coolant leak throttle body
Thread Starter
Instructor
Joined: Aug 2006
Posts: 121
Likes: 0
coolant leak throttle body
I tried to insert pics but I guess I don't know how yet. My '91 convert L98 has a coolant leak, again. Had the intake gasket replaced and found coolant on the engine shortly thereafter. The dealer said the thermostat housing was bad and patched it up. Saw a new leak and the dealer said they tightened a hose. I checked the engine over the weekend and saw coolant again. Checked the motor after removing the air filter and the throttle body cooling line looks like the clamp is way tight at the top. I tightened it up and ran it for awhile in the garage and it looked okay.
Is this a piece of hose or a specific part number? Hose size? Can I cheat and replace this without draining the coolant? How much will come out here? My FSM is at my bros house with the car. Maybe someone knows if this is just hose or a specific part such as an upper rad hose. Thanks
Is this a piece of hose or a specific part number? Hose size? Can I cheat and replace this without draining the coolant? How much will come out here? My FSM is at my bros house with the car. Maybe someone knows if this is just hose or a specific part such as an upper rad hose. Thanks
Slingshot
Joined: Dec 2001
Posts: 3,817
Likes: 24
From: Charlotte NC
Use Standard heater hose...
I replaced mine a couple of years ago with standard heater hose. 2 new clamps and a few inches of new hose and 20 minutes will do the job. You should lose less than a quart of coolant as I recall.
Team Owner
Joined: May 2002
Posts: 24,337
Likes: 25
From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
Which hose? There's no way you can hook up standard coolant hose on the front of the TB without kinking it completely.
Anyhow, coolant weeps out of there after you get the car up to temperature and have shut it off for about 10 minutes. That's when the coolant pressure and temperature is the highest.
Clean it up good then get under the hood and check it out. Overtightening a clamp on a cracked or rotted hose is not going to fix anything.
Anyhow, coolant weeps out of there after you get the car up to temperature and have shut it off for about 10 minutes. That's when the coolant pressure and temperature is the highest.
Clean it up good then get under the hood and check it out. Overtightening a clamp on a cracked or rotted hose is not going to fix anything.
Racer
Joined: Dec 2006
Posts: 325
Likes: 2
From: Chattanooga TN
the gasket on the bottom of the throttle body could be leaking as well.
and if it is, the screws that hold the TB heater plate sre probably so corroded that you may not get them out in one piece.
just bypass the TB heater...
and if it is, the screws that hold the TB heater plate sre probably so corroded that you may not get them out in one piece.
just bypass the TB heater...
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
You really need to pinpoint it - '91 uses a unique intake gasket that has retainers to keep it from slipping when you lay in the manifold. The front and rear bolt holes are counterbored and so it creates a larger, potentional leak path closer to the coolant passageways. Hopefully, they used the right gaskets. I'd clean it up. Start it up and start looking around while it warmed up, particularly when the thermostat opens.
Thread Starter
Instructor
Joined: Aug 2006
Posts: 121
Likes: 0
Thanks SunCR and all. When I tightened the clamp I let it get to operating temp and checked for leaks. There weren't any, but another post noted that the leak may happen after the car is turned off. I'd really like to think the intake gasket is not leaking. The dealer, Bergey Chev. in Colmar PA., are good vette mechanics. They have not indicated the leak is from the gasket. I hope not!
I don't like the looks of the throttle body hose. The top clamp had evidence of a corroded clamp and antifreeze was looking like it was coming through the clamp seems. I'm sure it was just on the outside but again I don't like the looks of it. Called Bergey's today. The TB hose is a part number. I ordered it. (Thanks for the post on bypassing the TB - I may do that if the leak persists). I should get this on Saturday afternoon. Also - only about a quart will leak? I'll get some rags and won't bother draining the coolant. Good time saver. This SHOULD be easy enough. Fresh clamps, fresh hose. I hope to be in and out. Famous last (vette) words!
I don't like the looks of the throttle body hose. The top clamp had evidence of a corroded clamp and antifreeze was looking like it was coming through the clamp seems. I'm sure it was just on the outside but again I don't like the looks of it. Called Bergey's today. The TB hose is a part number. I ordered it. (Thanks for the post on bypassing the TB - I may do that if the leak persists). I should get this on Saturday afternoon. Also - only about a quart will leak? I'll get some rags and won't bother draining the coolant. Good time saver. This SHOULD be easy enough. Fresh clamps, fresh hose. I hope to be in and out. Famous last (vette) words!
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Team Owner
Joined: May 2002
Posts: 24,337
Likes: 25
From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
Leaking intake gasket won't leak onto the top of the manifold. It will leak into the engine, or around the side of the manifold and down the head/block interface.
These don't leak from a bad gasket or too much pressure, they usually leak from corrosion when the coolant isn't serviced in forever.
These don't leak from a bad gasket or too much pressure, they usually leak from corrosion when the coolant isn't serviced in forever.
Safety Car
Joined: May 1999
Posts: 3,651
Likes: 5
From: Atlantis
Cruise-In I Veteran
This is a simple repair.........
The TB is easy to remove with minimum tools.
Drain out a couple quarts of coolant before you start and it won't leak at all. (Maybe a few drops)
Pour it back in when you get finished.
THe screws on the TB bottom cover are the 'star' type, can't remember which size. 'Torx' screws I think may be the term.
It may be a good time to make sure the IAC can be removed while you've got everything accessible. Sometimes they stick so you can put the IAC back in with some anti-sieze..
The TB is easy to remove with minimum tools.
Drain out a couple quarts of coolant before you start and it won't leak at all. (Maybe a few drops)
Pour it back in when you get finished.
THe screws on the TB bottom cover are the 'star' type, can't remember which size. 'Torx' screws I think may be the term.
It may be a good time to make sure the IAC can be removed while you've got everything accessible. Sometimes they stick so you can put the IAC back in with some anti-sieze..
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
"Leaking intake gasket won't leak onto the top of the manifold. It will leak into the engine, or around the side of the manifold and down the head/block interface"
Every aluminum head motor I've seen with this problem worked it's way to the top and that includes a couple of the 6's.
Every aluminum head motor I've seen with this problem worked it's way to the top and that includes a couple of the 6's.
