First off, I just wanted to say I'm glad I've come across this site.
It's a wealth of information!
Although I've been reading for awhile, this is my first real problem and my first post.

So I'm thinking my motor has a blown side-seal. Let me know what you think, whether I'm right or wrong I'm always willing to learn.

Here are the symtoms:
Rough idle, the whole car shakes at idle, but it holds idle fine and doesn't die out.
The car cranks and starts up with no problems though.
Car boosts fine, but feels weak.
Above ~3k rpm it smoothes out some.
~12-13 vacuum at idle, it doesn't bounce.
I did the "poor man's" compression test, ie pull plug & egi fuse, crack motor.
I get 3 "whooshes" on rear rotor and 2 "whooshes" on front rotor.

So, I'm guessing it's a side seal and not an apex seal (due to the 2, not 1, whooshes).
I'm going to be getting a compression tester just to get a better reading.

Anyways, what are your thoughts? Anything I can do short of a rebuild? Could it simply be a stuck side seal? How often does that happen?

Here's some more info on the car:
Mostly stock R1, rats nest removal, non-sequential mod, AST removal, HKS BOV, RB exhaust, HKS intake, manual boost controller, PFC.

~47k on reman.

Symtoms started out of the blue one day under normal driving. Came to a stop light and idle was rough.

Thanks for the help all!

 

I believe two wooshes means you lost an apex seal. Either way you are looking at a rebuild from what I have read. Speaking of which I was wondering when you lose an apex seal, does it take one or both of the turbos with it?

 

My understanding is that if you loose an apex seal you will loose compression on two faces as one apex seal seals two chambers.

Correct me if I'm wrong.

 

Oh right, you would only hear one woosh... well thats beyond me then. I dont know if a side seal would cause one woosh or not.

 

Anyone with anymore thoughts?

Thanks!

 

Im not exactally sure about your problem...But I am sure that you are a breath of fresh air for me. Thank you for making your first few posts worth while. Really, I appreciate it. Too many times lately there have been noobs on here askin what bov to get and what not.

From what your sayin it shoulds like its time for a rebuild. Thats no fun. But thats also a good excuse to get that thing ported, and put some more mods on it. Good luck with the project.

 

sounds like a side seal has gone mate - you will only get one woosh if you lose an apex as two chambers effectively turn into one, so you will only get one face producing compression = 1 woosh.

sorry to hear!

 

Guidlines for diagnosing engine internals based off compression readings. Obviously these are not set in stone.

3 even bounces of 85 PSI or above is GOOD. Readings above 110 PSI is GREAT!
3 even bounces of less than 85 PSI: indicates that motor is tired, and indicates engine should be rebuilt before causing damage to rotors or rotor housings.
2 high and 1 low: indicates problem with side seal (stuck, cracked, broken, etc.)
1 high and 2 low: indicates problem with apex seal (stuck, cracked, broken, etc.)
NO bounces: either incorrectly installed guage or destroyed rotor and housing.

You can try the numerous "unsticking" procedures using ATF, carb cleaner, water, etc etc . Chances are it needs a rebuild, but you should do a real compression test first, we have a "how-to" on our website if you are unfamiliar with the procedure using a stadard compression gauge.

 

In my opinion:

Take some time and read through all the similar posts. There are more things than you can imagine that can cause this behavior, a bad seal being only one of them. Engines with varying compression can run ok, and there is probably a fine line between a bad seal and a weak seal. You can be sure though, that these symptoms represent wear in the engine, and fixing the engine is very cost effective. If all your parts are re-useable, the cost of rebuild parts can be limited to say $750 + labor. If you run it to death, then you can be certain to throw a minimum of an extra $500 on up. You are basically talking a couple grand then.

A Mazda style compression test is best. It will tell you compression for each chamber in relation to the other chambers. It is the relative values (how much change from chamber to chamber) that indicate problems with seals that separate the chambers. It is absolute values the tell the general condition of the chamber seals and rotor housings. A regular piston compression tester can be used with good results. The problem is that it is hard to tell what the actual values are when the needle is constantly moving. I suggest using a video camera to record the movement. You then can review the video in slow-mo to get a better idea of the reading.

