(car is 87 turbo)

My car was just checked at a mazda dealership by an rx7 specialist. They said the car has low compression (they didn't give me the exact numbers but I will ask next phone call) My questions are: how is low compression bad (like what would it do to my engine) and what causes low compression? (blown seals, gaskets, carbon build up, etc.)

I just bought the car, do you think the dealership (seller) would have known it has low compression (car has crappy idle and some starting problems) and should they have disclosed this information to me?

Thanks.

 

I go out of state in about 2 hours andI really would like a reply soon, sorry for being impatient, but I have a limeted warranty and need ot contact the seller soon.

 

See what the seller will do. I doubt they will give you a new engine. You really should of had that done before you took possesion of the car.

Low compression is bad becouse the seals in your engine have worn. With low compression you have a bad idel and you are not making the power you should be. It also stesses the engine more becouse one rotor is weak.

Good news is if you havn't blown a apex seal yet and you are a decient machanic you can rebuild it for pretty cheap.

 

Low compressiomn is the result of worn apex seals mainly, but also some wear on the rotorhousings, this is natural with mileage, just like mileage wears piston rings and causes them to lose compression slowly too. Mazda sets the lowest acceptable compression limit at 85psi, so if you're lower than that then by all rights your warranty should replace the engine. If not, then it's probably not gonna happen. This is not something that a seller would tell a buyer unless the buyer asked...then the seller (if they know) should not lie about it. But if I were selling something and the buyer didnt ask any questions, I wouldnt shoot myself in the foot by bringing up every problem it had. But if they asked specifically about the compression I would also be honest and tell them if I knew.

Low compression will not tear up the engine; compression is what makes the engine 'go" so to speak. At a certain point those worn seals will get so thin they will break, and then the engine is "blown". So that is ultimately what will happen. In the meantime, the idle will slowly worsen, and you'll have hot start/flooding problems.

 

wtf kevin landers?

 

Can I help you?

 

You need to do a compression test yourself, the dealer is notorious for diagnosing engines as "bad", when it is something else. They really have no idea how to troubleshoot, the simple answer for them is that the engine needs to be replaced. Then they quote you and you crap youself, their hope is that you will put that money down on a new car instead of repairing a 19 year old vehicle. You could very easliy have a vacuum leak and the car would exhibit the similar symptoms.

Find out what they say the compression is, then do your own test.

 

IT should be noted that a heavily flooded engine can show low or no compression on a gauge, even if the test is otherwise done properly. This is where it gets tricky...you need to inject some oil or atf then start the car and let it burn all the crap out, THEN run the compression test to get a true reading.

 

As well don't you need to modify a normal compression tester to test the engine properly?

Something about a valve...I can't remember, I haven't checked compression in about a year.