MotoRotor

I'm in a sticky situation here. I have an FD that has possible blown side seals. Compression numbers(accurate, with a Mazda tester) are:
8.7, 6.7, 8.6 on the front rotor
9.3, 9.2, 9.3 on the rear rotor.

Mechanic tells me it's a cracked side seal but wouldn't that make compression become worse when the engine is hot? Basically, the car drives and runs well, but idle at cold start is kinda shaky. Not horribly so, but noticeable. And when it has become hot, it usually goes away.

Anyways, is there any way it could just be stuck? I tried the steam cleaning trick but it sucked the water in so fast that I was scared to try again. Anyways, assumming worse case scenario, seal is cracked and def needs a rebuild, should I drive it until the seal breaks and then rebuild it or should I rebuild it now and possibly reuse the housing(which should be fine, I presume) and other parts.

And assumming you guys recommend a rebuild at this time, would I technically be able to do it myself? For instance, can I just take the engine out, strip it apart, and replace the cracked seal and put everything back together? Or do I need special tools(air powered gun, or other very pricey tools) and machining work that would require the engine being sent out. Would I be able to do everything myself with standard tools and a workshop manual+the vid that is being sold on this site? Thanks in advance for any comments. Sorry for the long post.

MotoRotor

Oh yea, one thing I forgot to mention is that the motor only has around 10k miles on it, which is why I think I could reuse almost everything except for the seals.

dgeesaman

iTrader: (7)

Buy the video - it will show you what tools are needed, and give you an idea of if it's a reasonable project. Even if you pay someone else to do the rebuild, you'll know enough about it to hold a conversation with the engine builder - a good investment either way.

Dave

t-von

iTrader: (8)

Need more info on the condition of the engine before the apparent damage. Is the car stock? How much boost are you running? What mods do you have? What was the driving conditions at the time? Your rebuilt engine could easily just have the one stuck side seal from being improperly clearanced (too tight). If that's the case the engine will need to be torn down again.


Yes. Measure everything to make sure everything is within spec because you can't trust whomever rebuilt the engine in the first place.

cheng41328

Sorry, wrong login. Sharing computer at work.

MotoRotor

Let's see, condition of the engine before rebuild...Engine had about 10k miles on it, was never driven hard. Car is all stock, and thus, is running stock boost. Ran and idled fine until one day when I took it out and redlined the car. Car came back, idled roughly, then when I tried to start it again it wouldn't start. I did the MMO trick and it worked but now the car kinda shakes when idling and this is where I am at now. Also, could the stuck seal be loosened any other way besides taking the engine out? I ask because the engine is fairly new, with compression numbers that are far higher than those I am seeing on this forum off cars that are still running.

Thanks for the responses so far, more help would be appreciated. Thanks.

BlueTII

You can try all the seafoam, atf, mmo, water tricks, they wont repair a cracked seal, but they are worth a shot to avoid a rebuild. It is also very difficult to get a side seal free once it is lodged inside the rotor. Apex seals are much easier to free up.
You might want to get another compression reading from someone besides Mazda, they have a tendency to always say the engine needs replacement. The rough idle could be something as simple as a vacuum leak or you blew the line off the MAP sensor. Do you have a vac/boost gauge in the car? The vac at idle tells alot about the health of the engine.

Sgtblue

iTrader: (16)

But would any of those account for the rough idle symptom disappearing after warm-up as he's reporting? And I'm asking, not challenging, as occasionally I have the same thing.

t-von

iTrader: (8)

Red lining the engine under boost doesn't make side seals stick, excessive carbon build-up or improper clearencing does. The engine was previously rebuilt and I suspect a possibly poor rebuild or some clogged injectors that are not flowing correctly. Reason I say injectors is because the rear rotor is what usually goes first when the engine blows any seals because of the extra heat in the rear and the straighter less turbulent flow into the engine from the LIM(less bends). This imbalance automatically causes the rear rotor to run leaner but yet your front rotor has the lower compression. If the front rotor has injectors that are not flowing properly, then the front rotor can run lean under boost at high rpm. Anyways the facts are that stock engines on stock boost just don't blow side seals if everything else is working right.

t-von

iTrader: (8)

Exactly I would even go as far as to remove the turbos and manifold and pour in any solution you choose to free the seal. That's what I did on my 20b to free the seals from carbon sticking. I recently found that acetone does a great job in breaking down carbon. I use it to clean my rotors seals grooves in my rebuilds.

MotoRotor

Thanks for all the great responses guys. More opinions would be welcome and appreciated. My biggest question is pretty much why the car is fine or at least much better when the car is warmed up. Also, I got the compression readings done at Rick's Rotary so I trust that it's accurate. About the compression, I would think 6.7 isn't all that bad compared to the ones I've seen on here. What do you guys think?

dgeesaman

iTrader: (7)

6.7 when the other rotor is 9.3 is not a good indication. I say you should try a few of the de-carbonizing tricks first, but expect the rebuild soon.

Dave

Sweet7

Suprised no one else caught that...