Advice regarding reusing Rotors + Housings (pics)
11-02-17, 06:45 AM
#1
Full Member
Thread Starter
Advice regarding reusing Rotors + Housings (pics)
Just finished stripping down my first rotary. (Can't believe how easy it is, literally less than 1 hour after removing the flywheel nut)
And would like some advice regarding re-using the rotors and housings.
Quick background history of the engine, it came from a 1988 UK spec S4 that had sat unused in a garage for 20 years, the owner had attempted to start it, couldn't then sold it on. I'm going to assume he didn't pour any oil into the cylinders, and just went for it.
I got the engine running by cleaning the injectors and replacing the fuel pump, but wanted to strip it down as coolant poured into it mystically vanished, so probably seal failure.
- Rear rotor is absolutely fine, just need to measure tolerances.
- However rear housings is worn, no flaky chrome but score marks. They can be felt very easily with my finger, but they aren't sharp.
So I'm a little dubious about that.
Next up the front rotor.Not sure what has caused all the damage, especially around the end of where the Apex seal went.
Now to me that Rotor is junk, but if anyone else would like to correct me that would be good news. Or shed light on the likely cause.
Interestingly, the housing with the damaged rotor is actually perfect, and the good rotor is in the worn housing. (I've not mixed them up)
Apex seals are of the 2 piece type and seem in good condition.
Finally, the Eshaft, seems have evidence of burn marks, from lack of lubrication.
Thoughts?
Edit: Also I only have one oil sealing ring + spring on each rotor side, not two. Is this normal in older cars?
And would like some advice regarding re-using the rotors and housings.
Quick background history of the engine, it came from a 1988 UK spec S4 that had sat unused in a garage for 20 years, the owner had attempted to start it, couldn't then sold it on. I'm going to assume he didn't pour any oil into the cylinders, and just went for it.
I got the engine running by cleaning the injectors and replacing the fuel pump, but wanted to strip it down as coolant poured into it mystically vanished, so probably seal failure.
- Rear rotor is absolutely fine, just need to measure tolerances.
- However rear housings is worn, no flaky chrome but score marks. They can be felt very easily with my finger, but they aren't sharp.
So I'm a little dubious about that.
Next up the front rotor.Not sure what has caused all the damage, especially around the end of where the Apex seal went.
Now to me that Rotor is junk, but if anyone else would like to correct me that would be good news. Or shed light on the likely cause.
Interestingly, the housing with the damaged rotor is actually perfect, and the good rotor is in the worn housing. (I've not mixed them up)
Apex seals are of the 2 piece type and seem in good condition.
Finally, the Eshaft, seems have evidence of burn marks, from lack of lubrication.
Thoughts?
Edit: Also I only have one oil sealing ring + spring on each rotor side, not two. Is this normal in older cars?
Last edited by theDevilX; 11-02-17 at 07:15 AM.
11-02-17, 08:44 AM
#2
rotorhole
i rather doubt it had been sitting 20 years, unless he racked up a ton of miles when the car was less than 10 years old and then blew it up shortly after a rebuild. the cause could be anything, it looks to have 3mm seals and if it is a turbo engine(likely is, theres no reason to go 3mm on a naturally aspirated engine) could be due to many many causes, if it's an n/a engine it likely is due to improper rebuild procedures or something foreign got into the engine.
the blueing on the e-shaft is normal, its from the heat treating process to harden the metal. all e-shafts look just like that.
due to your overseas shipping costs, its probably not worthwhile for you to attempt to have the housing reconditioned and pay for shipping two ways, rather to just buy a decent pair of new or used housings.
many times engines fail initially due to a cause, many shops ignore the cause and rebuild the engine anyways and the owner promptly blows the engine up again in short order. without any history or information, one can only speculate as to the real cause of failure. however, those chatter lines in the first pic are from sustained or frequently high revs, telling me that the fresh engine had been abused right from the start, unless the housings initially were already that poor in condition.
by the amount of carbon on the rotors, the engine looks to have had only a few thousand miles put on it.
the blueing on the e-shaft is normal, its from the heat treating process to harden the metal. all e-shafts look just like that.
due to your overseas shipping costs, its probably not worthwhile for you to attempt to have the housing reconditioned and pay for shipping two ways, rather to just buy a decent pair of new or used housings.
many times engines fail initially due to a cause, many shops ignore the cause and rebuild the engine anyways and the owner promptly blows the engine up again in short order. without any history or information, one can only speculate as to the real cause of failure. however, those chatter lines in the first pic are from sustained or frequently high revs, telling me that the fresh engine had been abused right from the start, unless the housings initially were already that poor in condition.
by the amount of carbon on the rotors, the engine looks to have had only a few thousand miles put on it.
