Coolant flush
Thread Starter
Intermediate
Joined: Jun 2012
Posts: 41
Likes: 0
From: Hamden CT
Coolant flush
I had the coolant flushed today in my 1993. The mechanic said he had to flush it like 10 times before the water began to clear. I have been using this mechanic for a few years now and he says he is familiar with the C4. He said that i needn't be concerned but to ensure I flush it often. Should I be concerned of any motor damage. The car only has 27 k on it and I am hoping for years of enjoyment.
Team Owner
Joined: Aug 2005
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From: Riverside County Southern California
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I had the coolant flushed today in my 1993. The mechanic said he had to flush it like 10 times before the water began to clear. I have been using this mechanic for a few years now and he says he is familiar with the C4. He said that i needn't be concerned but to ensure I flush it often. Should I be concerned of any motor damage. The car only has 27 k on it and I am hoping for years of enjoyment.
That would be 40 gallons of water.Is your mechanic aware of knock sensors removal?
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
He should have removed the knock sensor ( 
) and the block plug on the driver's side to drain the block. Also drain the radiator and then run fresh water thru the radiator and into the block....letting it run out the two holes now open with the removal of the plug and the sensor. This will clean out the block....no need to flush 10 times. Chances are that there is still something in the block. Flush it next year....correctly.
) and the block plug on the driver's side to drain the block. Also drain the radiator and then run fresh water thru the radiator and into the block....letting it run out the two holes now open with the removal of the plug and the sensor. This will clean out the block....no need to flush 10 times. Chances are that there is still something in the block. Flush it next year....correctly.
Instructor
Joined: Mar 2012
Posts: 230
Likes: 5
From: Westerville Ohio
He should have removed the knock sensor ( ) and the block plug on the driver's side to drain the block. Also drain the radiator and then run fresh water thru the radiator and into the block....letting it run out the two holes now open with the removal of the plug and the sensor. This will clean out the block....no need to flush 10 times. Chances are that there is still something in the block. Flush it next year....correctly.
) and the block plug on the driver's side to drain the block. Also drain the radiator and then run fresh water thru the radiator and into the block....letting it run out the two holes now open with the removal of the plug and the sensor. This will clean out the block....no need to flush 10 times. Chances are that there is still something in the block. Flush it next year....correctly.I have heard of and found some pics of the knock sensor but have not heard anyone mention the block plug. Is it a screw out and back in situation?
When filling the radiator and letting it flow is this done with the engine off (have to assume yes and that fluid flows to the block through the return hose not past the thermo).
And is this done with the car lifted and level or does the front need to be higher?
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Coolant always flows to the Core on everything since 87 or 88. There's no reason to turn on anything, though it doesn't hurt to disconnect the hoses to flush it separately. Also, the LT motors have a checkvalve which some have posted as plugging up so checking it would probably be in order.
Melting Slicks
Joined: Aug 2008
Posts: 2,082
Likes: 50
From: Palmdale CA
Coolant always flows to the Core on everything since 87 or 88. There's no reason to turn on anything, though it doesn't hurt to disconnect the hoses to flush it separately. Also, the LT motors have a checkvalve which some have posted as plugging up so checking it would probably be in order.
except for the "check valve" I believe this is only a flow restrictor...
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Melting Slicks
Joined: Aug 2008
Posts: 2,082
Likes: 50
From: Palmdale CA
I don't recall a Block Plug, but I'm very familiar with the Knock Sensor's...Had one snap off...
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
There is a plug in the block on the driver's side that corresponds to the same hole as the knock sensor on the passenger side. Back in the "old days" before knock sensors there were plugs in both sides. It's quite common to pull out the plug and have no water come out because the water passages are full of crud. A poke with a screwdriver will result in a face full of water...
If you have the Z51 or oil cooler option there is a fitting and hose on the driver's side that connects to the oil cooler.
If you have the Z51 or oil cooler option there is a fitting and hose on the driver's side that connects to the oil cooler.