97 Mazda 626 engine heats within minutes and shuts off - URGENT HELP!!!
 

Hi,

I bought a second hand 1997 Mazda 626 V4 automatic 3 weeks back with 93K miles on it. The engine was doing fine until last week when the engine started to heat up all of a sudden and stopped in the middle of the road. I got it towed to the nearest Mazda dealer. He took a week to diagonize and told me that the compressor is bad and would cost a lot to repair it. So he suggested on changing the engine itself for $2600($900 engine[85K miles] + $1700 labor). Before this problem there was a lot of vibration in the engine during drive (D) and would come down a bit when in N or P. I do not know the cause for that! Can this be one of the reasons for the engine to heat fast and stop abruptly? Is there any other reason for the engine to heat up so fast and stall? Should I get the engine replaced or take it to any other local mechanic? I am student and can't afford to spend a lot on the car right now. Can anyone suggest what needs to be done?
Any replies will be greatly appreciated.

Thanks.

RE: 97 Mazda 626 engine heats within minutes and shuts off - URGENT HELP!!!
 

Are you talking about the A/C compressor? This dosen't make sense.

If you drove it until it died, I might think a head gasket or creacked cyl head. Will it run at all?

The vibration you were mentioning might be from a worn or broken motor mount. This is not a precursor to an engine dieing.

RE: 97 Mazda 626 engine heats within minutes and shuts off - URGENT HELP!!!
 

Sorry, he told me that the engine compression is very low/bad. Therefore he wants to change the engine itself. Also, he thinks this might have caused the engine to overheat. Is it a good idea to go to a Mazda dealer (quoted, US$2600) or a private mechanic?

Thanks

RE: 97 Mazda 626 engine heats within minutes and shuts off - URGENT HELP!!!
 

The low compression will not cause an engine to over heat. Low compression is most likely a result of driving until it died. I would have the cylinder head removed to check for a possible head gasket failure or cracked head. This is where you are most likely losing compression and the best place to start.

as for choice of a mechanic, a dealer or independent can both be a good choice if they are familiar and experienced with the car. I am not sure if what info you put on this site is straight from the mechanic you have now or if you mixed it up. If it is true, I would look for another mechanic.

RE: 97 Mazda 626 engine heats within minutes and shuts off - URGENT HELP!!!
 

Thank you for your help/reply.
Good news...The mechanic said, he has stopped the engine from overheating. He had to change the water hose for this. But he also told me that the compression is low/bad. He wants me to change the engine as soon as possible.
1) Can I drive my car with a low/bad compression? If so, for how long?
2) How will the low/bad compression effect the engine?
3) What must the ideal compression be for a 1997 626 Mazda I4 automatic?
4) Is the compression a serious problem?

He told me that head and head gasket are OK.
Is there a site where I can read more about all this stuff?
All the info that I have posted so far is from the mechanic.

Thanks again!

RE: 97 Mazda 626 engine heats within minutes and shuts off - URGENT HELP!!!
 

You can drive the car with low compression. It depends what the readings are on each cylinder for compression as to what could happen. If thet are all low but pretty uniform, it will not really hurt anything. If you have one very low cylinder and all other ones are good, it will not run evenly and damage could result.

A normal reading is about 170 PSI, with a minimum of 119 PSI per cylinder. It is best not to have a difference of 10% between highest to lowest readings.

The compression is what produces the power in the engine, so it is very important. If compression is low all around, you will have an engine that lacks power. If it is one or two of the cylinders that are bad, you will have a lack of power and an engine that runs rough and idles rough.

As for learning about an engine in general, i guess you can google the term four cycle engine. I am speaking from experience.

RE: 97 Mazda 626 engine heats within minutes and shuts off - URGENT HELP!!!
 

Thanks for your reply. Your information was very helpful. Thanks again!

RE: 97 Mazda 626 engine heats within minutes and shuts off - URGENT HELP!!!
 

Don't laugh too hard when you read this. A friend found a 1974 pinto that had sat indoors for over 20 years. Pulled the plugs and squirted some Marvel Mystery Oil into the cylinders and let it sit overnight. In the morning it cranked so he put new plugs in and it started! Didn't run well but ran. Pulled the plugs out and checked the compression and it was all over the place. Drained the oil and put in fresh oil anda can of Restore and fired it back up. After a couple of minutes the exaust smoke stopped and it could power itself around the back yard. After about 4 hours of running it and driving around the block the engine compression was between 120- 140, before it was 40-90 psi. Car had no rust so he fixed it up and still drives it once a month or so.