I did a headgasket, timing belt, water pump, and some other gaskets and replaced some leaking hoses on my 91 hatch about a month and a half ago. All has been fine but now after a long drive, I'll go to start my car, it'll stall out then it hardly starts the second time, feels like its running on 3 cylinders or something, and the exhaust emits so much white smoke its as if I ran seafoam through it. Isn't white smoke coolant? I had to put more in when I got home, but the temp gauge is also getting really hot then it'll go back down, then back up and so on. I'm stumped. Do I have an internal coolant leak or something? Help guys. Motors a D15 by the way. Thanks!

 

You are right about the white smoke, that is coolant being burned off.

The up and down temp. gauge is due to air in your cooling system.

I hate to say it but I think your head may be warped now, if it was all fine for a month or so.

You probably have another leak somewhere else which lead to:
air in system > overheat > blown head gasket

 

Damn. Well it's the original motor so, wouldn't be too surprised.. Any rough idea how much a replacement motor is? Haha

 

Got an update. So, first start of the day is always good, runs fine. But after driving for awhile when its warmed up, I'll turn it off, do what I gotta do, then go to start it again, and I have to give it gas while starting it or it'll bog out. It idles super rough like its bogging out or misfiring and it'll emit white smoke from the exhaust. Then it'll catch itself and run fine.. Any ideas?! I need a reliable car because I have another project, and if I can't fix this I'm gonna have to trade it away. Please help!!!

 

Did you initially replace the head gasket because it was blown?

It sounds like it may be blown again, my theory is that when you shut off the car the hot coolant (under pressure) makes its way into the cylinder/cylinders and when cranked again it struggles to start.

You can test this by driving it again (if safe) and shutting it off when it's up to normal temperature. Let it sit a little while (may 30 mins?) and before cranking it again - remove the sparkplugs. Then try cranking it and see if coolant shoots out of any of the sparkplug holes. This will at least tell you if coolant is making it's way into the cylinders.

Another easy test is smelling the coolant, if you smell exhaust you have a blown head gasket.

Alternatively, undo the rad cap and start your car. If you see bubbles coming to the surface, you have a blown head gasket.