ish behind the brake pedal) back to the engine and see where that goes. Make sure it is not split. Then look at every pipe that comes from the intake system - start with the inlet manifold and check all over it (by sight and feel if you can't see) and look for rubber hoses or a fitting with no rubber hose.
It's likely just a hose hanging off. It's extremely unlikely to be a big deal, given the circumstances. Just diligent backtracking over the job you did should find it. Either replace the hose (if it is cracked or looks like it might) or just push it back into place if it looks to be ok. Check all the other hoses even if you find the right one straight away. It's good practice.
posted by Brockles at 7:54 PM on September 5, 2015 [3 favorites]
Best answer: Here's a random picture (not of your car) of the main connection that runs the power brakes.
posted by fritley at 7:56 PM on September 5, 2015
posted by fritley at 7:56 PM on September 5, 2015
Best answer: Yep, brake booster vacuum hose. Done that a million times.
posted by notsnot at 7:04 AM on September 6, 2015 [2 favorites]
posted by notsnot at 7:04 AM on September 6, 2015 [2 favorites]
Response by poster: Notsnot you win the cigar. When I googled brake booster vacuum hose, I got a picture of exactly what it looked like... and I'll be damned... it was hanging off there, flaccid, useless. Plugged it back and now I have brakes again. The Dodge Forum still has no answer, ha ha. THANK YOU ALL! Marking as resolved.
posted by brownrd at 8:34 AM on September 6, 2015 [4 favorites]
posted by brownrd at 8:34 AM on September 6, 2015 [4 favorites]
This thread is closed to new comments.
The power brake system uses vacuum from the intake side of the engine to activate a rubber diaphram in the power brake booster.
You can diagnose a bad booster diaphram by putting a hose on it and trying to suck air out or blow into it. If you can do this easily, time for a new booster cylinder.
posted by rudd135 at 7:14 PM on September 5, 2015 [2 favorites]