# Changing spark plug, found coolant



## Ape Sapien (7 mo ago)

Car was misfiring, so I went to change the plugs and one of the wells was full to the brim with coolant. The well next to it had a little bit and the other two were dry. 
The coolant level hasn't noticeably dropped in the tank or the radiator, and the color looks normal. 
Any ideas would be appreciated. 
Thanks


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## rogoman (Dec 16, 2004)

There may be a crack in the head casting at the area of the filled plug well.


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## VStar650CL (Nov 12, 2020)

rogoman said:


> There may be a crack in the head casting at the area of the filled plug well.


Yep, there are really only two ways coolant can get into a plug well. One is a cracked head as Rogo mentioned, the other is a blown head gasket _plus_ loose spark plugs, which is pretty unlikely. It's bad news no matter how you cut it.


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## Ape Sapien (7 mo ago)

rogoman said:


> There may be a crack in the head casting at the area of the filled plug well.


Thanks for the response, I will investigate.


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## Ape Sapien (7 mo ago)

VStar650CL said:


> Yep, there are really only two ways coolant can get into a plug well. One is a cracked head as Rogo mentioned, the other is a blown head gasket _plus_ loose spark plugs, which is pretty unlikely. It's bad news no matter how you cut it.


Thanks for the response. I appreciate the help.


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## SilverFlocks (7 mo ago)

My girlfriends sentra needs a new tranny. Does anyone know what the best torque is for spark plugs on an 06 altima. I have a new torque wrench thats actually calibrated.


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## rogoman (Dec 16, 2004)

SilverFlocks said:


> My girlfriends sentra needs a new tranny. Does anyone know what the best torque is for spark plugs on an 06 altima. I have a new torque wrench thats actually calibrated.


Spark plug torque: 20 - 29 Nm (14 - 22 ft-lb)


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## johngenga (Oct 14, 2011)

Ape Sapien said:


> Car was misfiring, so I went to change the plugs and one of the wells was full to the brim with coolant. The well next to it had a little bit and the other two were dry.
> The coolant level hasn't noticeably dropped in the tank or the radiator, and the color looks normal.
> Any ideas would be appreciated.
> Thanks


Seems like the cylinder head gasket was worn out so coolant water is entering the cylinders and causing the misfiring and also causing the reduction in coolant water. You will need to change that ASAP because you will begin to notice overheating and probably worse damage to your engine.


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## VStar650CL (Nov 12, 2020)

johngenga said:


> Seems like the cylinder head gasket was worn out so coolant water is entering the cylinders and causing the misfiring and also causing the reduction in coolant water. You will need to change that ASAP because you will begin to notice overheating and probably worse damage to your engine.


The head gasket can only cause coolant to enter the wells if the spark plugs are loose in addition to the gasket being blown. That's possible, but not very likely. It's more likely the head is cracked.


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## TalkOrBell (Nov 30, 2021)

To be correct on this issue a blown head gasket OR a cracked head usually caused by a single instance or more of overheating maybe from stuck thermo or other...In the case of blown head gasket it could be starting vehicle & going full-bore without letting it warm up to temp...I have seen this with people who live close to freeway ramps...

This has nothing to do with the spark plugs...

This is the joint where the block surface meets the head surface & numerous cooling jacket 'paths' meet up through the head gasket. In some cases if you have an aluminum head on a cast iron block & you don't change out your coolant often there will start an electrolysis where the aluminum meets the cast iron eating one or the other away till there's a blow-out...This was rampant in the old Mazda Rotary Engines as they were a SANDWICH of aluminum-cast iron-aluminum-cast iron...

You should check your radiator overflow tank for strange debris & gas-coolant mix as there will no doubt be cylinder pressure entering the cooling system causing issues there...

Also seems like you should be getting a smoking problem when starting up that probably goes away when running but when you shut the car off the pressure of the cooling system OVERRIDES the cylinder pressure (which is gone) thus filling the cylinder up...


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## VStar650CL (Nov 12, 2020)

TalkOrBell said:


> Also seems like you should be getting a smoking problem when starting up that probably goes away when running but when you shut the car off the pressure of the cooling system OVERRIDES the cylinder pressure (which is gone) thus filling the cylinder up...


Y'all aren't listening to where the OP said the coolant was. He didn't say it was in the cylinder, he said it was in the _spark plug well_. On an MR cylinder head the well has nothing but the oily rocker cavity on the other side, _it has no contact whatsoever with the cooling jacket or the head gasket_. So the only way coolant from a head gasket leak could reach it is if the spark plug was loose in the bore and let it leak through under compression. If the plugs weren't loose then it's a cracked head. There are no other possibilities.


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