Rebuild vs. New Engine
 

Hi All,

My engine is out and apart (1993 FD - 87,000 miles - blown water seal) and I've come to the point where decisions must be made!

I'm told that the engine looks good with the exception of the rotor housings. Though 'usable,' it is recommended that I replace them and then rebuild with the remaining good parts. This re-build would feature upgraded apex seals, but no porting or polishing. My engine had the old-style, 3-piece seals.

The trouble I'm having is that with the expense of replacing the 2 rotor housings, it will be essentially the same cost as what I am told a brand new (not re-manufactured) engine from Mazda would cost. The Mazda engine would of course, have Mazda apex seals and would be built to, what I'm told, are somewhat lax tolerances - at least compared to what can be achieved in a re-build.

I keep going back and forth with the pros and cons for each choice and I thought I'd throw it out here to get some opinions - and find out all the obvious things I'm not thinking of!

Thanks!

Go new IMO. New oil control rings and seals, housings and irons, bearings and hard seals. Hopefully the new engine was built after MAZDA switched to 2 pc. Seems like they should be able to tell you that. Presumably less downtime and your old engine should be able to be parted out to off-set some costs. Worry about those tolerances on the new block in another 87k.

Thanks for the reply, Jim!

The rebuild would have all new seals and bearings as well ($$$), but of course would use my old rotors, e-shaft and plates. Would that make any difference in your opinion?

Thanks again!

Yes, neglected to mention irons (side plates). Though your old engines irons should be in spec, those would be new with the 'new' block too. You have to run the numbers. I'm sure you already have tear-down labor costs. But if it's close at all...
I did a pretty comprehensive rebuild at almost the exact same mileage and also for a coolant seal failure. If I wouldn't have been doing the work myself and had a reasonable option from a builder, I think I'd go new if costs were close. Especially if it was a later production engine with 2 pc apex seals.
If your builder hasn't mentioned them yet, there are some other 'nice to do' things at this time. Re-wrap engine harness, clean injectors, silicone hoses, new coil harness if it's crispy etc.

All new Mazda oem motors have the newer-style 2 piece seals. The 3 piece seals haven't been around for over a decade. The new motors I sell have been built recently. They aren't old stock. New is always better as like mentioned, all the hard parts (irons, rotors, housings, eshaft, oil pump, etc) will be brand new but unless you have the new motor torn down and gone through, you wont have the upgraded apex seals or my clearancing which is stricter than Mazda. It comes down to budget and what you want.

Where are you getting the new engine from?

I'm in roughly the same boat -- even though this engine had been built previously with 3mm apex seals, the tips on two of them still broke and damaged the rotors, housings, and turbos. Amazingly enough the engine still mostly worked, with 4/6 chambers showing compression. Maybe that's a testament to how good that first rebuild was?

Anyway, the most of the housings have to be replaced and one rotor, and the turbos need replacing. I looked into the crate motors because I thought it might be cheaper, but it seemed like if you wanted anything done to it it would come out to roughly the same or more than rebuilding

I have brand new Mazda 13brew engines available.

I thought there were no more new factory engines from mazda? someone was selling the last dozen or so right?

EDIT: I think that someone was IR Performance

Are these 13B-REW engines the Series 6 design?

I bought the entre stock of engines that were in the usa earlier this year. I can still get motor from Japan. These are series 6 with the updated metal front cover gasket.

I had purchased my 94 R1 at roughly 55k mi. The only mod I had done was Racing Beat muffler. Water seals were blown at about 85k mi., so I had a very similar experience to yours.

I was able to salvage most of the pieces of the motor and did a rebuild with new Rotary Aviation 2mm seals. Kept the ports stock. Went with 99 spec turbos and a custom V-mount. Drove it for about another 80k mi. and the water seals took a dump again.

I honestly think the seals are probably the least of your concerns, but I am no engine rebuilding expert. Just voicing my experience. I feel the water seals are the most sensitive aspect of the engine and if Mazda didn't do anything different, expect another 80k out of the motor, which isn't bad for a high performance engine.

