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Should I rebuild my engine while it's healthy?

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Should I rebuild my engine while it's healthy?

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Old 08-22-15, 08:15 PM
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CO Should I rebuild my engine while it's healthy?

I am no stranger to rotaries and have rebuilt 3 so far with unknown success since I sold them shortly after but did great while I had them. I have done N/A rebuilds in the past because of oil control ring issues.

I have an FD with ~71k miles one the whole thing and I'm quite sure the engine is the original. I'm basically the second owner and I have found on paperwork stating the opposite.

Engine runs great with smooth power delivery with the aid of the stock sequential twins, idle is great with no misfires and no hesitation. It still pulls great vacuum ~20 inHg under decel and ~15inHg at idle
The car is still mostly stock for the exception of mild reliability mods all done by me after I got the car.
Now I'm the type of guy that if it isn't broken don'y try and fix it kinda deal.

I haven't gotten around to doing a compression check yet.

So what do you say, dear reader? Should I wait or should I rebuild while she's still healthy?
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Old 08-22-15, 10:06 PM
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Should I rebuild my engine while it's healthy?

I don't think anyone here is going to suggest you rip apart a motor with literally no signs of fatigue. When you start noticing behavior outside of the norm or signs of "tiredness" is when I'd call it smart to rebuild before a catastrophic failure.
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Old 08-22-15, 10:51 PM
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Why even consider a rebuild when all is well? That's like asking someone to kick you in the nuts to see how it feels.
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Old 08-22-15, 11:05 PM
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Originally Posted by rxmiles View Post
I am no stranger to rotaries and have rebuilt 3 so far with unknown success since I sold them shortly after but did great while I had them. I have done N/A rebuilds in the past because of oil control ring issues.

I have an FD with ~71k miles one the whole thing and I'm quite sure the engine is the original. I'm basically the second owner and I have found on paperwork stating the opposite.

Engine runs great with smooth power delivery with the aid of the stock sequential twins, idle is great with no misfires and no hesitation. It still pulls great vacuum ~20 inHg under decel and ~15inHg at idle
The car is still mostly stock for the exception of mild reliability mods all done by me after I got the car.
Now I'm the type of guy that if it isn't broken don'y try and fix it kinda deal.

I haven't gotten around to doing a compression check yet.

So what do you say, dear reader? Should I wait or should I rebuild while she's still healthy?

The factory built motors are unmatched in quality. Once a rebuild occurs, very rarely are they ever quite as good again. Keep driving it until it starts to get tired or until it gives up, but don't fix it if it's not broken.
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Old 08-23-15, 12:53 AM
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15inHg at idle? What's your idle at? My original motor at 64k and 750rpm pulls 18inHg.

I suppose altitude and weather may play a part as well as electrical load. Just seems low to me.

I agree with everyone else though. If it ain't broke, don't fix it. If it doesn't smoke, hot starts like a champ, and runs fine, leave it be.

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Old 08-23-15, 09:36 AM
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What are your future power goals? A compression check will help answer your question IMO. How often has the coolant been changed during the life of the car?

I'd look into the coolant PH test strips to keep tabs on the status of your cooling system, as I'd be more worried about coolant o-ring failure than anything:

http://www.ebay.com/itm/Robinair-Coolant-Test-Strips-Bottle-of-50-75134-/131437408593?hash=item1e9a47b151&item=131437408593&vxp=mtr
If you plan to keep the car near stock with only bolt ons, your best bet is to perform fastidious maintenance and let that original engine hummmm for as long as she's able

As far as original engine build quality I'm inclined to agree. The Stealth Bomber (original 11k mile BB R1 that I bought years ago) had an insanely strong stock engine and ran so hard for a stock car that seasoned FD owners didn't believe the car wasn't modded.

Having said that---- that's not the case any more. Every new engine at IRP (with a few exceptions) gets opened up for some combination of porting, different seals, and checking/reclearancing. Let's just say the guys at the facilities nowadays don't know what 'attention to detail' means and I'll leave it at that
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Old 08-23-15, 09:49 AM
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Just perform regular maintenance including decarbonization of the engine and you are good to go.
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Old 08-23-15, 11:08 PM
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Perfect, I'll just let the engine be. I have never had engine problems in any of my 12 rx7's other than oil control rings on a 2nd gen. Engine runs great with and is smooth and quite
As far as my power goals are I want to keep it as close to stock as possible. Maybe add a PFS SMIC and sme BNR twins but I'm happy where she's at.
Coolant has been religiously changed as well as all other maintenance items. The car doesn't get driven much, only on good days. As far as the InHg it seems to be at ~15 to ~18 it's hard to read the gauge where it sits but I am at 5000ft altitude and have the FC thermoswhitch which kicks the fans on constantly.
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Old 08-24-15, 02:05 PM
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I may be on the same boat soon - interested in opinions on this.
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Old 08-24-15, 03:07 PM
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a friend of mine used to rebuild the engine on a cost/mileage ratio. its a bit hard to explain, but the cost for him to do an engine was about $5500, which included a clutch, pulsation damper, metering lines, all the water hoses, whatever vacuum lines, and then whatever else. after that job, the cars are actually reliable and are on a normal service schedule.

so if a 70k+ mile car came in that needed a pulsation damper, stat gear o ring, oil pan reseal, etc, he would often sell them the engine.

its more expensive now, but its more cost effective than resealing an old engine, and then have the coolant light start coming on.

and it wasn't like every car got an engine at 70k, he did have several cars that went over 100k with little more than normal servicing. its situational
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