Overheated '99 626
#1
09-26-2021, 08:00 AM
Overheated '99 626
Hey all! New member here! Sorry, this is a bit long, but I just joined today because of my daughter.
This will likely be a continuing saga of trying to fix the '99 626 that my daughter overheated...
And just for some background, my daughter bought her first car, a 1999 Mazda 626 2.5L with 130k miles. It had good maintenance records and an inspection sign-off from our mechanic.
The problem is the thermostat went out and my daughter drove it to the house until it overheated. It turns out she then decided to tell me "it had done that once before". I educated her on driving cars with no coolant but, crossing my fingers, I replaced the thermostat but now only a few weeks later, on a 200-mile drive to visit her boyfriend, she had to pull over on the side of the road because I believe, the head gasket is blown. The car won’t start.
First, the damn coil-over plug wires are melted into the plug tubes. What fun I’m going to have. I got a couple of the plugs out and measured compression. 50PSI on one, and 80PSI on the other. Ouch.
I was preparing to take the front head off to check the gasket, so was getting cylinder #1 to TDC. The issue is that all the timing marks, camshaft gears, camshaft sprocket, and crankshaft, all showed they were dead on, but the #1 piston was closer to the bottom of the stroke? To be fair, it was on its way to the top of the compression stroke though. Still odd to me.
I'm wondering if, when the car overheated, died, and she had to pull over if that messed up the timing? We thought the compression was related to a blown head gasket but are now wondering if it's also timing? If the timing was truly off, to begin with, could that have lead to overheating issues? I don't see how. but crazier things have happened.
Lots of questions, but really my first task has me just wondering if the piston should be at TDC when the marks are aligned?
Thanks for any help!
This will likely be a continuing saga of trying to fix the '99 626 that my daughter overheated...
And just for some background, my daughter bought her first car, a 1999 Mazda 626 2.5L with 130k miles. It had good maintenance records and an inspection sign-off from our mechanic.
The problem is the thermostat went out and my daughter drove it to the house until it overheated. It turns out she then decided to tell me "it had done that once before". I educated her on driving cars with no coolant but, crossing my fingers, I replaced the thermostat but now only a few weeks later, on a 200-mile drive to visit her boyfriend, she had to pull over on the side of the road because I believe, the head gasket is blown. The car won’t start.
First, the damn coil-over plug wires are melted into the plug tubes. What fun I’m going to have. I got a couple of the plugs out and measured compression. 50PSI on one, and 80PSI on the other. Ouch.
I was preparing to take the front head off to check the gasket, so was getting cylinder #1 to TDC. The issue is that all the timing marks, camshaft gears, camshaft sprocket, and crankshaft, all showed they were dead on, but the #1 piston was closer to the bottom of the stroke? To be fair, it was on its way to the top of the compression stroke though. Still odd to me.
I'm wondering if, when the car overheated, died, and she had to pull over if that messed up the timing? We thought the compression was related to a blown head gasket but are now wondering if it's also timing? If the timing was truly off, to begin with, could that have lead to overheating issues? I don't see how. but crazier things have happened.
Lots of questions, but really my first task has me just wondering if the piston should be at TDC when the marks are aligned?
Thanks for any help!
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