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Replaced head gasket, now what?

There’s lots of sweet water vapor coming out of the tailpipe, I’ve got water vapor in the oil and gunky oil in the water, especially in the overflow bottle. The engine overheats after a while as well. All the classic head gasket failure signs. I have replaced the head gasket twice, just to be sure. The head has been magnafluxed, pressure tested and planed. The only other thing I can think of that would cause the oil-water interchange is a cracked cylinder wall. Is there anything else it could be? I want to make sure there isn’t anything I’m missing before I start working on the block.

87 Toyota Corolla, 1.6L, 4ALC/4AC engine, FWD, SOHC, Carbureted

JMHO, but I would not suspect the engine block.
I’d start by considering one of the following, and keep in mind I’m not a heavy on Toyota expert here and off the top of my head cannot remember the engine layout.

Carburetor base gasket as many Asian vehicles flow hot coolant under the carburetor to prevent throttle body icing.
Timing cover or timing cover gasket rot. Some of the small block Fords were prone to something like this over time. This would not cause a sweet smell out the tailpipe but can lead to coolant and oil mixing.

If the car were mine I would examine the carb base gaskets if it appears that coolant flows underneath the throttle body.

The water in the overflow won’t come from the warm water under the carburetor. I would guess that you didn’t look at the cylinder walls because you were reluctant to move the crankshaft. The Haynes manual should tell you which bolts on the front of the engine require sealant. The head bolts need sealant on some engines. There could be water coming up the head bolts and leaking into the top of the head (never saw that happening before) but that shouldn’t affect the exhaust. Your car is old, so if you have any driveability problems, I always recommend the newer car.

Thanks for the replies! Keep them coming!

There isn’t any coolant under the carb.

This engine doesn’t need sealant on the bolts.

Newer cars cost too much, but then again this one might end up that way.

I did rotate the crankshaft to inspect the cylinders. There is major vertical scoring in one cylinder and some minor in the other three. The sleeves seem to be a little over 1/8 inch thick. I am not sure how thick sleeves are, but there is 1/8 inch of steel, then the iron of the block when I looked at it. Iron block, steel cylinder sleeves, aluminum head! The scoring seems to be very old and there is evidence something dropped in there at some point since the piston and combustion chamber both have some gouges. The scoring in the cylinder wall didn’t seem much deeper than a fingernail’s thickness but it hasn’t been magnafluxed so I don’t know if it’s grown into a crack since the scoring originally happened. There is no evidence of welding except for the factory seam (slightly discolored, 3/16 inch wide, vertical line) in each cylinder wall.

The vapor from the tailpipe increases tenfold after the thermostat opens too. This leads me to believe that coolant is entering at the cylinder wall (scored & 183K miles old), the head gasket (new), or the combustion chamber (magnafluxed and pressure tested) unless there is something else that explains large amounts of water vapor in the exaust and an oil-water interchange.

I really don’t want it to be the cylinder. Keep the ideas coming!

It’s labor intensive, but if you really want to find your leak, you can do this:

remove the intake manifold and block all coolant passages in the head. Use a heavy piece of flat plate steel, like maybe quarter inch plate. Drill holes in the plate so you can use available intake manifold bolts to hold the plate on. Use some gasket material to seal it. Drill a hole in one of the plates so you can mount a tire valve to it. Plug all coolant hoses. Fill the block with water and finish sealing the motor, then apply 10 pounds of air pressure to the tire valve. Look for your leak. If it’s in one of the cylinders it’ll make itself evident eventually. You might even try rotating the engine by hand to see if you have any coolant showing up in intake ports.