Last edited by insightful; 11-02-17 at 09:01 AM.
11-02-17, 09:32 AM
#3
Full Member
Thread Starter
Thanks for the reply. And while I hesitate to tell someone they're wrong, I can categorically state that the car has been off the road a long time.
The 20 years was an exaggeration as I couldn't remember the exact figure, but the last time the car was on the road was 2001, corroborated by tax discs and the MOT history. (Checked online, through the governments website) So its actually 15 years off the road. This was also backed up by the state of the engine bay, full of dust, cobwebs all sorts, but also completely dry, no rust on the chassis, which is unheard of in old cars on salty UK roads and the fact that the fuel in the fuel tank had obviously been sat there for a long time. Trust me, this car has not been on the road any time recently, although I've no idea why it was taken off.
Engine is a NA and the mileage was 94,000 miles.
The apex seals are 2 piece 3mm.
One possible explanation is that the UK cars didn't have all the emssions stuff you had, we had distributors rather than electronic ignition, so is it possible that we have the 13b that went into the last model of the FB rx7?
The engine did start and run once I changed the injectors.
I have another UK engine from an earlier car that I also need to tear down, so it will be interesting to note any differences if any.
UK companies do offer housing resurfacing, so there's no need for me to send it all the way to the states. I just needed confirmation that its a definite no go on that housing.
Edit: Just found this listing for an S4 Rotor from a UK engine, this also looks to be a 3mm apex seal.
https://www.ebay.co.uk/itm/RX7-FC-13...UAAOSw9fRZvQPG
The 20 years was an exaggeration as I couldn't remember the exact figure, but the last time the car was on the road was 2001, corroborated by tax discs and the MOT history. (Checked online, through the governments website) So its actually 15 years off the road. This was also backed up by the state of the engine bay, full of dust, cobwebs all sorts, but also completely dry, no rust on the chassis, which is unheard of in old cars on salty UK roads and the fact that the fuel in the fuel tank had obviously been sat there for a long time. Trust me, this car has not been on the road any time recently, although I've no idea why it was taken off.
Engine is a NA and the mileage was 94,000 miles.
The apex seals are 2 piece 3mm.
One possible explanation is that the UK cars didn't have all the emssions stuff you had, we had distributors rather than electronic ignition, so is it possible that we have the 13b that went into the last model of the FB rx7?
The engine did start and run once I changed the injectors.
I have another UK engine from an earlier car that I also need to tear down, so it will be interesting to note any differences if any.
UK companies do offer housing resurfacing, so there's no need for me to send it all the way to the states. I just needed confirmation that its a definite no go on that housing.
Edit: Just found this listing for an S4 Rotor from a UK engine, this also looks to be a 3mm apex seal.
https://www.ebay.co.uk/itm/RX7-FC-13...UAAOSw9fRZvQPG
Last edited by theDevilX; 11-02-17 at 09:39 AM.
11-02-17, 10:03 AM
#4
rotorhole
well i guess that makes sense now, i semi recall you had it running recently but were doing work with the UIM off? i don't mean to sound rude, but it wouldn't be the first time i've seen someone accidentally drop something in the intake while working on the engine. it really doesn't take much more than a pebble to destroy an engine, and might have been a fluke that something just blew into it while you weren't looking.
i guess my point was that it's obvious that engine has ran recently, you kind of left out some key pieces of information initially. it didn't sound blown in the initial videos you posted but it surely is blown now. so something happened while you were restoring and working on it.
as well the 3mm seals are overkill and unecessary for a n/a engine, they will just wear it out faster and obviously only offer marginal additional protection. the chatter lines are from their heavier weight and high engine speeds digging them into the chrome. but since you have a 3mm rotor, you may as well stick with them... or sell yours and buy a matched pair of 2mm ones.
