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Index > Engine/Drivetrain > Thread: To rebuild or to Replace...that is the question...
Thread: To rebuild or to Replace...that is the question...
repu1977


1st Gear
Posts: 47
posted February 24, 2008 12:05 PM

To rebuild or to Replace...that is the question...

I would like to pose a question to those with much more experience with REPU's than I...
I purchased a repu about 3 or 4 years ago, it only has 63K original miles on her but smokes like a smoke stack.
She was left abandoned in the hills of salt lake for about 8 years. then started by someone who knows nothing about rotarys. I'm sure the seals are shot.

My question, is it better to rebuild the original motor, remembering it does not have nitride coating and thus has a low millage future?
OR
Replace with a later model 13b with nitride coatings and longer millage life.
____________
77 REPU "Yellow"
82 380SL
93 f250 4X4 turbo Diesel
66 Benelli
94 740 IL

       
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Klaus44


Redlining
Posts: 365
posted February 24, 2008 12:39 PM
Edited By: Klaus44 on 24 Feb 2008 12:51

Before answering your question...

...there are a few things to consider. Such as: Is the mileage truly correct, and if so, what caused the failure... and was this engine ever rebuilt previously, and if so, what are the odds they didn't do it properly?

If it was not overheated...

Have you tried changing the oil, fuel, and coolant, and tried adding a solid dose of Techron additive (not injector cleaner) to the gas... and tuned it, and cleaned the engine using AmsOil Power Foam...? The Techron can, in some cases, condition the oil seals sufficiently to allow for further use... and fresh oil of a proper grade can help, as well. Used properly, the Power Foam will de-carbon and de-varnish your entire intake and combustion zone, and can also free up seals that may not be able to move freely due to the carbon...
(Fresh plugs and a strong ignition are very nessecary, though!)

--The Techron is no instant fix, mind you... if it's going to work, it will take a while--.

If all else has failed, and to answer your question -- All depends on what you want, and how much money you have to make it so...


       
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sparky


Redlining
Posts: 299
posted February 24, 2008 11:15 PM

I say upgrade to a series 5 engine. Lighter rotors with higher compression= more power and higher revs. I'm looking forward to this if they ever roll back vehicle emmissions for 1977 in CA.

       
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Hunter


Hauling
Posts: 178
posted February 25, 2008 05:50 AM

side housings

seems to me that I have seen various treatments applied to the side housing before and after 1977. I would have to go back and read thru all my books to talk definitively on this subject. A chronology of different side housing treatments would be interesting reading.
Bruce Toski

       
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Brad


Rotorhead
Posts: 1672
posted February 25, 2008 08:13 AM

If the REPU plates have enough thickness for one or two more lappings, you can always have the REPU plates nitrided. pineappleracing.com can do it.

If they're worn then go with 12a plates, all of which are nitrided. The front plate is NLA from MAZDA new anymore and used plates are getting hard to find in usable shape.
____________
-brad-
74 REPU Lawn Green
81 Rx-7 racecar. 12a J-
Bridge

       
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repu1977


1st Gear
Posts: 47
posted March 13, 2008 10:35 AM

Sorry been out of town...


for a while and could not reply to this thread.


Klaus44...you stated "Used properly, the Power Foam will de-carbon and de-varnish your entire intake and combustion zone, and can also free up seals that may not be able to move freely due to the carbon..."

I am about to purchase this product and wondered if you could enlighten me on how to "properly" use use it?

I have replaced all fluids and tunned up the vehicle already. It smokes like a smoke stack sometimes when it is revved over 6K then the oil level dramatically drops after a smoke session.

Thanks very much for EVERYONE'S expertise!!


____________
77 REPU "Yellow"
82 380SL
93 f250 4X4 turbo Diesel
66 Benelli
94 740 IL

       
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Klaus44


Redlining
Posts: 365
posted March 13, 2008 12:24 PM
Edited By: Klaus44 on 13 Mar 2008 12:27

Power Foam:

Others may disagree, and there are other methods... but the way I was introduced to cleaning a rotary engine with the stuff is this: Prep engine (and vehicle) to be run and driven 50 or more miles (more is better!) immediately following the treatment. With engine fully warmed up and running, spray the entire contents of the can into the carburetor. When this kills the motor, keep filling the carb/intake with the rest of the can, and let it sit until the foam dissipates. (Try to work the throttle while spraying to keep it running longer prior to choking out, but keep it under 3K RPM.) Now, don your respirator, with appropriate cartridges installed... and be prepared for the black cloud that's about to exit your tailpipe! Fire it up, and keep it running. Don't shut it off -- immediately go for your 50 + mile drive; freeway is good...
Your motor should keep running better for perhaps even the next 500 miles.

Now, considering your description of your oil consumption issue...:

1.) What oil are you running? (You might find running a 20/50 helpful...) Synthetics may be too fluid to be of much use in this situation. Even a fresh rotary is hard on the oil; consider that with an engine such as your's, fuel dilution may also be a consideration... (if excess oil is entering the combustion zone, fuel is likely accumulating in your oil, as well...).

2.) If you want to try 'conditioning' your worn oil seals with Techron (bottled) additive via the fuel, the time to start is immediately. If it's going to help, it will take some time to do whatever it can...

3.) In the meantime, if higher RPM's are where you're sucking the most oil... avoid revving it up that high! Sounds like the oil is getting sucked past the seals when you take your foot off the gas, after revving it up... am I right?

Hope some of this helps! If it does, maybe it's bought you a little more time to save up for a fresh rebuild... ;)

       
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ovquick


Redlining
Posts: 253
posted March 13, 2008 04:55 PM

Smokes

I had a 77 that did nearly the same as you describe. Ran well enough if you kept the turns down, but as soon as you went above 6,000 RPM the thing just poured out oil smoke like you were laying down a smoke screen. (It was so predictable I could do it on command)The problem in this case was the little "tab" on the oil seal that prevents it from turning with the rotor was not engaging for some reason or another. I was "playing with the smoke" one day. Ran it realy quick in third, let it decel with the engine load on it, when I heard a strange noise, after that the problem went away,to be replaced by an unrelated ignition or fuel problem several years later.
Orville
____________
Manteca Mazda Asylum
where a boy and his cat live, without adult supervision

       
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