Coolant problem
Thread Starter
Instructor
Joined: Aug 2009
Posts: 137
Likes: 1
From: Easley SC
Coolant problem
I drained the coolant out of my 91 Coupe and flushed the system. I also replaced the thermostat. When fillling it up with the coolant I am supposed to put in almost 4 gallons of liquid but I can only get 2 into the system even after running it for fifteen minutes. Has anyone experianced this problem before? How should I solve this? Currently the Vette is running at about 180 degrees. Is this about what everyone else is running at?
Burning Brakes
Joined: Oct 2004
Posts: 1,210
Likes: 1
From: fighter pilots make movies, bomber pilots make history
Henry,
You have to remove the NPT drain plugs (Knock sensors if LT-1) on the sides of block under the exhaust manifold to drain more fluid. Some fluid remains in the block unless you pull the plugs or sensors.
If you flushed long enough to get get clear water, you got the bad stuff out. It is really not need to pull those plugs or knock.
If you refilled with 100% glycol coolant, you are about 50/50 glycol/water. If you refilled with two gallons of pre-diluted coolant mix which is 50/50, you have about 25% glycol coolant which is OK. It is not going to get cold enough in SC to need lower freeze protection than 25% glycol concentration.
Enjoy the Vette, drive safe
Joe
You have to remove the NPT drain plugs (Knock sensors if LT-1) on the sides of block under the exhaust manifold to drain more fluid. Some fluid remains in the block unless you pull the plugs or sensors.
If you flushed long enough to get get clear water, you got the bad stuff out. It is really not need to pull those plugs or knock.
If you refilled with 100% glycol coolant, you are about 50/50 glycol/water. If you refilled with two gallons of pre-diluted coolant mix which is 50/50, you have about 25% glycol coolant which is OK. It is not going to get cold enough in SC to need lower freeze protection than 25% glycol concentration.
Enjoy the Vette, drive safe
Joe
Last edited by devildog; Nov 24, 2009 at 08:39 PM.
Racer
Joined: Aug 2009
Posts: 289
Likes: 1
From: Tucson Arizona
I only drained about 9 quarts of coolant from my '86 after draining the radiator and removing the driver's side drain plug. Never did find the drain plug on the passenger side (is removing the knock sensor the answer?). Cooling system capacity is supposed to be 17 quarts according to the owners manual.
Steve
Steve
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 32
From: The Top of Utah
The FSM lists the coolant capacity at 14.5 to 14.8 quarts, just short of 4 gallons. Could the optional oil cooler boost it beyond 16 quarts?RACE ON!!!
Thread Starter
Instructor
Joined: Aug 2009
Posts: 137
Likes: 1
From: Easley SC
Henry,
You have to remove the NPT drain plugs (Knock sensors if LT-1) on the sides of block under the exhaust manifold to drain more fluid. Some fluid remains in the block unless you pull the plugs or sensors.
If you flushed long enough to get get clear water, you got the bad stuff out. It is really not need to pull those plugs or knock.
If you refilled with 100% glycol coolant, you are about 50/50 glycol/water. If you refilled with two gallons of pre-diluted coolant mix which is 50/50, you have about 25% glycol coolant which is OK. It is not going to get cold enough in SC to need lower freeze protection than 25% glycol concentration.
Enjoy the Vette, drive safe
Joe
You have to remove the NPT drain plugs (Knock sensors if LT-1) on the sides of block under the exhaust manifold to drain more fluid. Some fluid remains in the block unless you pull the plugs or sensors.
If you flushed long enough to get get clear water, you got the bad stuff out. It is really not need to pull those plugs or knock.
If you refilled with 100% glycol coolant, you are about 50/50 glycol/water. If you refilled with two gallons of pre-diluted coolant mix which is 50/50, you have about 25% glycol coolant which is OK. It is not going to get cold enough in SC to need lower freeze protection than 25% glycol concentration.
Enjoy the Vette, drive safe
Joe
Great information. What does NPT stand for? What does this drain plug look like? Any more specific information on the location of the plug?
Team Owner
Joined: Jan 2003
Posts: 20,254
Likes: 221
From: Summerland B.C. Canada
On the bottom center of block, both sides, is where you drain the block. Pass side will have a knock sensor in the hole, drivers side will have a plug or nipple for cooler hose.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
There are no pipe plugs on the '91 (except the left head, but that will only drain the left head). You can remove the oil cooler hose at the filter (left side) and the Knock Sensor right side or you can try pulling the lower hose with nose pointed downhill.
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Burning Brakes
Joined: Oct 2004
Posts: 1,210
Likes: 1
From: fighter pilots make movies, bomber pilots make history
Henry,
Suggestion for you, buy the FSM (field service manual) for your 91. They are a bit pricey, but you will save the cost many times over when you need to service or repair your 91.
They are thick about 3 inches, but have all the diagnostics, wiring diagrams, component locations, etc.
continue to ask questions on this forum, good guys and gals that will want to help you. But, with big, official service manual you can ask better questions and understand the answers in a more meaningful way.
A good gift for Christmas. Maybe someone will chime in and tell you where to order the FSM.
If you race that thing, take it to the track.
Joe
Suggestion for you, buy the FSM (field service manual) for your 91. They are a bit pricey, but you will save the cost many times over when you need to service or repair your 91.
They are thick about 3 inches, but have all the diagnostics, wiring diagrams, component locations, etc.
continue to ask questions on this forum, good guys and gals that will want to help you. But, with big, official service manual you can ask better questions and understand the answers in a more meaningful way.
A good gift for Christmas. Maybe someone will chime in and tell you where to order the FSM.
If you race that thing, take it to the track.
Joe
Drifting
Joined: Sep 2003
Posts: 1,363
Likes: 7
From: 1994 LT1 Coupe 6-speed with FX3 & 2000 LS1 Vert 6-Speed with F45 Hunterdon County, NJ
I drained the coolant out of my 91 Coupe and flushed the system. I also replaced the thermostat. When fillling it up with the coolant I am supposed to put in almost 4 gallons of liquid but I can only get 2 into the system even after running it for fifteen minutes. Has anyone experianced this problem before? How should I solve this? Currently the Vette is running at about 180 degrees. Is this about what everyone else is running at?
One other technique (aside of the block draining) that has worked for many is to use a shop vac on 'blow' mode and apply it to the 'surge tank' if so equipped (black tank by windshield). This has successfully pushed-out all of the coolant for many.
ALso, be sure the heat for inside the car is 'turned on', as some years has a valve which prevented coolant draining/exchange from the heater-core if closed.
