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#16
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Re: Noise Under Load and Vibration From Engine
Could the timing belt be off by a tooth cause the vibration? Idles smooth and runs smooth. Only vibrates at 1500 and 5500 RPM. Does not seem to have the power it should either.
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---------------------------------- 94 Laguna Blue LSI 126k (stock) 92 Silver LSL 106K (highly modified) |
#17
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Re: Noise Under Load and Vibration From Engine
Ok so I pulled the front end off the engine, changed the crank pulley and checked the timing belt to see if it had jumped a tooth. Cams were spot on. Cranked the engine vibration still there at around 1500 and 5500. Ugh!!!! I am going to push this thing off a cliff...
But wait I started reading and although I see no one describing the problem as a vibration I did note that the engine has always seemed to have less power that my other SVX which is an automatic. So let's put two and two together, a vibration at two points only through the RPM range and lack of power. The Iris valve apparently transitions or changes open/closed state at 2000ish and 4000ish RPM and if it is not functioning can cause lack of power. So I pulled the power steering resevoir again and got to the iris control vacuum check valve and did the (blow/suck) test (ok no jokes please this has been painful enough) and it is not functioning properly (does not check). So I went to Advanced auto and got an off the shelf $5 vacuum check valve and replaced it. Problem solved, No vibration and it runs like a bat out of the really hot place. So take it from me, check the check valve first....
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---------------------------------- 94 Laguna Blue LSI 126k (stock) 92 Silver LSL 106K (highly modified) |
#18
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Re: Noise Under Load and Vibration From Engine
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#19
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Re: Noise Under Load and Vibration From Engine
Thank you, yes that one made me pull my hair out a bit...
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---------------------------------- 94 Laguna Blue LSI 126k (stock) 92 Silver LSL 106K (highly modified) |
#20
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Re: Noise Under Load and Vibration From Engine
Nice find! I know it would make me pull my hair out trying to find it. I tested mine when I pulled everything apart but good to know what a failure will cause.
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#21
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Re: Noise Under Load and Vibration From Engine
Did this happen after replacing the clutch? If so you have the Flywheel/Pressure plate balancing marks out of alignment.
Last edited by Bonestock; 02-15-2010 at 04:20 PM. Reason: nevermind... see you found the problem |
#22
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Re: Noise Under Load and Vibration From Engine
The pressure plate would only go on one way with the pins on the flywheel that align to the pressure plate holes. Did I miss something?
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---------------------------------- 94 Laguna Blue LSI 126k (stock) 92 Silver LSL 106K (highly modified) |
#23
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Re: Noise Under Load and Vibration From Engine
On Subaru flywheels and pressure plates, you must absolutely align them properly. If not you will know (a bit late.. at start up) when the clutch pedal starts to vibrate.
http://www.competitionclutch.com/ima...structions.pdf |
#24
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Re: Noise Under Load and Vibration From Engine
So if understand the directions correctly the pressure plate has a "0" mark on it as does the flywheel. The pressure plate must be at least 120 degrees off of the "0" mark in order to be in balance or the engine would vibrate. Is this correct?
I think I was a bit over excited by the sudden increase in power now that the Iris valve is working correctly and did not notice the vibration was still there. I will pull the transmission replace the flywheel "just as a precaution as it had been resurfaced" and ensure the pressure plate is properly timed for proper engine balance as you suggested. Thank you for the information and detailed instructions.
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---------------------------------- 94 Laguna Blue LSI 126k (stock) 92 Silver LSL 106K (highly modified) |
#25
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Re: Noise Under Load and Vibration From Engine
I have transmission out and flywheel off. I have a new flywheel but do not see any marks on it. The ACT pressure plate has a mark that looks like an arrow stamped in it. Any ideas on the flywheel? Any way to tell if no marks on it?
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---------------------------------- 94 Laguna Blue LSI 126k (stock) 92 Silver LSL 106K (highly modified) |
#26
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Re: Noise Under Load and Vibration From Engine
Called the Flywheel company and they said the flywheel is zero balanced and therefore does not have any marks on it. You can put the pressure plate in any position and it should be fine.
On another note I was looking through flywheel diagrams and noticed the small plate that is put on with an AT flyweel does not go on with a MT flywheel. I had put that on with mine. Could this cause an imbalance?
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---------------------------------- 94 Laguna Blue LSI 126k (stock) 92 Silver LSL 106K (highly modified) |
#27
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Re: Noise Under Load and Vibration From Engine
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1992 SVX LS-L: For sale 1995 Lexus SC400- Lexta Z |
#28
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Re: Noise Under Load and Vibration From Engine
Iris valve vacuum check valve is located just behind the power steering pump under the intake. It is black and cylindrical shaped and connected to two vacuum lines. I would replace it with a new one from an auto parts store (advance auto Part No. 47149) . Universal fit works fine. Replace the vacuum lines while you are at it. Make sure your orient it properly so that the the intake can draw vacuum into the vacuum tank (intake side can suck vacuum through the valve) but will not let the vacuum escape from the tank (valve does not allow vacuum to escape the tank).
You may have to remove the power steering tank (replace the power steering tank o-ring while you are at it) to get to the iris valve. Once you have it back together reach under the intake (be careful watch your hands) to the iris valve acuator arm and rev the motor over 4000 rpm for a few seconds. You should feel it move activating the iris valve. If you don't you may still have a vacuum leak or have the check vavle on backwards.
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---------------------------------- 94 Laguna Blue LSI 126k (stock) 92 Silver LSL 106K (highly modified) |
#29
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Re: Noise Under Load and Vibration From Engine
Update on the noise under load. Pulled the 5MT and tore it down had three bad bearings in the transmission. No wonder it made noise under load. Changing all seals and gaskets while I have it down. Transmission repair not for the light hearted. lots of gears, and bearings, and syncronizers, Oh my...
Bought a new flywheel and took it with my pressure plate to a machine shop to have them balanced together just to be darn sure no vibration will occur. I'll report more once it is all back together.
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---------------------------------- 94 Laguna Blue LSI 126k (stock) 92 Silver LSL 106K (highly modified) |
#30
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Re: Noise Under Load and Vibration From Engine
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1994 SVX L - FWD Barcelona Red 190K miles ~ SOLD 1994 SVX LS - 5spd AWD Emerald Green 202k miles PWR Radiator, HID 5000k, New paint job with issues, 17" STI BBS wheels, converted to 5spd AWD from FWD. Purchased from SVXyGirl 2/20/09 -- Undergoing complete rebuild 1993 Justy 4wd 5door- Teal of sorts , beater. 2008 OBXT Newport Pearl 65k miles |
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