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6/26/09 1:03pm - Original Message: 'Radiator Cap'
KDADDY79
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Dutchess County, NY - USA

Vette(s):
White '79 Corvette. It's a driver.

Joined: 8/27/2007
Posts: 2484
Howdy!
For the last year or so I have had five different water necks (thermostat housings) fail. I have used the O-Ring type gaskets when called for and the paper type gaskets when called for. Recently I used the blue colored silicone sealer under a scuffed up O-Ring type water neck without success. The stock type water necks with the silicone failed too.
What normally happens is after the motor cools down overnight I find a puddle of antifreeze on the (Edelbrock Performer) intake manifold.
Question is;
Would a radiator cap with a lower pressure solve this problem?
Any bad side effects from using a radiator cap with lower pressure?
This is driving me NUTZ!!! Wits End
Thanks for any suggestions.
Kevin
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6/26/09 2:42pm - Reply: 'Radiator Cap'
indy99
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Newport, MI - USA

Vette(s):
1980 L-48 still in the middle of a frame-off.

Joined: 6/9/2005
Posts: 926
Are the mounting surfaces of the housing and the intake square???  Place a straight edge on top of the mounting area on the intake and see if it is flat.  Check the the t-housing too. If you have a high or low spot then that is where the leak is. I would look at the hose also.
 
I know I know, I have problems drwaing stick people too.


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6/26/09 5:41pm - Reply: 'Radiator Cap'
KDADDY79
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Dutchess County, NY - USA

Vette(s):
White '79 Corvette. It's a driver.

Joined: 8/27/2007
Posts: 2484
Hey Indy,
Yeah, I have checked the intake manifold with a metal straight edge and found it to be without any irregularities. The housings too. I've also made sure that both surfaces are clean and dry before getting to work.
I replaced the radiator hoses two years ago as preventative maintanance and recently I went with a 180 degree t-stat. The car has always run without overheating issues.
I just dunno!
I'm thinking the lighter pressure radiator cap might be worth trying. I'll wait for some more feedback. 
Thanks for your reply.
Kevin


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6/26/09 6:09pm - Reply: 'Radiator Cap'
jp75vette
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Bloomfield Hills, MI - USA

Vette(s):
1975 Corvette coupe, 4 speed manual, 383 ci 9.5:1,Edelbrock dual plane Air Gap intake, Alum Heads,Comp Cam, roller Rockers, PS,PB,Tilt

Joined: 6/29/2008
Posts: 199
I have a similar issue with the Edelbrock, so I would also be interested in a solution.

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6/26/09 6:43pm - Reply: 'Radiator Cap'
suncountry Lifetime Member
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Moses Lake, WA - USA

Vette(s):
1976 L48 4-spd, Mahogany Metalic exterior, Buckskin interior 350ci/350hp, 3rd owner, fiberglass spring, 255/50-16's Torq-Thrust II

Joined: 4/16/2005
Posts: 2134
I am going to ask a dumb question. Are you sure the leak is from the T houshing. If I remember right one of the bolts that hold down the intake manifold up front goes into the head water jacket.

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6/26/09 7:29pm - Reply: 'Radiator Cap'
lukesvette Lifetime Member
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HOWELL, NJ - USA

Vette(s):
1979, Targa Blue (72 Color), Pace Car rear spoiler, L88 hood, Dark blue factory interior, 525HP 406, HD 700R4, 370 gears,Steeroids, composite rear spring, TT IIs wrapped in T/A Radials.

Joined: 5/18/2004
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have you actually seen coolant leak from the housing?

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6/26/09 8:20pm - Reply: 'Radiator Cap'
eddie20875 Lifetime Member
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Lanoka Harbor, NJ - USA

Vette(s):
1975 metallic blue coupe with t-tops,L48, t/t steering, black leather interior. 1990 L98, white/red leather interior, auto,a/c

Joined: 12/21/2006
Posts: 828
kevin, i had a stat cover with the o ring type gasket. started it up one time and was leaking. i took it off and checked everything and it appeared ok. what i found when i was reinstalling it was that the bolts i was using were just a hair too long and i installed a washer on both bolts and it solved the problem. don't know why i didn't notice it when i first put the housing on or why it didn't leak for a while but just figured i was lucky. hope this might help.Thumbs Up

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6/26/09 8:50pm - Reply: 'Radiator Cap'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
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Going to a lower pressure rad cap is not a good idea...it's gonna spit coolant out before it gets to normal operating temp, plus, the higher the pressure in the system, the higher the boiling point of the coolant is.
I've run into situations similar to yours, and I've found that the leak will stop itself eventually. This is assuming that the leak is actually coming from between the neck and the intake....
I wouldn't recommend using any type of sealant on the gasket, neck, or intake...just clean & dry.


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6/26/09 8:56pm - Reply: 'Radiator Cap'
KDADDY79
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Dutchess County, NY - USA

Vette(s):
White '79 Corvette. It's a driver.

Joined: 8/27/2007
Posts: 2484
I'm pretty darn sure it's coming from the t-stat housing. Reason is that I can see a stain where the green antifreeze runs out from just under the housing on to the manifold.
As far as the bolts go, I used washers on the last one without success.
Any input as to the lower pressure radiator cap?
Lem'me know.


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6/26/09 9:52pm - Reply: 'Radiator Cap'
KDADDY79
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Dutchess County, NY - USA

Vette(s):
White '79 Corvette. It's a driver.

Joined: 8/27/2007
Posts: 2484
Hey Joel,
Looks like we were typing at the same time.
I picked up another housing today. This one's polished aluminum with an O-Ring. The guy at the speed shop has had some good advice in the past and he says he hasn't had any complaints with this one.
Your info on the radiator cap makes good sense. I'll stay with the original cap.
Wish me luck. Pinch


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6/27/09 8:17pm - Reply: 'Radiator Cap'
KDADDY79
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Dutchess County, NY - USA

Vette(s):
White '79 Corvette. It's a driver.

Joined: 8/27/2007
Posts: 2484
I'm thinkin' I might have fixed it today.
On went the new alum. water neck with the O-Ring gasket. Put it on bare back...no sealants or such, just the O-Ring.
After letting it warm up, I shut it down and let it sit for 3 hours or so and saw no leaks. Later I even took it out for a ride for the first time in weeks and saw no leaks.
I sure hope I'm not speaking too soon, but it's looking good.
I'm going to keep an eye on the upper radiator hose because I had to muscle it on a bit. This water neck rose up at a different angle than the others. Hood clearance was OK, though.
Thanks to the bunch for the input.
Kevin


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6/27/09 11:36pm - Reply: 'Radiator Cap'
anips
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sonoma, CA - USA

Vette(s):
72 LT-1 AC coupe,69 l-36 coupe

Joined: 8/9/2002
Posts: 783
the chrome ones are the worst, first you have two disimular metals, chrome and alum., chrome and cast iron, after a while electrolist starts to eat the chrome, on the neck, or the alumn,or both, then a leak, also the chrome is so slick the RTV won't stick or seal ,maybe take a piece of glass and wet and dry sand paper and rough up the bottom of the neck,  if the neck mounting holes go through into the manifold water jacket make sure both threads are clean  use Permatex none hardning gasket sealer, and let it set, personlly I don"t like RTV in water jacket bolt threads or intake bolts, Permatex seems to seal better. anips2009-06-27 21:48:18

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