JayWB has a good idea of pressure checking the block with air; but, anyway you test it, the tests will be less than perfect. Some of the problems: air will go through places where water won’t – even pressurized water. Higher temperatures (lower?) will open cracks and other openings, such as cylinder walls, and mating points. The cylinder head might, I say might, have cracks, or be porous, only when hot. Same thing for the cylinder walls.
You had the cylinder head milled flat; but, what of the top of the block? I don’t mean milling. I mean, did you check the block deck for flatness with a true flat?
The bolts holes may be pulled higher. A flat would reveal that.
Did you make absolutely sure that the gasket covers the correct water passage holes in the head and the block? Did you use a sealant? Maybe, you shouldn’t. Maybe, you should. I’ve seen instructions for one, or, the other.
If the engine is all together, remove the spark plugs. attach air pressure (less than 15 psi) to the cooling system. Watch the pressure gauge, and listen for air escaping into (or, out of) the engine. Turn the crankshaft 1/4 turn. Watch and listen. Again, 1/4 turn. Now, put water in the cooling system, and repeat the procedure.

Google for dye-penetrant test kits for the cylinder walls. The exhaust passages are another potential place leaks may occur.

My question is, how do you magnaflux an aluminum cylinder head?


Wow. That sounds like no fun at all. I’ll hold it in reserve for a last resort. I didn’t think about pressure testing it myself. I’ll try to work that.

You can’t if you are using magnetic particle inspection. You can if you are using Magnaflux’s dye penetrant. Unfortunately Magnaflux is a brand name and it’s just easier to say the name than the test type. It was checked for cracks. That’s it. Sorry if I wasn’t clear.

I didn’t have the block milled. If I do that I might as well get it magnafluxed and get the crank done. I didn’t have a macninist’s rule to check the block but I used a carpenter’s square. There is pitting in the iron of the block but I didn’t have any measurements over .006 which is the maximum warpage for iron blocks before milling is recommended (according to the almighty internet). My measurements could be quite wrong because of that square though.

The new gaskets had the same exact holes as the one originally on there. The first one I put on was a felpro crush-type. The one that is on there now is a stock-type with a bead of silicone around all the bolt holes and oil drains. I didn’t find anything that recommended using sealant. Maybe that would counteract the pitting and slight warpage though. Hmmm.

I’ll try the pressure test and get back to you all with the result.

The dye-penetrants that I’ve seen are $100 or more. I’ll try to find cheaper. That would be better than removing it to take it to a shop.

Thanks for all the great ideas. I’ll get back to you.

The dye process is sometimes called ZyGlo.

I’m not sure on this but I think AutoZone, etc.? has a cooling system pressure tester as part of their tool loaner program.
Why not rent that (you get the money back when you return the tool), pressure up the system, and see what happens?
If you do this and the pressure does not start bleeding off quickly then it’s best to wait 15-20 minutes and see what happens.

I’m still not sold on a cracked block.

I’ll check that out. Thanks.

Edit: Just called AutoZone. They’ve got it. It’s a self-contained hand-pump. $75 deposit. As soon as my wife gets back from the store with our one working vehicle, I’ll go get it. I’ll try it with coolant first since it’s already filled. Then I’ll go dry like jayWB and hellokit suggested.

I hope it’s not a cracked block. The cylinder walls seem pretty thick. I’m not sure if they pressure tested or ZyGlo’d the intake/exhaust channels when they did the combustion chambers. I guess it could be a pinhole in the intake side. That would fit with the higher volume of water vapor in the exhaust after the thermostat opens. But I don’t see how it could explain the oil-water mixing. A cylinder wall crack or an improper head gasket seal would.

Whatever it is, I hope it is completely evident after the pressure test.

Well, the pressure tester was too big for my little radiator’s neck. I’ll figure something else out to get some pressure on it.

Did you clean the threads on the head bolts before they were reinstalled? Did you chase the threads in the engine block that the head bolts thread into to clean them? And did you apply a little oil to the threads of the head bolts before they were reinstalled and torqued down?


The pressure tester that Auto Zone has is one designed for yesterday’s cars. It WILL work, but, you need to get an adapter to fit today’s different radiator, or pressurized overflow bottle necks. You’ll see them on ebay. here’s an example:

If you can afford a newer Corolla or Civic, you may want to be thinking about it.