If i were to fix a "blown motor" what would this entail? I have heard that all you have to do is replace the seals. If this is so, how easy is that to do?

 

That's a complete engine rebuild.

 

step one is to tear down engine and see what is bad and what is reusable still.

 

This picture shows the engine block all taken apart. The seals go in the grooves of the rotors. As you can see, its impossible to get the rotors or seals out without completely disassembling the engine.

 

but if that is the problem, is it that hard to take apart the engine, it really doesnt look that complicated. It almost looks as if the hardest part is getting the engine out of the car.

 

I am by no means an expert, nor have I ever done a rebuild myself, but I think the hardest part is knowing what type of damages to look for.

That and to properly do a rebuild there are several instruments to check housings, plates, ect to make sure they are still within tolerances that are considered reusible.

If you don't do a complete and accurate diagnostic on the internals and you rebuild just what looks visibly damaged you could be wasting time and money.


With all that said, I have been researching, as well as buying rebuild DVD's and plan on doing my own rebuild if it comes to that (possible coolant o-ring failure).

 

since this is obviously your first time, i'd say take nothing for granted. you're correct. it's not hard to disassemble a motor. pulling the main bolts (front cover and flywheel) are perhaps the hardest part because the average person doesn't have the tools required, but with that said, care MUST be taken when removing the housings and internal parts from the stack.

 

Taking one apart isn't hard. Putting one together isn't hard either. Putting one together, right, that will run well can be hard. There is a reason some builders charge $2000-3000 for a rebuild.

 

They have to make a profit.

I rebuilt my own(about 4k miles on it now), but didn't do everything as I should have (measure and clearence everything), and did some things I probably shouldn't have (eccentric shaft jetting, not replacing the bearings). But when it comes down to it, its just an engine, a unique engine, but an engine none the less. If it spins and has compression it should work. (timebomb maybe?)

To answer your question, you have to pull the motor, tear it apart, measure, measure, measure, then verry carefully put everything in its correct location, the correct way (the rotor oil seal springs with tabs lined up on the rotors and seals), lube everything up as your stacking the pieces of the cake, then bolt it all together, and cross your fingers that you don't have any problems outside the motor.

I think you could rebuild a good low milage motor for less than $1000.

Good luck, and tear it apart, hey you can't break an already blown engine.

 

from a functional standpoint, you're 100% correct. from a financial standpoint, patience and care are invaluable and can be the difference between buying new hard parts or using what you disassembled (gouge, nick or crack a housing) - as long as they are spec.

 

Actually, it's their experience you are paying for... Many people have rebuilt their own engines only to have them self-destruct. The main problem is that the second rebuild can be even more costly if more parts are rendered unusable from a build mistake.

The problem is, when you are doing something for the first time, you don't often know you are doing something wrong until after its done and failed.

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/rebuilt-engine-boat-anchor-pics-inside-466493/

I'm not saying its hard, but there are some gotchas that can be pretty costly. That's what you are paying to avoid when having a shop do the rebuild.

 

I've rebuilt a few motors...takes time and about $500 for all new seals.

 

yogart man by the way u sound u shouldnt cosider doin it yourself..just got done with my t2 and it is very more elaborate then how it sounds..u need a flywheel puller and flywheel holder which tools alone are bout hundred bucks from rb. then all vacum lines ontop of bolts u might round off or stripp....belive me when i say this if ur going down that route research it become very familuar with it then go from there...not trying to be an ******* just very time consuming and mayb i just had a bad experience

 

flywheel puller = big hammer and a block of wood
flywheel holder = long piece of wood wedged between the studs of the flywheel

like todd said - it will be time consuming if its your first time. like any repair, something you did not think about will happen and slow you down...but hey, if you have any problems just post here for answers =)

 

flywheel holder=a piece of chain, use an bolt on the rear iron and a clutch mounting bolt, but try to protect the flywheel teeth.

How do you use a piece of wood to hold it?

I'd like to add, "They have to make a profit, and you also don't know exactly whats in you motor."

 

SO WHO OUT OF EVERY ONE HERE HAS REBUILT A THERD GEN FD MOTOR??? I'm about to rebuild mine my self, cause she is about to go single. I have built many american motors 350's and v6's and a froze up 454. but I here this a a diff ball park, what are some of the tricky things you have to be carfull about , and where is the best place to order your motor seals kit for the rebuild??? please let me know. thanks guys
Nyle

 

I guess the "Difficulty" level of rebuilding a rotary engine is based on your ability to comprehend how the engine works, your availablility of the proper tools (or availability of makeshift tools) and your ability to use those tools and your over all technical ability.

I would call the job easy but I was an aircraft mechanic for 10 years. My wife on the other hand, given the same tools and technical material (factory manual, haynes manual) would call it mission impossible.

 

If you are good at disassembling things and putting them back together again, are careful, observant, patient and can follow directions, it's not that hard.

If you tend to lose things, throw things, or get upset or frustrated and break things, then you'll want someone else to do it.

 

There isn't much difference between the generations of the RX7 core engine. Anyone who has built a 2nd Gen motor can give you invaluable help and information for rebuilding a 3rd Gen motor.

As far as seals, you should do some research here on the forum. There are many threads about the different seals available with lots of conversation discussing the benefits and drawbacks to each one. Do some reading so you can make an informed decision what's best for your application.

 

I've heard people who say the Rotary Aviation seals don't work well, but then I've heard from someone who races 13b's at 12000 rpms that they're fine. When I ordered mine I got them just as cheap or cheaper through Mazda. A full rebuild will set you back quite a bit - if you just blew a coolant seal, you can fix that for usually less than $200 depending on what went (coolant seals usually break because of a crack in the coolant jacket - $200 would replace the rubber seals and pay for a good used iron to replace the broken one)

 

OK Guys so here the deal, My motor is comming out to paint my engine bay, and I was going to do a single turbo, thats why I whas going to go through and replace srings seals o ring throw out barring new 3mm apexis and so on cause the motor will be out already, the motor has 35000 miles on it. should I just single turbo it without changing the seals?

 

At 35,000 miles, you're plenty safe not changing the seals. FDs were designed for boost from the factory, it doesn't know how many turbochargers you've got on it.

Save the money so that you'll have it when something DOES go wrong. If you were looking at 75,000 miles, I'd be leaning more toward "Well, you've already got it out . . ."

 

OK...but if it blows up it's your fault!!! lol j/p I like that it does not know how many turbos are on it!

 

If you're really in doubt, check the compression. If it's low, you might benefit from a rebuild, but don't forget to adjust for starter rpms. I had just rebuilt mine and my compression seemed mega low - but it turns out my starter was spinning 200 rpms too slow, and I was right on target.

 

thanks man I'll keep that in mined!