Head gasket symptoms

**Fast56k** · 11-25-2007, 01:29 PM

I have a mopar remote start on my car and it is wired into cylinder 7. I have been getting cylinder 7 misfire at startup and last week took the remote start wire off and soldered the wires to try and isolate the problem. I found the plug in cylinder 7 cleaner than the rest and thought it was due to less firing than the other cylinders. Then, I have been getting some black stuff in the radiator overflow that is turning the overflow container black, and I am seeing the radiator full of pressure even when cool. It is forcing the coolant out into the overflow. I have had it in at the dealer and they said the black stuff is normal but they didn't know why it was forcing the coolant into the overflow. I also run a fan mod that I keep on most of the time and it keeps my temps below boiling. Well reading up on these symptoms today, I have come to the conclusion I have a head gasket leak.

Coolant reservoir dirty looking
Coolant being forced into the overflow
Spark plug cleaner than others
Misfire in one cylinder at startup
Car heating fast under hard acceleration
Pressure in radiator when cool.

C.

**Hurst Equipped** · 11-25-2007, 01:36 PM

if it was a bad head gasket, why would it still hold pressure in the cooling system? replace the one coil pack and see it that gets rid of the misfire code. it did for me.

**HoP1** · 11-25-2007, 01:39 PM

You can do a block test to verify if CO is entering the cooling system. Follow it up with a compression check. As for your misfires on cylinder 7 are you taking voltage away from the number 7 coil pack? You mention something about soldering wires. If you do have the remote start wired into the number 7 coil pack, it is possible that you are causing a significant voltage drop to that coil pack.
Double check your T stat, it could be causing your pressure build up.

**Fast56k** · 11-25-2007, 01:40 PM

Originally Posted by 65standard

if it was a bad head gasket, why would it still hold pressure in the cooling system? replace the one coil pack and see it that gets rid of the misfire code. it did for me.

Good suggestion. I did that and replaced the plugs. Still get misfire at startup. Was thinking maybe it was the cam, but I am convinced it is the head gasket. It is the cheapest of the other possible problems anyway (head leaking into exhaust or warped head/block). There is no water in the oil so I am hopefull. As far as holding pressure, that argues for head gasket too. Under load it is leaking into coolant. It is such a small leak that it doesn't release back when a heavy load is removed.

C.

**Hemi31** · 11-25-2007, 02:01 PM

Do a leak down test.....that will confirm a bad head gasket immediately.

**ZMagnum** · 11-25-2007, 02:04 PM

After driving it if your oil looks milky it could be a gasket leak. Also, pressure problems could be a bad radiator cap. I recently had to replace mine on my Durango. $5 fix.

I've heard you can get test strips to determine if there are exhaust gases in your coolant. I don't know where to get them though.

**Fast56k** · 11-25-2007, 02:17 PM

Originally Posted by HoP1

You can do a block test to verify if CO is entering the cooling system. Follow it up with a compression check. As for your misfires on cylinder 7 are you taking voltage away from the number 7 coil pack? You mention something about soldering wires. If you do have the remote start wired into the number 7 coil pack, it is possible that you are causing a significant voltage drop to that coil pack.
Double check your T stat, it could be causing your pressure build up.

Exactly my thoughts. That is why I took the remote start out of the equation. I also replaced the tstat. That was my first guess. I was running with a viper last night coming back from CA and I was riding his bumper, but the darned car was getting hot. I had to pull over and let it cool and then slowly let the pressure out of the radiator before I could get going again. I got up to like 250 (temp not speed

) and shut it off and coasted over to the side. My wife wasn't very happy with my escapade.

C.

**ZMagnum** · 11-25-2007, 02:21 PM

My Durango was getting too hot highway driving. Radiator cap replacement fixed it. Now the temps are normal.

**HoP1** · 11-25-2007, 02:50 PM

If your running a low temp t stat i.e. 170, and doing a 3 mile race on the I -5 chances are you will over heat. Water switches pllaces at about 175 degrees, sounds like in your situation the water or coolant never had a chance to sit in the radiator and let the radiator do it's job. I think you'd be better off running a 190 degree t stat, go out on the interstate and try duplicating your condition. I'd bet you'd run cooler.

**Hemi31** · 11-25-2007, 02:54 PM

A 170* can keep up just fine unless the t-stat is bad.

**mullens** · 11-25-2007, 03:44 PM

Another symptom of a bad head gasket is coolant spewing from the cap under high load. With a bad HG, compression forces the coolant back through the system causing the pressure in the degas bottle.