2nd Generation Specific 1986-1992 Discussion

Jspec With No Compression Mmo?

Old 02-10-2005, 10:14 AM
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So i finally got my jspec in and came to find out there is no compression in the rear housing. I have heard of the MMO trick but never tried it. Could all my problem be carbon lock? I hope so. So someone correct me if im wrong, Just squirt it in the housing on all three seals and let it set for 24-48 hours. Or do i need to spin the engine while its in there? Any help would be great. Thanks guys.
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Old 02-10-2005, 10:42 AM
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I am in the middle of building a J-spec for a buddy right now. When we took it apart it was very apparent that it would never make any good compression.



All seals were locked in place by a dry carbon/rust mix. After lots of cleaning I just clearenced the rotors and everything looks good.



I guess the point I am trying to make is that although you may get the apex seals to come loose you will never get the side seals to be in good working order without taking the engine apart. Plus the s4/s5 corner seal springs are worthless compared to the s6 corner seal springs.



If you saw the ammount of carbon that comes out of the apex and side seal grooves you would realize that your never going to get it out without taking the engine apart.



I have had ok luck with using carb cleaner and atf for lubrication. Take off exhast mani and open up the plug holes. Squirt in liberal ammounts of atf. Then go at it with the carb cleaner. You can get in the exhast ports with a tooth brush to thelp things along. It usually takes about 3 cans of carb cleaner and about a bottle of ATF. Not all at one time mind you. Lots of scrubbing and spinning and spraying, lubing.



Still, chances are your going to have a side seal stick no matter how well you spray carb cleaner in the engine. There is just no way to get the carbon that is behind the seals out without taking the engine apart.



J-specs are the ****, specailly when you take them apart and throw a gasket and 0 ring kit at them. Chances are they will spec out good enough to be used with the stock turbo. But unless you take the engine apart your just asking for trouble.



GregW
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Old 02-10-2005, 10:51 AM
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Just wanted to add that with the rotors out of various engines I have tried



Kerosene

MMO

ATF

Carb Cleaner

Break Cleaner

3m TB cleaner

Gas

Disel

Mineral Spirits

Engine Degreaser

Various water based soaps



Im my opinion Kerosene works the best if you have time to leave it sit for a couple of days. However, I just confirmed that it WILL make the oil control O Rings distort bigtime and permanantly.



3m TB cleaner is hands down the best, A small brass brush and some of that **** and your good to go. Its also spendy as hell.



3m Carb cleaner is my favorite. It makes very quick work of carbon and with a little elbo grease the carbon gets soft. However, due to the nature of the carb cleaner it drys very quickly.



Anyways....there, hope that helps.





GregW
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Old 02-10-2005, 10:54 AM
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MMO or ATF is definitely worth a try. Both are high detergent oils that can free up stuck compression seals.



If it works, then wash some regular motor oil through to protect the oil control rings.
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Old 02-10-2005, 11:08 AM
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Originally Posted by sureshot' date='Feb 10 2005, 08:53 AM
MMO or ATF is definitely worth a try. Both are high detergent oils that can free up stuck compression seals.



If it works, then wash some regular motor oil through to protect the oil control rings.





MMO and ATF really dont do **** to the carbon. Like I did, grab a rotor fresh out of an engine and put some atf on one side and some MMO on the other. Let it sit over night. It really does not do a thing compared to carb cleaner.



The atf/mmo helps keep the carbon soft and in solution after you use carb cleaner.
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Old 02-10-2005, 12:15 PM
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Ok. thanks for the fast replys guys. It sounds to me that if i end up using this engine i am gonna have to rebuild it. Thats a real bummer.Ill try the mmo just to make sure, but i wont hope for anything remarkable. Since its a jspec do you think i can get away with just using a basic rebuild kit from Aviation. Its like $400 cheaper. The front had plenty of compression, but if i have it apart ill probably change atleast the apex seals. I guess i would also have to do a street port on it too.
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Old 02-10-2005, 03:05 PM
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Originally Posted by GMON' date='Feb 10 2005, 09:08 AM
MMO and ATF really dont do **** to the carbon. Like I did, grab a rotor fresh out of an engine and put some atf on one side and some MMO on the other. Let it sit over night. It really does not do a thing compared to carb cleaner.



The atf/mmo helps keep the carbon soft and in solution after you use carb cleaner.



You're absolutely right about carb cleaner.

It’s a way better solvent.

I have not tested it on the oil control rings.

Just in case we have any chemists out there, we know we are not dissolving carbon, just the combustion gum & varnish residue that trap it.



FWIW: To “dissolve” pure carbon you need molten steel.
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