Mazmart

iTrader: (12)

I had the pleasure of doing the rebuild of an engine previously owned by olddragger and have compiled pictures of the internals with some commentary on what we've found. It had 59k on it and experienced fuel starvation on one rotor (Rear) due to an injector mishap. I'll allow Olddragger himself to elaborate on that if he cares to. This engine had 45k when he acquired it and he ran it supercharged with good quality oil and premixing.

Paul.

Mazmart

iTrader: (12)

Here are some more pictures. What I'll show are the main stages of dis-assembly with some comments.

Paul.

Mazmart

iTrader: (12)

The above pics show a very normal kind of condition several parts including the water pump. That corrosion on the impeller is quite normal. The motor was relatively clean showing no signs of oil leaks. The rear stationary gear has some signs of bearing wear. Could be MUCH worse.

Paul.

Mazmart

iTrader: (12)

Here are a few more. These show a cleaner than average condition of rotors. I wish I couild have illustrated the side seal clearances. They were normal but that's a lot compared to rotaries of old.

Paul.

Mazmart

iTrader: (12)

Here are some good pics of the rotors showing the extent of carbon and the type of damage caused by an apex seal having a minor breakage.

Paul.

9krpmrx8

iTrader: (46)

Awesome, so this was a used motor?

Mazmart

iTrader: (12)

Yes. He bought it with 45k on it which affects our ability to totally comment on his maintenance in relation to the parts you see. He put 15k on it, all supercharged. Now he has a MAZMART RE-medy engine with our water pump and thermostat as well.

Paul.

9krpmrx8

iTrader: (46)

Yeah hard to judge maintenance without history. I wonder if he knows the history of the motor. Paging OD.

JinDesu

iTrader: (2)

That housing looks nice and shiny! The stationary gear looks much better than the other engine taken apart (at 100K, I forgot whose it was but there was a thread somewhere).

The scars on the rotor: are those scars from the apex seal breaking? Is that reflected in the respective housing as well?

9krpmrx8

iTrader: (46)

The bearing wear seems to be an issue. Are there any pics of an engine taken apart without significant bearing wear? I just wonder how much is maintenance and how much is viscosity.

Mazmart

iTrader: (12)

Here are some more pics that show the rotor housing damage. The scars are from the broken apex seal.

Paul.

Note: Wrong rotor. This rotor is FD RX7 from another engine we just built that ingested some metal. The housing is correct. These pics were taken yesterday while the others were a week ago when the build was in process.

PhillipM

I'll get some pictures of ours at the next teardown in July, but ours is showing nothing unusual so far.

Mazmart

iTrader: (12)

Here is the front main bearing. I've seen worse but this is not good at all. We need to consider that he did not own this engine for a portion of time and also the effects of the supercharger belt possibly being overtightened.

Paul.

JinDesu

iTrader: (2)

Ouch. You stated before that the carbon was a result of the broken apex seal? There is a lot of carbon deposit on the rotor; how does the broken apex seal cause that? Was the motor being used after the apex seal was broken?

Picture 4 shows a lot of untouched carbon on the rotor, and picture one shows the scarring from the apex seal cutting into the carbon. Wouldn't picture one mean the carbon was there before the apex blew?

Mazmart

iTrader: (12)

Of course, we maintain that sufficient viscosity is the main answer for reducing this condition to the front bearing.

Paul.

Mazmart

iTrader: (12)

Nope. The carbon is the result of this particular combustion environment. It's not unusual to see much more than this. I think excessive fuel enrichment (For cat life?) is the culprit.

Paul.

olddragger

iTrader: (3)

we have set a record for the times "old" was used in a thread title................ and it is appropiate!
Alas--when you buy a used engine the maintainence history is unk. All I do know was the milage and that it was not taken to a dealership on a regular basis. It did have good compression numbers when I received it.

The gas starvation was on the back straightaway at Road Atlanta. Short version---gas line spacer came out and starved the engine before I knew what was going on--I was doing about 100mph at the time.

