Headgasket blown and looking for opinions

Cornbread52 · Dec 3, 2014

The head gasket in my 98 GT is blown (compression was around 150 in every cylinder except 2 and 3 which has 120). I have a set of PI heads Ill install when I do this, but the motor has 175K miles. I'm considering pulling the motor to do the head swap, and if I do pull the motor, I'm considering rebuilding the bottom of the motor. Since it's a manual, I'll probably replace the clutch and get an aluminum flywheel. I'm also considering slapping headers on it since the motor will be out. Does it seem like I'm going overboard? Money is an issue, but I have another vehicle so this can sit while I acquire parts.

punched281 · Dec 3, 2014

Did you put oil in there after you did all them dry? I would try putting a dose of oil in the cylinder, if the pressure goes up then most likely it isn't a head gasket probably looking at rings. Never had to do it and have never really seen if proved but this is what some of my old hot rod buddies say.

D3VST8R96GT · Dec 3, 2014

I usually take a dry pressure 2x and then a wet pressure once and move to the next cylinder

Cornbread52 · Dec 3, 2014

I also had a coolant smell, a loss of coolant, and the code that bank 1 was detecting lean.

96blak54 · Dec 3, 2014

Sounds to me youre wanting to build hp on the cheap and the blown head gasket is the ticket into it.
I find blown rings hard to believe only if you are sure of the engines history. If its ever been supercharged/force induced or nitrous then I would be suspicious of rings including head gaskets, but if not, im banking on just gaskets. An over heated engine blows gaskets easily, ...really doesnt blow them, the head bolts stretch more than they should and loose the tensile needed to keep a seal..

Pi heads/pi cams is a great idea with some flat top pistons only if you are 100% going to dyno tune the car with 93octane.

And...NO...you're not going overboard,...you own a Mustang

Cornbread52 · Dec 4, 2014

I bought the car back in 2002 for my wife and it had 50k on it, the car not the wife. It didn't appear to have ever had power adders. Is rebuilding the engine at 175k a bit much and is there anything I should be aware of besides it's a nightmare to set the timing.

CC'S95GT · Dec 4, 2014

A compression test won't tell you everything.
Do a cyl leak down test. The low compression could be valves, rings, or HG. Make sure before you pull everything out..

Cornbread52 · Dec 4, 2014

If i can find someone with the cylinder leak tester, I'll give it a shot. Figuring I'm losing coolant, smell coolant whenever it warms up, and develop a slight miss once it warms up, and two cylinders next to each other have less pressure, I feel good about blaming the head gasket. The heads I have are going to a head shop just to make sure they are good. At this point, I'm doing the PI head swap. I'm just not sure if I should rebuild the motor while its out. I'm also considering painting everything while its out.

D3VST8R96GT · Dec 4, 2014

Unless there is coolant in the oil I wouldn't rebuild

Cornbread52 · Dec 4, 2014

I'll check that when I get home. I parked her after the compression test just because I didn't want to do any damage and I already had the heads sitting in the garage awaiting funding.

96blak54 · Dec 4, 2014

Exsecive coolant washes the rings out, so keep that in mind. Im thinking, while you have the engine out, just go through it all,..new bearings, rings,...all of it.

punched281 · Dec 4, 2014

I agree ^ It would suck to put that time in to it and then once you put the motor back in and have it just eating a hole in your head because you didn't go through it.

WARNING* It is easy to do the "Since I am here, I may as well put some good pistons and rods, and hell a crank too. Oh yea and arp2000 hardware. And a windage trey." Before you know it you'll have yourself a built motor haha.

My vote is to just go through it.

Cornbread52 · Dec 4, 2014

I am drawing a line somewhere, I just haven't drawn it yet...

punched281 · Dec 4, 2014

Avoid machine work. If I would have just done stock bore size on my build, it would have cut about 1,300 off the overall price. I didn't gain anything off .020 over either. No point other than I got a good deal on a rotating assembly that had pistons .020 over.