COOLANT LEAK FROM EXHAUST

Mafia Mustang · Oct 20, 2006

hey guys I just built my first engine and when i started it up .It started leaking coolant from the headers on both side I dont know what this could possibly be I had my block machined and exchanged my head please help

Johnny

vristang · Oct 20, 2006

Welcome to stangnet.
Wish you could have found us in a better situation.

I guess I don't understand.

either the coolant came from on top of the head, or it is running inside the header tubes?

Please clarify where you are seeing the coolant.

jason

Mafia Mustang · Oct 20, 2006

coolant

Every thing is put toghter I have an x pipe on it and it is coming out of the space between the header and x pipe and the back of the x pipe so it traveling though the exhaust somehow and its alot of coolant not just a drip its a steady stream

mob · Oct 20, 2006

wouldnt it just burn into white smoke by the time it gets there? This is very weird And if fluid can come out of there you have an exhaust leak.

My guess is its coming from somewhere like the intake or heatercore, and dripping down to where it looks like its coming from that spot. Check the back of your engine area, or top of the tranny, see if you can spot any coolant around there.

Mafia Mustang · Oct 20, 2006

coolant

It happens as soon as i fire the car so it dosen't get hot enough to make it smoke ans im sure its coming out of he exhaust.

Glaze · Oct 20, 2006

Im assuming you havent bolted the x pipe tight yet...right?

Check for water in oil yet? Might show up on dipstick or top of oil cap.

Did machine shop mill the heads or block head surface at all?

Mike97gt · Oct 21, 2006

This is not good.

It's either coming from the intake and traveling thru one or more cylinders or it's coming from a head gasket sealing problem.. either way not good.. check to see if there is coolant in the oil yet.

94GTCoupe · Oct 21, 2006

could be wrong,improperly installed head gaskets? good luck.

BlownFiveLiter · Oct 21, 2006

If you're losing that much coolant through your exhaust, that points to head gaskets. Did you use new bolts when installing the heads? What technique did you use to bolt the heads down, and what torque spec?

Mafia Mustang · Oct 21, 2006

Coolant

On one of the heads was warped so I had it shaved just a little bit cuz i was getting a leak out of front of te head but that fixed it so I have been though a couple head gaskets fel pro from summit and one from ford and they all looked the same. I have cast Iron heads on it do I need new bolts I though that was just on aluminum heads?

Johnny

BlownFiveLiter · Oct 21, 2006

If you reused factory torque to yield bolts, you'll never get the correct torque spec on the bolts. The same applies for iron or aluminum heads. Buy a set of ARP bolts or studs before you drive yourself nuts and go broke replacing head gaskets.

stangjunkie · Oct 21, 2006

theoretically you should replace the bolts but that wont cause this problem... are you sure its coolant and not just water?? this would be a big dofference. if you find that it is just water where do you live??

Mafia Mustang · Oct 21, 2006

ya

I think Im going to order new bolts and gaskets and put a diffrent set of heads on there if that dosent take care of it im gonna scream lol
thanks for the imput guys.

Johnny

sunil6784 · Oct 21, 2006

I'm with stangjunkie, my sentra does the same thing...leaks a little water where the midpipe connects to the manifold. No biggie, but it is water.

Did you check your coolant level ? Is it going down ?

vristang · Oct 22, 2006

There is no need to replace the head bolts on the 302.
Until they break, they are just fine.
ARP's would be better, but unless your gonna spring for them, the stockers will work well.

Perform a Coolant Pressure test.
With the engine off, pressurize the coolant system.
You will find leaks with in a few minutes.

Normally, coolant doesn't leak from the exhaust, but rather from the heater lines or maybe the back of the block.
Most likely, the midpipe flange is where you first noticed the coolant.
It is probably getting there from somewhere else.

jason

sevenfilmz · Jun 13, 2026

vristang said:
There is no need to replace the head bolts on the 302.
Until they break, they are just fine.
ARP's would be better, but unless your gonna spring for them, the stockers will work well.

Perform a Coolant Pressure test.
With the engine off, pressurize the coolant system.
You will find leaks with in a few minutes.

Normally, coolant doesn't leak from the exhaust, but rather from the heater lines or maybe the back of the block.
Most likely, the midpipe flange is where you first noticed the coolant.
It is probably getting there from somewhere else.

jason

Now, if coolant does leak from the passenger side exhaust pipe during a coolant pressure test with the car off what could that signify

Noobz347 · Jun 13, 2026

sevenfilmz said:
Now, if coolant does leak from the passenger side exhaust pipe during a coolant pressure test with the car off what could that signify

A bad head gasket is the most likely culprit.

Other possibilities are way worse.

Pull your plugs and see if any of the cylinders are wet from your pressure test.

COOLANT LEAK FROM EXHAUST

Mafia Mustang

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