I drove the car approx 100miles home on one rotor after the rear rotor let go.

Maintainace ---
once i received and installed , it was good. I pre mixed 1/2 oz to the gallon , high test gas only of course, i run a pettit s.c. with no more than 9lbs of boost, it nevers sees coolant or oil temp over 210F. Usually it is around 170-190 range, I also run an intermitent w/m system. It is not on all the time. I will use maybe 1 gallon every 2 wks or 250miles.
I was pulling 320 g/secs maf flow so the engine was in fair shape.

After I received it there was never anything under a 40W oil in it. I used Castrol GT 10/40W on the street and 20W 50 on the track--this was before i discovered deisel oil. It has about 4-5 track events on it. That = to about 1K miles of track use?

Changed oil every 3 K, along with filter. Filters I used were either mobil 1's or a Pure one Purolater, + 1 K&N.
It was decarboned once with the mazda stuff about 1 1/2 yrs ago.
I do not drive that hard on the street--dont redline once a day
Oh yea since I have had the s.c. up and running my redline is now 7.5 K with super max redline of 8 K
My s.c belt is adjusted to normal tension as the other belts on the car.
It also has a dedicated belt for the s.c. only.

The engine is clean--oil pan--really clean.
Pretty good shape if you ask me.
Thanks Paul---a bunch.
The new engine rocks also---Rick E/Paul engines are a good way to go.
olddragger

olddragger

iTrader: (3)

Sparkplug holes doesnt show any cracks?
AND GUESS WHAT__MY !ST ENGINE SHOWED BEARING WEAR IN THAT SAME EXTACT SPOT.
It was not s.c. very long at all. It had about 50K on it when it let go.
I have a pic somewhere.
OD

JinDesu

iTrader: (2)

I understand. Would pre-mix (with carbon cleaning detergents, i.e. FP+) assist on the rotors? Or would those only help with the exhaust port carbon buildup?

@Olddragger, perhaps you can chime in for my question above? Do you think de-carbing the engine would have an appreciable effect on carbon buildup on the rotors, or mainly on the exhaust ports?

I don't know what effect the carbon on the rotors have, especially since you say it's a normal occurance. Just to guess, would it possibly get into the seal area and cause issues? What about weight and balance effect on the rotor (although the rotor is pretty heavy, so I don't think it should be a factor at all)?

And I guess the best solution is to lean out the mixture and not give a damn about the cat then. Do high-flow/super cats get affected as much by a lean fuel mixture?

@Olddragger - the opening post said you premixed, what did you use?

Mazmart

iTrader: (12)

That's the normal area. What was your oil choice back then (Speaking viscosity of course)?

Paul.

9krpmrx8

iTrader: (46)

Hell I even only use Shell 93 because it supposedly reduces carbon build up. If using the Mobil1 0W-40, Single Oil Cooler, upgraded water pump, Lucas UCL, SOHN adapter, and top quality gas doesn't make my motor last beyond 100k then I give up. If I tear apart my motor and I have this type of wear i will drive my 8 into a lake.

olddragger

iTrader: (3)

my 1st engine i used the 5w/20 for about 1 yr before i knew better --after that it was a 10/30 RP for every day use and 10/40 for the track. It also saw higher heat. It was my beginning learning years.
Some carbon is inevitable on any combustion engine. You should have seen my 1st one.
Pre mix i used was a little of this and a little of that--all twc3 stuff and a good while with just MMO.
Doesnt look like i was getting a large amount of seal skip?
OD

@!!narotordo

Hi I have a few questions for ya, if you dont mind;

Can you overtighten a after market pully like the AP or overtighten a OEM blet and get the same effects?

Is that the result of Mazda's factory tune? can you change this with the Cobb AP?

Thanks

Dont give up. Get a Rick E/Paul engine Must rebuild. So how much for a rebuild?

swoope

iTrader: (5)

good stuff paul and denny..

cant wait to see my stuff apart

beers

Brettus

iTrader: (2)

hmmmmmmmmm- disturbing