MK3Brent

iTrader: (6)

Greetings, all.

I've read the shop manuals and FAQ's about the 13B-REW.

It seems many say compression testing, if done correctly at 250rpm should give you as accurate results as possible.

I found an engine with 87psi on one housing, and 85psi on the other.

Considering the spec, these are low values with only 2psi difference between the two.

Also, I've read anything lower than 90psi would be considered a ticking time bomb.


What do you think?
Would you stay away from an engine like that, and hold out till you find a better compression engine?

Rebuilding wouldn't be an issue, but I would definitely like to just drive on an engine as is for a while.

What are your thoughts?

Thanks,

Mazda RX-7 EFINI TYPE

How long was it sitting for? If it's been sitting for a while, throwing a small amount of engine oil through the spark plug holes then turning over should yield some better compression numbers

Narfle

iTrader: (16)

Was the engine warm? The balanced numbers were a good sign, but you should have 3 values for each rotor.

MK3Brent

iTrader: (6)

The ad said cold and dry.

It's an e-bay sale, so I'm ever cautious. (Been burned before.)

I was interested in the balanced values, which is why I post this thread at all.

Is there anything I should ask them to get a better idea?

djseven

iTrader: (56)

Without a coolant system pressure test those numbers are useless. Needs a rebuild with those numbers either way. Depending on the price it might be a fair deal. Used, good condition engine parts are getting more rare by the day. Dollar to Yen exchange rates aren't helping either.

dguy

iTrader: (8)

You're correct that those numbers are useless as far as gauging how healthy the engine is without a pressure test at temperature, but you're contradicting yourself on your second statement. 85-90 PSI on a stone cold engine isn't bad if everything else is functioning properly.

edit: Just an FYI I don't advocate 'Jspecs' or other used engines, and wouldn't install one in my FD. But those numbers don't necessarily mean that it needs a rebuild, just that you're only getting half the story.

Natey

iTrader: (19)

My realistic expectation would be to have money set aside for the rebuild before I even bought the engine, especially if it was from Japan.

Even an REW with 20k on it is still 20 years old and that nightmare flood affected a lot of things you wouldn't expect.

druggist

iTrader: (4)

Those ebay sellers usually dont do compression tests properly, they dont remove the valve from the tester, or they dont hold the release button when they test, it gives the highest value, so if one seal is out, it is misleading.

ZE Power MX6

iTrader: (159)

How is 85-90psi cold any good? Compression drop when the engine warm up.

MK3Brent

iTrader: (6)

Thanks all.

I can definitely rebuild once I have something, it's just trying to start off right that's tricky.

Definitely not looking to go crazy for power, just need something reliable for weekend driving... mostly just for fun.

I hear the housings are the most trouble. Finding good ones that is. Guess I'll find out sooner or later.

SA3R

I've seen some used engines that sat for years cold and dry, try to fire them up and they just dont have the compression to fire. Tow starting them usually results in them running (usually a bit smokey and not very crisp sounding), they get warm, and then they either restart fine, or they dont start again without a tow and need to be rebuilt.

On the other end of the scale, I have good reason to believe my car sat parked for a few years in Japan because the registration fees and Japanese 'shaken' process was too costly for the owner, and it then went for auction.
It started and ran fine (after fixing fouled plugs), and has done for years since, no problems. It may be a freak or an uncommon situation, but having an original unopened factory engine in 2013 with fairly low mileage is part of its attraction for me, I guess.

Would I buy one from Fleabay, with cold compression numbers like 85/87psi? Yeah I would, if the rest of the engine looked in good condition. In my back pocket I would have spare cash for a rebuild though, if it needed a rebuild. And in the back of my mind I wouldnt harbor any strong hope one way or the other that it would be a runner or not.

MK3Brent

iTrader: (6)

That's essentially where I stand right now.

Got cash to buy engines + rebuilds, and the ones I'm looking at are definitely "clean" looking. I may just pull the trigger if I don't find anything nicer in the next week.

dguy

iTrader: (8)

Uhm. No.

Tem120

iTrader: (5)

My JDM engine with 100 Compression lasted all of 1 year LOL .

This is my opinion simply based on my short experience . But having the engine rebuilt is alot better then having it blow , then mess up the housings mess up the rotors , and the rebuild be more expensive , and leave you stranded 1000 miles from home .

Natey

iTrader: (19)

I remember a long time ago someone told me this:

The RX-7 is the only car on the road that can do 100mph with a blown engine.

MK3Brent

iTrader: (6)

Well, the company in TX agreed to $1500 shipped.

Looks very clean, but I'm not expecting too much.
Most likely will be rebuilt sooner than later.

Complete engine, transmission, wiring, and ECU.

I figure another couple thousand in work, and it should be a nice stout reliable start.