Mazda 13BREW Engine, NEW | IRPerformance

In your signature, it says brand new 13b engines at $4300. If we give you a tired motor, you can credit us another $1000?

Ken

$4300 is with a core. Mazda recently dropped the core fee from $1000 to $400. I'm low on core parts so I prefer you provide a core. It can be complete junk, just has to include everything the new motor does: short block with oil pan, flywheel, pulleys, etc. Without a core pricing is $4700

on facebook i saw you advertised it for $4500 plus shipping with out core

and here its $4700 on your website its $5,799.00
which one is it sir :scratch: im interested :icon_tup:

Mazda upped the price by about $100 on me last week. Website needs to be updated. I apologize about that.

Mazda has upgraded these engines as they went along. for instance, when they changed the rotor housings in 99, they only had the 99 style housing from then on. etc etc.

or in other words, you haven't been able to buy a series 6 engine since 1996.

this is directed toward the guy asking the question, but the OEM's update prices monthly, which was last week.

Good to know. I've been planning to gradually upgrade to 99-spec parts.

I noticed that you want to sell your FD.

So are you just posting nonsense to get your post count up because you think it makes you more credible? If anything it does the opposite because now I'm wondering if you even have an FD to sell...


https://www.rx7club.com/search.php?searchid=14898190


^^°Keep it up and no one will trust you.

Pay the $4700.00 for a new engine and sell the parts of your old one. Good irons are pulling $6-900 a set right now. Your housings are probably perfect candidates to be resurfaced and are worth $2-400 a set as is. Good Rotors if not heavily pitted worth $350-500 per set.

Shops can talk about the loose clearance of new engines or remans but they almost always run smoother than a rebuilt engine from a shop.

The reality is that new parts always trump 25 year old parts. Depending on your goals, a new Mazda crate engine is the best choice (Ray Crowe tells me he has been selling a lot of them lately).

If your goals include over 400 rwhp, have the engine opened up by a competent professional for things like upgraded apex seals, heavy duty coolant o-rings, intake and exhaust port work, etc.

I've noticed over the years many folks don't like to press in new stationary gear bearings, clearance new side seals nice and tight, or install new (and pricey) metal oil control rings. You get all of these parts new with a new crate engine, along with a new (and possibly non-leaking, lol) oil pan, flywheel, tension bolt set, stationary gears etc etc.

I will tell you though--- More than once I've torn down a reman with loose seals, backwards seals, and once---a missing side seal spring. Crazy stuff. The quality control on the new engines has been much better.

For my rebuild, I think I ended up spending close to if not more than what a crate engine would cost. I went with all OEM seals from Pineapple, gasket/o-ring kits from Atkins. I replaced one rotor housing bought from a forum member and had Rick's Rotary press in new bearings.

But I think a huge thing is time. Working full time, I spent well over 2-3 months just cleaning internal engine components (given, I am a lazy bum and like to sleep in on weekends). Scraping out water seals, oil control ring grooves, apex seal grooves, side seal grooves etc. I was also very worried about what product to use to clean and bought pretty much every degreaser, paint thinner, mineral spirit...

This rebuild was mainly preventative and to solve some issues I could not resolve (2nd turbo boost, oil leaks and consumption, smoking on boost). I'm glad I did so because of the chattering I discovered on the front housing.
But if this engine were to actually go kaput, I would have to consider a new crate engine over a rebuild

Montego,
Yes, I am trying to sell my fd and yes also to up my post count. I am not used to posting. I have been a member for a long time but never posted since I am probably about 15 years older than most of the guys on this forum and not that great with tech. I am not trying to piss anyone off. Sorry. I just rather sell my beloved fd to a guy who will appreciate it. My car has given me 20 years of joy.

Was reading this dated link below from 2012. Anyone tearing down new engine blocks from Mazda encounter the same issues with rust and gunk in the coolant passage ways?

https://www.rx7club.com/3rd-generati...ngines-983731/

Does flushing without a teardown work?
​​​​​​​

this doesn't seem to be the case on the new ones now. They definitely used some kind of coolant instead of water in the one I got from raye crowe earlier this year, was built 3 months before I got it, and when I tore it down for upgrades there was basicly no rust in it.