what i am getting at, the naturally aspirated engines are reliable and don't fail like this without a good reason. that reason was probably foreign debris, always tape up or stuff rags in the intake while working. you probably won't ever know what really caused it, all you can do is try to build the engine properly and to be more attentive in the future.
the housing can be resurfaced, there isn't too much gouging so it looks like a possible candidate for reconditioning if you have the sources locally.
i guess my point was that it's obvious that engine has ran recently, you kind of left out some key pieces of information initially. it didn't sound blown in the initial videos you posted but it surely is blown now. so something happened while you were restoring and working on it.
as well the 3mm seals are overkill and unecessary for a n/a engine, they will just wear it out faster and obviously only offer marginal additional protection. the chatter lines are from their heavier weight and high engine speeds digging them into the chrome. but since you have a 3mm rotor, you may as well stick with them... or sell yours and buy a matched pair of 2mm ones.
what i am getting at, the naturally aspirated engines are reliable and don't fail like this without a good reason. that reason was probably foreign debris, always tape up or stuff rags in the intake while working. you probably won't ever know what really caused it, all you can do is try to build the engine properly and to be more attentive in the future.
the housing can be resurfaced, there isn't too much gouging so it looks like a possible candidate for reconditioning if you have the sources locally.
Last edited by insightful; 11-02-17 at 10:23 AM.
11-02-17, 10:28 AM
#5
Full Member
Thread Starter
well i guess that makes sense now, i semi recall you had it running recently but were doing work with the UIM off? i don't mean to sound rude, but it wouldn't be the first time i've seen someone accidentally drop something in the intake while working on the engine. it really doesn't take much more than a pebble to destroy an engine, and might have been a fluke that something just blew into it while you weren't looking.
i guess my point was that it's obvious that engine has ran recently, you kind of left out some key pieces of information initially. it didn't sound blown in the initial videos you posted but it surely is blown now. so something happened while you were restoring and working on it.
as well the 3mm seals are overkill and unecessary for a n/a engine, they will just wear it out faster and obviously only offer marginal additional protection. the chatter lines are from their heavier weight and high engine speeds digging them into the chrome. but since you have a 3mm rotor, you may as well stick with them... or sell yours and buy a matched pair of 2mm ones.
what i am getting at, the naturally aspirated engines are reliable and don't fail like this without a good reason. that reason was probably foreign debris, always tape up or stuff rags in the intake while working. you probably won't ever know what really caused it, all you can do is try to build the engine properly and to be more attentive in the future.
the housing can be resurfaced, there isn't too much gouging so it looks like a possible candidate for reconditioning if you have the sources locally.
i guess my point was that it's obvious that engine has ran recently, you kind of left out some key pieces of information initially. it didn't sound blown in the initial videos you posted but it surely is blown now. so something happened while you were restoring and working on it.
as well the 3mm seals are overkill and unecessary for a n/a engine, they will just wear it out faster and obviously only offer marginal additional protection. the chatter lines are from their heavier weight and high engine speeds digging them into the chrome. but since you have a 3mm rotor, you may as well stick with them... or sell yours and buy a matched pair of 2mm ones.
what i am getting at, the naturally aspirated engines are reliable and don't fail like this without a good reason. that reason was probably foreign debris, always tape up or stuff rags in the intake while working. you probably won't ever know what really caused it, all you can do is try to build the engine properly and to be more attentive in the future.
the housing can be resurfaced, there isn't too much gouging so it looks like a possible candidate for reconditioning if you have the sources locally.
I have 2 Rx7s. One I'm restoring, the other I bought simply for the engine.
The one I bought purely for the engine is the one I was referring too in the other thread.
This engine I'm posting about here is the one that came with the car I'm restoring, so a totally different engine, I'm only stripping this one down because of the trouble with the other one, it makes sense for me to strip this first as its already out the car and on the stand.
So disregard the other thread, this is a totally different engine.
As far as I know this engine hasn't failed, I had it running before I took it out the car, I only stripped it because of a suspected coolant seal failure. And sure enough they were absolutely fubarred.
