I'm wondering if there are enough not-radically-modified 13B engines at this date still running to get an idea of the "average" life between overhauls. Our '94 FD, bought new in Sept. 1994, with 105K miles so far, stills acts 'new.' Peripheral parts had some troubles in the past, but never any work needed on the basic engine itself. Except for decreasing fuel mileage over the last year or so, the thing sounds and runs perfectly fine.

Are there any knowledgeable estimates on this subject? (No interest here in "My engine blew up at 25K miles" from attempts at extracting 400 rwhp, etc.)

 

I would also love this information. My last 1994 lost the water seals at 104,000 only because a lean tune installed on the Power FC (not by me)!

I had all bolt-ons, upgraded fuel system, exhaust, running stock sequential turbos @ 15lbs with a SMIC.

 

My buddies car gave out at ~72K about 1.5 years ago. The coolant seals had given out at that point. It seemed to be more of an age factor to the failure. He was running m2 intake & intercooler & ecu, DP, exhaust, at 12 psi. It still had decent compression at that point.

My personal FD is on engine #4 at 105k miles. Mind you I have never driven it, but it came with detailed service records and the only non-stock items were the downpipe and intake.

Best way I know to judge your engines health is a basic compression test.

~125psi is nearly new
~100psi is getting weak
~85psi is the minimum and will be difficult to start, low on power and tend to flood.

Vince

 

Mine had coolant seal / overheating problems beginning around 75k miles. Stock engine, stock ECU, aftermarket downpipe. As far as I know it was the original engine, the car had 45k miles when I got it.

 

Still not sure of the "right" way to test compression. Special gauge required? Have done this on piston engines but never a rotary.



Is the "champagne test" an adequate method for checking coolant seals, or is there another, better method? Not seeing any loss/usage of coolant whatsoever here, nor any signs of overheating.

 

friend got 110k out of his original engine, lasted from 1994-2002 and had only a downpipe and AST

 

At 101,000 an oil control seal cracked. Compression was getting on the low side but still ran great, except for an occasional pop during idle. Rotor housings looked worn and had a small amount of chatter on them. (could have been that 100mph third gear attempt...(young/dumb)) Rotor bearings perfect, main bearings a bit worn. Now, new housings, main bearings, and apex seals and she purrs like a kitten.

 

I do two tests with a standard compression tester.

First test is with the release pressed in and someone else cranks it. Look for even bounces.

Second test is a standard test to see peak compression.

This will be accurate enough to give you a good understanding of the engine's health.

As far as the champagne test, that is a very good indicator of a bad coolant seal.

Another alternative is to have a shop check for hydrocarbons in the cooling system. Basically a fixture that contains a special chemical is held into the filler neck and air from the cooling system is drawn through the liquid. If hydrocarbons exist in the coolant the fluid will change color.

This is really a useless test on rotaries because nearly all coolant seal failure modes will exhibit noticeable and unmistakable symptoms.

Vince

 

I appreciate all the responses... thanks for taking the time, folks!

 

10 years and 104,000 miles on stock mazda reman w/basic bolt-ons before coolant seal failure; however, motor still ran good and had decent compression when pulled.

 

my original engine died at 108K miles due to carbon buildup in the rotor housings. It was 100% stock.

 

my original engine is still going @100k, it hasn't had any work done to it, it still has the paper intake gasket, turbos have never been off. i believe i changed the turbo water hoses though.

it seems like the normal life span is 80-120k. i've seen higher, and lower. usually the low mileage failures had some trauma, like a blown water hose, or somesuch

 

^^yup. I believe that my engne would have lasted longer if I would had steamed cleaned the internals from time to time.

 

It would be extremely interesting to know what type of longevity the Mazda development team experienced when they were racking up miles in their test mules, in all types of weather and driving conditions, but all the while maintaining the engines properly. In other words, when the car was first introduced for sale, how long did Mazda expect the engines to last?