1991 knock sensor
Thread Starter
5th Gear
Joined: Jun 2012
Posts: 5
Likes: 0
From: Norfolk VA
1991 knock sensor
Hi!. I have a 1991 , I drove it to work parked and saw smoke coming out the drivers side of the hood, then some nasty brown water fluid came out the bottom, , I was scared to drive it, had it towed home, and there she sits!... I was doing some reading that it may be a knocker sensor , or freeze plug... Any idea which I should check first?. I had no dash codes , it was running a little warm, water pump , temp sensor and thermostat was recently replaced, and since it's water that was leaking , I'm not sure where to look?.. Any suggestions would be Greatly appreciated, since I try and do the work myself!. Thanks in advance!.. Oh also how tough are these to replace??
Team Owner
Joined: Sep 2003
Posts: 25,365
Likes: 2,731
Hi!. I have a 1991 , I drove it to work parked and saw smoke coming out the drivers side of the hood, then some nasty brown water fluid came out the bottom, , I was scared to drive it, had it towed home, and there she sits!... I was doing some reading that it may be a knocker sensor , or freeze plug... Any idea which I should check first?. I had no dash codes , it was running a little warm, water pump , temp sensor and thermostat was recently replaced, and since it's water that was leaking , I'm not sure where to look?.. Any suggestions would be Greatly appreciated, since I try and do the work myself!. Thanks in advance!.. Oh also how tough are these to replace??
http://corvetteparts.com/item/hose-s...tion-1990-1991
If you don't have the KC4 option the freeze plug or knock sensor catastrophic failure are the next more likely I would think. In the driveway neither is a pleasant task, freeze plug is likely a "shop job" but the knock sensor a possibility.
You made one very good decision! You "towed it"
Last edited by WVZR-1; Jul 30, 2014 at 07:38 PM.
Thread Starter
5th Gear
Joined: Jun 2012
Posts: 5
Likes: 0
From: Norfolk VA
Ok, it's been parked for a week, haven't really had time to even check it out, I do know the radiator is empty, but there is a little coolant left in the resovior, what came out underneath was a brown rusty color. Are the freeze plugs difficult to replace,? Thank you!
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
That depends on which one is bad. The rear one is easy. The front one is behind the motor mount. That one is tough. If it's the front one I recommend taking off the exhaust manifold to get access to it. The motor mount needs to come out.
Safety Car
Joined: Jan 2004
Posts: 3,783
Likes: 15
From: Northern California
It could be anything?...The throttle body coolant lines could've leaked, radiator hoses, intake manifold leak...Also, brown water is a sign of neglected cooling system service.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
You need to clean up the area under the engine to find out where the water is coming from.
When I had a coolant leak it appeared to be coming from the oil cooler hoses. After I tightened them up I found that the front freeze plug had a hole in it and it was dripping down onto the oil cooler hoses.
When I had a coolant leak it appeared to be coming from the oil cooler hoses. After I tightened them up I found that the front freeze plug had a hole in it and it was dripping down onto the oil cooler hoses.
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