tmking66

What are some symptoms of coolant leaking around the intake manifold? I think I may have this going on but wanted to hear what syptoms this causes with the engine performance.

Also, is it possible to remove the intake manifold with the engine still in the car? I was looking at the bolts and nuts that hold it on and some of them seem to be impossible to reach with the engine in the car.

Glazedham42

iTrader: (4)

The only real symptom that I can think of would be if you can see coolant leaking out the bottom of the intake. I guess there is a small possiblity that you could have a small vacuum leak in a situation like this, but the leaking coolant is going to be your main symptom.

There are two rubber o-rings that could also be leaking. I would make a guess that this is your problem, not necessarily the intake gasket itself. There is a cut out section in the intake gasket where the o-rings press inside a recessed portion of the intake manifold and fit up next to the engine.

As far as removing the intake manifold, yes it is possible with the engine in the car. It is actually quite easy after you do it for the first time. Disconnect all of the linkages and hoses and wiring to your carburetor, depending on how much of the emissions equipment you have remaining. Drain the coolant out. Remove your carburetor (4 12mm nuts?). Lift the carb off of the intake manifold. After that you have to remove the nuts and bolts that hold the manifold on. If I remember right there are 4 bolts on the outside corners, and then two nuts in the top middle of the intake. I think they are all 14mm. After you remove these six things the manifold should pull right away from the engine. You are also going to get some more coolant out after you pull it off, so have some rags or a bucket ready to catch it.

Hope this makes sense and helps....

Jamie

tmking66

Well, here is what I have going on. The car is an 82 with auto tranny. The engine runs but will not hold an idle. The car revs well but dies at about 1100 rpms. When I shift the tranny into gear the engine dies unless I quickly hit the gas and hold the brake and keep the rpms above 1500k. I have tested and tested for vac. leaks and have found none. There is a little bit of coolant puddling on top of the engine under the carb. I have cleaned it off and it comes back after the engine is run for a bit. Could a small amount of coolant getting sucked into the intake cause the poor engine performance? I can't really check the timing because I cant get the car to idle below 1100K. At that rpm the timing mark would probably be starting to advance wouldn't it?

Glazedham42

iTrader: (4)

I'm not sure when the car actually hits vacuum advance, but I think it is a little higher than that. My '85 GS used to be an automatic before I converted it to a 5 spd, and it did the EXACT same thing that you are describing. Here is what I suggest that you try to start with.

First of all, if you are able I would recommend removing ALL of the emissions equipment on the car. I don't know if TN has testing, or if your car is exempt, but doing an emissions removal GREATLY simplifies the car and could eliminate a lot of potential problems. Next, I would pull off the carburetor and intake manifold and try changing the gaskets and the o-rings. This should only cost about $7-10 if you do it yourself, and will answer your question about whether or not the intake is leaking. If this still doesn't fix the leak, then I would guess that your engine's coolant seal is starting to go bad, or has already gone bad. Coolant puddling on top of the engine is usually a symptom of this, but I wouldn't jump to that conclusion this early.

Finally, I'm going to venture a guess that your car's stalling problem is attributed to a bad carburetor. I would recommend doing a rebuild on the carburetor. That is ultimately what solved my car's problems. After a while these carburetors just can't go any longer, and they need to be rebuilt. When I had mine rebuilt it changed the whole feel of the car. It ran like brand new. So I would start by looking into these three things, and I'm guessing that they are the causes/solutions to your problems.

Jamie

tmking66

Thanks for the input so far. I will try some of these things this afternoon. I am pretty sure the carb is good. When I got this car someone had "tried" to do the emissions removal and messed it up. There were vac. leaks everywhere. The carb. that came on the car was "rebuilt" but apparently by someone who did not know what they were doing. There was an aftermarket fuel pump which was pushing too much pressure. When I got the car it would only stay running if I kept the rpms above 3k. I have returned the car to its stock config. I used another carb. that was taken from a car that was running well but whose body had rusted away. I replaced the emissions equipment and installed a stock fuel pump. I really do not want to remove the emissions system since I am planning to sell this car eventually and keeping the emissions intact may make it sellable to more people.

I will get the intake off today and replace the O rings and gasket. While I have it off is there anyway to tell if the coolant is coming from anywhere else? If the transmission continues to stall the car I may replace it with a 5 speed. I just happen to have one and all the other parts required for the swap. When you did your tranny swap did you have to swap the front counter weight?

Glazedham42

iTrader: (4)

You don't have to swap the front counterweight when you do the swap. You do have to make sure that you are putting on the appropriate flywheel for your engine though. You can't just stick any flywheel on there because some of them have different inertias than others, depending on how heavy the rotors in your engine are. Mazda changed the rotor design a couple of times during the 12A production run, so there are 2 or 3 different types of flywheels depending on what year your engine is. You'll have to make sure you get the correct flywheel for your specific engine or things are going to be out of balance...

tmking66

Thanks. I knew about the flywheels but wasn't sure if mazda used a different counter weight in engines with auto transmissions or not. The flywheel I have is from an 81 and would be going on a car with an 82 engine. According to Mazdatrix those two year models use the same flywheel.

tmking66

Well, I tore into the motor today and found the source of some of my problems. First thing I found upon removing the carb. was that the shutter valve was stuck closed. Please correct me if I am wrong but is this valve not supposed to remain open and then shut on decceleration? So, I got that fixed up. Next thing I found upon removing the intake manifold was that someone (probably the person who had been screwing with the original carb. and tried to remove the emissions) had removed the intake manifold at some point and used the wrong size O rings when they put it back on. One of the O rings was split where it had been pinched between the manifold and the engine, so, of course it was leaking coolant. I had to order another manifold gasket so I couldn't reassemble it all today. Hopefully when I do this will help with some of the idle problems that the car has. Is there anything else I should do or look at while I have the carb. and intake off the car?

Thanks again!!