Dan Postelnicu

Has anyone done a rebuild where all parts are in-spec pates are surfaced new seals, gaskets and apex? What compression gains? The reason I am asking did this and I had massive water leak, weak compression on manufactured engine 99k on odometer so engine is probally less then 50k. All parts are in spec including apex seals.
I had plates surfaced and purchased:
atkins ARE317
Water Jacket Seals
Viton O-Rings (Rotor O-Rings)
Dowel Pin O-Rings
Rear Stationary Gear O-Ring
Front Cover O-Ring
Front Hub Bolt O-Ring
Front Main Seal
Rear Main Seal
Tension Bolt Seals
04-08 Rx8 6-Port Manual Engine Gasket Kit (N3Z3-10-S50C)

Getting only 60psi now, rotor housing looked great, rotors seals gaps, bearings... all in spec

sinkas

Why did uou do the rebuild? Was it due to overheating?

Dan Postelnicu

Water in chamber and out, no compression, blown water seals

sinkas

Sounds like you need to check for housing warping etc

Zachary Verge

I am having no issues with heating or leaks but am running low compression. I would like to look in to replacing just the apex seals and the gaskets. Are there any suggestions and would this work?
My car has a little under 110xxx miles and is run on non synthetic 5w-20 oil with no premix. Compression around 60 at 250rmp. Only ever had issues with cold starts when she sits for a week but she will start after 10-15 seconds

9krpmrx8

iTrader: (46)

No, if you are going to pull it then get it rebuilt by someone who has a clue. Just look at the "fresh rebuild, engine won't run" threads that are here now.

Do it right, or don't do it at all.

Mr. Pockets

I don't know, man. Anecdotally, I see engines built by people who 'have a clue' come back with low compression all the time. It's not the sure bet you're making it out to be.

Zachary Verge

Are you saying you have "no clue" i asked if with these symptoms, starting with ordering just apex seals which is where most compression is lost from, to fix the solution. I understand rebuilding engines can turn in to a maze of other things wrong. I'm asking if anything besides apex seals could be wrong.
note: i'd probably order new springs too and have those fitted.
Looking for advice not a "get a professional to do it" kind of answer

9krpmrx8

iTrader: (46)

Yes, lots could be wrong and if you don't understand that already, then you should not attempt to rebuild any engine.

sinkas

Apex seals are not the primary point of failure for loss of compression, make sure your side seals are to spec

Loki

iTrader: (1)

Also 60psi at 250rpm? How does this car even start?
You sure the test was done correctly?

TeamRX8

iTrader: (25)

I'd advise you to have some more humility and try to listen better, with which you might then be more inquisitive about why he would post that rather than getting defensive. You might also likely need new rotors and rotor housings and maybe side plates too or have them resurfaced if you want to do it right, but without the expensive tools required to to measure everything properly wouldn't have any idea about it.

Or you might be wiser to do more research and reading to perhaps come across a thread like the link below because frankly, your responses making incorrect statements emphatically demonstrate how little you understand about the endeavor to the people who do understand it.

https://www.rx8club.com/series-i-tec...azmart-265994/

The reality is you can't know what it really needs until you actually tear it down to inspect and measure. Even if you know some parts like seal kit etc. is required, it doesn't serve any purpose to order it now when you will need to order other stuff later. Unless you intend to buy uncut side seals to measure and hand cut/fit them you have to look at the part code on the side of the rotor to order the proper length pre-cut ones from Mazda. If you re-use the rotors do you have the tools and equipment to R&R the bearings, and so on?

If you think you're going to buy some parts to just slap them in and go it will end up just like 9k pointed out it did for the other people who thought that way too.

.

Zachary Verge

car starts fine, only has issue if not driven for over a week and then it can take 10-15 seconds instead of 3-5
bottom plugs were used, all three chambers were right around the same, need bounced to right around 60psi and i used an obd program to measure rpms
the car seems to be "functioning" fine but runs rich and shows minor symptoms of compression loss, such as rare misfires which i have already done coils and plugs (not wires)

I do understand the multiple types of seals involved and the possibility of warping and ect.
this is not my only vehicle and i would like to start by ordering what would be necessary and move from there. i see no need to replace eeeevery piece if it is not overly warn.

the point of this thread was to evaluate if everything was in spec, if replacing just apex and gaskets was possible.