11-02-17, 10:31 AM
#6
rotorhole
well it has failed though, the engine can still run on a single rotor while the other merely freewheels. but what caused it is anyone's guess. if there are witness marks on the rotors, those are your only clues, all i mostly see is apex seal debris marrings but there is a dent from something that was not an apex seal, however it didn't leave an impression to give you an idea of what went through the engine.
apex seals rarely leave dents like this, and it isn't caused by detonation because only a boosted engine pushes enough air to collapse a rotor and detonation dents are centralized on the rotor and directly between the seal land and the compression pocket, not in a random location like in your pic.
apex seals rarely leave dents like this, and it isn't caused by detonation because only a boosted engine pushes enough air to collapse a rotor and detonation dents are centralized on the rotor and directly between the seal land and the compression pocket, not in a random location like in your pic.
Last edited by insightful; 11-02-17 at 10:39 AM.
11-02-17, 02:26 PM
#7
Full Member
Thread Starter
Very odd that all the apex seals are intact and the housing is perfect, and the other housing is worn but the rotor is perfect. Either way when I strip down the other engine, between the two I hope I'll have two good rotors and housings.
Thanks for the advice anyway, at least I know where I stand with them.
Thanks for the advice anyway, at least I know where I stand with them.
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11-02-17, 02:44 PM
#8
rotorhole
i see, so someone reused that rotor? wow.
that thing is a paperweight, should never have been reused. if the damage was minor and it was cleaned up, perhaps but with that damage and the dent? nope, it's trash. the gouges and dent alone will alter the compression enough that it likely wouldn't give even compression readings even if the seals don't stick in the channels, let alone hot spots the will cause preignition.
that thing is a paperweight, should never have been reused. if the damage was minor and it was cleaned up, perhaps but with that damage and the dent? nope, it's trash. the gouges and dent alone will alter the compression enough that it likely wouldn't give even compression readings even if the seals don't stick in the channels, let alone hot spots the will cause preignition.
Last edited by insightful; 11-02-17 at 02:47 PM.
11-02-17, 03:02 PM
#9
Full Member
Thread Starter
Surprisingly when I compression tested it using my standard tester with schrader valve removed, it was recording consistent bumps of 120 psi from both housings. Just goes to show they can take a surprising amount of abuse.
I'll be making a clock out of this one I think.
I'll be making a clock out of this one I think.
11-02-17, 03:07 PM
#10
Full Member
Thread Starter
Okay, so I went and double checked something.
My grooves for my water seals are on the rotor housing itself, not the irons. Which from what I'm reading online means that the UK S4s must have got the 13b engine from the earlier model of RX7. Which would explain the 3mm apex seals, distributor ignition and thermal reactor setup.
Though the Front cover number is N326. which according to Mazdatrix is the correct one for a S4 NA. So its possible that its a mish-mash Mazda came up with for the European market.
This looks like a massive PITA as these housings according to rotary Resurrection are not compatible with say the Rotors you got on the FCs in the states.
My grooves for my water seals are on the rotor housing itself, not the irons. Which from what I'm reading online means that the UK S4s must have got the 13b engine from the earlier model of RX7. Which would explain the 3mm apex seals, distributor ignition and thermal reactor setup.
Though the Front cover number is N326. which according to Mazdatrix is the correct one for a S4 NA. So its possible that its a mish-mash Mazda came up with for the European market.
This looks like a massive PITA as these housings according to rotary Resurrection are not compatible with say the Rotors you got on the FCs in the states.
Last edited by theDevilX; 11-02-17 at 03:40 PM.
11-02-17, 03:43 PM
#11
rotorhole
i see, so the UK early series 4 is basically a bastardized GSL-SE engine with the series 4 fuel injection and FB distributor.
worst case, if you can't find a proper housing, you can have a machine shop mill the coolant seal channels into a USDM housing, juse be sure you get the proper one, as the spark plugs on the series 5 USDM and japanese series 4+5 housings are wider apart than the earlier housings.
worst case, if you can't find a proper housing, you can have a machine shop mill the coolant seal channels into a USDM housing, juse be sure you get the proper one, as the spark plugs on the series 5 USDM and japanese series 4+5 housings are wider apart than the earlier housings.