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possible bad head gasket?

7K views 15 replies 9 participants last post by  mjordan130 
#1 ·
Hi everyone! I'm a fairly new owner of a 68 mustang convertible and i've been slowly working on it but i've noticed lately that that exhaust smells like it's burning a little coolant as it has a sweeter smell. Also another issue is that when i drove it for maybe 30 mins my overflow tank for the coolant overfilled and sprayed around the engine bay while i was driving, now the car hasn't overheated or anything and i haven't driven it anywhere since as i'm worried i may have a blown head gasket. Could a leaking intake manifold cause the same issue? I'd like to consider myself very handy and believe i could do the work myself even if it is a blown head gasket but would just like to know what these symptoms would mean. I just rebuilt the carb but did not remove the intake manifold. Any help is very much appreciated!
Thanks!
Jordan
 
#2 ·
You need to run a cylinder pressure test and see if all the pressures are the same. Likely one is low indicating a possible blown head gasket.

Also check your oil to see if there is any sign of antifreeze in it.
 
#3 · (Edited)
That can happen if the radiator is filled too high, but also if you have a blown head gasket. Fill the radiator so the tank above the fins is only 1/2 full, leaving at least an inch of air space before the neck. Then drive it to see if the spewing occurs again.

But it does sound like the head gasket is blown you don't say if it's a V-8 or not, but if it is, replace both head gaskets while you are at it.

Z
 
#4 ·
Hi zray, it's a 289. I thought it may be too full as well so i didn't top it off when i noticed the first time that it was overflowing but now there's no coolant left in the overflow tank so i'm afraid to drive the car before figuring out what the issue is. I believe it is a blown gasket as well but i just wanted to post and see what others thought of it as well.
 
#9 ·
Since it sounds like you have a compression tester and, possibly, even a small air compressor, pull the plugs and, cylinder by cylinder, thread in the compression tester hose, connect it to an air line, watch your fingers, and look/listen for the air escaping.

Hint: If your compression tester hose has a schraeder valve in it, remove the core.

Bubbles/pressure in the radiator will expose the cylinder(s) leaking into the cooling system. Air from the carburetor will mean a leaking intake valve. Air in the exhaust, a leaking exhaust valve. Air from the breather, leaky rings.
 
#10 ·
I believe they still make a dip test that will check for combustion products. This works pretty well especially if you think you are smelling antifreeze.
 
#13 ·
I assume when you say 'it', you actually mean 'them', right? You'll have the entire top end off to do one side, I'd definitely recommend doing the other at the same time. The gaskets come as a pair, so all you're short is the additional labor involved, right? Also- if you get a top end kit, it'll come with intake gaskets for the heads, and cork gasket strips for the front and back ends of the intake manifold. Take both of those cork gaskets out and toss them in the trash- they're worthless! Instead, use a nice solid bead of silicone along both edges- you'll be much better off this way.
 
#14 ·
Hey everyone, Just an update. I did replace both head gaskets, Also replaced the timing chain while I had part of the engine apart and replaced all the gaskets for those items! Cars running great and I just need to get the timing and idle tuned in! First time ever doing it and boy were those heads heavy haha. Great experience overall!
 
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