If your compression test reveals a very low chamber compression in relation to the others, then you can expect poor combustion from that chamber, hence a rough idle. Normal driving will smooth this out likely, unless the seals are all the way toast. Two chambers would be worse. If the seals are broken, chipped, cracked, etc. but still in place, some compression will occur and some functionality will remain. If they let go, you will be sorry at rebuild time, so correct diagnosis is important. The compression test is key.

I had the same symptoms you described, but the problem was a plugged fuel filter. I do have three fair chambers on the front rotor though....

 

Thanks
I try not to ask questions that's been asked many times before.
Even this question I'm asking I feel that there's alot of info already.
I feel kinda 'guilty' asking but just wanted to make sure my diagnosis is correct before taking further steps.

 

Thanks for the info, I just purchased a piston motor compression tester and will modify it and test my motor later this evening.
Hopefully it will produce some more useful data.

I'll probably also try some 'unsticking' procedures also, hopefully its simply a stuck seal. I've got some MMO in the garage I can use.

Anyone have any comments to using water also? I've read about it being used to clean out carbon and stuck seals.

 

Thanks for all the info.
I'm definately going to perform a compression test today to get a better picture of things.
I should check the fuel filter also, as well as the PD to make sure it's not leaking and running the front rotor lean.

 

You have not mentioned steam. Blown side seals usually produce steam & a coolant smell in the exhaust.

 

They're talking about the side seals on the rotor, not the o-rings on the housing...

 

oops.

 

very odd problem. apex seals break at the first hint of detonation, but i have only seen one stuck side seal in all my years of FD ownership and also shop ownership.

try running some distilled water through a vac hose into one of the nipples on the pass side of the UIM. rev the car to 3k and let the motor ingest 12 ounces or so. then go redline the car in first gear. worked for me the one time i saw this symptom on an FD .

 

I'm going to give that a shot tonight.
Hopefully it does the trick

 

Well, ran some water through the vacuum nipple, white smoke POURED out the exhaust. haha I hope my neighbors didn't call the fire department!

Anyways I didn't drive the car afterwards but revved it up a bit. Idle didn't seem to change much afterwards and the car still shakes like a paint shaker. It could just be my optemistic imagination but it "seems" to not shake as much though.

Is this normal? Along with white smoke I get water flying out my exhaust! It was almost like I had a sprinkler in my muffler.

So, conclusion SO FAR is not much changed.
I guess I'll try to soak in MMO or do more water treatment.
Couldn't hurt to try right? (Correct me if I'm wrong. I don't want to hurt the motor more and have to replace rotors/housings when I rebuild.)

 

Oh yeah, on the front rotor I still have 2 strong bounces and 1 weak bounce on the compression tester. I get 3 solid (~100) bounces on the rear rotor.

 

Sorry to hear it didn't help much. I guess you could try soaking it, but I don't think you are going to see much of an improvement if the water trick didn't work. Sounds like you are going to be looking at a rebuild. At least it doesn't sound like you didn't blow it up and damaged housings and/or rotors. Should be pretty cheap like was mentioned before. Hey, its always nice to have a fresh motor anyway! Good luck!

--Andrew

 

You only did half the job. After you run the water through, go out and hit 8000 rpms on boost in first gear. shouldnt hurt a thing, and can only help loosen a stuck seal.

 

There are alot of posts on this. More than not say it works and the difference is noticable. What people do not agree on is how it works!!! *belly laugh*

Be careful running a lot of water through the engine at once. The CAT will heat, unnoticed to the technician holding the water bottle. Heat means fire danger and fire means major heart break if not a garage fire. Yadda yadda yadda...you get the picture. Just don't run a two liter bottle of water through it without paying attention.

I tried it and it works. The difference is noticable in running and driving.

 

Yeah, I know I should, just didn't get a chance too last night. Neighbors were probably complaining about the smoke already and it was getting a bit late. I didn't want to give them some major noise polution also! I'll try more water today and redline it during the day today when most of my neighbors are at work still.

 

Thanks for the warning
But, no cat = no probs

 

What you do not want to do is take it to 8K RPM in first gear with full boost if there is something cracked in your engine or you are running lean for some reason. This will/can cause severe damage to rotors and housings if something lets loose. Be careful overreving it and boosting to high until you have figured out the problem.