Bad head gasket?

[scitzz]

Did the old girl overheat any during all this?

When I have cooling system problems, here is what I check.

Fill system, run to operating temp. Check all hoses for heat. If the bottom hose has none, and the heater isn't blowing hot, then coolant isn't moving for some reason. WP, therm, blockage. Remove the thermostat, put housing back on with RTV, check for flow. No flow, bad WP, flow, replace thermostat.

If I suspect problems with the head gasket, good signs to look for. Water in the oil, oil level is above normal, and looks milky. Rarely, but it happens, oil can go to the coolant instead. Coolant looks like milk. Coolant in the cylinders. Look for steam/water in the exhaust. Pull the plugs, and look for coolant in the cylinders. You have them out, do a compression test. Low numbers on two adjacent cylinders CAN be a blown gasket, but you will be pretty sure if that is the case already. Loud bubbling from the overflow from too much pressure MIGHT mean head gasket leaking compression chamber gasses, but can also accompany an over heat.

Let it cool, and check/top it of. Let it run to temp, and idle for quite a while. Shut her down if she overheats. If not, let her run, see if everything else checks out. Turn her off, let her cool some, and check the coolant level again.

[Safety Guy]

Thanks guys.

I haven't run her again. Let her cool and then checked rad fluid. It's way down and the overflow bottle is nearly full.

I was getting heat inside the car, but the radiator was totally cool. I didn't check the bottom hose though.

I'm thinking either bad t-stat or bad head gasket. I could take off the t-stat first, then drop in into boiling water to see if it opens. It was a new, correct Mazda part two years ago.

I'll also check spark plugs, maybe do all this tomorrow. There is no sign of coolant in the oil though. Oil is correct level and looks good.

Karl

[FestYboy]

Karl, how new is your pressure cap? is the system holding pressure at all? with the engine cold, how long does it take for the rad hose to be pressurised if at all?

[Safety Guy]

Arty, I'll find out tomorrow. The cap is only two years old or less. Same with the radiator and most of the rest of the hoses. I think the hose or hoses just behind the engine on the transaxle side may be older.

I'll be getting back to Aqua tomorrow around 2pm.

Right now here's my plan:

-top off fluids
-run engine up to temp (if it sounds okay)
-see how long it takes to pressurize the top rad hose & check bottom rad hose for warmth
-turn off engine
-check spark plugs for signs of coolant, etc.
-take off t-stat housing and check t-stat in hot water

Sound good so far?

Karl

[FestYboy]

thats a good start

[scitzz]

is the system holding pressure at all? with the engine cold, how long does it take for the rad hose to be pressurised if at all?

Why do I never think to mention that? I mean, when I feel the hoses, I feel for temp, and feel for pressure, but I never think to tell someone to check that. Weird.

Yeesh, some days I am an idiot.

Anywho. He says the radiator seems cool, but the heat works, so he has some coolant flow. Perhaps he should keep in the back of his head that a blocked up rad is possible. If so, what, in your opinion, is the best way to diagnose this?

[Safety Guy]

History:

I've been hearing burbling noises after stopping the car for the past few days. I didn't check until yesterday morning when I heard tapping from my engine and felt for the heat--no heat. I pulled over and checked my oil, etc. Then continued home after letting it cool off a bit. I coasted downhill when I could. When I let her cool off, I found very low coolant level.

After topping off coolant a bit, I started car with rad cap off and the level slowly overflowed. I stopped car and put the cap back on after topping off a bit more (it had gone down).

Then I let her run to warm up, did short test drive, and had heat (but remember, I had added a lot of coolant by then). After cool down, when I removed cap, it spurted out. So overpressure continues.

Then when I ran her some more, I heard the engine slowing down and getting quieter. I turned it off, fearing damage. Upper rad hose was cool. Rad was cool. Rad cap was cool. However, I didn't check lower rad hose.

Barring some "bubble" in my system, or a blockage, I'm thinking head gasket. There is some evidence of leakage on the back of the engine behind the distributor, so it may be a failure around cylinder #4. Just a guess, but I didn't see any hoses leaking back there.

Today I'll check what I posted earlier.

So I think this has all happened in the past couple days. It came up quickly.

Karl

[zoom zoom]

I'd swap those thermostats karl, it sounds like yours is stuck shut so the fluid in the radiator isnt making it's way through the rest of the engine. also just FYI, the radiator sucks fluid from the overflow when everything is working properly.. I always thought it was just a one way overflow, until I got that 626 and the fluid went from it to the coolant system when it got low.

if your really worried about the hg, maybe you could just pull the VC and retorque the bolts.

[scitzz]

Remove the rad cap, start her up, and check for fluid movement. You are looking for the therm to open, of course. If after some time, overheating has not occurred but the engine has been at temp for a while, remove the water outlet, remove the thermostat, then replace the outlet with RTV. Repeat. I betcha you get movement, instantly. If so, replace the thermostat.

I have noticed the B3 likes to "tap" or even sound like a sewing machine with cooling system problems. zoom zoom is sniffing the same thing I am, upper hose, after the therm, sounds like a bad therm.

Leakage on the back of the head. Think IAC. those two coolant lines, or the heater hose. I am not saying it isn't possible, but in 20 years of car repair, I have yet to see a head leak coolant externally. This is speaking of MY experience, meaning I think it would have to be rare. Hear hooves, think horses, not zebras.

[zoe60]

Take the radiator cap off and start it up when the engine is cool. If water shoots out of the radiator you have a bad head gasket. That's what my original engine did when I first bought the car about 6 years ago. Maybe your thermostat won't open. That would cause no heat and engine overheating leading to head gasket failure. Sorry, I was too late!

[crazyrog17]

Grab a new thermostat. I found a two stage thermostat at O'Reilly's by asking for a '90 Mazda 323 thermostat. The only thermostat housing gasket that works for me is the one from autozone with a rubber lip around the inside. The self adhesive ones leak like sieves with or without gasket sealer.

[Safety Guy]

So when I start her up with an open rad cap, will the fluid slowly rise like before with a bad HG? Or does it have to "shoot out" with more force? It slowly rose up and overflowed yesterday when I topped it off and started it with no rad cap on. I had to shut the engine off and put the cap on then, and after my test drive she overflowed into the plastic overflow bottle.

Karl

[zoom zoom]

it's plugged up...just remove the thermostat altogether and watch it flow like it should!

[Safety Guy]

Well I just ran the car for about 10 seconds, with the rad fluid level just around the top of the cooling vanes. It began rising so I shut her off before it overflowed.

Gonna do what ZZ suggested and start taking off the t-stat housing to try it with no t-stat. Crossing fingers and toes that its this simple!!

Karl

[Safety Guy]

I think I found it. I went out to take off the t-stat housing and then got the idea to pull the plugs. Here they are, #1 to #4 left to right:



Numbers three and four are darker, while one and two are lighter. I also stuck a screwdriver into two cylinder holes. Number one was dry and charcoal like. Number four had FLUID.

Methinks the head gasket has failed around cylinders 3 and 4.

What think you?

Methinks tomorrow I'm starting a head gasket job, but I'll also check the t-stat in hot water to make sure it's operating. My work today is not a waste since I have to take that off anyway.

Thanks to all, and confirmation and more comments welcome!

Karl