RX8Soldier

iTrader: (24)

The apex seals aren't wearing away like cheese slices. So ordering new apex seals won't guarantee restoring compression. Tear the sucker down, properly measure the engine parts, then start ordering what's required.

Take you're time and do it right. Or, have someone (reputable) do it for you.

Oh, and just as a side note- your diagnosis of lost compression doesn't sound overly confident. 10-15 sec to start doesn't necessarily mean compression loss. Did you verify with a ROTARY SPECIFIC compression tester?

Loki

iTrader: (1)

If there are no symptoms (and cold start problems are not a symptom), then the only thing causing you to even consider engine work is that test, which sounds flat wrong. 60psi at 250 is so far below spec that it shouldn't start at all. So, are you sure you want to dig into a potentially healthy motor?

If it's running rich, that may be causing said misfires. Diagnose that first, otherwise when you put everything back together after the rebuild, you'll have not solved the problem.

Zachary Verge

these are things i really appreciate hearing, i will dig in to the misfires
i also was afraid it might need an actual computer tune up which i wanted to research and learn about getting the mazdaedit
i used a standard piston compression tester. mazda's actual test (with the rotary specific meter) is pretty expensive right?

TeamRX8

iTrader: (25)

It's a hypothetical question asking for guesses on parts for an engine condition that you are guessing at. That should end well ...

sinkas

Cheaper than a rebuild,

sinkas

Cheaper than a rebuild,

NotAPreppie

If you rebuild it yourself, it'll be at least $1000 in parts alone (bare minimum if you do it right). For the first build.

Then, in pretty short order, you're going to have to do it again. You will likely find more stuff to replace (housings, irons, etc) and it will cost you even more than the first time. Lets say another $2000 on the low end.

A compression test at the dealer will be 1-2 hours of labor so expect in the $100-$200 range.

Or, you can try to find somebody in your area with a compression tester and bribe them with beer or pizza or something to check your car. If you're in the Chicago area, I can help you with that (as soon as Mr. Pockets returns my compression tester).

Alternately, you can buy your own RCT-V5 for $350-ish from official site vendor RotaryCompressionTester.com. If you're planning on owning a rotary for a while, your own compression tester is a really nice thing to have. Especially if you're going through the process of deciding on what to do about a tired engine.

OutlawShank

Hey, I know this is an existing thread but for some reason I'm unable to start my own threads. (Help with that would be appreciated too) Anyway, I have an 05 Rx-8 with the 4sp auto. She recently overheated and I'm being told it fried the motor. I'm trying to decide if I should replace the motor or do a rebuild. The issue is I'm not sure exactly what is damaged by overheating in a rotory (this is my first) so I don't know what all I'll need to do the rebuild. Does anyone know what TYPICALLY needs to be done to rebuild a motor that overheated?

Loki

iTrader: (1)

You can start new threads in the new member section until you have 10 posts. Your best bet is buying an already rebuilt replacement motor. Big parts like housings can be damaged by overheating, you don't want to take it all apart only to find out you need to spend money/time looking for replacements.

There are a few reputable rebuilders you can contact for pricing: Pettit Racing, Rotary Resurrection, Pineapple Racing, Derwin Tuning. They may take your engine as core.

OutlawShank

Great, thanks for you info! Thats what I was thinking as well, just to replace the motor. I live in Atlanta so we have a place called Mazmart here that basically told me it would cost more to rebuild the motor than to get a new one. I'll look into those other builders as well, I really appreciate the input.

Loki

iTrader: (1)

Mazmart is great as well.

TeamRX8

iTrader: (25)

Let's back up just a minute. Who told you it was "fried" and what are they basing that assessment on? I'm only asking because you didn't provide any details to support that the engine was actually damaged. Just because it overheated doesn't automatically result in damage requiring a rebuild. So I'm just trying to make sure you are being informed accurately.