Coolant leak near firewall

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May 19, 2013 | 03:27 PM

Dave13077

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Intermediate

Joined: Mar 2013

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From: Truxton, NY

Coolant leak near firewall

I have a 85 coupe. It has a coolant leak. Sorry in advance as I am fairly new at engine work. There is a round cylinder with a spring attached near the firewall that seems to control the coolant into the heater core. Once under pressure coolant leaks at the point that the arm on the cylinder pivots. Any ideas? I have some pictures of the part if needed. Thanks.

Update: After some additional research it appears to be the Heater hose water shut off value. Should I try to replace this with another one or just bypass it? Thanks

Last edited by Dave13077; May 19, 2013 at 04:13 PM.

May 19, 2013 | 04:59 PM

GKK

Safety Car

Joined: Jan 2004

Posts: 3,783

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From: Northern California

Replace the Valve with another one.

The Bypass Valve keeps hot coolant from the Heater Core so, the interior stays a little cooler in the hotter months.

May 19, 2013 | 05:30 PM

powerpigz-51

Drifting

Joined: May 2006

Posts: 1,428

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From: Chewelah Wa

I have an 85, and mine has been leaking a long time. Today is when I fix it. http://forums.corvetteforum.com/c4-t...-corvette.html. Off to Autozone i go!

May 20, 2013 | 01:29 PM

Dave13077

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Joined: Mar 2013

Posts: 36

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From: Truxton, NY

Update #2:

I ordered a new hot water control valve. I guess if this one leaks after awhile I may just try to bypass it. One question I have, the current valve in the car has a spring attached to the arm of the valve that is run to the engine compartment. Does this spring need to be attached to the new valve or was it something the previous owner rigged up? It is vacuum controlled correct?? Also if I just remove the old one and replace it with the new one, reattach the vacuum line will it be in the correct position?

Thanks again for the help...

May 20, 2013 | 04:24 PM

peyc2

Burning Brakes

Joined: Oct 2012

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I recently changed mine, bought the Ecklers unit. There was no spring on the orginal, nor the replacment heater control valve. Just the vacum connection. Perhaps the PO rigged it to stay closed, as it may have leaked if it opened? I changed mine about a month ago. Pretty striaght forward, but, I ended up putting the NAPA U tube on the end connecting to the heater core, as that is also leaking. Now its bypassed. The heater core will be a late fall/winter swap. I hear its one of the worst possible replacements in a vette.

May 24, 2013 | 08:55 PM

powerpigz-51

Drifting

Joined: May 2006

Posts: 1,428

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From: Chewelah Wa

My long overdue valve fix is complete. I bought the Malibu one from Autozone for 35 bucks (they had to order it) and swapped out the guts into my 85. Was pretty easy, hardest part was getting the plastic stuff and rubber out of the old valve. It basically was fragile as an egg shell and the rubber was part of the metal on the inside....very nasty. I just had to remove the nut and bolt holding the assembly to the firewall without removing any of the hoses, and bend the tabs back to pop out the old valve guts. Piece of cake!

May 25, 2013 | 10:00 AM

Dave13077

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From: Truxton, NY

I replaced it yesterday with a new one purchased from Corvette America. Job wasn't too bad as I am a newbie. Took about 2 hours, but this includes a second trip to NAPA after I realized that the 2 hoses are different sizes

We are going to put some miles on her this weekend so I guess I will see if I did it correctly........

May 25, 2013 | 12:18 PM

powerpigz-51

Drifting

Joined: May 2006

Posts: 1,428

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From: Chewelah Wa

Mine had been leaking for years. I always had to top off my radiator, and my overflow tank was always full, as it would never hold pressure long enough while sitting to suck the coolant back into the radiator. The old valve was soooo cooked, probably from the days when my radiator was clogged from the outside, and I could not drive it on hot days without it overheating. The leak was just a small drip, but people kept informing me of the small puddle under my car. Everything else has been restored on my car, now it's time to take care of all the little stuff. My thanks to C4Boy for the heater valve write up, saved me some bucks!

Last edited by powerpigz-51; May 25, 2013 at 12:21 PM.