Jonny878

Just had a compression test on the engine and had an even 7 across all lobes. I believe this is the minimum for tolerance on the lobe. The prior history of the engine is not clear. Runs a little ruff, possible vaccum line/gasket problem, still being researched. The car has 72000 miles on the orignal engine. With that knowledge at hand, would it be wisest to invest in a new engine or fork out some cash $800 to $1400 dollar to keep her going.

I am leaning towards the engine replacement. A little help in one way or the other would be helpful.

Thanks,
Jon

rynberg

Engine sounds good, compression wise. Even numbers on all faces are at least as important as high numbers, as the results can vary depending on testing conditions.

BTW, the minimum is 6, not 7. Mazda lowered the threshold after 93.

ijneb

Dont spend money to keep it going, as it will pop sooner or later. Go ahead and get a rebuilt motor, and if you can afford, go street port and oil passage mods (and all that fun stuff) Even if you dont use it now, youll have it when you want it later.

Edit: My car (2 months now) had high 7's all the way around, and runs perfect, it keeps right behind a modded z28 (~300RWHP) and mine is almost stock.
My car had 71,000 on it when I got it.
I think my turbo's are leaking oil now

Rx-7$4$me

I have 85 k on my original motor and turbo's and I lost to a z06 by two cars, and beat an STI with full exhaust intake boost controller at 16 psi by about a car.

so mines till pushing

Not sure what my compression is though.

paw140

In my opinion, it's foolish to rebuild your engine based only on the fact that it has 72K miles on it. Your compression is good; I would spend the money and keep it going. It could easily go for another 20K+ miles.

1st to 3rd

Where are those $$ figures coming from? Even if you put a new engine in, you're still going to have to fork over the money to fix the vacuum & peripheral problems you have. There is nothing wrong with compression in the 7's. Hell, mine compression is lower then that and it is one of the stronger running RX-7's (with similar mods) I've been in.

DaedelGT

This is my sort of situation. I keep getting told by the local group people that I should rebuild around 60k because it is bound to go soon afterward. My question is, is that if I go by some way other than a blown apex seal, what can I harm by running it until it finally looses compression somehow?

Have you considered diagnosing it yourself? It would cost a lot less.

rynberg

Unless you are doing a lot of mods at the same time -- single turbo, clutch, injectors, etc., I think that's stupid advice.

A lot of moderately modded cars seem to be making the 85-100k mileage mark. Even if you put 10k miles a year on the car, that's 2.5-4 years from now.....

turbojeff

iTrader: (30)

Depending on what is wrong with the motor you might just consider putting a rebuild in it.

The reason I say it is because of labor charges, assuming you are paying someone else to fix it.

I had a FD with 88K miles, the previous owner had an ext warranty and they paid big $$ to replace the oil pan gasket, then the front cover gasket, then the lower intake manifold gasket. If you added up all those labor charges they would have been better off to just install a rebuild. The motor ended up loosing a water seal shortly after all that work anyway.

7 even is a little on the low side although Mazda did change the spec to 6. I think you need to look at the cranking speed, spec is 250rpm. If your speed was a little low then your fine, if your speed was high then it might make a guy wonder.

Jonny878

I missed the mechanic today and have not had a chance to get more details on what has been found. What I was told is if all vaccum lines and related items were replaced then i would be looking at the lower price, But if the intake has to come off and one of the turbos has to be removed to get to a seal (not sure on the name of that) then I would be looking at the $1200+ cost. These were ruff estimates and "what if's" so an exact amount I am not sure of.

That is good news to see that a flat 7 on the lobe still means the engine might be worth repairing and getting a little more life out of it. It currently shows no sign of fluid gasket leaks. A complete vaccum line/accessory change out would be manitory on a new engine install, so maybe I will go that route and see if that might fix the problem. Then I will only be out in labor cost if that does not remedy the problem. I will know more Monday.