Author Topic: Small head gasket leak  (Read 1527 times)

Offline loco340cuda

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Small head gasket leak
« on: January 24, 2009 - 05:59:44 PM »
I drove my Cuda last weekend and today I came out and looked under the car and saw about 4-5 drops of what seems like coolant on the garage floor. After doing some investigating it looks like it is coming from the seem between the passenger side head and block. It appears to only be toward the very front but on the side of the engine not the front of the engine.

This is not a big leak, if you look at the were the head gasket is it looks damp with a small film of where it looks like coolant might be slightly seeping out and I do mean very slightly.

So my questions are first, is this normal for a motor that was built 2 years ago and has 1000 mile on it, and occasionally gets spun up to 6500 thru the gears or is this something that is a major problem waiting to happen?

And second, is this something that I can fix by re-torquing down the head or am I looking at having to replace the head gasket?

The motor is a stroked 340 with stock iron 'x' heads and I believe felpro gaskets but not completely sure on that. Any advice here would be greatly appricated.

-Thanks
1970 Cuda 340 4-speed - now stroked to 416ci (SOLD)
2017 Mustang Shelby GT350




Offline Oldschool

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Re: Small head gasket leak
« Reply #1 on: January 24, 2009 - 06:07:42 PM »
I would dry it off and then pressure test the cooling system to try and isolate the leak before I started turning bolts....    :2cents:   
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craigsmytcudas

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Re: Small head gasket leak
« Reply #2 on: January 24, 2009 - 11:03:25 PM »
Pressure check with the plugs removed all 8 . dont retorque the gaskets when soaked with coolant . dont restart if a cylinder fills with coolant you could hydrolic and bend a rod . gaskets are cheap .most likely loose bolts check the lower line of bolts below the exhaust before you remove to confirm .also look at the intake ends were the block deck and head meet some times when the intake leaks the fluid travels the head gasket down the sides then along the block .c

Offline Chryco Psycho

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Re: Small head gasket leak
« Reply #3 on: January 25, 2009 - 01:45:53 AM »
it is uncommon to have a heads gasket leak especially with Fel Pro , I suspect it is coming from the intake or studs , check it over carefully under pressure before taking the head off

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Offline loco340cuda

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Re: Small head gasket leak
« Reply #4 on: January 27, 2009 - 07:51:28 PM »
Hey guys, thanks for all the replys. 

Here is an update.  The leak is so slow and small that it seems to take a few days of the car sitting to let it drip enough to figure out where it might be coming from.  So after a few days I can now see a couple of drops on the floor that I can now get a point of reference where it might be coming from.  It looks like it might be coming from a freeze plug.  I will verify for sure this weekend.

So my next question is assuming I can get to the freeze plug how hard are they to replace?  Is this something that would be better to take to a shop or tackle myself?  I am mechanically savoy so I think I could do it I'm just not sure what tools are needed and if it is worth the time and hassle to do it myself to save a few bucks?
1970 Cuda 340 4-speed - now stroked to 416ci (SOLD)
2017 Mustang Shelby GT350

Offline Changin Gears

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Re: Small head gasket leak
« Reply #5 on: January 27, 2009 - 07:59:25 PM »
Freeze plugs are pretty straight forward to replace.  To get the old one out you tap on the edge of it forcing that edge into the block and forcing the opposite edge out.  Then pull it out the rest of the way with pliers.  When you put the new one in put some sealer on the block ( if you put it on the freeze plug it just get scraped off) and hammer the plug in with a socket that fits inside the plug.


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Offline duodec

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Re: Small head gasket leak
« Reply #6 on: January 29, 2009 - 12:42:17 AM »
Don't they sell the fluorescent dye for coolant any more?  I used some years ago to locate leaks in my old truck with a black light and it worked great; even the coolant trail that had 'dried' on the metal surfaces was still discernible in the black light.

Offline dutch

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Re: Small head gasket leak
« Reply #7 on: January 29, 2009 - 05:41:32 AM »
you can use some tallow powder to locate the leak. the coolant will leave traces in the powder.
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Offline loco340cuda

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Re: Small head gasket leak
« Reply #8 on: January 31, 2009 - 02:56:48 PM »
Okay another update, I confirmed it is the freeze plug that is leaking.  It is the freeze plug that is on the passenger side of the block the one that is just to the rear of the motor mount.  In looking at it, it looks like it might be a bugger to replace due to the motor mount slightly interfering as well as possibly the steering linkage.  My guess is that I will have to remove the motor mount and possibly the steering linkage to get at it to tap it in place.  It also seems like it would be a pain to do this on the garage floor with the jack holding up the engine.  The alternative is to pull the engine but I really don't want to do that. 

If any one has any ideas please let me know.  I might take it to a shop where I occasionally get work on it done and see if they can fix it with out pulling the motor.  It might just be the lesser of all the evils to pay them to fix it then to have to yank the motor.   :(
1970 Cuda 340 4-speed - now stroked to 416ci (SOLD)
2017 Mustang Shelby GT350

Offline loco340cuda

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Re: Small head gasket leak
« Reply #9 on: January 31, 2009 - 03:48:49 PM »
I also head the idea that maybe I could try to tap it in some more and maybe that would help it to seal.  Any thoughts on this idea?
1970 Cuda 340 4-speed - now stroked to 416ci (SOLD)
2017 Mustang Shelby GT350

Offline dutch

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Re: Small head gasket leak
« Reply #10 on: January 31, 2009 - 04:21:18 PM »
it is probably leaking due to corrosion so that won`t help
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Offline Chryco Psycho

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Re: Small head gasket leak
« Reply #11 on: February 01, 2009 - 02:45:53 AM »
is it a new plug or an old one ? tapping it in may help a new plug if it is not seated fully , if it is an old one you may be ebtter off to pull the engine & replace them all

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Offline loco340cuda

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Re: Small head gasket leak
« Reply #12 on: February 01, 2009 - 05:09:51 PM »
New plug, engine was rebuilt 2 years ago and only has about 1000 miles on it.
1970 Cuda 340 4-speed - now stroked to 416ci (SOLD)
2017 Mustang Shelby GT350

Offline IMNCARN82

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Re: Small head gasket leak
« Reply #13 on: February 05, 2009 - 10:04:06 AM »
Smak it with a hammer like CP said.  I had one leaking. Chose to clean up the engine at that time. When i finally got it all back together another plug started spraying on break-in. One smak with a hammer and havn't had a problem.5500 miles later.    I hit it on the edge. Not just right in the middle.   
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Offline loco340cuda

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Re: Small head gasket leak
« Reply #14 on: February 05, 2009 - 02:55:53 PM »
IMNCAR82, thanks for the advise. 

Last weekend I hit it a couple of times but not terriblely hard due to I was afraid I would push it into the block and it would start pouring anti-freeze all over the place (not even sure that is possible, but paranoid none the less).  Anyhow, it seems to have slowed down the leak but not completely stopped it.  When I checked a few days after I drove the car there were not drops of anti-freeze on the floor (like what would normally happen) but I could feel the freeze plug had some wetness around and under it so there is still a very small leak.  I will hit it a couple more times this weekend and see if I can get it to seal completely, if not I guess I will have to replace it.
1970 Cuda 340 4-speed - now stroked to 416ci (SOLD)
2017 Mustang Shelby GT350